NEW:: if you need a certificate of participation please send a request to cosmo2022.rio@gmail.com informing your name, and title of the work presented if applicable
here is a tutorial on how to upload your talk directly to the website (bypassing the dropbox link which was sent).
here is a summary of options for Lunch
Posters should be in A0 format (portrait mode), or similar size. We recommend you to print it before the event and bring it with you.
Preliminary timetable updated with all the contributed (plenary and parallel) talks.
Attention: Everyone who submitted abstracts must also register in order to be able to participate in COSMO'22.
Contribution List (accepted abstracts) and Participant List (registered participants) are now displayed. Abstract acceptance can be found in Contribution List. We received around twice as many talk requests as there were available slots, and could not accommodate all who deserved a slot.
Note that due to a problem with the system, abstracts accepted for Posters sometimes originated 2 confirmation emails, the first for the selected submission type, the second confirming it was accepted as a Poster. So if you received both emails, your submission was accepted as a poster. If there are cancellations in the future some posters may be promoted to parallel talks.
The 25th annual International Conference on Particle Physics and Cosmology (COSMO'22) will be held fully in-person at the Planetarium of Rio de Janeiro from 22 to 26 of August. As in previous editions, the conference main topics are:
Invited speakers:
Importante deadlines:
Registration fee:
Grant application: Students, post-docs and researchers without personal grants may apply for two options of grants: (i) 50% discount on the registration fee; (ii) 50% discount on the registration fee plus accommodation for 5 nights (shared room with another participant). Funds for grants are limited, and acceptance of abstract for presentation is a pre-requisite for grant concession. The deadline for grant application is the same as for abstract submission.
Childcare: We have limited spaces available for childcare in-situ during the conference lectures. Recreational activities will be provided for the kids and there will be English speaking staff.
Important note: COSMO will be a fully in-person conference. The conference committee is carefully monitoring the COVID-19 pandemic developments. We will take all necessary precautions to ensure the safety of the participants, as guided by the pandemic levels around July and August. Current local regulations demand the full vaccination with at least 2 doses from all participants. These rules remain in place as of early August and are unlikely to change until the conference.
Since its discovery, the study of the cosmic microwave background anisotropies has been pursued from space, balloons and the ground with great success. The results have helped in shaping the current standard cosmological model, and forged the new questions we are now trying to answer. I will review the main legacy of past experiments, and discuss the scientific goals and expectations for the current and upcoming experiments.
The Vera C. Rubin Observatory under construction in Chile will conduct the 10-year Legacy Survey of Space and Time (LSST) that will produce an unprecedented astronomical data set. This data set will be used to explore several different aspects of the universe, such as: the nature of dark energy and dark matter, objects in the solar system, mapping the Milky Way and transient phenomena in the sky. In this talk I'll briefly describe the project and comment on the opportunities and challenges, focusing on the perspective from the Brazilian Participation Group.
ESA's Euclid satellite, designed to map the geometry of the Universe and scheduled for launch in 2023, will observe billions of galaxies with the ultimate goal of unveiling the nature of dark matter and dark energy. I will give an overview of the instrument and the current status of the Euclid mission. I will then focus on one of its main probes, galaxy clustering, and describe the challenges and approaches we are taking in order to maximise the amount of information extracted from the unprecedented high-precision measurements of cosmic expansion and structure growth that Euclid will provide.
Axions and axion-like particles are a leading candidate for composing the dark matter in the universe. After reviewing how they emerge in the context of particle physics, we will discuss their production in the early Universe and the prospects for their detection. Interestingly, the distribution of axions is generically expected to be non-homogeneous, and we will discuss how this may lead to the production of primordial black holes or be linked to the mysterious fast radio bursts.
This talk will be divided into two pieces. In the first part of the talk, I will present the generalized SU(2) Proca theory (GSU2P for short). As a modified gravity theory that introduces new gravitational degrees of freedom, the GSU2P is the non-Abelian version of the well known generalized Proca theory where the action is invariant under global transformations of the SU(2) group. New interesting possibilities arise in this framework because of the existence of new interactions of purely non-Abelian character and new configurations of the vector field resulting in spatial spherical symmetry and the cosmological dynamics being driven by the propagating degrees of freedom. In the second part of the talk, I will show what the impact of the GSU2P is on the cosmic primordial inflation epoch. Inflation is of the constant-roll type, featuring de Sitter expansion, and shows as an attractor straight line with an attraction basin covering most of the phase space. No Big-Bang singularities appear in this scenario. The predictions on the primordial curvature perturbation spectrum and bispectrum are obtained and shown to be in agreement with observations.
In this talk, we explore the possibility of primordial black holes (PBHs) forming from the gravitational collapse of either the structures virialized during reheating (referred as inflaton halos or inflaton clusters), or from the collapse of the central core of these configurations (referred as inflaton stars). We compute the threshold amplitude for the density contrast to undergo this process, for both the free and self-interacting scalar fields. We discuss our results in light of the constraints to PBHs abundances at the lower end of the mass spectrum and apply our findings to an example inflationary scenario.
Antisymmetric tensor field (two-form field) is a ubiquitous component in string theory and generally couples to the scalar sector through its kinetic term. In this paper, we propose a cosmological scenario that the particle production of two-form field, which is triggered by the background motion of the coupled inflaton field, occurs at the intermediate stage of inflation and generates the sizable amount of primordial black holes as dark matter after inflation. We also compute the secondary gravitational waves sourced by the curvature perturbation and show that the resultant power spectra are testable with the future space- based laser interferometers.
We examine the validity of the classical approximation of the waterfall phase transition in hybrid inflation from an effective field theory (EFT) point of view. The EFT is constructed by integrating out the waterfall field fluctuations, up to one-loop order in the perturbative expansion. Assuming slow-roll conditions are obeyed, right after the onset of the waterfall phase, we find the backreaction of the waterfall field fluctuations to the evolution of the system can be dominant. In this case the classical approximation is completely spoiled. We derive the necessary constraint that ensures the validity of the EFT.
Identifying the particle content of inflation is one of the most important targets of primordial cosmology. In this respect, how the masses and spins of new particles active during inflation can be read off from the statistical properties of primordial density fluctuations is well understood. However, not when the propagation speeds of the new degrees of freedom and of the curvature
perturbation differ, which is the generic situation in the effective field theory of inflationary fluctuations. In this talk, I will explain how recently developed bootstrap techniques can be used to find exact analytical solutions for primordial 2-,3- and 4-point correlation functions in this context, and I will discuss the associated observational consequences. In particular, I will show the existence of new signatures of heavy fields when coupled to the curvature perturbation propagating at a reduced sound speed, manifesting in the form of resonances in the squeezed limit of the bispectrum, a phenomenon that we call the low speed collider. Based on 2205.10340
The distribution of baryons in the cosmic web contains a wealth of cosmological and astrophysical information. In particular, measurements of the hot gas in anisotropic structures—such as filaments and superclusters—are important for the census of cosmic baryons. Such localized anisotropic measures can also provide cosmological information beyond two-point statistics and help to constrain models of baryonic feedback. Although hot gas is observable in CMB data through the the thermal Sunyaev-Zel’dovich (tSZ) effect, the signals from low-mass halos and unbound filament gas are weak, necessitating the use of stacking methods to boost signal-to-noise. By applying oriented stacking in selected regions of the cosmic web, we measure the anisotropic large-scale superclustering of thermal energy around galaxy clusters in tSZ maps from the Atacama Cosmology Telescope and Planck satellite. We compare with oriented measurements of galaxy density and weak lensing from Dark Energy Survey data. Our analysis probes the projected relationships between hot gas, galaxies, and the underlying matter density in filaments and superclusters. Comparisons to theory and simulations elucidate some of the successes and limitations of the current modelling of cosmic baryons.
