Inka Astronomy

• Milton Rojas Gamarra (Physics Department, Faculty of Science, UNSAAC)

The Inkas had their own "Science", in all areas of knowledge. In this contribution, we will present their ancestral knowledge which refers to Astronomy, mainly we will present its constellations. This study is based on the triangulation of the chronicles, oral tradition and the complexes and archaeological elements that we can still locate.

Cosmology of the Incas

• Steven Gullberg (University of Oklahoma)

The Incas worshipped the Sun, with light and shadow effects in their constructs commonly denoting such events as the solstices and equinoxes. They as well honored and venerated many features of both natural and man-made landscapes that they felt to be endowed with superhuman powers. In Quechua, these shrines were known as huacas, and at the time of the Spanish conquest there were thousands of them. Soon after subduing the Inca empire, the Spaniards began a campaign against the indigenous religion that included a systematic eradication of huacas. Shrines that were large carved stones and outcroppings survived, however, and were subjects of this research for astronomical orientations marking significant solar events. The Incas built multiple towers on the horizons of Cusco to mark the positions of the rising or setting Sun on specific dates of the year. They used these solar pillars to mark time passage for purposes of crop management and religious festivals. All were destroyed. Beyond Cusco, however, two solar pillars overlooking the modern village of Urubamba escaped the Spanish purge. This research has verified, when viewed from a large granite boulder in the center of the Huayna Capac’s palace, Qwespiwanka, that they mark the position of the rising Sun at June solstice. Additionally, from the same boulder and in the direction of the December solstice sunrise, are located enigmatic stone structures on the summit of Cerro Unoraqui. Below Machu Picchu, near the Urubamba River, lies a large and complex shrine initially identified by Hiram Bingham as the Urubamba Intihuatana. The massive granite stone lies between the Sacred Plaza of Machu Picchu and the Sun Temple of Llactapata along the axis of the June solstice sunrise and December solstice sunset. With the scientific discovery of Llactapata in 2003 came the realization that a great ceremonial complex once existed between Machu Picchu, the River Intihuatana, and Llactapata. These and other examples of Inca astronomy are explored in this paper. The approach is a holistic one in that it considers multiples levels of meaning including cultural motifs, topographic and astronomical contexts, sightlines, as well as light and shadow effects throughout the year, especially at times of the solstice, equinox, zenith and anti-zenith suns. Astronomy was thoroughly interwoven throughout many facets of Inca society.

Thermodynamics of noncommutative black holes

• Eri Mena (Universidad de Guadalajara)

We study the noncommutative formalism for black holes and their thermodynamics properties in the classical and quantum scenarios.

Some remarks on black holes with fluid of strings: solutions, thermodynamics and Hawking radiation

• Geusa Marques (Universidade Federal de Campina Grande)

In the early 1980´s, Letelier introduced a gauge invariant model of a fluid of strings with the aim to treat gravity coupled to these array of strings, in the framework of general relativity. Thus, using the fluid formed by strings as a source of the gravitational field, he obtained a solution of the Einstein equations corresponding to a spherically symmetric space-time. In the case of spherical symmetry, he obtained a generalization of the Schwarzschild solution to the one corresponding to a black hole surrounded by a spherically symmetric fluid of strings. These results were based on a similar formalism introduced by him, to treat a cloud of strings, which means that the pressure is not taken into account. In this scenario, he obtained a class of solutions of the Einstein equations corresponding to plane-symmetric, spherically and cylindrically symmetric space-times. The main motivation to construct those models was based on the fact that the universe can be represented, in principle, by a collection of extended objects, like one-dimensional strings, rather than of point particles, in a more appropriate way. Recent theoretical developments suggest that it is necessary to consider extended objects because they offered a potential alternative to be used as the fundamental elements to describe physical phenomena which occur in the universe. From the gravitational point of view, it is important to investigate, for example, a black hole immersed in a fluid of strings, due to the fact that these sources have astrophysical observable consequences. In this talk, we obtain the solution corresponding to a static and spherically symmetric charged de Sitter-anti de Sitter black hole immersed in a fluid of strings. We discuss some aspects of the thermodynamics. We also present a discussion about Hawking radiation of particles, in the background under consideration.

Particle motion analysis in a regular black hole solution

• Katharine Ivette Cuba Quispe (Universidad Nacional de Trujillo, Universidad Privada del Norte)

The main goal of this work is to analyze the motion of diferent types of particles in a regular black hole solution obtained by Bronnikov in 2001. The trajectories are obtained through numerical integration of the equations of the orbits (using the program Maple), after the analysis of the effective potential of each case. The results are compared to those of the Reissner-Nordstrom black hole. It is also important to mention that we look to expand this work to study the energy conditions at the center of the regular solution. Due to Raychaudhuri's theorem, the regularity of the solution has to do with the violation of the strong energy condition.

Non-linear perturbation of black branes at large D

• Umpei Miyamoto (Akita Prefectural University)

The Einstein equations describing the black-brane dynamics both in Minkowski and AdS background were recently recast in the form of coupled diffusion equations in the large-$D$(imension) limit. Using such results in the literature, we formulate a higher-order perturbation theory of black branes in time domain and present the general form of solutions for arbitrary initial conditions. For illustrative purposes, the solutions up to the first or second order are explicitly written down for several kind of initial conditions, such as a Gaussian wave packet, shock wave, and rather general superposed sinusoidal waves. These could be the first examples describing the non-trivial evolution of black-brane horizons in time domain. In particular, we learn some interesting aspects of black-brane dynamics such as the Gregory-Laflamme (GL) instability and non-equilibrium steady state (NESS). The formalism presented here would be applicable to the analysis of various black branes and their holographically dual field theories.

Evolution of stellar binaries from supermassive black hole binaries

• Ye-Fei Yuan (University of Science and Technology of China)

The evolution of main-sequence binaries resided in the galactic centre is influenced a lot by the central supermassive black hole (SMBH). Due to this perturbation, the stars in a dense environment are likely to experience mergers or collisions through secular or non-secular interactions. In this work, we study the dynamics of the stellar binaries at galactic centre, perturbed by another distant SMBH. Geometrically, such a four-body system is supposed to be decomposed into the inner triple (SMBH–star–star) and the outer triple (SMBH stellar binary–SMBH). We survey the parameter space and determine the criteria analytically for the stellar mergers and the tidal disruption events (TDEs). For a relative distant and equal masses SMBH binary, the stars have more opportunities to merge as a result from the Lidov–Kozai (LK) oscillations in the inner triple. With a sample of tight stellar binaries, our numerical experiments reveal that a significant fraction of the binaries, ∼70 per cent, experience merger eventually. Whereas the majority of the stellar TDEs are likely to occur at a close periapses to the SMBH, induced by the outer Kozai effect. The tidal disruptions are found numerically as many as ∼10 per cent for a close SMBH binary that is enhanced significantly than the one without the external SMBH. These effects require the outer perturber to have an inclined orbit ($\geq 40^\circ$) relatively to the inner orbital plane and may lead to a burst of the extremely astronomical events associated with the detection of the SMBH binary.

Study of white dwarfs, neutron stars and black holes through astrometric microlensing

• Kailash Sahu (Space Telescope Science Institute)

Astrometric microlensing provides a powerful tool to study white dwarfs, neutron stars and black holes, particularly the isolated ones. We have two such projects to study stellar remnants through astrometric microlensing, the details of which will be discussed: (i) In a reprise of the famous 1919 solar eclipse experiment that confirmed Einstein's general theory of relativity, the nearby white dwarf Stein 2051B passed very close to a background star in March 2014. As Stein 2051 B passed by, the background star's position was deflected. Measurement of this deflection with HST - the first such measurement of deflection by a star outside the solar system - allowed us to determine the mass of Stein 2051 B as $0.675 \pm 0.051$ solar mass. (ii) All stars with initial masses of larger than 20 solar mass are expected to end their lives as black holes (BHs). Theoretical studies suggest that there should be about 100 million stellar-mass BHs in the Galaxy, and a large fraction of these BHs are expected to be single. Yet, no isolated BH has ever been unambiguously found within our Galaxy. The only technique available to detect such isolated BHs is astrometric microlensing. Initial results from our HST programs specifically aimed at the first detection of solitary BHs through astrometric microlensing will be presented.

