Progress on Old and New Themes in cosmology (PONT) 2014

Session

Afternoon session

14 Apr 2014, 15:15

Chambre du Trésorier (Palais des Papes, Avignon)

65. Closing in on Axion Dark Matter

Javier Redondo (LMU/MPP Munich)

14/04/2014, 15:15

The axion is well motivated dark matter candidate with a very different phenomenology than WIMPs. It is produced non-thermally in the early universe and its low mass, $m_a<$meV, and feeble interactions makes its detection very demanding, requiring highly specialised experiments for even slightly different axion masses. In this talk I review the predictions for the axion mass focusing on the...

34. UV-completing Ghost Inflation

Sergey Sibiryakov (CERN & EPFL)

14/04/2014, 15:45

Astroparticles

We present a setup that provides a UV-completion of the ghost inflation model up to a scale which can be almost as high as the Planck mass. This is achieved by coupling the inflaton to the Lorentz-violating sector described by the Einstein-aether theory or its khronometric version. Compared to previous works on ghost inflation our setup allows to go beyond the study of small perturbations and...

20. The full CMB temperature bispectrum from single-field inflation

Dr Filippo Vernizzi (IPhT, CEA/Saclay)

14/04/2014, 16:05

CMB non-Gaussianity can be used to discriminate between models of the early universe. However, to correctly measure a primordial signal we must remove any contamination from intrinsic non-linear effects intervening between the initial conditions and the CMB anisotropies. I will compute these effects, first when one of the momenta is much smaller than the others (squeezed limit) and then with a...

38. Minimal models for inflation

Fedor Bezrukov (UConn & CERN & BNL)

14/04/2014, 16:55

Experimental results of the past several years favor the very minimal inflationary models. I will discuss some realizations of inflation in minimal extensions of the Standard Model, where no new scales are present between the Electroweak scale and inflationary scale and the amount of new particles is minimal -- Higgs inflation, $R^2$ inflation, non-minimally coupled inflation with light...

36. Non-gaussian imprints of primordial magnetic fields from inflation

Rajeev Kumar Jain (CP3-Origins)

14/04/2014, 17:15

If cosmic magnetic fields are produced during inflation, they are likely to be correlated with the primordial curvature perturbations that are responsible for the Cosmic Microwave Background anisotropies and Large Scale Structure. We compute the three-point cross-correlation function of the curvature perturbation with two powers of the electromagnetic field in a typical model of inflationary...

30. Searching for primordial correlations between the magnetic field and the density perturbation using \mu-distortion

Mr Jonathan Ganc (CP3-Origins, University of Southern Denmark)

14/04/2014, 17:35

Damping of non-uniform magnetic field between redshifts of about $10^4$ and $10^6$ cause the observed CMB to deviate from a perfect blackbody spectrum, producing a so-called $\mu$-distortion. This allows us to search for a correlation $\langle\zeta B^2\rangle$ between the magnetic field $B$ and the density perturbation $\zeta$ by looking for a $\mu T$ correlation in the CMB, where $T$ is the...

29. A new consequence of Inflation: Imprinting the Standard Model in the sky

daniel figueroa

14/04/2014, 17:55

The existence of the Standard Model (SM) Higgs implies that a gravitational wave (GW) background is generated, soon after the end of inflation, by the decay products of the Higgs. Theoretically all Yukawa and SU(2) gauge couplings of the SM are imprinted as features in the GW spectrum. In practice, the signal from the most strongly coupled species dominates, rendering inaccesible the...

18. Gaia: science and status - and an update on ultra-faint feedback

Gerry Gilmore (Institute of Astronomy, cambridge,UK)

15/04/2014, 14:30

Gaia is in orbit, well into commissioning. I will will give an overview of Gaia's status, and potential to quantify mass distributions on interesting scales. i shall also briefly summarise recent work on chemical evolution in ultrafaint dSph galaxies, and the implications for feedback as a mechanism to perturb - or not - dark matter cusps and cores.

13. Primordial black holes as dark matter candidates: closing the remaining mass window

Peter Tinyakov (U)

15/04/2014, 15:00

Primordial black holes (PBH), if they constitute a fraction of dark matter, can be captured by compact stars and lead to a rapid destruction of the latter. Thus, a mere observation of neutron stars and white dwarfs implies constraints on the PBH abundance. We will consider capture of BPH both at the stage of formation of the star and during its lifetime, and derive corresponding constraints.