Precise measurements at small angles of the cosmic microwave background (CMB) angular power spectrum (APS), done by the Planck collaboration, have stimulated accurate analyses of the lensing amplitude parameter $A_L$ to confirm if it satisfies the value expected by the flat $\Lambda$CDM concordance model, i.e. $A_L = 1$.
We discuss a possible excess in the Planck APS not accounted by the $\Lambda$CDM APS. Firstly, we test the hypothesis that the residual APS (i.e., the measured APS minus the $\Lambda$CDM APS) is white noise, or not. Then we quantify how much lensing amplitude is lacking in the Planck analyses of the flat $\Lambda$CDM concordance model (with $A_L = 1$ as a premise). We find that, indeed, there is a residual gravitational lensing signal that is well explained as a lacking lensing amplitude, in the $\Lambda$CDM APS, of around 15%.
We present a fully differential, field level emulator for large-scale structure formation that is accurate in the deeply nonlinear regime. Our emulator consists of two convolutional neural networks trained to output the nonlinear displacements and velocities of N-body simulation particles based on their linear inputs. Cosmology dependence is encoded in the form of style parameters at each layer of the neural network, enabling the emulator to effectively interpolate the outcomes of structure formation between different flat $\Lambda\mathrm{CDM}$ cosmologies over a wide range of background matter densities. The neural network architecture makes the model differentiable by construction, providing a powerful tool for fast field level inference. We test the accuracy of our method by considering several summary statistics, including the density power spectrum with and without redshift space distortions, the displacement power spectrum, the momentum power spectrum, the density bispectrum, halo abundances, and halo profiles with and without redshift space distortions. We compare these statistics from our emulator with the full N-body results, the COLA method, and a fiducial neural network with no cosmological dependence. We find our emulator gives accurate results down to scales of $k\sim 1\ \mathrm{Mpc}^{-1}\, h$, representing a considerable improvement over both COLA and the fiducial neural network. We also demonstrate that our emulator generalizes well to initial conditions containing primordial nongaussianity, without the need for any additional style parameters or retraining.
A new and promising technique for observing the Universe and study the dark sector is the intensity mapping of the redshifted 21-cm line of neutral hydrogen (HI). The Baryon Acoustic Oscillations [BAO] from Integrated Neutral Gas Observations (BINGO) radio telescope will use the 21-cm line to map the Universe in the redshift range $0.127 \le z \le 0.449$, in a tomographic approach, with the main goal of probing BAO.
This work presents the forecasts of measuring the transversal BAO signal during the BINGO Phase 1 operation. We use two clustering estimators: the two-point angular correlation function (ACF), in configuration space, and the angular power spectrum (APS), in harmonic space, and a template-based method to model the ACF and APS estimated from simulations of the BINGO region and extract the BAO information. The tomographic approach allows the combination of redshift bins to improve the template fitting performance. We compute the ACF and the APS for each of the 30 redshift bins and measure the BAO signal in 3 consecutive redshift blocks (lower, intermediate and higher) of 10 channels each. Robustness tests are used to evaluate several aspects of the BAO fitting pipeline for both clustering estimators.
We find that each clustering estimator shows different sensitivities to specific redshift ranges, although both of them perform better at higher redshifts. In general, the APS estimator provides slightly better estimates, with smaller uncertainties and larger probability of detection of the BAO signal, achieving $\sim 90$\% at higher redshifts. We investigate the contribution from instrumental noise and residual foreground signals and find that the former has the greater impact, getting more significant as the redshift increases, in particular the APS estimator. Indeed, including noise in the analysis increases the uncertainty up to a factor of $\sim 2.2$ at higher redshifts. Foreground residuals, in contrast, do not significantly affect our final uncertainties. In summary, our results show that, even including realistic systematic effects, BINGO has the potential to successfully measure the BAO scale in radio frequencies.
Covariance matrices are a fundamental component in the process of constraining physical models from observations, determining the sensibility of the dataset to modifications in the model parameters. However, estimating them correctly presents many challenges; in particular, when computing this quantity using simulations, one must assume a galaxy formation model and a set of fiducial parameters. This represents a twofold limitation: on the one hand, the model or the chosen parameters may not represent well the relevant galaxy population; on the other hand, populating simulations with galaxies represents a large computational cost that sums to the already costly process of generating thousands of dark-matter only simulations. In this work, we are able to circumvent these issues by presenting an application of the bias formalism which allows us to obtain covariances for galaxies as a linear combination of quantities estimated from dark-matter only simulations, weighted by constant bias parameters. This allows one to vary agnostically the galaxy formation model used to build the covariances at essentially no computational cost.
We investigate the structure of quark stars in the framework of $f(R)=R+\alpha R^2$ gravity using an equation of state for cold quark matter obtained from perturbative QCD, parametrized only by the renormalization scale. We show that a considerably large range of the free parameter $\alpha$, within and even beyond the constraints previously reported in the literature, yield non-negligible modifications in the mass and radius of stars with large central mass densities. Besides, their stability against baryon evaporation is analyzed through the behavior of the associated total binding energies for which we show that these energies are slightly affected by the modified gravity term in the regime of high proper (baryon) masses
We study the polarizations of gravitational waves (GWs) in generic higher-curvature gravity (HCG) whose Lagrangian is an arbitrary polynomial of the Riemann tensor. On a flat background, the linear dynamical degrees of freedom in this theory are identified as massless spin-2, massive spin-2, and massive spin-0 fields. Employing a fully gauge-invariant formalism, we demonstrate that (i) the massless spin-2 is the ordinary graviton with 2 tensor-type (helicity-2) polarizations, (ii) the massive spin-2 breaks down into 2 tensor-type (helicity-2), 2 vector-type (helicity-1) and 1 scalar-type (helicity-0) polarizations, and (iii) the massive spin-0 provides 1 scalar-type (helicity-0) polarization. Therefore, GWs in generic HCG exhibit 6 massive polarizations on top of the ordinary 2 massless ones. In particular, we find convenient representations of the scalar-polarization modes connected directly to the theory parameters of HCG. They are utilized to discuss methods to determine the theory parameters by GW-polarization observations.
In general, modified gravity theories can be seen as dark energy theories using the effective fluid approach. In this work, we apply this formalism to the most general second-order scalar-vector-tensor (SVT) theory of gravity. This will allow us to encompass all the free functions of the theory in terms of the equation of state, speed of sound, velocity, and anisotropic stress of a very general dark energy fluid. We show that under the quasi-static and sub-horizon approximations it is possible to obtain analytical expressions for the fields and the gravitational potentials, and thus fairly condensed expressions for the perturbations of the fluid. Using these analytical results, we reproduce some well-known computations in cosmological models within the SVT framework, such as quintessence, kinetic gravity braiding, f(R), and others, in order to test the accuracy of our approach. Furthermore, we propose a designer dark energy model whose background evolution is identical to that of the standard cosmological model, but different at the linear perturbative level. For this designer model, we compute some cosmological observables, such as the growth factor, the angular power spectrum, and the matter power spectrum, and compare them with the predictions given by the standard cosmological model.
In this paper, we have emphasized the stability analysis of the accelerating cosmological models obtained in $f(T)$ gravity theory. The behaviour of the models based on the evolution of the equation of state parameter shows phantom-like behaviour at the present epoch. The scalar perturbation technique is used to create the perturbed evolution equations, and the stability of the models has been demonstrated. Also, we have performed the dynamical system analysis for both the models. In the two specific $f(T)$ gravity models, three critical points are obtained in each model. In each model, at least one critical point has been observed to be stable.
We re-examine sterile neutrino dark matter in gauged $U(1)_{B-L}$ model. Improvements have been made by proper inclusion of all relevant processes and tracing the evolution of the number densities of sterile neutrino and extra neutral gauge boson $Z'$. The energy density of $Z'$ turns out to to be much greater than in earlier studies. We revise the space of the viable parameters .