Oscillations of black hole accretion disks and neutron star atmospheres

• Wlodek Kluzniak (Copernicus Astronomical Center)

Quasi-periodic oscillations (QPOs) in the kHz range have been reported in the X-ray flux of several accreting black hole and neutron star systems. While several models have been suggested, such variability has been difficult to reproduce in numerical simulations. I will report on Radiative General Relativistic Hydrodynamic Simulations of accretion disks in which several high-frequency oscillations of the accretion disk have been found, and their nature identified. Similar periodicities have also been reported during thermonuclear X-ray bursts in neutron stars. A calculation of damped oscillations of neutron star atmospheres in the super-Eddington regime will be presented, which allows a direct and simultaneous determination of the mass and radius of the neutron star from the value of the maximum oscillation frequency alone. Refs.: Mishra et al. 2017, 2018; Bollimpali et al. 2018.

Black holes binaries from globular clusters as sources of gravitational waves

• Dorota Rosinska (University of Zielona Gora)

The direct detection of gravitational waves from binary black hole mergers by the advanced Laser Interferometer Gravitational-Wave Observatories has ushered astrophysics into a new era of observing cosmic events that were previously invisible. Using results for around two thousand star cluster models simulated using well-tested the MOCCA Monte Carlo code for star cluster evolution we determine the astrophysical properties and local merger rate densities for coalescing binary black holes (BBHs) originating from globular clusters. We extracted information for all coalescing BBHs that escape clusters and subsequently merge within Hubble time along with BBHs that are retained in our GC models and merge inside the cluster via gravitational wave (GW) emission or collide. By obtaining results from a substantial number of realistic star cluster models that cover different initial parameters (masses,metalicities, densities etc), we have an extremely large statistical sample of BBHs that merge within Hubble time. In my talk I will discuss the importance of BBH mergers originating from GC for gravitational wave observations.

Probing astrophysical black holes via gravitational lensing

• Q. Daniel Wang (University of Massachusetts)

Black holes (BHs) represent the most extreme objects in the universe and play an important role in astrophysics. We have been exploring various ideas of using gravitational lensing to probe the population and astrophysics of BHs. Supermassive BHs of million solar masses or greater are usually detected as active galactic nuclei (AGN). We show that the innermost X-ray-emitting structure of AGN can be greatly amplified and hence effectively probed by microlensing of nearby foreground stars. For stellar mass BHs in our Galaxy, we may estimate their overall population via their astrometric microlensing effect on background sources. This capability is within the reach of available near-IR/radio interferometry facilities. Particularly interesting is the possibility to detect a concentration of stellar mass BHs (including ones of ~30 solar masses, similar to those discovered recently via gravitational waves) around the very center of our Galaxy. Furthermore, we can effectively study the formation and evolution of both stellar mass and supermassive BHs at high redshifts via strong gravitational lensing by foreground massive galaxies or galaxy clusters.

Nucleus 3-flavored

• Renxin Xu (Peking University)

Normal nuclei inside atoms are 2-flavored. What if normal baryonic matter is compressed intensely by gravity so that a huge number of nuclei would gradually merge to form a gigantic nucleus? It is proposed that gigantic nuclei could be 3-flavored, to be manifested in the form of compact stars, cosmic rays, and even dark matter.

Relativistic corrections to large scale structures

• Clement Stahl (PUCV)

We investigate the relativistic corrections to the standard model of formation of large scale structures. In matter domination and in the Poisson gauge, we use the weak-field approximation which allows to keep compact expressions even for the one-loop bispectrum. Whereas in the Newtonian limit, the choice of gauge is marginally important as all gauge coincides, when relativistic corrections are taken into account, it matters as a change of gauge may induce a change of gravitational potential and introduce fictitious modes in the finial result for the power spectrum. It is precisely what happens in the example presented in this talk as the equivalence principle is not fulfilled in the Poisson gauge and the cancellation of the IR divergence at one-loop does not occur. We will discuss how other choices of gauge may solve this issue.

Magnetic field effect on the effective potential of a heavy charged scalar field

• Angel Sanchez Cecilio (Facultad de Ciencias, Universidad Nacional Autónoma de México)

In the context of a warm inflation scenario in this work we study the effects of a primordial magnetic field on the effective potential of a heavy charged scalar field in a magnetized thermal bath. It is known that models, based on global supersymmetry with a new-inflation-type potential and a coupling between the inflaton and a heavy intermediate superfield, preserve the flatness required for slow-roll conditions even after including thermal contributions. Preliminary results indicate that the magnetic field makes the potential even flatter, retarding the transition and rendering it smoother.

Infinite nuclear matter characteristics of finite nuclei within relativistic mean field formalism

• Mrutunjaya Bhuyan (Instituto Tecnologico de Aeronautica)

The present study establishes a correlation between the neutron skin thickness and the infinite nuclear matter characteristics for the even−even isotopes of Fe, Ni, Zn, Ge, Se, and Kr. The axially deformed self-consistent relativistic mean field for the non-linear NL3$^*$ is used for the analysis. The coherent density functional method is adopted to formulate the symmetry energy, the neutron pressure and the curvature of finite nuclei as a function of the nuclear radius. The mass dependence on the symmetry energy in terms of the neutron-proton asymmetry for mass 70 ≤ A ≤ 96 are studied. From this analysis, we found a notable signature of a shell closure at N = 50 in the isotopic chains of Fe, Ni, Zn, Ge, Se and Kr nuclei. The present study reveals an interrelationship between the characteristics of infinite nuclear matter and the neutron skin thickness of finite nuclei

Strongly interacting matter under intense magnetic fields

• Norberto Scoccola (Comisión Nacional de Energía Atómica)

Different aspects of the behavior of quark and hadronic matter under intense magnetic fields are analyzed within the framework of Nambu-Jona-Lasinio models.

Equations of boson-fermion star and the basic equation discussions under Newtonian approximation

• Zhifu Gao (Xinjiang Astronomical Observatory, Chinese Academy of Sciences, 150, Science 1-Street, Urumqi, Xinjiang 830011, China)

There is accumulating evidence that scalar fields may exist in nature. The gravitational collapse of a boson cloud would lead to the formation of a boson star just like white dwarfs and neutron star. In generally, as one of candidates of dark matter, a boson star holds a stable configuration and has deserved intensive attention and extensive researches in the past 50 years. At first, we examined the properties of a complex-scalar–field boson star, and analyze the ground state solutions, then analyzed the configuration of a star composed of bosons and fermions, and gave coupling equations. At last, we considered the hydrostatic equilibrium equation of the boson-fermion star, and gave the virial equation with different orders and investigated how scale fields impact the virial equation.

Testing black-hole near-horizon effects and pseudo-complex general relativity with gravitational waves

• Alex Nielsen (Max Planck Institute for Gravitational Physics (AEI))

The detection of gravitation waves by LIGO has allowed a great number of new tests of strong gravity and near-horizon models for black holes. One such model, pseudo-complex general relativity, agrees with Einstein gravity in the weak-field limit, but diverges dramatically in the near-horizon regime, with certain parameter ranges excluding the existence of black holes altogether. We show how simple limits can be placed on this model in both the inspiral and ringdown phase of coalescing compact objects. We discuss how these bounds relate to current observational limits and future prospects with gravitational wave observations and the Event Horizon Telescope.

Numerical analysis of the Biermann battery mechanism of magnetogenesis for relativistic MHD turbulence

• David Garrison (University of Houston Clear Lake)

We present the results of Relativistic Magnetohydrodynamic simulations utilizing a range of initial conditions in order to see if seed magnetic fields may be generated via the Biermann battery mechanism of magnetogenesis. These simulations occur in a simulated early universe around the time of the electroweak era ${10}^{-11}$ seconds after the Big Bang. Our results are characterized by the characteristic turbulent velocity of the magneto fluid and whether or not the relativistic version of the Biermann battery was utilized.

Equation of state at finite chemical potential, based on the PNJL Lagrangian

• Joerg Aichelin (Subatech/CNRS)

The NJL and PNJL approach had problems to describe the lattice equation of state for zero chemical potential. This made this Lagrangian, despite of its great merits, less attractive to study what happens for a finite baryon chemcial potential. A finite baryon chemical potential is expected for the experiments at FAIR/Germany and NICA, Russia but also during the merger of two neutron stars which has been observed recently by gravitational waves. Using a systematic expansion of the Lagrangian in next to leading order in $N_c$ and modifying slightly the interaction between the quarks and the Polyakov loop potential we obtained now result which are in the error bars of the present lattice calculations for zero chemical potential. For the PNJL Lagrangian the extension to finite chemical potential is straight forward. We present these results and discuss what kind of phase transition is expected at low temperature and finite chemical potential and hope to give also preliminary results for the termodynamical properties of merging neutron stars.