11. Dark Matter Interpretations of Extended Gamma Ray Emission towards the Galactic Center

Dr Shunsaku Horiuchi (UC Irvine)

15/04/2014, 15:20

We construct empirical models of the diffuse gamma-ray background towards the Galactic Center. Including all known point sources and a template of emission associated with interactions of cosmic rays with molecular gas, we show that the extended emission observed by the Fermi Gamma Ray Telescope toward the Galactic Center is detected at high significance for all permutations of the diffuse...

7. Internal bremsstrahlung signatures of Dark Matter annihilations in light of direct detection and collider searches

Mathias Garny (CERN)

15/04/2014, 15:40

If dark matter annihilates into light fermions mediated by colored or charged scalar particles, the effect of internal bremsstrahlung yields a sharp spectral feature in the gamma spectrum. This line-like feature could be detetcted in the cosmic gamma-ray flux by current and future observatories, while being in agreement with constraints from secondary gamma-rays and antiprotons. We discuss...

4. Recent results from the LUX dark matter search

Simon Fiorucci (Brown University)

15/04/2014, 16:00

We will present recent results from the LUX experiment, including the first dark matter search results made public in November 2013, as well as the results of additional studies of relevance to the field.

21. Indirect Search for Dark Matter with the ANTARES Neutrino Telescope

Vincent Bertin (Centre National de la Recherche Scientifique (FR))

15/04/2014, 16:50

The ANTARES Collaboration is operating the largest water Cherenkov neutrino telescope in the Northern hemisphere, installed in the Mediterranean Sea offshore France. One major goal of ANTARES is the search for neutrinos produced in self-annihilation of Dark Matter particles, for instance in the direction of the Sun or the Galactic Centre. The results on the search for Dark Matter...

22. Probing Nu-Forces at IceCube

Ian Shoemaker (Los Alamos)

15/04/2014, 17:10

The IceCube experiment has recently detected the highest-energy neutrino events yet recorded. This data is remarkable both for the significant excess of neutrino events above known backgrounds, and also for the conspicuous lack of events both above and below 1 PeV. I’ll discuss a simple model of neutrino self-interactions mediated by a MeV-scale boson that can account for these peculiar...

6. Anti-nuclei from Dark Matter

Andrea Vittino (Universita' di Torino and IPhT/CEA Saclay)

15/04/2014, 17:30

Light anti-nuclei, namely anti-deuteron and anti-helium, can be produced through the nuclear coalescence of the anti-protons and the anti-neutrons that are originated in a dark matter pair annihilation event. At low kinetic energies, the fluxes of these bound states are found to dominate over the astrophysical background and thus anti-nuclei may be considered as a very promising channel for a...

57. Search for Ultra-high energy neutrinos at the Pierre Auger Observatory:

Francesco Salamida (Institut de Physique Nucléaire d'Orsay)

15/04/2014, 17:50

Neutrinos in the sub-EeV energy range and above can be detected with the Surface Detector array (SD) of the Pierre Auger Observatory. They can be identified through the broad time-structure of the signals expected to be induced in the SD stations. The identification can be done for neutrinos of all flavours interacting in the atmosphere at large zenith angles, in the ranges 60-75 deg and 75-90...

28. Higher order dark matter annihilations in the Sun and implications for IceCube

Maximilian Totzauer (Technische Universität München)

15/04/2014, 18:10

Dark matter particles that have been captured inside the Sun can annihilate producing high-energy neutrinos which would be a smoking-gun signal if observed in terrestrial neutrino detectors such as IceCube. Annihilation channels like $e^+e^-$ or $\mu^+ \mu^-$, or $q \bar{q}$ however, only produce neutrinos in the MeV range due to the interaction of the annihilation products with the solar...

31. Dark matter annihilations and decays after the AMS-02 positron measurements

Anna Lamperstorfer (TUM)

15/04/2014, 18:20

We use the new positron data from the AMS-02 experiment to set limits on dark matter annihilations and decays in different channels. In this work it is assumed that the positron background consists of secondary positrons from spallations and an additional primary component of astrophysical origin. We show that the positron flux and the positron fraction give competitive limits on the dark...