We present a finite temperature model for dark matter. In this work, we show coupled equations for self-interacting scalar dark matter which can include both a condensed, low momentum fuzzy component and one with higher momenta that may be described as a collection of classical particles. We do this from first principles, using two distinct but equivalent approaches: firstly via the Schwinger-Keldysh path integral and secondly using the operator evolution equation of the density matrix, also known as the ZNG formalism in the cold atom community. The resulting coupled equations consist of a modified Gross-Pitaevskii equation describing the condensate, a kinetic equation describing the higher momentum modes (the particles), and the Poisson equation for the gravitational potential sourced by the two components.
Gravitational production of massive particles due to cosmic expansion can be significant during the inflationary and reheating period of the Universe. In this work, we focus on the gravitational production of light vector bosons that couple feebly to the Standard Model (SM) particles. Due to the very feeble coupling, the light vector bosons never reach thermal equilibrium and if the Hubble scale at the end of inflation is above 108 GeV, the gravitational production can overwhelm the thermal production via freeze-in mechanism by many orders of magnitude. As a result, much stronger constraints from the Big Bang Nucleosynthesis (BBN) can be placed on the lifetime and mass of the vector bosons compared to the scenario where
only thermal production is considered.1 As an example, we study the sub-GeV scale dark photons which couple to the SM only through kinetic mixing and derive constraints from the photodisintegration effects on the light element abundances relevant at the end of the BBN when the cosmic age was around 3 hours.
A prediction of the standard LCDM cosmological model is that dark matter (DM) halos are teeming with numerous self-bound substructure, or subhalos. The most massive ones host the observed dwarf satellite galaxies, while smaller subhalos may host no stars/gas at all and thus may have no visible astrophysical counterparts and would remain completely dark. Yet, some of these ‘dark satellites’ are expected to be excellent targets for gamma-ray DM searches given their typical distances and structural properties. In this talk, I will discuss the importance that DM subhalos may have for DM searches with present or future gamma-ray observatories, such as the NASA Fermi satellite and the future Cherenkov Telescope Array (CTA). I will also describe the recent efforts we have made to search for dark satellites in Fermi-LAT data and to set constraints (predictions, for CTA) on the nature of the DM particle using these elusive targets. [This talk will be based on results from 1906.11896, 1910.14429, 2101.10003 and 2204.00267.]
The first three observing runs of the LIGO-Virgo-KAGRA detector network have led to 90 detections of compact binary coalescences and have ushered in a wealth of results in fundamental physics, astrophysics and cosmology. In this talk we give a brief overview of the observations and focus on standard-siren cosmology, namely the use of compact binaries as standard distance indicators to measure cosmological parameters such as the Hubble constant. We discuss the current results, with and without use of bright electromagnetic counterparts, and discuss the prospects and challenges towards precision cosmography using gravitational-waves.
The HIBEAM/NNBAR experiment is a two stage experiment for the European Spallation
Source (ESS) to search for baryon number violation. The experiment would make high sensitivity searches for baryon number violating processes: n → nbar and n → n′(neutron to sterile neutron), corresponding to the selection rules in baryon number ΔB = 2, 1 , respectively. The experiment addresses topical open questions such as baryogenesis and dark matter, and is sensitive to a scale of new physics substantially in excess of that available at colliders. This is a cross-disciplinary experiment with a clear particle physics goal. The community encompasses physicists from large collider experiments and low energy nuclear physics experiments, together with scientists specialising in neutronics and magnetics. European, US and Asian communities are represented. The experiment would increase the sensitivity to neutron conversion probabilities by three orders of magnitude compared with previous searches. The opportunity to make such a leap in sensitivity in tests of a global symmetry is a rare one.
The Dark Energy Survey (DES) is a 5000 square degree galaxy imaging survey which completed six years of observations in 2019. By measuring the shapes and colors of more than 200 million galaxies in addition to conducting a supernova survey, DES is a multi-purpose experiment that is able to study the large-scale properties of the Universe using measurements of weak gravitational lensing, galaxy clustering, galaxy clusters, and supernovae in order to test LCDM as the standard cosmological model. This talk will primarily focus on the survey's combined analysis of galaxy clustering and weak lensing. I will describe how we use those measurements to constrain cosmology and will give an overview of the findings from the analysis of the survey's first three years of data, highlighting the recently released constraints on several model extensions to LCDM.
I will review the role that galaxy clusters have as tracers of growth of cosmic structures and to constrain the Dark Sector of the Universe. After overviewing the current state of cluster cosmology, I will show one example of cosmic tension arising when comparing cosmological posteriors derived from galaxy clusters and Lyman-alpha forest. Within this context, I will critically discuss the systematics, possibly at the origin of this tension, that need to be understood to fully exploit the potential of ongoing and future surveys (e.g. Euclid/LSST). I will then highlight the important role played by simulations within this context, and show a few examples of systematics that have been addressed thanks to the use of such simulations.
The detection of gravitational waves (GW) has opened a new window for cosmology. The current tension between the measurement of the Hubble constant H0 from Cosmic Microwave Background and Supernova analyses makes an independent, standard siren measurement of H0 from gravitational waves particularly interesting.
However, up to date, the astronomical community has confidently identified only one optical counterpart to a GW event, GW170817. In the cases where no counterpart is identified, it is possible to use a statistical approach, also known as the “dark siren” method, which needs a complete galaxy catalog over the GW localization area. In this contribution, we present a new constraint on the Hubble constant using a sample of well-localized gravitational wave events detected up to as statistical standard sirens, using data from Dark Energy Spectroscopic Instrument (DESI) imaging combined with the bright standard siren measurement from GW170817.
Due to the possible association of the gravitational-wave (GW) binary black hole (BBH) merger GW190521 with a flare in the Active Galactic Nuclei (AGN) J124942.3+344929, we explore the possibility of Standard Sirens in association with BBH flares. Current constraints suggest that from 25% to 80% of BBHs are associated with AGN disks. Furthermore, our formalism allows us to jointly infer cosmological parameters from a sample of BBH events that include chance coincidence flares.
Since the first gravitational wave detection from a merging binary black hole system by the large interferometers LIGO, a new window of the Universe was opened leading us to use these waves to probe the expansion of the Universe. Gravitational wave sources with electromagnetic counterparts, called bright standard sirens, are very useful to cosmology as their luminosity distances can be measured from the gravitational wave signal amplitude and their redshifts from the host galaxy identification. As the current gravitational waves detectors have detected only one bright standard siren, we explore the power of future third generation detectors, such as Einstein Telescope and Cosmic Explorer, to detect them, and perform forecasts on cosmological analysis with them. We show that a few hundred bright sirens, detected by Einstein Telescope, is more than enough to constrain $H_0$ with better accuracies than that one measured by SH0ES. We also show how many detections will be required to rank nested cosmological models and how the distributions of these detections can affect our results.
We investigate a recently proposed method for measuring the Hubble constant from gravitational wave detections of binary black hole coalescences without electromagnetic counterparts. In the absence of a direct redshift measurement, the missing information on the left-hand side of the Hubble-Lemaître law is provided by the statistical knowledge on the redshift distribution of sources. We assume that source distribution in redshift depends on unknown hyperparameters, modeling our ignorance of the astrophysical binary black hole distribution. With tens of thousands of these "black sirens" -- a realistic figure for the third generation detectors Einstein Telescope and Cosmic Explorer -- an observational constraint on the value of the Hubble parameter at percent level can be obtained.