Electromagnetic probes of QGP

• Elena Bratkovskaya (FIAS)

Dileptons are considered as one of the cleanest signals of the quark-gluon plasma (QGP), however, the QGP radiation is masked by many 'background' sources from either hadronic decays or semileptonic decays from correlated charm pairs. We investigated the relative contribution of these channels in heavy-ion collisions from $\sqrt{s_{\rm NN}}=$ 8 GeV to 5 TeV with a focus on the competition between the thermal QGP radiation and the semileptonic decays from correlated $D-$meson pairs. As a 'tool' we employ the parton-hadron-string dynamics (PHSD) transport approach to study dilepton spectra in Pb+Pb (Au+Au) collisions in a wide energy range incorporating for the first time a fully microscopic treatment of the charm dynamics and their semileptonic decays. We find that the dileptons from correlated $D-$meson decays dominate the 'thermal' radiation from the QGP in central Pb+Pb collisionsat the intermediate masses (1.2 GeV $< M <$ 3 GeV) for $\sqrt{s_{NN}} > $ 40 GeV, while for $\sqrt{s_{\rm NN}}=$ 8 to 20 GeV the contribution from $D,{\bar D}$ decays to the intermediate mass dilepton spectra is subleading such that one should observe a rather clear signal from the QGP radiation. We, furthermore, study the $p_T$-spectra and the $R_{AA}(p_T)$ of single electrons at different energies as well as the excitation function of the inverse slope of the $m_T$- spectra for intermediate-mass dileptons from the QGP and from charm decays. We find moderate but characteristic changes in the inverse slope parameter for $\sqrt{s_{NN}} > $ 20 GeV which can be observed experimentally in high statistics data.

The Athena X-ray observatory

• Giorgio Matt (Dipartimento di Matematica e Fisica, Universita' Roma Tre)

Athena (the Advanced Telescope for High-Energy Astrophysics) will continue the series of large X-ray observatories inaugurated by Chandra and XMM-Newton, offering transformational capabilities in several key areas. It is the second large-class ESA mission (L2), and it is planned for a launch towards the end of the next decade. In this talk, the main science objectives of Athena, and its main technical characteristics, will be presented and discussed.

The imaging X-ray Polarimetry Explorer

• Giorgio Matt (Dipartimento di Matematica e Fisica, Universita' Roma Tre)

IXPE, the Imaging X-ray Polarimetry Explorer, has been selected by NASA on January 2017 as the next mission in the Small Explorer Program, for a launch in early 2021. IXPE, a collaboration between NASA and ASI (the Italian Space Agency), is led by M. Weisskopf (MSFC) and is composed by three identical telescopes with, at the focal plane, a Gax Pixel Detector based on the photoelectric effect. In this talk the main characteristics of the mission and its scientific objectives will be described.

Observation of ultra-high-energy cosmic rays with the Telescope Array experiment

• Kazumasa Kawata

The Telescope Array (TA) is the largest ultra-high-energy cosmic-ray (UHECR) detector in the northern hemisphere, which consists of 507 surface detector covering a total 700 km^2 and three fluorescence detector stations. In this presentation, we will discuss our recent results on the UHECR energy spectrum, mass composition and anisotropy based on the latest dataset collected by the Telescope Array experiment. Finally, we will introduce current status of the TAx4 project which will cover 4 times larger detection area than that of the TA.

The X-Ray Astronomy Recovery Mission

• Brian Williams (NASA GSFC)

The X-Ray Astronomy Recovery Mission (XARM), an international collaboration led by JAXA and involving major participation from NASA and ESA, will employ an advanced X-ray observatory with capabilities to carry out a science program to address some of the important questions of present-day astrophysics. XARM is essentially a rebuild of the the Hitomi (Astro-H) spacecraft that was lost due to an operational mishap early in the mission in 2016, but only employs two of the original four instruments on Hitomi. The Resolve Soft X-ray Spectrometer is being developed jointly by a team led by NASA/GSFC and institutions in Japan under the direction of JAXA’s Institute of Space and Astronautical Science. It is a high-resolution, non-dispersive X-ray spectrometer operating between 0.3-12 keV. It is the core instrument on XARM, providing a high-resolution spectroscopic capability (~ 5 eV) for the mission and covering the energy band where all of the astrophysically abundant elements have characteristic emission lines that can be used for a wide range of spectral studies of matter under extreme conditions. The other instrument, called Xtend and provided by JAXA, extends the field of view to produce an observatory with extraordinary capabilities using a state of the art X-ray charged couple device camera. Xtend is the responsibility of JAXA, but NASA will provide an X-ray Mirror Assembly for the instrument identical in design to the Resolve mirror assembly. XARM will be launched into low-Earth orbit (nominally 575 km circular, 31° inclination) from the Tanegashima Space Center, Japan, using a JAXA H-IIA rocket. This talk will summarize the status of the mission, and will outline the science objectives to be addressed, namely: 1) structure formation of the Universe and evolution of clusters of galaxies; 2) the life cycle of baryonic matter in the universe; 3) evolution and feedback from black holes; and 4) new science achieved through unprecedented high resolution X-ray spectroscopy.

Exploring the structure of neutron stars in low-mass X-ray binaries

• Dany Page (Universidad Nacional Autonoma de Mexico)

Transient low-mass X-ray binaries containing a neutron star which sporadically accrete matter from a low-mass companion provide a unique opportunity to study the internal structure of neutron stars. During accretion phase the neutron star is heated and driven out of thermal equilibrium. During the following quiescent phase, when no accretion is occurring, the thermal relaxation of the neutron star can, and has, been observed. Modelling of these sequences of accretion/heating and cooling has allowed to find evidence for extremely fast neutrino emission in the neutron star core by the Direct Urca process, and to put constraint on the specific heat of the core. Several properties of the neutron star crust are also naturally being constrained, as its thermal conductivity and specific heat, and possibly the presence of neutron superfluid.

Relativistic X-ray jets at high redshift

• Dan Schwartz (Smithsonian Astrophysical Observatory)

Powerful radio sources and quasars emit relativistic jets of plasma and magnetic fields that travel hundreds of kilo-parsecs, ultimately depositing energy into the external medium. In the rest frame of the jet, the energy density of the cosmic microwave background is enhanced by the bulk Lorentz factor as $\Gamma^2$, and when this exceeds the magnetic energy density the primary loss mechanism of the relativistic electrons is via inverse Compton scattering. At large redshift, the microwave energy density is further enhanced by a factor (1+z)$^4$. We are surveying a z > 3 sub-sample of radio sources selected with flux density > 70 mJy, and with a spectroscopic redshift. We find cases of the X-rays extending beyond the detectable radio jet, and a case we interpret as an X-ray lobe where the radio emitting electrons have faded below detectable limits.

Fermi/GBM’s key role at the dawn of the era of multimessenger astronomy

• Andreas von Kienlin (MPE)

The detection of the gravitational wave event GW170817 by LIGO and Virgo was accompanied by the independent detection of the short Gamma-ray Burst GRB 170817A by the Gamma-ray Burst Monitor (GBM) of NASA’s Fermi mission. This discovery was complemented by the detection of a weak coincident signal in the data of the Anti-Coincidence Shield ACS of Spectrometer SPI onboard ESA’s INTEGRAL mission. Here we focus on the results by Fermi-GBM, discussing the characteristics of this ordinary short GRB, which extraordinarily confirms that at least some short GRBs are produced by binary compact mergers. We show that the observed time delay between the gravitational and electromagnetic event of about 1.7 s could impose constraints on fundamental physics. Finally, we want to discuss Fermi/GBM’s prospects for the upcoming O3 observation run of LIGO/Virgo.

The 4 meter New Robotic Telescope

• Carlos Gutierrez (Instituto de Astrofisica de Canarias)

The time domain astronomy will radically change in the coming decade, with the advent of facilities like LSST, SKA, CTA, etc that will find huge numbers of transients across the electromagnetic spectrum, and with the detections via non-electromagnetic signals, such as gravitational waves. Within this context, we plan to build the New Robotic Telescope (NRT), a 4 m optical and near infrared telescope that will be installed at the ORM observatory in La Palma (Spain), and will operate in an entirey autonomous and robotic way. The project is promoted by the Liverpool John Moores University (UK) and the Instituto de Astrofisica de Canarias (Spain). The telescope is being designed for extremely rapid response, so it will be able to start collecting take data within 30 seconds after receiving a trigger from another facility. When NRT enters into operation in 2023 will make it a world-leading facility for the study of fast fading transients and explosive phenomena discovered at early times. In addition, it will allow great efficiency for large-scale programmes of low-to-intermediate resolution spectral classification of transients. Here, we present the status and scheduling of the project, and the main science drivers.