10. Non-local gravity and dark energy

Michele Maggiore (University of Geneva)

16/04/2014, 14:30

We discuss recent work on non-local modifications of gravity obtained adding a term $m^2 R\Box^{-2}R$ to the Einstein-Hilbert action. We find that, despite the presence of a mass parameter, the resulting theory has no ghost, no vDVZ discontinuity, and no no Vainshtein radius below which the theory becomes strongly coupled. For $m$ of order $H_0$ the theory therefore recovers all successes...

37. Dark Energy phenomenology: the effective field theory approach

Dr Federico Piazza (APC)

16/04/2014, 15:00

The discovery of the accelerating expansion of the Universe is motivating an impressive amount of theoretical and observational activity. I will focus on recent and ongoing works that aim at a unifying description of dark energy and modified gravity models containing a scalar degree of freedom in addition to general relativity. Such an effective field theory approach allows, on the one hand, a...

49. On the non-linear scale of cosmological perturbation theory

Thomas Konstandin (DESY, Hamburg)

16/04/2014, 15:30

I discuss the use of perturbative methods to study the evolution of matter fluctuations in the context of large scale structure formation. After an short introduction, I compare several techniques in perturbation theory as renormalized perturbation theory, the eikonal approximation and Pade resummation.

2. Large-scale structures in some modified-gravity scenarios

Patrick Valageas (CEA)

16/04/2014, 16:00

We study the effects of screened modified gravity of the $f(R)$, dilaton and symmetron types on structure formation, from the quasi-linear to the non-linear regime, using semi-analytical methods. For such models, where the range of the new scalar field is typically within the Mpc range and below in the cosmological context, non-linear techniques are required to understand the deviations of the...

32. Cosmological constraints on Lorentz Invariance of the Universe

Mikhail Ivanov (Moscow State University)

16/04/2014, 16:50

Lorentz Invariance is believed to be a fundamental property of Nature. However, recently this assertion has come under scrutiny, which is motivated on one hand by the Lorentz-violating proposals for quantum gravity and on the other hand, by the fact that Lorentz Invariance has been tested with ultimately high precision only in the sector of Standard Model of particles. For other sectors the...

14. Dark D-brane Cosmology

Tomi Koivisto (Nordita)

16/04/2014, 17:10

The talk is about the possibility of matter residing on a brane moving in extra dimensions. Such matter would be disformally coupled to gravity. Due to a screening mechanism, the coupling could be viable even in the visible sector. The Dirac-Born-Infeld set-up in type II string theory is used to illustrate how the coupling functions can be explicitly deduced from the higher dimensional...

68. Consistency relations for large scale structure

Jérôme GLEYZES

16/04/2014, 17:30

Consistency relations for large scale structure are relations between an n-point and an (n+1)-point correlation function of the matter or galaxy distribution, in the limit in which one of the momenta is much smaller than the others. I will show that these relations are non perturbative in the small modes. Moreover, since they are consequence of the Equivalence Principle, their violation can be...

23. Backreaction in Swiss Cheese models

Mikko Lavinto (University of Helsinki)

16/04/2014, 17:40

Inhomogeneous cosmological models are often constructed using the Swiss Cheese scheme. I will show that under certain physical assumptions, backreaction must always be small in these models. However, it is possible to break one of these conditions to construct a consistent (but un-physical) solution where backreaction can be large. Finally I will discuss how supernova observations would be...

24. Beyond single stream with the Schrödinger method

Mrs Cora Uhlemann (Arnold Sommerfeld Center for Theoretical Physics, LMU)

16/04/2014, 17:50

We investigate large scale structure formation of collisionless dark matter in the phase-space description based on the Vlasov (or collisionless Boltzmann) equation whose nonlinearity is induced solely by gravitational interaction according to the Poisson equation. Determining the time-evolution of density and peculiar velocity demands solving the full Vlasov hierarchy for the moments of the...

41. Probing non-standard gravity with the growth index of cosmologicl perturbations

Mr Heinrich Steigerwald (Aix-Marseille University / Centre de Physique Théorique)

16/04/2014, 18:00

The growth index of cosmological perturbations is one of the most powerful probes of the nature of Dark Energy (DE), the mysterious mechanism driving the late epoch acceleration of the universe. Unlike classical geometrical observables, such as distances, which only probe the background sector of a cosmological model, this observable provides insight into first order dynamical effects, and it...