We study kink-antikink scattering in the sine-Gordon model in the presence of interactions with an additional scalar field, ψ, that is in its quantum vacuum. In contrast to the classical scattering, now there is quantum radiation of ψ quanta and the kink-antikink may form bound states that resemble breathers of the sine-Gordon model. We quantify the rate of radiation and map the parameters for which bound states are formed. Even these bound states radiate and decay, and eventually there is a transition into long-lived oscillons.
Phase correlations have been proposed as an efficient higher-order statistic able to extract cosmological and astrophysical information that is largely independent from the two-point function or power spectrum. In this talk, we develop an estimator for the line correlation function of projected fields, corresponding to the correlation between the harmonic-space phases of the field at three equi-distant points on a great circle. We then use this estimator to make a first measurement of phase correlations on data from the 2MASS photometric survey. Finally, we demonstrate that the projected line correlation function contains information that is largely orthogonal to the power spectrum. Focusing on the galaxy-halo connection, we show that this can lead to a dramatic reduction in the final parameter uncertainties.
I will describe recent developments on the nonlinear modelling of LSS, in the context of momentum-exchange interacting dark energy. I will review the Dark Scattering model and show how it can alleviate the current $S_8$ tension between early and late-Universe data. I will present new constraints on this interaction from a likelihood analysis of the BOSS DR12 power spectrum multipoles, while briefly describing the EFT-based model and likelihood used in the analysis. I will show a hint of a detection of this dark coupling, driven by the preference of late-time data for a lower amplitude. If confirmed, this result could restore concordance between the early and the late Universe.
In this talk, I will present a method to extract the Scalar Vector Tensor (SVT) first order perturbations from the Cosmological Perturbations Theory developed in a homogeneous and isotropic Geodesic Light Cone (GLC) background. Due to its adapted light-cone decomposition, the GLC-SVT relation becomes involved, notwithstanding, I will present two different strategies to easy this relation. In the first one I will show how different gauge fixings may simplify these relations, however, at the cost of losing the GLC adaptability to cosmological observables. In the second one I will show how screen projected degrees of freedom have simple formulae when expressed in terms of spin raising and lowering operators, preserving the past light-cone symmetries in terms of
well-known physical quantities and its respective E and B modes.
Axionlike particles (ALPs) are among the most well-motivated extensions of the Standard Model of particle physics, and are increasingly popular dark matter candidates. Extreme astrophysical environments, such as dense and hot supernovae, or vast and magnetised galaxy clusters, provide unique opportunities to test the theory. In this talk, I will discuss recent progress in searching for ALPs using classical and quantum phenomena.
First, classical ALP-photon mixing underlies the most powerful probes of light ALPs, but often hinges on astrophysical magnetic fields that are poorly known. In this talk, I will combine theoretical arguments about the structure of ALP-photon conversion with state-of-the-art magnetic field models, including those from new magnetohydrodynamic (MHD) simulations, to test the robustness of the ALP predictions. Magnetic non-Gaussianity of MHD models leads to novel ‟fat tails” in the distribution of conversion probabilities, but simpler models often generate conservative predictions.
Second, quantum ALP-photon mixing can be of critical importance even for ALPs that only couple to electrons at tree-level. I will show that properly accounting for the quantum effective couplings has drastic implications for ALP dark matter searches by direct detection experiments, and leads to new, subtle predictions for ALP production in supernovae.
Axions are often accompanied by discrete symmetries that are
spontaneously broken in the early universe and lead to the formation of
a network of cosmic domain walls (DW).
In this talk, I will discuss the stochastic gravitational wave (GW)
background produced by such networks. I will show that in some heavy QCD
axion models, the GW signal is within reach of current and future
detectors and is accompanied by a correction to the neutron (proton)
electric dipole momentum that can be detected by future experiments.
I will also present a recent search for GWs from cosmic DWs in pulsar
timing array data that shows that DWs can explain the signals that have
been detected and lead to striking correlated signals at CMB and
laboratory/collider experiments.
We study axion dark matter production from a misalignment mechanism in scenarios featuring a general nonstandard cosmology. Before the onset of Big Bang nucleosynthesis, the energy density of the universe is dominated by a particle field $\phi$ described by a general equation of state $\omega$. The ensuing enhancement of the Hubble expansion rate decreases the temperature at which axions start to oscillate, opening this way the possibility for axions heavier than in the standard window. This is the case for kination, or in general for scenarios with $\omega > 1/3$. However, if $\omega < 1/3$, as in the case of an early matter domination, the decay of $\phi$ injects additional entropy relative to the case of the standard model, diluting this way the preexisting axion abundance, and rendering lighter axions viable. Interestingly, the coupling axion-photon in such a wider range can be probed with next generation experiments such as ABRACADABRA, KLASH, ADMX, MADMAX, and ORGAN.
We report on the status and latest results of the KM3NeT neutrino telescope in the Mediterranean Sea. KM3NeT has two detectors, KM3NeT/ORCA in France, optimized for the measurement of atmospheric neutrinos, and KM3NeT/ARCA in Italy, focussed on the detection of cosmic neutrinos. Although the detector is still under construction, first results with data using configurations of six lines in ORCA and six lines in ARCA are presented. These includes measurements of neutrino oscillations and limits on non-standard interactions, neutrino decay and quantum decoherence, as well as searches for cosmic neutrino sources and follow-ups of alerts of transient phenomena in a multi-messenger context. An outlook will be presented, including the sensitivity to the neutrino mass ordering.
This talk will provide an overview of neutrinos in physics, astrophysics and cosmology. I will broadly cover detection of neutrinos over a wide range of energies, highlighting several ongoing and future projects.
The BINGO instrument is being constructed with the goal to be the first radio telescope to detect Baryonic Acoustic Oscillations (BAO) in the radio frequency band (~ 1 GHz) using the 21 cm hyperfine transition of the neutral hydrogen using an observation technique known as intensity mapping (IM). However, the 21 cm signal is a few orders of magnitude weaker than the emission from other astrophysical processes in the same frequency band. This difference in signal magnitude demanded that the instrumental requirements contemplated a very clean beam profile, low sidelobes levels, and a rejection of cross-polarization better than 99%. In recent works of the collaboration, we showed that the optical design meets these requirements, with a focal arrangement composed of 28 feed horns. The mechanical design allows the vertical displacement of the horns for better sky sampling. We are currently using the foreground extraction packages GNILC, GMCA, and FastICA, to accurately recover the 21 cm signal from simulated sky maps with white noise. Additional steps on this matter contemplates the inclusion of radio frequency interference (RFI) contamination and 1/f noise.
The 21 cm hydrogen line is arguably one of the most powerful probes to explore the Universe, from recombination to the present times. To recover it, it is essential to separate the cosmological signal from the much stronger foreground contributions at radio frequencies. The Baryon Acoustic Oscillations from Integrated Neutral Gas Observations (BINGO) radio telescope is designed to measure the 21 cm line and detect baryon acoustic oscillations (BAOs) using the intensity mapping technique. This work, analyses the performance of the Generalized Needlet Internal Linear Combination (GNILC) method, combined with a power spectrum debiasing procedure. The method was applied to a simulated BINGO mission. It compares two different synchrotron emission models and different instrumental configurations, in addition to the combination with ancillary data to optimize both the foreground removal and recovery of the 21 cm signal across the full BINGO frequency band, as well as to determine an optimal number of frequency (redshift) bands for the signal recovery.
With the recent development of projects for the gathering of cosmological data through radioastronomy, mainly using the redshifted 21 cm signal line, various systematic effects have been analysed to improve sensibility and precision. This includes instrumental features such as beam analysis, which involves studying the how the reflectors modify the data through optical aberrations, and how it is possible to adequately handle this issue. Usually, in literature, only the beam main lobe's effects are considered and taken out of the final results, but it is known that sidelobe residuals remain on the final data. In this work, I present the impact of sidelobe contamination on sky maps using the framework of the BINGO Telescope's reflectors and its 28 horns. This is achieved using a Zernike Polynomials decomposition of the beams, inserted into the HIDE & SEEK softwares, which perform survey simulations and mapmaking.