Probing the universe at the highest energies with the Pierre Auger Observatory

• Jakub Vicha (Institute of Physics of the Czech Academy of Sciences)

The Pierre Auger Observatory is the currently largest cosmic-ray detector covering ultra-high energies from 10$^{18}$ eV to 10$^{20}$ eV. The size of exposure accumulated since 2004 granted measurements of unprecedented precisions on energy spectrum, mass composition and anisotropy searches. These measurements guide us slowly to the sources of ultra-high energy cosmic rays, which is a tantalizing mystery of physics. A brief introduction of the Pierre Auger Observatory will be given. Then, an overview of the most interesting results of the Observatory will follow with aim to the recent findings on anisotropy searches and multi-messenger surveys.

High-precision cosmology from the Sloan Digital Sky Survey

• Alexander Mayer (N/A)

Analysis of galaxy redshift data and theta-z data from the Sloan Digital Sky Survey (SDSS) provides surprising new insights in cosmology, which overturn prior results.

Characterization of orbits for the MacMillan problem with test particle of variable mass

• Edgar Andrés Acosta Pinzón (Universidad Industrial de Santander)

In the present study, we conduct a numerical analysis of the MacMillan problem in which the mass of the test particle varies in time according to the Jeans’ law. The MacMillan problem is a particular case of the circular three body problem, where the third body moves along an axis passing through the center of mass of the system, and is perpendicular to the plane of the primaries. Since the formulation of the MacMillan equations of motion, several variations of this problem have been addressed in the literature, all of them with something in common: cons- tant mass. In this master thesis, the focus is laid on the characterization of orbits for the MacMillan problem, assuming that the mass of the third body is variable in time according to the Jeans’ law.

Classical features of polynomial higher-derivative gravities

• Breno Giacchini (Centro Brasileiro de Pesquisas Físicas)

Local gravitational theories with more than four derivatives have remarkable quantum properties. Namely, they are super-renormalizable and may be unitary in the Lee-Wick sense, if the massive poles of the propagator are complex. It is important, therefore, to explore also the IR limit of these theories and identify possible observable signatures of the higher derivatives. In this talk we present recent results in this direction. Specifically, we discuss the effect that those higher-order terms can have on the Newtonian potential and related singularities. The result is that any polynomial model with at least six derivatives in both spin-2 and spin-0 sectors has regular curvature invariants in the weak-field limit. Under this same condition the collapse of spherical null shells is also regular. We also discuss the viability of a gravitational seesaw-like mechanism, which could be a mean of avoiding the Planck suppression of the higher derivatives' effects.

Merger of two compact stars: predictions from the two-families scenario

• Giuseppe Pagliara

The detection of GW170817 and its electromagnetic counterparts has marked the beginning of multi-messenger astrophysics which could allow, in the near future, to finally establish which is the internal composition of neutron stars. I will discuss what we have learned from this first binary neutron star GW's detection on the equation of state in particular concerning the possibility of having "strange matter" in the form of hyperonic matter and/or strange quark matter. Finally, I will present a scenario in which two families of compact stars co-exist: hadronic stars and quark stars and I will discuss what are the expectations, within this scenario, for the next future GW's detections and their counterparts (short-GRBs and kilonovae). The talk is based on the following papers: Astrophys.J. 852 (2018) no.2, L32; Astrophys.J. 846 (2017) no.2, 163; Eur.Phys.J. A52 (2016) no.2, 41; Eur.Phys.J. A52 (2016) no.2, 40.

The primordial B-modes search in the CMB polarization with LSPE/SWIPE

• Fabio Columbro (Sapienza, University of Rome)

Measurements of the cosmic microwave background (CMB) polarization represent the best technique to study physical phenomena happening a split-second within the big bang and to test the standard cosmological model. In this scenario, the Large-Scale Polarization Explorer (LSPE) aims at the measurement of polarization at the largest angular scales, where cosmic inflation left its imprint in the form of a curly pattern (B-modes) of linear polarization. The LSPE is a coordinated ground-based and balloon-borne experiment. The balloon-borne instrument of LSPE, named SWIPE (Short Wavelength Instrument on the Polarization Explorer), is in an advanced phase of development, aiming at a long-duration polar-night flight for a two-weeks-long observation, in the Arctic region. This allows SWIPE to reach a sensitivity in terms of tensor to scalar ratio $r=0.01$, roughly 10 times better than current upper limits. SWIPE will observe $25\%$ of sky in 3 frequency bands (90 GHz, 220 GHz and 240 GHz) by means of an array of 330 multi-mode TES bolometers, cooled at 0.3 K, collecting a total of 8800 modes of the CMB. The detectors are fed by a 500 mm aperture cryogenic Stokes polarimeter/telescope, with a continuously rotating polarization modulator as the first optical element. The half-wave plate (HWP) is cooled at 4 K to reduce the radiative loading on the detectors, and spins at 120 rpm, thanks to a superconducting magnetic bearing with a very low friction electromagnetic motor. In this contribution we describe the SWIPE instrument, its development, and present a forecast performance study. See http://planck.roma1.infn.it/lspe for further information.

Reconstruction of large-scale CMB temperature anisotropies with primordial CMB induced in galaxy cluster

• Guo Chin Liu (Tamkang University)

Scattering of cosmic microwave background radiation in galaxy clusters induces polarization signals determined by the quadrupole anisotropy in the photon distribution at the location of clusters. This remote quadrupole derived from the measurements of the induced polarization in galaxy clusters provides the information of local CMB temperature anisotropies. Here we present an algorithm of the reconstruction of large-scale CMB temperature map and conclude that the reconstruction can be good enough to be a consistency test on the puzzles of CMB anomaly, especially for the low quadrupole and axis of evil problems reported in WMAP and Planck data.

Time-domain astrophysics of galactic nuclei in radio to submillimeter

• Q. Daniel Wang (University of Massachusetts)

I will review ideas as to how a joint monitoring program at radio to submillimeter wavelengths may be used to study the relativistic jet formation and circumnuclear environment of supermassive black holes. At least some tidal disruption events (TDE) of (sub-)stellar objects around black holes form relativistic jets. Such a jet can first be detected in (sub)millimeter and only gradually become optically thin and observable at longer wavelengths. The jet evolution depends strongly on the density structure of the circumnuclear gas, including the accretion flow, while its associated magnetic field can be traced by the Faraday's rotation of polarization as a function of time. I will use the nearest known TDE, IGR J12580+0134, in NGC 4845 (d = 17 Mpc) as an example to illustrate both the existing feasibility and the potential power of such a (sub)millimeter to radio follow-up program.

Cosmological mass transport on galactic nuclei and the growth of high z quasars

• Andres Escala Astorquiza (Universidad de Chile)

By using AMR cosmological hydrodynamic N-body zoom-in simulations, with the RAMSES code, we studied the mass transport processes onto galactic nuclei from high redshift up to $z\sim 6$. Due to the large dynamical range of the simulations we were able to study the mass accretion process on scales from $\sim 50$ kpc to $\sim$ pc. The SMBHs are modelled as a sink particles at the center of our galaxies, which allowed us to quantify the BH growth in relation with the mass transport processes associated to different angular momentum fluxes. Such a quantification allowed us to identify the main mass transport process as a function of the scales of the problem. We found that in simulations that include radiative cooling and SNe feedback, the SMBH grows at the Eddington limit most of the time, transporting mass at a rate of $\sim$ 1-10 $M_\odot$/yr. Only if efficient AGN feedback is included in tandem with SNe feedback, the mass transport decreases at a rate below $\sim 1$ $M_\odot$/yr. This level of SMBHs accretion rates found in our cosmological simulation, are needed in all models of SMBH growth attempted to explain the formation of redshift 6-7 quasars.

Magnetic field effect on the decay process of a neutral scalar boson

• Gabriella Piccinelli Bocchi (Universidad Nacional Autónoma de México)

The effect of a homogeneous weak magnetic field on the decay process of a neutral scalar field to a pair of charged fermions is studied. The decay rate is calculated through the imaginary part of the self-energy of the scalar particle interacting with the charged fermions, at one loop. We find that the effect depends on the kinematical regime of the progenitor particle: for low transverse momenta, the decay is inhibited, while for high ones, the process is favored. We briefly discuss the possible physical reasons for this situation. The phenomenon can be relevant in early universe events or in high energy collisions.

Observational constraints on the NS equation of state

• Zhaosheng Li (Department of Physics, Xiangtan University, China)

The measurement of neutron star mass and radius is one of the most direct ways to distinguish between various dense matter equations of state. The mass and radius of accreting neutron stars hosted in low-mass X-ray binaries can be constrained by several methods, including photospheric radius expansion from type I X-ray bursts, gravitational redshift measurement and from quiescent spectra. In this talk, I will report the neutron star mass and radius constraints in Aql X-1 and GRS 1747-312.

