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On the role of AGN feedback on the thermal and chemodynamical properties
of the hot intra-cluster medium: We present an analysis of the properties of the ICM in an extended set of
cosmological hydrodynamical simulations of galaxy clusters and groups performed
with the TreePM+SPH GADGET-3 code. Besides a set of non-ra... | Observing the molecular composition of galaxies: The recent availability of wideband receivers and high sensitivity
instruments in the mm and submm wavelengths has opened the possibility of
studying in detail the chemistry of the interstellar medium in extragalactic
objects. Within the central few hundred parsec of gal... |
Optimal 1D Ly-$α$ Forest Power Spectrum Estimation I: DESI-Lite
Spectra: The 1D Ly-$\alpha$ forest flux power spectrum $P_{\mathrm{1D}}$ is sensitive
to scales smaller than a typical galaxy survey, and hence ties to the
intergalactic medium's thermal state, suppression from neutrino masses and new
dark matter models.... | Recovering cores and cusps in dark matter haloes using mock velocity
field observations: We present mock DensePak Integral Field Unit (IFU) velocity fields, rotation
curves, and halo fits for disc galaxies formed in spherical and triaxial cuspy
dark matter haloes, and spherical cored dark matter haloes. The simulated... |
Radiative transfer of Lyman-$α$ photons at cosmic dawn with
realistic gas physics: The cosmic dawn 21-cm signal is enabled by Ly~$\alpha$ photons through a
process called the Wouthuysen-Field effect. An accurate model of the signal in
this epoch hinges on the accuracy of the computation of the Ly~$\alpha$
coupling, w... | A thermally stable heating mechanism for the intracluster medium:
turbulence, magnetic fields and plasma instabilities: We consider the problem of self-regulated heating and cooling in galaxy
clusters and the implications for cluster magnetic fields and turbulence.
Viscous heating of a weakly collisional magnetised p... |
CMB at small scales: Cosmology from tSZ power spectrum: Small scale CMB angular power spectrum contains not only primordial CMB
information but also many contaminants coming from secondary anisotropies. Most
of the latter depend on the cosmological model but are often marginalised over.
We propose a new analysis of the... | Incorporating galaxy cluster triaxiality in stacked cluster weak lensing
analyses: Counts of galaxy clusters offer a high-precision probe of cosmology, but
control of systematic errors will determine the accuracy of this measurement.
Using Buzzard simulations, we quantify one such systematic, the triaxiality
distribu... |
Isotropic N-Point Basis Functions and Their Properties: Isotropic functions of positions $\hat{\bf r}_1, \hat{\bf r}_2,\ldots,
\hat{\bf r}_N$, i.e. functions invariant under simultaneous rotations of all
the coordinates, are conveniently formed using spherical harmonics and
Clebsch-Gordan coefficients. An orthonormal b... | SDSS DR17: The Cosmic Slime Value Added Catalog: The "cosmic web", the filamentary large-scale structure in a cold dark matter
Universe, is readily apparent via galaxy tracers in spectroscopic surveys.
However, the underlying dark matter structure is as of yet unobservable and
mapping the diffuse gas permeating it lies... |
Evaporating primordial black holes as varying dark energy: If light enough primordial black holes (PBH) account for dark matter, then
its density decreases with time as they lose mass via Hawking radiation. We
show that this time-dependence of the matter density can be formulated as an
equivalent $w(z)$ dark energy mod... | A Search for Axionic Dark Matter Using the Magnetar PSR J1745-2900: We report on a search for dark matter axion conversion photons from the
magnetosphere of the Galactic Center magnetar PSR J1745-2900 using spectra
obtained from the Karl G. Jansky Very Large Array. No significant spectral
features are detected. Using a... |
Radiative stability and observational constraints on dark energy and
modified gravity: We investigate the radiative stability of Horndeski scalar-tensor theories
with luminally propagating gravitational waves (as extensively discussed in the
wake of GW170817) and show that in general there is a tension between obtain... | Probing modified gravity theories with multiple measurements of
high-redshift quasars: In this paper, we quantify the ability of multiple measurements of
high-redshift quasars (QSOs) to constrain several theories of modified gravity,
including the Dvali-Gabadadze-Porrati braneworld scenario, generalized
Chaplygin gas... |
On Synthetic Gravitational Waves from Multi-field Inflation: We revisit the possibility of producing observable tensor modes through a
continuous particle production process during inflation. Particularly, we focus
on the multi-field realization of inflation where a spectator pseudo-scalar
$\sigma$ induces a significan... | Bayesian Estimation of the D(p,$γ$)$^3$He Thermonuclear Reaction
Rate: Big bang nucleosynthesis (BBN) is the standard model theory for the
production of the light nuclides during the early stages of the universe,
taking place for a period of about 20 minutes after the big bang. Deuterium
production, in particular, is... |
Measuring the speed of light with updated Hubble diagram of
high-redshift standard candles: The possible time variation of the fundamental constants of nature has been
an active subject of research in modern physics. In this paper, we propose a
new method to investigate such possible time variation of the speed of li... | Zooming in on accretion - I. The structure of halo gas: We study the properties of gas in and around 10^12 solar mass halos at z=2
using a suite of high-resolution cosmological hydrodynamic 'zoom' simulations.