Stars whose initial mass is between approximately 150 and 240 M$_\odot$ face a fate of complete explosion in a pair instability supernova (PISN). However, by injecting energy into the star, it may be possible in some cases to avoid this fate. We outline conditions on this energy injection which can lead to the survival or incomplete explosion of the star, and we discuss how dark matter annihilations throughout a star may offer one mechanism to provide this energy. Finally, we begin to explore the range of energy conditions which may allow stars to avoid PISN.
Gravitational-wave interferometers can be used to probe the existence of dark matter. Different types of dark matter, such as primordial black holes, ultralight boson clouds around spinning black holes, axions and dark photons, could leave different imprints on gravitational-wave detectors. While arising from physically different sources, such gravitational-wave and dark-matter signals share common traits, and can be searched for with similar methods. In this talk, I explain how persistent, quasi-monochromatic signals in ground- and space-based detectors could arise from each of the aforementioned dark matter candidates. I also describe various methods and summarize search results from the most recent observing runs of Advanced LIGO, Virgo, and KAGRA.
The nature of dark matter is one of the outstanding open questions in physics. Although the observational evidence for the existence of a non-baryonic, non-luminous and non-relativistic component of the universe has been strengthen in recent years, its nature still remains unknown. A class of theoretically-motivated non-relativistic particles with masses approximately in the GeV to TeV range, commonly referred to as Weakly Interacting Massive Particles (WIMPs), has been extensively investigated as a constituent of dark matter. Direct detection experiments aim to detect WIMPs by looking for the energy deposited in a detector when a WIMP from our galactic halo scatters off a nucleus of a target/detector sensitive material. In recent years, such detectors have reached the multi-ton scale and even larger ones are being planned. They will become sensitive to astrophysics neutrinos that will generate events via coherent elastic neutrino-nucleus scattering (CEνNS), similar to those of the WIMPs.
Here, we overview the recent progress in WIMP direct detection experiments, discuss the impact of the so called "neutrino fog" and present future directions for WIMP search.
I will review recent progress to address the generation of primordial non-Gaussianity during cosmic inflation. I will focus my attention on the origin of non-Gaussian signals that are poorly parametrized by the bispectrum (the three-point function). Such non-Gaussian deformations of the statistics may be crucial to understand the generation of primordial black holes, and necessarily require non-perturbative techniques taking into account every n-point function.
I will review the status of the dark matter theory and phenomenology.
Primordial Black Holes might comprise a significant fraction of dark matter in the Universe and can give rise to observable signatures at current and future gravitational wave experiments. First, we review the PBH model and discuss how accretion and clustering may affect the properties of PBH binaries. Second, we confront the PBH model with LIGO/Virgo/KAGRA data showing its upsides and shortcomings, by also including state-of-the-art astrophysical models in a multi-population inference. Finally, we discuss how future generation detectors may be able to discover a PBH population by searching for high redshift merger events.
New degrees of freedom active during inflation lead to nontrivial signatures across scalar and tensor primordial spectra. We will discuss how such deviations from single-field, slow-roll inflation, manifested as particle excitations, lead to distinct signals in the stochastic gravitational wave background generated during inflation and how its characteristics are related to sharp features of the inflationary dynamics.
Boson-stars are self-gravitating Bose-Einstein condensates of ultra-light boson fields, which are widely considered as strong candidates to account for at least part of Dark Matter. Boson-star mergers can produce gravitational-wave signals observable by current detectors such as Advanced LIGO and Virgo. I will present a systematic comparison of existing (high-mass) gravitational-wave signals to a catalog of ~800 numerical simulations of (vector) boson-star mergers, performing model selection with respect to the canonical black-hole merger scenario. In particular I will show that the controversial event GW190521 slightly prefers the boson-star merger model over the black-hole merger one and that all analysed events yield consistent boson-mass estimates. Finally, I will present preliminar results on the potential population of these objects.
The supernova, which is the event at the last moment of the massive star's life, is the next promising candidate as the gravitational wave source. Up to now, gravitational waves from supernova explosions have been mainly discussed via numerical simulation. These results tell us the existence of the gravitational waves whose frequencies increase from a few hundred hertz up to kHz within a second. However, the physics behind this signal has been unclear. In this talk, we discuss the supernova gravitational waves from the approach with asteroseismology and we show the empirical relation in the supernova gravitational waves.
The Gibbons-Maeda-Garfinkle-Horowitz-Strominger (GMGHS)
black hole is an influential solution of the low energy heterotic
string theory. As it is well known, it presents a singular extremal
limit. We construct a regular extension of the GMGHS extremal black
hole in a model with $\mathcal{O}(\alpha')$ corrections in the action,
by solving the fully non-linear equations of motion. The
de-singularization is supported by the $\mathcal{O}(\alpha')$-terms.
The regularised extremal GMGHS BHs are asymptotically flat, possess a
regular (non-zero size) horizon of spherical topology, with an
$AdS_2\times S^2$ near horizon geometry, and their entropy is
proportional to the electric charge. The near horizon solution is
obtained analytically and some illustrative bulk solutions are
constructed numerically.
Future generations of galaxy redshift surveys will sample the large-scale structure of the Universe over unprecedented volumes with high-density tracers, allowing for precise measurements of the clustering statistics. In order to properly exploit the full potential of such data, a robust likelihood pipeline is required, starting with an accurate theoretical prediction of cosmological observables, down to constraints on cosmological parameters. The main probe used in the context of spectroscopic galaxy surveys is the two point correlation function, or its Fourier transform, the power spectrum. However, it has been shown that the inclusion of higher order correlation functions in the analysis can significantly improve the accuracy with which cosmological parameters are measured. I will present a software for the joint likelihood analysis of the galaxy power spectrum and bispectrum, which includes for the first time also higher order bispectrum multipoles, and describe its validation against a large set of N-body simulations that allows to assess possible systematics in the theoretical model. Moreover, I will present forecasts for the joint analysis of power spectrum and bispectrum for future stage-IV galaxy surveys, both for the standard model and beyond-LCDM models.
We study the spherical collapse of non-top-hat matter fluctuations in the presence of dark energy with arbitrary sound speed ($c_s$). The model is described by a system of partial differential equations solved using a pseudo-spectral method with collocation points. This method can reproduce the known analytical solutions in the linear regime with an accuracy better than $10^{-6}$ % and better than $10^{-2}$ % for the classical results of the spherical collapse model. We show the impact of nonlinear dark energy fluctuations on matter profiles and discuss some issues regarding phantom dark energy models. We also compute how dark energy sound speed affects the threshold for collapse and virialization density of halos. We confirm previous results for clustering dark energy $c_s→ 0$ and homogenous dark energy $c_s→ 1$, and extend them to arbitrary values of $c_s$. Finally, show how the gravitational potential and halo mass functions are impacted by $c_s$.