Unification of strongly magnetized neutron stars with regard to X-ray emission from hot spots

• Tomokage Yoneyama (Osaka University)

Strongly magnetized isolated neutron stars (NSs) are categorised into two families, according mainly to their magnetic field strength. The one with a higher magnetic field of $10^{14}$ - $10^{15}$ Gauss is called “magnetar”, and the other is the X-ray isolated neutron star (XINS) with $10^{13}$ Gauss. Both magnetars and XINSs show thermal emission in X-rays, whose spectra are different. The spectrum of a magnetar is reproduced with a two-temperature blackbody (2BB), whereas that of an XINS show only a single-temperature blackbody (1BB) with the temperature being even lower. On the basis of the magnetic field and temperature, it is often speculated that XINSs may be old and cooled magnetars. However, no strong observational evidence has yet been reported to support the speculation. Here we report that all the seven known XINSs show high-temperature emission, which should have a similar origin to that of magnetars. Analysing all the XMM-Newton data of the XINSs with the highest statistics ever achieved, we find that their X-ray spectra are all reproduced with a 2BB model, similar to magnetars, as opposed to the traditional 1BB model. Their emission radii and temperature ratios are also similar to those of magnetars except for two XINSs, which show significantly smaller radii than the others. The remarkable similarity in the X-ray spectra between XINSs and magnetars suggests that their origins of the emission are also the same. The lower temperature in XINSs can be explained if XINSs are older than magnetars. Therefore, this results is the first observational indication that supports the standard hypothesis of classification of highly-magnetised NSs. With our results, new questions have also emerged. For example, the temperature is separated clearly between magnetars and XINSs, which may suggest potential existence of a “missing link” between them.

The high time resolution universe survey for pulsars

• Marilyn Cruces (Max-Planck Institute for Radioastronomy)

Abstract: Pulsars are neutron stars, detected mainly through the pulses of electromagnetic radiation emitted from their poles, which is modulated by their stable rotation. Since their discovery in 1967 they have become fundamental tools for understanding subject such as stellar evolution, theories of gravity, the electron content of our Galaxy and understanding the behavior of matter at extreme conditions. Further discoveries will allow us to advance in these areas. Although more than 2500 pulsars have been found so far, most of them are normal isolated pulsars. Of the more rare objects, only fewer than 20 are double neutron stars systems and just one is a double pulsar system. Moreover, no neutron star-black hole system has been detected to date. With the aim of finding the most intriguing pulsars and potentially a pulsar-black-hole binary, in early 2008 the High Time Resolution Universe (HTRU) collaboration began, an all sky blind survey for pulsars and radio-transients. In the southern hemisphere the survey was conducted with the 64-m Parkes radio telescope, while in the northern hemisphere the observations were carried out with the 100-m radio telescope Effelsberg. The data have a high time- and frequency-resolution that allows an unprecedented volume of the Galaxy to be searched. This has led to the discovery of hundreds of new pulsars, among them tens of pulsars with millisecond spin periods, gamma-ray pulsar, the first radio-loud magnetar, two pulsar-planet systems and the most relativistic pulsar to date. Additionally, among its findings, the HTRU establish the existence of a cosmological population of Fast Radio Bursts (millisecond duration radio bursts whose origins remain unknown).

Investigations of the Ohmic decay and the soft X-ray emission of high-braking index pulsar PSR J1640$-$4631

• Zhifu Gao (Xinjiang Astronomical Observatory, Chinese Academy of Sciences, 150, Science 1-Street, Urumqi, Xinjiang 830011, China)

In this work, we investigate the Ohmic decay of surface dipole magnetic field of high-braking index pulsar PSR J1640$-$4631, and interpret the observed soft X-ray flux $F_{x}^{\infty}[2-10\rm keV]$ from $Chandra +NuStar$ telescopes. We obtain the ohmic decay timescale $\tau_{\rm ohm}\sim 3.23\times10^{6}$ yr. Observations indicate that magnetic multipole fields could exist in a neutron star and the toroidal component of multipole fields at and near the pulsar cap is thought to be responsible for the star's unique pulse profile. A possible application of ohmic decay timescale to thermoplastic wave (TPW) heating due to toroidal fields dispassion is studied for interpreting the observed soft x-ray emission of PSR J1640$-$4631, and other heating mechanisms for the star's surface thermal emission are also investigated.

Anti-correlation between X-ray luminosity and pulsed fraction in the Small Magellanic Cloud pulsar SXP 1323

• Jun Yang (University of Utah)

We report the evidence for the anti-correlation between pulsed fraction (PF) and luminosity of the X-ray pulsar SXP 1323, found for the first time in a luminosity range $10^{35}$--$10^{37}$ erg s$^{-1}$ from observations spanning 15 years. The phenomenon of a decrease in X-ray PF when the source flux increases has been observed in our pipeline analysis of other X-ray pulsars in the Small Magellanic Cloud (SMC). It is expected that the luminosity under a certain value decreases as the PF decreases due to the propeller effect. Above the propeller region, an anti-correlation between the PF and flux might occur either as a result of an increase in the un-pulsed component of the total emission or a decrease of the pulsed component. Additional modes of accretion may also be possible, such as spherical accretion and a change in emission geometry. At higher mass accretion rates, the accretion disk could also extend closer to the neutron star (NS) surface, where a reduced inner radius leads to hotter inner disk emission. These modes of plasma accretion may affect the change in the beam configuration to fan-beam dominant emission.

Pions near condensation under compact star conditions

• Cristian Villavicencio (Universidad del Bio-Bio)

The behavior of pions is studied in systems where their normal leptonic decay is forbidden. When thermal fluctuations are present, a low decay rate is generated, and as a consequence of lepton recombination, the amount of pions remains almost unaltered. Compact stars conditions are favorable for the formation of such intermediate state of charged pions: near condensation and almost stable, leading to a continuum source of anti-neutrinos. In particular, protoneutron stars could be an scenario where this state of matter is relevant.

Electron-positron pair creation in pulsars

• Andrey Timokhin (NASA/GSFC)

Pulsars are among the most extreme objects in the universe, where physical processes work in regimes of extreme densities as well as gravitational and electromagnetic field strengths. It is widely agreed upon that pulsar activity is intimately connected to the copious generation of electron-positron pairs in the magnetosphere - a rapidly rotating magnetized neutron star is active as pulsar only as long as it can create pairs. Here I briefly overview recent progress in theoretical studies of pulsar magnetospheres and report on the most recent results of self-consistent numerical simulations of pair creation in pulsars. I discuss the implication of these results for our understanding of the physics of pulsars and Pulsar Wind Nebulae.

Cooling of small and massive hyperonic stars

• Rodrigo Negreiros (Universidade Federal Fluminense)

We perform cooling simulations for isolated neutron stars using recently developed equations of state for their core. The equations of state are obtained from new parametrizations of the FSU2 relativistic mean-field functional that reproduce the properties of nuclear matter and finite nuclei, while fulfilling the restrictions on high-density matter deduced from heavy-ion collisions, measurements of massive 2$M_{\odot}$ neutron stars, and neutron star radii below 13 km. We find that two of the models studied show very good agreement with cooling observations, even without including extensive nucleon pairing. This suggests that the cooling observations are compatible with an equation of state that produces a soft nuclear symmetry energy and, hence, generates small neutron star radii.

Was GW170817 indeed a merger of two neutron stars?