We quantify the thermal and dynamical structure of these gaseous reservoirs in
terms of their mean radial dist... |
Gas Accretion is Dominated by Warm Ionized Gas in Milky Way-Mass
Galaxies at z ~ 0: We perform high-resolution hydrodynamic simulations of a Milky Way-mass
galaxy in a fully cosmological setting using the adaptive mesh refinement code,
Enzo, and study the kinematics of gas in the simulated galactic halo. We find
that... | Mergers of primordial black holes in extreme clusters and the $H_0$
tension: We consider a cosmological model with dark matter in the form of
$\sim10^{-12}M_\odot$ primordial black holes in dense weakly relativistic
clusters with masses $18-560M_\odot$. It is shown that during the multiple
collisions of the black hol... |
Constraining the interacting dark energy models from weak gravity
conjecture and recent observations: We examine the effectiveness of the weak gravity conjecture in constraining
the dark energy by comparing with observations. For general dark energy models
with plausible phenomenological interactions between dark sec... | What collisional debris can tell us about galaxies: I review what tidal tails in particular, collisional debris in general, might
tell us about galaxies (their structure, current content and past mass
assembly) about mergers in the nearby and distant Universe (major vs minor, wet
vs dry, number evolution) and finally a... |
Comparing different realizations of modified Newtonian dynamics: virial
theorem and elliptical shells: There exists several modified gravity theories designed to reproduce the
empirical Milgrom's formula (MOND). Here we derive analytical results in the
context of the static weak-field limit of two of them (BIMOND, le... | Pseudoscalar sterile neutrino self-interactions in light of Planck, SPT
and ACT data: We reassess the viability of a cosmological model including a fourth
additional sterile neutrino species that self-interacts through a new
pseudoscalar degree of freedom. We perform a series of extensive analyses
fitting various com... |
Defrosting in an Emergent Galileon Cosmology: We study the transition from an Emergent Galileon condensate phase of the
early universe to a later expanding radiation phase. This "defrosting" or
"preheating" transition is a consequence of the excitation of matter
fluctuations by the coherent Galileon condensate, in anal... | An Alternative String Landscape Cosmology: Eliminating Bizarreness: In what has become a standard eternal inflation picture of the string
landscape there are many problematic consequences and a difficulty defining
probabilities for the occurrence of each type of universe. One feature in
particular that might be philoso... |
The anatomy of an extreme starburst within 1.3Gyr of the Big Bang
revealed by ALMA: We present further analysis of the [CII] 158$\mu$m fine structure line and
thermal dust continuum emission from the archetype extreme starburst/AGN group
of galaxies in the early Universe, BRI 1202-0725 at $z=4.7$, using the Atacama
L... | The DEHVILS Survey Overview and Initial Data Release: High-Quality
Near-Infrared Type Ia Supernova Light Curves at Low Redshift: While the sample of optical Type Ia Supernova (SN Ia) light curves (LCs)
usable for cosmological parameter measurements surpasses 2000, the sample of
published, cosmologically viable near-i... |
Lagrangian cosmological perturbation theory at shell-crossing: We consider the growth of primordial dark matter halos seeded by three
crossed initial sine waves of various amplitudes. Using a Lagrangian treatment
of cosmological gravitational dynamics, we examine the convergence properties
of a high-order perturbative ... | On the use of the local prior on the absolute magnitude of Type Ia
supernovae in cosmological inference: A dark-energy which behaves as the cosmological constant until a sudden
phantom transition at very-low redshift ($z<0.1$) seems to solve the >4$\sigma$
disagreement between the local and high-redshift determinatio... |
Simulated Analogs of Merging Galaxy Clusters Constrain the Viewing Angle: A key uncertainty in interpreting observations of bimodal merging galaxy
clusters is the unknown angle between the subcluster separation vector and the
plane of the sky. We present a new method for constraining this key parameter.