General Relativity (GR) has been successfully tested mainly at Solar system scales; however, in the last few decades, galaxy-scale tests have become popular. In particular, some recent works dedicate close attention to the $\eta_{\text{PPN}}$ parameter, which is commonly associated with the spatial curvature generated per unit mass. Under the assumption of GR, and a vanish anisotropic stress tensor, $\eta_{\text{PPN}} = 1$. In this work, using ALMA, HST, and VLT/MUSE data, we combine mass measurements, using gravitational lensing and galactic dynamics, for the SDP.81 elliptical lens galaxy ($z = 0.299$) to constrain the slip parameter. We assume a self-consistent mass profile, parameterised by a sum of elliptical Gaussians, which is flexible enough to allow us to decompose the mass profile into two components: (i) a stellar-mass component, obtained by deprojecting the observed lens surface brightness profile; (ii) a dark matter halo, described by a Navarro-Frank-White profile. We model the gravitational lensing effect by solving the lens equation and reconstructing the source object, whereas the kinematical data were modelled by solving the Jeans equations. We infer, for our fiducial model, $\eta_{\text{PPN}} = 1.42 \pm 0.27$, which is in tension with GR within $1\sigma$. For this result, we take into account possible systematic uncertainties, for instance, the mass profile adopted, the uncertainty in the Hubble constant, and the impact of the stellar templates used to fit the kinematic data. However, this result should be faced with care. Although we carry out a thorough analysis, it is necessary to highlight that our kinematic data have poor quality and can bias the results. Nonetheless, we notice that if we choose a narrow Gaussian prior that privileges GR, i.e. centred at GR predictions, we found $\eta_{\text{PPN}} = 1.13 \pm 0.27$, which recovers their predictions. Although, we believe that such a prior should not be used, as it assumes that GR could be valid from the beginning. Some recent works using a sample of strong gravitational lenses and their velocity dispersions have found higher values for $\eta_{\text{PPN}}$ as well, typically in statistical accordance with our fiducial model result. A common feature between those results and ours is the inclusion of galaxies at intermediate redshift, which may be bringing $\eta_{\text{PPN}}$ to higher values. To clarify this issue, better kinematic data are needed. In that regard, the newer state-of-art NIRSpec instrument, onboard JWST, will play an essential role, possibly providing data with a higher signal-to-noise ratio and more spatial resolution, allowing strong constraints in the dynamic mass of galaxies at intermediate redshift.
In this talk I will present the formulation of the Effective Field Theory (EFT) of black hole perturbations within scalar-tensor theories on an inhomogeneous background. In particular, the EFT is constructed while keeping a background of a scalar field to be timelike, which spontaneously breaks the time diffeomorphism. I will then discuss a set of consistency relations that are imposed by the invariance of the EFT under the 3d spatial diffeomorphism. Finally, I will discuss the dynamics of black hole perturbations around a spherically symmetric, static background metric using our EFT.
I will introduce a fast and complementary approach to study galaxy rotation curves directly from the sample data, instead of first performing individual rotation curve fits. The method is based on a dimensionless difference between the observational rotation curve and the expected one from the baryonic matter ($\delta V^2$). It is named as Normalized Additional Velocity (NAV). Using 153 galaxies from the SPARC galaxy sample, we find the observational distribution of $\delta V^2$. This result is used to compare with the model-inferred distributions of the same quantity. We consider the following five models to illustrate the method, which include a dark matter model and four modified gravity models: Burkert profile, MOND, Palatini $f(R)$ gravity, Eddington-inspired-Born-Infeld (EiBI) and general relativity with renormalization group effects (RGGR). We find that the Burkert profile, MOND and RGGR have reasonable agreement with the observational data, the Burkert profile being the best model. The method also singles out specific difficulties of each one of these models. Such indications can be useful for future phenomenological improvements. The NAV method is sufficient to indicate that Palatini $f(R)$ and EiBI gravities cannot be used to replace dark matter in galaxies, since their results are in strong tension with the observational data sample.
The standard cosmological model, namely the flat LCDM model, has been tremendously successful in describing cosmological observations for over two decades. Still, it suffers from theoretical caveats, in addition to recent problems like the SH0ES tension between H0 measurements from the early- and late-time Universe. In light of these issues, I will show results of some null tests of fundamental assumptions underlying the standard model in a model-independent fashion, such as a null test of the FLRW assumption, the variability of the speed of light, and the evidence for late-time cosmic acceleration.
We perform a general test of the ΛCDM and wCDM cosmological models by comparing constraints on the geometry of the expansion history to those on the growth of structure. Specifically, we split the total matter energy density, Ωm , and (for wCDM) dark energy equation of state, w, into two parameters each: one that captures the geometry, and another that captures the growth. We constrain our split models using current cosmological data, including type Ia supernovae, baryon acoustic oscillations, redshift space distortions, gravitational lensing, and cosmic microwave background (CMB) anisotropies. We focus on two tasks: (i) constraining deviations from the standard model, captured by the parameters ∆Ωm ≡ Ωm^{grow} − Ωm^{geom} and ∆w ≡ w^{grow} − w^{geom}, and (ii) investigating whether the S8 tension between the CMB and weak lensing can be translated into a tension between geometry and growth, i.e. ∆Ωm ≠ 0, ∆w ≠ 0. In both the split ΛCDM and wCDM cases, our results from combining all data are consistent with ∆Ωm = 0 and ∆w = 0. If we omit BAO/RSD data and constrain the split wCDM cosmology, we find the data prefers ∆w < 0 at 3.6σ significance and ∆Ωm > 0 at 4.2σ evidence. We also find that for both CMB and weak lensing, ∆Ωm and S8 are correlated, with CMB showing a slightly stronger correlation. The general broadening of the contours in our extended model does alleviate the S8 tension, but the allowed nonzero values of ∆Ωm do not encompass the S8 values that would point toward a mismatch between geometry and growth as the origin of the tension.
We test the usual hypothesis that the Cosmic Microwave Background (CMB) dipole, its largest anisotropy, is due to our peculiar velocity with respect to the Hubble flow by measuring independently the Doppler and aberration effects on the CMB using Planck 2018 data. We remove the spurious contributions from the conversion of intensity into temperature and arrive at measurements which are independent from the CMB dipole itself for both temperature and polarization maps and both SMICA and NILC component-separation methods. Combining these new measurements with the dipole one we get the first constraints on the intrinsic CMB dipole. Assuming a standard dipolar lensing contribution we can put an upper limit on the intrinsic amplitude: 3.7 mK (95% CI). We estimate the peculiar velocity of the solar system without assuming a negligible intrinsic dipole contribution: v=(300+111−93) km/s with (l,b)=(276±33,51±19)∘ [SMICA], and v=(296+111−88) km/s with (l,b)=(280±33,50±20)∘ [NILC] with negligible systematic contributions. These values are consistent with the peculiar velocity hypothesis of the dipole.
Dark matter not only provides the invisible scaffolding from which the birth of galaxies takes place, but by studying its distribution in our Universe we can infer a great deal of information regarding the growth of structure and cosmic expansion. Measuring the gravitational lensing of the CMB allows the mapping of all the matter distribution (for which the majority is dark matter) to very high redshifts. New observations with the Atacama Cosmology Telescope will allow CMB lensing measurements to reach higher precision than those derived from Planck, reporting preliminary measurements of CMB lensing at $50 \sigma$. This high signal-to-noise lensing spectrum will translate into a few percent determination of $\sigma_8$, hence providing a robust test of low amplitudes reported by galaxy lensing surveys and also one of the tightest constraints on the sum of neutrino masses. This measurement also sets the foundation for ground-based high-resolution lensing covering a large fraction of the sky. Novel methods to tackle problems related to atmospheric noise and extragalactic foregrounds, along with almost 200 null tests, were employed to provide this state of the art lensing measurements. In my talk, I will discuss how these methods are implemented in detail, as well as the relevance of our results in the context of cosmological tensions.
Superconducting nanowires, a mature technology originally developed for quantum sensing, can be used as a target and sensor with which to search for dark matter interactions with electrons. We leverage recent developments in the theory of dark matter interactions in dielectrics to robustly predict the event rate in a nanowire device, fully accounting for the many-body physics of the detector. As a proof of concept, we use data from a 180-hour measurement of a prototype device to place new constraints on dark matter--electron interactions, including the strongest terrestrial constraints to date on sub-MeV (sub-eV) dark matter that interacts with electrons via scattering (absorption) processes. We present a roadmap for the development of future experiments and demonstrate the prospects for superconducting nanowires to lead exploration of the light dark matter parameter space.