• David Blaschke (University of Wroclaw)

The merger of two compact stars is the celebrated event in Astrophysics which provides highest baryon densities and temperatures simultaneously as well as compact objects at the limit of stability, most likely in a transition stage to a black hole which, triggered by a gravitational wave signal, is then observable in all wavelengths of the electromagnetic spectrum, in some cases also in neutrinos. The first example of such an event is GW170817 [1] which marks the begin of the era of multi-messenger Astronomy and is traditionally referred to as “neutron star (NS) merger”. With a total mass of 2.73 M$_\odot$ its progenitor was most likely a binary system like the Hulse-Taylor system of the “double pulsar” system J0737-3039 with stars of the typical binary radio pulsar mass of 1.35 M$_\odot$ involved. We discuss the characteristic features of an equation of state (EoS) of compact star matter with a strong phase transition that would allow for the occurrence of mass twin compact stars in that mass range as a consequence of a “third family” branch of hybrid stars (HSs) in the mass range from ~1.3 to ~2.0 M$_\odot$ [2-5]. This offers the possibility of a scenario of HS-NS or HS-HS merger for GW170817 which should therefore be taken into consideration when implications of GW170817 for nuclear and particle physics are discussed. If the NICER experiment on board of the ISS would measure a large radius of ~14 km for the nearest millisecond pulsar PSR J0437-4715, this would give strong support to the idea that a HS was involved in GW170817 [2]. [1] B.P. Abbott et al. [LIGO Scientific and Virgo Collaborations], Phys. Rev. Lett. 119, 161101 (2017). [2] D. Blaschke and N. Chamel, “Phases of dense matter in compact stars”, [arxiv:1803.01836] (2018). [3] A. Ayriyan et al., Phys. Rev. C 97, 045802 (2018). [4] V. Paschalidis et al., Phys. Rev. D 97, 084038 (2018). [5] D. E. Alvarez-Castillo et al., “Third family of compact stars within a nonlocal chiral quark model equation of state”, [arxiv:1805.04105] (2018).

Properties of hypothetical quark-hadron lattices in the cores of neutron stars

• Fridolin Weber (Department of Physics, San Diego State University and Center for Astrophysics and Space Sciences, University of California, San Diego)

In this talk, we investigate the effect a crystalline quark-hadron mixed phase can have on the neutrino emissivity from the cores of neutron stars. To this end we use relativistic mean-field equations of state to model hadronic matter and a nonlocal extension of the three-flavor Nambu-Jona-Lasinio model for quark matter. The extent of the quark-hadron mixed phase and its crystalline structure is determined using the Glendenning construction, which allows for the formation of spherical blob, rod, and slab rare phase geometries. The neutrino emissivity due to electron-lattice interactions are calculated utilizing the formalism developed for the analogous process in neutron star crusts. It is found that the contribution to the neutrino emissivity due to the presence of a crystalline quark-hadron mixed phase is substantial compared to other mechanisms at fairly low temperatures ($< 10^9$ K) and quark fractions ($< 30\%$), and that contributions due to lattice vibrations are insignificant compared to static-lattice contributions.

The evolving story of pulsar wind nebulae

• Patrick Slane

The expanding winds generated by pulsars produce nebulae whose properties track both the composition and energetics of the winds and the properties of the environments into which they expand. From early expansion through cold supernova ejecta, through re-formation after disruption from interactions with the supernova remnant reverse shock, the evolution of a pulsar wind nebula is complex. However, recent modeling coupled with important observations from nearly all parts of the electromagnetic spectrum has placed important constraints on a significant number of individual systems and their host remnants, and on the population as a whole. Here I summarize results from such observations and modeling efforts with particular concentration on recent hydrodynamical studies of PWNe evolving within their host supernova remnants.

Can loop quantum cosmology describe an unified and consistent scenario since bounce until the end of inflation?

• Eunice Valtânia de Jesus Bezerra (Instituto Nacional de Pesquisas Espaciais (INPE))

The inflationary model was introduced by Guth in the 80's as a way of solving the so-called three cosmological problems: flatness of the space-time, the problem of the horizon, and the question of the magnetic monopoles. Since it was proposed, inflation has become much more than a cosmological model. The inflationary period may perhaps give us some clues about the transition from a continuum space-time (as is the universe at the end of the inflationary period) to a space-time still quantized at the beginning of the inflationary period. In this work, we try to establish a possible transition scenario between loop quantum gravity and inflation (as described by a Higgs model). The main characteristics of this possible connection will be discussed in the present work.

Correlations functions of primordial perturbations from symmetries

• Josué Motoa-Manzano (Universidad del Valle)

In this work we use the correspondence between a field theory in de Sitter space in 4-dimensions and the dual conformal field theory in an euclidean space in 3-dimensions to constraint the form of correlation functions of primordial perturbations. To this end, we use an inflationary model, in which the inflaton field is interacting with a vector field trough the term $f1(\phi)F_{μ\nu} F^{μ\nu} +f2(\phi)\tilde{F}_{μ\nu} F^{μ\nu}$. The first step of this method consists in solving the equations of motion for the fields in de Sitter 4D space-time, then evaluate these solutions in super-Hubble scales and compute the conformal weight of the projection of these fields in the 3D space. In a second stage, we propose a general form for the correlators, which involves scalar, vector and tensor perturbations and, using the result of the first step, find its momentum dependence by imposing that those are invariant under dilatations and special conformal transformation (SCT).

Magnetars: Pi in the sky?

• Nayasinganahalli Hari Dass (TIFR Hyderabad)

Abstract: Magnetars are incredible astrophysical objects with the largest ever observed magnetic fiels that are more than a thousand times larger than Pulsar magnetic fields.They are also associated with some of the most powerful flares ever seen. The origin of such strong magnetic fields is a fascinating problem in physics. I shall describe in this talk work done with V. Soni, with earlier participation by Dipankar Bhattacharya, wherein we have proposed neutral pion condensation in high baryon density phase transitions as the source for such strong magnetic fields. I will also review related work by Nielsen and Soni. This model naturally explains many highly puzzling features of magnetars. A full understanding of magnetars will require ideas and concepts from particle physics, condensed matter physics and plasma physics.

Lethal radiation from nearby supernovae helps to explain the small cosmological constant

• Tomonori Totani (Univ. of Tokyo)

The observed value $\Lambda_{obs}$ of the cosmological constant $\Lambda$ is extremely smaller than theoretical expectations, and the anthropic argument has been proposed as a solution to this problem because galaxies do not form when $\Lambda \gg \Lambda_{obs}$. However, the contemporary galaxy formation theory predicts that stars form even with a high value of $\Lambda / \Lambda_{obs} \sim 50$, which makes the anthropic argument less persuasive. Here we calculate the probability distribution of $\Lambda$ using a model of cosmological galaxy formation, considering extinction of observers caused by radiation from nearby supernovae. The life survival probability decreases in a large $\Lambda$ universe because of higher stellar density. Using a reasonable rate of lethal supernovae, we find that the mean expectation value of $\Lambda$ can be close to $\Lambda_{obs},$ and hence this effect may be essential to understand the small but nonzero value of $\Lambda$. It is predicted that we are located on the edge of habitable regions about stellar density in the Galaxy, which may be tested by future exoplanet studies.

Progenitor mass distribution of core-collapse supernova remnants in our galaxy and Magellanic Clouds

• Satoru Katsuda (Saitama University)

We investigate a progenitor mass distribution of core-collapse supernova remnants (CCSNRs) in our Galaxy and the Large and Small Magellanic Clouds, for the first time. We use the zero-age main-sequence mass, $M_{\rm ZAMS}$, estimated from elemental abundances and count the number of the CCSNRs in three mass ranges: A: $M_{\rm ZAMS} < 15\ {\rm M}_\odot$, B: $15\ {\rm M}_\odot < M_{\rm ZAMS} < 22.5\ {\rm M}_\odot$, C: $22.5\ {\rm M}_\odot < M_{\rm ZAMS}$. Simple compilation of progenitor masses in the literature yields a progenitor mass distribution of $f_{\rm A}: f_{\rm B}: f_{\rm C} =0.24:0.28:0.48$, where $f$ is the number fraction of the progenitors. The distribution is inconsistent with any standard initial mass functions. We notice, however, that previous mass estimates are subject to large systematic uncertainties because most of the relative abundances (X/Si) are not really good probe for the progenitor masses. Instead, we propose to rely only on the Fe/Si ratio which is sensitive to the CO core mass ($M_{\rm COcore}$) and $M_{\rm ZAMS}$. Comparing Fe/Si ratios in SNRs in the literature with the newest theoretical model, we estimate 33 $M_{\rm COcore}$ and $M_{\rm ZAMS}$, leading to a revised progenitor mass distribution of $f_{\rm A}: f_{\rm B}: f_{\rm C} = 0.47: 0.32 : 0.21$. This is consistent with the standard Salpeter initial mass function, implying that the most massive progenitors in $6\ {\rm M}_\odot < M_{\rm COcore}$ or $22.5\ {\rm M}_\odot < M_{\rm ZAMS}$, which have often been considered to collapse to black holes without explosions, can actually explode. However, the relation between $M_{\rm COcore}$ and $M_{\rm ZAMS}$ could be affected by binary evolution which is not taken into account in this study. The effect of stellar multiplicity should be considered in the future work to derive a better progenitor mass distribution estimate.