42. Probing the power spectrum of matter with the galaxy clustering ratio

Julien Bel (Osservatorio Astronomico di Brera)

16/04/2014, 18:10

The galaxy clustering ratio (Bel & Marinoni 2014 A&A, 563, 36, Bel et al. 2014 A&A 563, 37) is a new clustering statistic that provides access to characteristic parameters of the power spectrum of mass density fluctuations without the need to specify the galaxy biasing function nor a model for peculiar velocity distortions. I will demonstrate the method using galaxy simulations as...

3. A new approach to chameleon theories

Dr Lucila Kraiselburd (Facultad de Ciencias Astronomicas y Geofisicas-Universidad Nacional de La Plata, Argentina)

16/04/2014, 18:20

Most theories that predict time and/or space variation of fundamental constants also predict violations of the Weak Equivalence Principle (WEP). Khoury and Weltmann proposed the chameleon model in 2004 and claimed that this model avoids experimental bounds on WEP. Mota and Shaw analized the non-linear regime and concluded that only this case predicts no violations of the WEP while the linear...

16. Massive black holes and galaxy formation: state of the art and implications in cosmology

marta volonteri

17/04/2014, 14:30

Massive black holes, weighing millions to billions of solar masses, inhabit the centers of today's galaxies. The progenitors of these black holes powered luminous quasars within the first billion years of the Universe. The first massive black holes must therefore have formed around the time the first stars and galaxies appeared and then evolved along with their hosts for the past thirteen...

19. Supermassive black holes, gravitational waves and cosmology

Dr Alberto Sesana (Albert Einstein Institute)

17/04/2014, 15:00

Within this decade the detection of gravitational waves (GWs) may be a reality, opening a completely new window on the Universe. The low frequency window will be dominated by signals emitted by a cosmological population of massive black hole binaries (MBHBs). I will review several aspect of MBH physics, including their formation, evolution, interaction with their environment and gravitational...

15. Cosmology with the 21 cm line

Yi Mao (Institut d'Astrophysique de Paris)

17/04/2014, 15:30

Three-dimensional mapping of neutral hydrogen gas at the high redshift using the redshifted 21 cm line has recently emerged as a promising cosmological probe. I will discuss the prospects for constraining cosmological parameters, including those beyond the standard LCDM model, using the 21 cm line.

26. Measuring relativistic effects with anti-symmetric galaxy correlations

Camille Bonvin (University of Cambridge)

17/04/2014, 16:00

In the past few years it has been shown that the two-point correlation function of galaxies is affected by relativistic effects at large scales. Various terms like gravitational redshift, Doppler effects or time delay corrections induce subtle changes in the correlation function. These effects are however subdominant at all but the largest scales, rendering their detection challenging. In this...

48. Dark Energy Survey: Status Report and Early Cluster Science

August Evrard (University of Michigan)

17/04/2014, 16:50

The Dark Energy Survey (DES) is in the early phases of a five-year project to survey 5000 sq degrees of sky to ~24th mag in 5 optical bands and employ the data to test cosmic acceleration using weak lensing, supernovae, galaxy clustering and clusters of galaxies. I will present a status summary of DES and provide some examples of early science, particularly focused on clusters of galaxies.

33. Cosmic variance on the local expansion rate.

Wessel Valkenburg (Leiden University)

17/04/2014, 17:10

The local expansion rate as observed by for example the HST, is not the same as the global expansion rate in the FLRW metric. In a standard LCDM universe, the effect of local dynamics on the apparent expansion rate turns out to be significant, especially compared to the tight error bars in today's precision cosmology. I show how the linear power spectrum of perturbations gives a...

25. Cosmology with photometric quasars

Mr Boris Leistedt (University College London)

17/04/2014, 17:30

Quasars are highly biased tracers of the large-scale structure and therefore powerful probes of the initial conditions and the evolution of the universe. However, current spectroscopic catalogues are too small for studying the clustering of quasars on large-scales and over extended redshift ranges. Hence one must resort to photometric catalogues, which include large numbers of quasars...

39. Probing beyond standard model physics via Hawking radiated gravitational waves

Mr Tomohiro Fujita (Kavli IPMU, Tokyo University)

17/04/2014, 17:50

We propose a novel technique to probe the high energy physics beyond the standard model (BSM). By observing gravitational waves emitted by the Hawking radiation of black holes, we can scan the unknown high energy physics for the following reasons. (i) A particles is emitted by black holes only if its mass is smaller than the Hawking temperature $T_{BH}$ of a black hole. (ii) Since a black...