The Euclid space-based survey will observe and map the distribution of galaxies with unprecedented accuracy, allowing us to improve the knowledge of the Universe and its dynamics as well as the nature of the so-called dark matter that contributes up to a quarter of the total energy density of the Universe. Furthermore, key research will involve the measurements of the subtle features produced by neutrinos on the cosmological observables, providing new constraints on the sum of the neutrino masses with a precision better than 0.03 eV at 1-sigma level. Observations will be taken by two instruments located inside the payload of the satellite, one taking data from light in the visual spectrum (VIS) and the second one in the near-infrared spectrum (NISP). NISP will allow two observing modes: photometric and spectroscopic imaging, the latter via slit-less spectroscopy. In the presentation, we will focus on the status and the perspectives of the first period of the NISP instrument.
Padua is responsible for all the activities related to the NISP warm electronics assembly, software integration and validation. Currently, we are in the latest phase of the hardware tests, just before the launch of the satellite. Ground tests were performed using both a telescope simulator and the Euclid telescope. They provide emulations of point-like sources at different wavelengths, dark reference exposures and flat-field illumination. All the results from these tests will be shown during the presentation, focusing on the performance of the NISP instrument and its observation strategy. Finally, we will present the comparison of data to simulations, currently used to calibrate and validate the algorithms developed within the Euclid consortium to extract galaxy redshifts from image data.
The evidence for dark matter is overwhelming, yet there has not been an unambiguous detection of a dark matter particle. The XENON collaboration has operated successively larger experiments in the hunt for WIMP-dark matter using dual phase time projection chambers with xenon as the target material. The XENON collaboration is one of the leading collaborations in constraining the WIMP-nucleon scattering cross-sections, as well as being sensitive to other rare processes such as solar-axions coherent elastic scattering of solar neutrinos and two-neutrino double electron capture in $^{124}$Xe. The XENONnT detector with a target mass of 8000kg is operated at the INFN Gran Sasso National Laboratory in Italy and in this talk I will discuss results of XENONnT and its predecessor, XENON1T, along with the plans for operating XENONnT in the future.
A kinetic coupling between the photon and a dark photon, a massless U(1)-gauge boson in the dark sector, transfers dark photon’s birefringence to observed cosmic birefringence. Regardless of the origin of the dark birefringence, the amplitude and unique frequency-dependence of the cosmic birefringence depend on the kinetic-coupling constant and the dark-photon temperature. To explain the reported tantalizing 3-sigma hint of cosmic birefringence, the dark photon temperature must exceed 0.82 K, corresponding to $\Delta{N}_\text{eff} \geq 0.022$, which is within reach of the CMB Stage-4.
Em 1922 o matemático russo Alexander Friedmann publicou o artigo em que pela primeira vez na história se evocava a possibilidade que o universo fosse dinâmico e pudesse estar em expansão. A expansão do universo seria pouco depois confirmada pelas observações. Desse momento em diante, o moderno modelo cosmológico foi sendo paulatinamente construído. Hoje ele se alicerça sobre vários sólidos pilares, mas convive por outro lado com várias dificuldades e tensões. Este seminário procura discutir a construção do atual modelo cosmológico padrão, seus sucessos e seus problemas.
The Euclid survey will map the large scale structure with the aim of measuring the parameters of the standard cosmological model with unprecedented precision.
However, the great sensitivity of Euclid can also be exploited to test the most fundamental assumptions at the basis of the standard cosmological model. Here we present two works of the Euclid Consortium where, forecasts from Euclid together with data from other surveys, are used to constrain the cosmic distance duality relation and the assumptions of homogeneity and isotropy of the universe on large scales.
The J-PAS (Javalambre Physics of the Accelerating Universe Astrophysical Survey) scans the sky through 56 narrow band (~140 Å) + 3 broad band optical filters that render a R~50 spectra of every object detected in the footprint. The first square degree covered by the miniJPAS survey has produced \sigma_{NMAD}<0.005 x (1+z) for most galaxies with r<22.5, thus enabling an accurate reconstruction of the cosmic web conforming Large Scale Structure (LSS) of the universe. The first tests with realistic photo-z PDFs on simulated mocks are also providing an optimal recovery of the 3D power spectrum up to scales of k ~ 0.1-0.2~h/Mpc. The miniJPAS survey has also allowed the identification of ~100 groups with masses above 5x10^{13} M_sun, with high level of purity and completeness up to z~0.4. Likewise, the narrow band filters are particularly sensitive to broad band features such as QSO/AGN emission lines, enabling miniJPAS to identify and pin the redshift of hundreds of QSOs, to be further followed up spectroscopically with WEAVE-QSO. Finally, J-PAS’ sister survey, J-PLUS, with only 12 (7 narrow band + 5 broad band) optical filters, has just covered 3,000 square degrees, and has identified hundreds of thousands of galaxies with high accuracy photo-zs (\sigma_{NMAD}<0.01 x (1+z)). The associated preliminary clustering analyses are demonstrating the potential of spectro-photometric surveys like J-PAS and S-PLUS.
The next galaxy cluster survey has the potential of being a very competitive cosmological probe. The main cosmological inference done with clusters is the so-called number counts, within which the halo mass function (HMF) is a vital theoretical quantity. This talk revises the calibration of the HMF, focusing on the numeric and theoretical systematic effects from the simulation’s purely numerical aspects to the baryonic feedback. While statistical and numerical systematic errors marginally impact the final cosmological constraints forecasted for future surveys, different halo definitions, and baryonic physics can systematically bias the results, raising awareness on the need for better understanding the connection between simulations and observations clusters are identified consistently in both.
We explore observational signatures from multi-field inflationary models with more than two fields. We first revisit the two-field case where the attractor solution with either small or large turn rate can be found analytically and investigate under what conditions the same procedure can be generalised for more fields. For three fields in the slow-roll, slow-twist and extreme turning regime we provide elegant expressions for the attractor solution for generic field-space geometries and potentials and study the behaviour of first order perturbations. In addition, we find that multiple (sharp) turns can significantly enhance the power spectrum and can therefore lead to efficient primordial black holes production. Finally, we apply our discussion to concrete supergravity models.
The problem of finding a vacuum definition for a single quantum field in curved spaces is discussed under a new geometrical perspective. The minimum complex structure in phase space necessary to define a vacuum state is mapped to a 2-dimensional hyperbolic space in which distances can be defined. It is shown that well known vacuum prescriptions in the literature correspond to points in this hyperbolic space from which all mapped phase space solutions move on circles around it in the time-independent case, or within thin annular regions in the time-dependent case when the adiabatic approximation is valid. These properties are shown to be equivalent to the stability of the vacuum choice. The analysis is extended to time-dependent cases in which the adiabatic approximation is not valid, in the super-Hubble or low frequency regime. It is shown that stability points or curves can also be found in these situations, and stable quantum vacua can be obtained. This new formalism is applied to two situations: de Sitter space, where the Bunch-Davies vacuum is obtained in a complete different manner through an analysis in the super-Hubble regime, and in the context of cosmological bouncing models in which the contracting phase is dominated by a cosmological
constant in the asymptotic past. A new vacuum state for cosmological perturbations is proposed in this situation.
In this work we analyze the stability criteria in $f(R)$ theories of gravity in the metric formalism under the approach of a thermodynamics analogy proposed in [C.D. Peralta and S.E. Jorás JCAP06(2020)053] for $\phi^4$ and double well inflationary potentials. We starting from the mentioned potentials in the Einstein frame, and obtain a parametric form of $f(R)$ in the corresponding Jordan frame. Such approach yields plenty of new pieces of information, namely a self-terminating inflationary solution with a linear Lagrangian, a robust criterion for stability of such theories, and a dynamical effective potential for the Ricci scalar $R$.