Magnetorotational instability in supernova explosion

• Sergey Moiseenko (Space Research Institute)

We represent results of numerical simulation of magnetorotational (MR) instability which develops in MR core-collapsed supernova explosion. The MR instability leads to the exponential growth of all components of the magnetic field. It significantly reduce the time for the development of MR exlosion. The MR instability is of Tayler type with rotation. The maximal values of magnetic field found in our simulations is 10(16) Gauss.

Mergers and GRBs: past, present and future

• Tsvi Piran (The Hebrew University)

The observed GRB (170817A) that followed GW170817 confirmed the longstanding prediction of association of short GRBs with neutron star mergers. The unique large scale observational campaign that followed provided numerous surprising observations. I discuss past predictions concerning binary mergers. I then turn to current observations of GW 170817 and its EM counterpart and their interpretation that lead to deciphering of the exact geometry of this event and their implications. I also discuss future prospects of joint detection of GRBs and GW signals. Among the latter, most exciting is the possibility that the gravitational waves observations will teach us about the nature of the inner engine and the acceleration process of relativistic jets.

Neutrinos from SN1987A: temperature models for two neutrinos’ bursts

• Rodolfo Valentim (Unifesp - Diadema)

The neutrinos’ burst from SN1987A were detected on different experiments around the World on February in 1987 until today it is theme of discussions and re-analysis. All events were approximately twenty five in the following detectors: Kamiokande II (KII) in Japan ~ 12, Irvine-Michigan-Brookhaven (IMB) in USA~8 and Baksan in Soviet Union ~ 5. The neutrinos play a key role on cooling mechanism into Neutron Star (NS) remnant, ~ 99% energy of collapse was lost with neutrinos emission in the first few seconds and it is possible “to see” the inner structure of NS in the initial instants after newborn NS. This work proposes to analyze two temperature models that presuppose two neutrinos’ bursts with temporal interval ~ 5s between them. The main motivation is: the dataset shows two distinct groups of neutrinos where the second group would come from Strange Quark Matter scenario. We used Bayesian Information Criterion (BIC) to select the best model with two temperatures.

Searching for baryon number violation with neutrino experiments

• Jennifer Raaf (Fermi National Accelerator Laboratory)

The observation of a violation of baryon number conservation would have tremendous impact and implications for the fields of particle and astrophysics and cosmology. Observation of baryon number violating processes such as proton decay or neutron-antineutron oscillation would point to grand unification of the EM, strong, and weak forces at very high energies. This talk will present the motivation to search for baryon number violation and give the landscape of neutrino experiments capable of performing these searches.

Everything you were eager to know about information relativity theory (but were afraid to ask)

• Ramzi Suleiman (Triangle Center for Research & Decvelopment)

Information Relativity Theory is a simple, axiom-free, epistemic relativizing of Newtonian physics. It attempts to answer the following question: What information will a proper measurement device in laboratory A, register about an occurrence in another laboratory B, which is in a state of motion relative to A. We assume that information about the respective occurrence (e.g., the start, and end times of an experiment conducted in B) is conveyed to A using an information carrier, which travels with constant and known velocity, $V_c$, in the medium which connects A and B. We put no restrictions on the nature of the information carrier (wave or matter), nor on its velocity $V_c$, except for the practical condition: $V_c > v$, where $v$ is the mean velocity of B relative to A during the occurrence. However, to avoid futile conflicts with Einstein's ontological relativity, we unwillingly restrict our theorizing to situations, in which $V_c$ is strictly lower than $c$, where $c$ is the velocity of light in vacuum. For the situation described above we derive transformations for predicting the time interval, length, mass, and energy densities, measured in A, as functions of the corresponding physical variables as measured in B, and the normalized velocity $\beta\, (= v/V_c)$. We show that the same set of derived equations is successful for predicting and explaining a multitude of physical phenomena in the fields of small particle physics, quantum mechanics, astrophysics, and cosmology, and in proposing natural and testable answers to key standing questions, including the nature of dark matter and dark energy. We shall also point to the aesthetic beauty of the new theory, and the connectedness it unveils between physics, the rest of sciences, and the arts.

Celestial tidal effect on clock comparison

• Yujie Tan (Huazhong University of Science & Technology)

With the rapid development of the clock technology, the unprecedented accuracy and stability provides a potential to measure the solar gravitational redshift with the clock-comparison experiments in the laboratory. The clock-comparison model is discussed in both the Barycentric Celestial Reference System (BCRS) and the Geocentric Celestial Reference System (GCRS), in which the transformations of the coordinates and the metric related to the gravitational potential between the two systems are also analyzed. In the GCRS, one must note that the influence of external matters (such as the solar and moon) on clock comparison should be treated as the tiny tidal potential, which has been suppressed due to the equivalence principle.

Experimental design and progress for testing Lorentz symmetry in gravity

• Chenggang Shao (Huazhong University of Science & Technology)

Local Lorentz invariance (LLI) is an important component of General Relativity (GR). The test of LLI can not only probe the foundation stone of GR, but also help to explore the physics beyond GR and Standard Model. In the previous work, we have limited the LLI coefficients with the gravitational experiments (gravitational inverse square law) performed in our lab. As the Lorentz-violation signal between two parallel plates is dominated by the edge effects, we made a special experimental design to enhance the violation signal, hoping to test LLI at a more accuracy level. At present, the experiment is ongoing.

Gravity waves speed in the non-Abelian Galileon vector theory

• Yeinzon Rodriguez Garcia (UAN & UIS (Colombia))

Galileon theories are built with the purpose of having the most general scalar-tensor theory free of the Ostrogradski instability. Quite recently, the vector Galileon theories have been formulated, in particular its non-Abelian version (invariance under a global SU(2) symmetry). The theory, together with a cosmic triad configuration, is able to reproduce the present dark energy epoch, following a nice self-tuning mechanism. However, the theory inevitably contains non-minimal couplings to gravity that can alter the gravity waves speed. This may rule out the theory in view of the recent constraints coming from the detection of a gravity wave and its electromagnetic counterpart from the merger of two neutron stars, as it has happened with most of the Galileon scalar and single-vector field theories. The purpose of this talk is to describe the gravity waves speed calculation in the non-Abelian Galileon vector theory, in a Friedman-Lemaitre-Robertson-Walker background, in order to determine whether the theory is ruled out or not.

The galaxy center with scalar field dark matter (ultra-light boson) haloes

• Tonatiuh Matos (Cinvestav IPN, México)

Recent analysis of the rotation curves of a large sample of galaxies with very diverse stellar properties reveal a relation between the radial acceleration purely due to the baryonic matter and the one inferred directly from the observed rotation curves. Assuming the dark matter (DM) exists, this acceleration relation is tantamount to an acceleration relation between DM and baryons. This leads us to a universal maximum acceleration for all halos. Using the latter in DM profiles that predict inner cores implies that the central surface density $\mu_{DM} = \rho_s r_s$ must be a universal constant, as suggested by previous studies in selected galaxies, revealing a strong correlation between the density $\rho_s$ and scale $r_s$ parameters in each profile. We then explore the consequences of the constancy of $\mu_{DM}$ in the context of the ultra-light scalar field dark matter model (SFDM). We find that for this model $\mu_{DM} = 648 M_\odot/\text{pc}^2$, and that the so-called WaveDM soliton profile should be an universal feature of the DM halos. Comparing with data from the Milky Way and Andromeda satellites, we find that they are consistent with a boson mass of the scalar field particle of the order of $10^{−21}$ eV/$c^2$, which puts the SFDM model in agreement with recent cosmological constraints.

Inflation, dark energy and dark matter in supergravity

• Sergei Ketov (Tokyo Metropolitan University and Kavli IPMU)

We review some recent developments in describing cosmological inflation, dark energy, dark matter and primordial black holes in supergravity. Their relations to string cosmology on the one side, and to reheating after inflation, on the other side, are also outlined. Open problems of the theory are emphasised too. Literature: our papers in arXiv:1708.05393, 1703.08993, 1701.08240, 1701.02450, 1607.05293, 1607.05366, 1606.02817, 1510.03524, 1509.00953, 1408.6524, 1406.0252, 1309.7494.

The Euclid survey: a new window on the last 10 billion years of cosmic history

• Xavier Dupac (ESA)

Observational cosmology has made incredible progress in the last couple of decades, thanks to, notably, very precise observations of the Cosmic Microwave Background fluctuations, supernovae, galaxy clusters and large galaxy surveys. We now have good evidence that we live in an ever-expanding, accelerating Universe, spatially very close to flat, and the main cosmological parameters have been determined with accuracy, even though some residual controversies may remain on H0 and others. However, the “elephant in the room” of this picture-perfect knowledge of our Universe is the massive presence of Dark Matter and Dark Energy (or vacuum energy), together accounting for ~95% of the energy content of the Universe. In order to better understand these mysterious components, the European Space Agency is implementing the Euclid mission, a 1.2 m space telescope with two focal instruments: the Visual Imaging Channel (VIS) and the Near-Infrared Spectrometer and Photometer (NISP). Each field of view is a 0.8 x 0.7 deg. tile with four dithers, with each dither in turn split into VIS imaging, NISP imaging and NISP spectrometry observations. VIS observes in a large unique visible band (0.55 – 0.9 µm) with a 24.5 mag (10 σ ext.) sensitivity thanks to 36 4kx4k CCD arrays, and reaches a pixel size of about 0.1”. NISP photometry consists of three wide near-infrared bands (Y: 0.9 – 1.1 µm, J: 1.1 – 1.4 µm, H: 1.4 – 2 µm) with a sensitivity of 24 mag (5 σ point source) and 0.3” pixel size. The NISP slit-less spectrometer works in the 1.1 – 1.85 µm range with a spectral resolution > 380 assuming a 0.5” aperture. Euclid will be launched in 2021 by Soyuz from Kourou, French Guiana, to the Sun-Earth L2 point. In this presentation, I will explain how the Euclid survey will help bettering our knowledge of DM and DE, through a very large survey of galaxies, most of them at z < 3, and also through three deep fields that are targeting higher-redshift galaxies. I will also give some details on the way the Euclid team is building the survey and plans to operate it during the six years of Euclid lifetime.

Generalized equations in the (S,0)+(0,S) representations of the Lorentz group

• Valeriy Dvoeglazov (Universidad de Zacatecas)

I present several explicit examples of generalizations in relativistic quantum mechanics which may be used in astrophysics and cosmology. First of all, I discuss the generalized spin-1/2 equations for neutrinos. They have been obtained by means of the Gersten-Sakurai method for derivations of arbitrary-spin relativistic equations. Possible physical consequences are discussed. Particularly, we look for relations between the corresponding solutions and dark 4-spinorsin the Ahluwalia-Grumiller elko model. They are also not the eigenstates of the helicity. They may also be applied to the known helicity flip of neutrinos in stars. Next, it is easy to check that both Dirac algebraic equation $\det (\hat p - m) =0$ and $\det (\hat p + m) =0$ for $u-$ and $v-$ 4-spinors have solutions with $p_0= \pm E_p =\pm \sqrt{{\bf p}^2 +m^2}$. The same is true for higher-spin equations. Meanwhile, every book considers the equality $p_0=E_p$ for both $u-$ and $v-$ spinors of the $(1/2,0)\oplus (0,1/2))$ representation only, thus applying the Dirac-Feynman-Stueckelberg procedure for elimination of the negative-energy solutions. The recent Ziino works (and, independently, the articles of several others) show that the Fock space can be doubled. We reconsider this possibility on the quantum field level for both $S=1/2$ and higher spin particles. The third example is: we postulate the non-commutativity of 4-momenta, and we derive the mass splitting in the Dirac equation. The applications are discussed.

Zerilli equation within a modified theory of General Relativity

• Peter Hess (Instituto de Ciencias Nucleares, Universidad Nacional Autónoma de México)

For a modified theory of General Relativity, the pseudo-complex version, the stability of the Schwarzschild solution is investigated. The extended Zerilli equation is derived and the scattering of graviational waves investigated, which are the solutions of the Zerilli equation. Consequences for the ring-down frequency, after the fusion of two black holes, are studied.

Effects of delta-matter in neutron stars structure

• Riccardo Belvedere (CBPF - Centro Brasileiro de Pesquisas Físicas, Brazil)

We investigate the effects due to the introduction of delta resonances in the neutron star matter. We compare and contrast the mass-radius diagram obtained for four different nuclear equations of state in the relativistic mean field theory. More precisely we vary the coupling constants for the delta-mesons interactions in the limits defined by the constraints on the relativistic mean field of delta-isobar in nuclear matter. Our aim is to suggest a new equation of state that could better fit the observational data of neutron stars, as well as to use the last observational constraints to narrow the range allowed for the delta-meson's coupling constants values.

Born-Infeld magnetars: larger than classical toroidal magnetic fields and implications for gravitational-wave astronomy

• Jonas P. Pereira (Federal University of ABC & University of Southampton)

Magnetars are neutron stars presenting bursts and outbursts of X- and soft-gamma rays that can be understood with the presence of very large magnetic fields. In this setting, nonlinear electrodynamics should be taken into account for a more accurate description of such compact systems. We study that in the context of ideal magnetohydrodynamics and make a realization of our analysis to the case of the well known Born-Infeld (BI) electromagnetism in order to come up with some of its astrophysical consequences. We focus here on toroidal magnetic fields as motivated by already known magnetars with low dipolar magnetic fields and their expected relevance in highly magnetized stars. We show that BI electrodynamics leads to larger toroidal magnetic fields when compared to Maxwell's electrodynamics. Hence, one should expect higher production of gravitational waves (GWs) and even more energetic giant flares from nonlinear stars. Given current constraints on BI's scale field, giant flare energetics and magnetic fields in magnetars, we also find that the maximum magnitude of magnetar ellipticities should be $10^{-6}-10^{-5}$. Besides, BI electrodynamics may lead to a maximum increase of order $10\%-20\%$ of the GW energy radiated from a magnetar when compared to Maxwell's, while much larger percentages may arise for other physically motivated scenarios. Thus, nonlinear theories of the electromagnetism might also be probed in the near future with the improvement of GW detectors.

Gravitational waves from protoneutron stars and nuclear EOS

• Hajime Sotani (National Astronomical Observatory of Japan)

We focus on spacetime oscillations, the so-called w-modes, of gravitational waves emitted from a protoneutron star in the postbounce phase of core-collapse supernovae. By adopting numerical results from recent relativistic three-dimensional supernova models, we find that the w1-mode frequency multiplied by the radius of the protoneutron star is expressed as a linear function with respect to the stellar compactness insensitively to the nuclear equation of state. Combining with another universal relation of the f-mode oscillations, which are a kind of acoustic oscillations, it is shown that the time dependent mass-radius relation of the protoneutron star can be obtained by observing both the f- and w1-mode gravitational waves simultaneously. That is, the simultaneous detection of the two modes could provide a new probe into finite-temperature nuclear equation of state that predominantly determines the protoneutron star evolution.

Gravitational waves astrophysics - a review talk

• Dorota Rosinska (University of Zielona Gora)

One of the most important prediction of Einstein's general theory of gravity is gravitational radiation. I will discuss the importance of the recent LIGO and Virgo direct detections of gravitational-waves. The observations of gravitational waves provide a different view on astrophysical processes hidden from electromagnetic astronomy and expand our knowledge of the Universe dramatically. I will outline the current state and the future for gravitational wave astronomy.

Oblique magnetic fields and the role of frame dragging

• Vladimir Karas (Astronomical Institute, Czech Academy of Sciences)

Magnetic null points can develop near the ergosphere boundary of a rotating black hole by the combined effects of strong gravitational field and the frame-dragging mechanism. The electric component does not vanish in the magnetic null and an efficient process or particle acceleration can occur. The situation is relevant for low-accretion-rate nuclei of some galaxies which exhibit episodic accretion events (such as the Milky Way's supermassive black hole) embedded in magnetic field field of an external origin. We propose that such a situation develops while a magnetized neutron star approaches the supermassive black hole during late stages of its inspiral motion. The field lines of the neutron star dipole thread the black hole's event horizon.

Gravitational waves from core-collapse supernovae

• Gennady Bisnovatyi-Kogan (Space Research Institute RAS)

Gravitational waves from core-collapse Supernovae. G.S. Bisnovatyi-Kogan, S.G. Moiseenko A mechanism of formation of gravitational waves in the universe is considered for the nonspherical collapse of matter. Nonspherical collapse results are presented for a uniform spheroid of dust, and a finite entropy spheroid. Numerical simulation results on core-collapse supernova explosion are presented for the neutrino and magneto-rotational models. These results are used to estimate the nondimensional amplitude of the gravitational wave of a frequency about 1000 Hz, radiated during the collapse (calculated by the authors in 2D) of the rotating nucleus of a pre-supernova. This estimate agrees well with many other calculations, which have been done in 2D and 3D settings and which rely on more exact and sophisticated calculations of the gravitational wave amplitude. It is noted that the gravitational wave radiated during a core-collapse supernova flash in our Galaxy is of sufficient amplitude to be detected by existing gravitational wave telescopes.

IWARA2018 Review

• Jorge Horvath (IAG-USP)