The addition of an ad-hoc Cosmological Constant in the Einstein frame leads to a Thermodynamical interpretation of this physical system described by a Van der Waals like behavior, which allows whole thermodynamics picture then follows: a equation of state, binodal and spinodal curves, phase transition, critical quantities (pressure, volume and temperature), entropy jumps, specific-heat divergence (and the corresponding critical exponent).
Gravitational arcs are strongly magnified images of distant galaxies (known as sources) caused by the deflection of light produced by a foreground galaxy or galaxy cluster (the lens). This strong lensing phenomenon has been used to study high-redshift sources, to assess the mass distribution in the lens, to constrain cosmological parameters and to set limits on modified gravity. In addition, merging lensing systems have been used to set constraints on dark matter properties, such as a possible self-interaction cross section. In this work we present a detailed analysis of the strong lensing system J083933.4-014044.4, originally discovered in the Survey of Gravitationally-lensed Objects in HSC Imaging (SuGOHI). The lens is an early-type galaxy in the dense environment of a galaxy cluster and the images have the characteristic shape of a large arc with three bright peaks and a counter image. This configuration allows one to carry out the so-called lens inversion, providing parameters of the lens, such as the mass within the Einstein radius and the ellipticity of the mass distribution, and a coarse reconstruction of the (unlensed) source. A closer look into this system reveals the presence of tidal tails connecting the central galaxy with two dwarf spheroidals. Therefore, this object offers a unique opportunity of contrasting the complex dynamics of the merging systems with a lensing mass estimate. Furthermore, the unusual fact that the images are red, makes this system particularly relevant for studying the distant lensed galaxy. We have made a “dissection” of this system, first fitting and subtracting a smooth model of the lensing galaxy. This enhances the tidal features and removes contamination of the lens light for modeling the images. We then perform the lens inversion, obtaining parameters of the lens mass distribution and reconstructing the source shape. This lensing model is also used to subtract the arcs from the original images, providing a further “cleaned” view of the tidal features. Motivated by the potential applications of this system we have carried out spectroscopic observations with the Southern Astrophysical Research (SOAR) and Gemini telescopes, aiming at: i) obtaining the redshift of the source, ii) measuring the velocity dispersion of the lens, iii) obtaining redshifts of the dwarf spheroidals, to confirm the collision interpretation, iv) deriving physical properties of the lens and the source. Preliminary analysis of the data yielded the redshift of the source. A comparison between the lens velocity dispersion and the lensing mass estimate will allow us to quantify the effects of the mergers on the global dynamics of the lens galaxy. The detailed modelling of this peculiar lensing system may not only unveil aspects of its history and dynamics, but may also set constraints on dark matter properties.
Primordial Black Holes (PBHs), first postulated more than half a century ago, remain an active and fascinating area of research and provide an exciting prospect for accounting for Dark Matter. In this talk I will discuss the possibilities for production of PBHs near to Dark Matter mass scales from realistic multi-field inflation models that arise naturally from supergravity. These models fit neatly within the current status of inflationary models as constrained by CMB observations; they behave effectively as a single-field models for much of their evolution, and the isocurvature modes remain heavy throughout. Moreover, such models yield efficient post-inflation reheating with $N_{\rm reh} \sim O(1)$ e-folds after the end of inflation. I will demonstrate how our class of two-field models in particular give rise to inflationary dynamics that yield predictions for observables in close agreement with recent empirical data, such as the spectral index and ratio of power spectra for tensor to scalar perturbations. As has been noted in previous studies of PBH formation resulting from a period of ultra slow-roll inflation, we found that at least one dimensionless parameter must be fine-tuned, but I will show that we nonetheless find such models yield accurate predictions for a significant number of observable quantities using a smaller number of free parameters.
Through their observable properties, the first and smallest dark matter halos represent a rare probe of subkiloparsec-scale variations in the density of the early Universe. These density variations could hold clues to the nature of inflation, the postinflationary cosmic history, and the identity of dark matter. The first halos are understood to possess a uniquely compact central mass distribution in which density scales with radius as $\rho\propto r^{-3/2}$, but this property has been largely neglected owing to doubts about its persistence. I will show new results demonstrating how this feature can persist as a halo grows and evolves, and I will discuss why previous works underestimated its survival prospects. The compact central structure boosts microhalos' observational prospects, particularly in models where dark matter annihilates; for some models this effect can boost the annihilation rate by a factor of order 10. Additionally, the $\rho\propto r^{-3/2}$ structure is highly resistant to tidal stripping, so the abundance of microhalos inside larger halos (such as the Galactic halo) may be much greater than previously assumed. I will also discuss how as a probe of cosmology, the $\rho\propto r^{-3/2}$ feature is particularly convenient because its details are tightly connected to the properties of the primordial density field.
The production of dark relics from the decay of the primordial inflaton condensate must always be considered when building models of the very early Universe. Even in the absence of direct couplings, dark matter and radiation can be produced from the gravitational interaction between the dark and inflaton sectors. In this talk I will discuss the non-equilibrated production of scalar dark matter during inflation and (p)reheating in the weakly and strongly coupled regimes, combining perturbative (Boltzmann) and non-perturbative (Hartree/Lattice) approaches. For weak (strong) coupling I will present the corresponding phase space distributions and show how the relic abundance is dominantly populated during inflation (reheating). Relic abundance, reheating, and structure formation constraints from the observation of the Lyman-$\alpha$ forest will be presented and discussed in detail.
We study the E and B mode polarisation of the cosmic microwave background (CMB) originating from the transverse peculiar velocity of free electrons during reionisation and post reionisation era. Interestingly, apart from having a blackbody part, the spectrum also contains a Sunyaev Zel'dovich (SZ) type (y-type) distortion, which makes it distinguishable from primordial polarisation as well as from other secondary sources, such as gravitational lensing. Furthermore, it is also differentiable from other y-type signals such as from the thermal SZ effect as it involves polarised radiation. The E and B modes of y-type distortion provide a way to beat the cosmic variance of primary CMB anisotropies and are an independent measurement of the cosmological parameters.
In this talk I will introduce a new CMB lensing power spectrum estimator for deep polarisation surveys. Thanks to the B modes of polarisation produced by gravitational lensing, upcoming surveys will optimally reconstruct the lensing field by iteratively delensing the observed polarisation maps. I will show that despite the increased complexity of the reconstructed lensing map, its power spectrum shares similarities to the state-of-the-art quadratic estimator. I will demonstrate that this new spectrum estimator and its likelihood are robust to modelling biases and can improve the signal to noise ratio of the lensing amplitude by 80% while keeping the numerical cost under control. This new lensing estimator can improve the constraints on a combination of cosmological parameters of interest, including the neutrino mass, by 30%.
We discuss compact stars consisting of cold quark matter and fermionic dark matter treated as two admixed fluids. After the computation of the stellar structure and fundamental radial oscillation frequencies for different masses of the dark fermion in the cases of weak and strong self-interacting dark matter, we show that the fundamental frequency can be dramatically modified and, in some cases, stable dark strange planets and dark strangelets with very low masses and radii can be formed. We also discuss effects from a strong magnetic field.
We address the issue of black hole scalarization and its compatibility with cosmic inflation and big bang cosmology from an effective field theory (EFT) point of view. In practice, using a well-defined and healthy toy model which (in part) has been broadly considered in the literature, we consider how higher-order theories of gravity, up to cubic operators in Riemann curvature, fit within this context. Interestingly enough, we find that already at this minimal level, there is a non-trivial interplay between the Wilson coefficients which are otherwise completely independent, constraining the parameter space where scalarization may actually occur. Conclusively, we claim that the EFT does exhibit black hole scalarization, remaining compatible with the inflationary paradigm, and admitting General Relativity as a cosmological attractor.