We find analogs... | Constraints on Dark Energy from New Observations including Pan-STARRS: In this paper, we set the new limits on the equation of state parameter (EoS)
of dark energy with the observations of cosmic microwave background radiation
(CMB) from Planck satellite, the type Ia supernovae from Pan-STARRS and the
baryon acoustic o... |
Observational challenges in dark energy models: Cosmological distances inferred from supernova Ia observations constitute the
most direct and solid evidence for the recently detected accelerated expansion
of the universe. In this contribution, we show some inconsistencies between two
of the main light-curve fitters use... | Understanding WIMP-baryon interactions with direct detection: A Roadmap: We study prospects of dark-matter direct-detection searches for probing
non-relativistic effective theory for WIMP-baryon scattering. We simulate a
large set of noisy recoil-energy spectra for different scattering scenarios
(beyond the standard mo... |
Coincidence problem within dark energy as a coupled self-interacting
Bose-Einstein gas: A late accelerated expansion of the Universe is obtained from
non-relativistic particles with a short-range attractive interaction, and low
enough temperature to produce a Bose-Einstein condensate; by considering
coupled dark-ener... | The cosmic radio dipole: Bayesian estimators on new and old radio
surveys: The cosmic radio dipole is an anisotropy in the number counts of radio
sources, analogous to the dipole seen in the cosmic microwave background (CMB).
Measurements of source counts of large radio surveys have shown that though the
radio dipole... |
The Properties of the Interstellar Medium within a Star-Forming Galaxy
at z=2.3: We present an analysis of the molecular and atomic gas emission in the
rest-frame far-infrared and sub-millimetre, from the lensed z=2.3
sub-millimetre galaxy SMM J2135-0102. We obtain very high signal-to-noise
detections of 11 transitio... | Probing the Growth of Massive Black Holes with Black Hole-Host Galaxy
Spin Correlations: Supermassive black holes (SMBHs) are commonly found at the centers of their
host galaxies, but their formation still remains an open question. In light of
the tight correlation between the BH mass and the velocity dispersions of ... |
Probing non-Gaussian Stochastic Gravitational Wave Backgrounds with LISA: The stochastic gravitational wave background (SGWB) contains a wealth of
information on astrophysical and cosmological processes. A major challenge of
upcoming years will be to extract the information contained in this background
and to disentang... | Galaxy-Scale Outflows Driven by Active Galactic Nuclei: We present hydrodynamical simulations of major mergers of galaxies and study
the effects of winds produced by active galactic nuclei (AGN) on interstellar
gas in the AGN's host galaxy. We consider winds with initial velocities ~
10,000 km/s and an initial momentum... |
Lensed Cosmic Microwave Background Constraints on Post-General
Relativity Parameters: The constraints on departures from general relativity (GR) at cosmological
length scales due to cosmic microwave background (CMB) data are discussed. The
departure from GR is measured by the ratio, parameterized as $1 +\varpi_0 (1 +... | Cluster-Void Degeneracy Breaking: Dark Energy, Planck and the Largest
Cluster & Void: Combining galaxy cluster and void abundances breaks the degeneracy between
mean matter density $\Omega_{\rm m}$ and power spectrum normalization
$\sigma_8$. In a first for voids, we constrain $\Omega_{\rm m} = 0.21 \pm 0.10$
and $\s... |
Cosmological model-independent constraints on spatial curvature from
strong gravitational lensing and type Ia supernova observations: Applying the distance sum rule in strong gravitational lensing (SGL) and type
Ia supernova (SN Ia) observations, one can provide an interesting cosmological
model-independent method to... | Discovery of nine extended ionized gas clouds in a z=0.4 cluster: From deep H-alpha imaging data of Suprime-Cam/Subaru, we discovered nine
extended ionized gas clouds (EIG) around galaxies in Abell 851 cluster (A851)
at z=0.4. We surveyed 30 x 25 arcmin region, and the EIGs were found only near
the cluster center (<2.3... |
The synergy between the Dark Energy Survey and the South Pole Telescope: The Dark Energy Survey (DES) has recently completed the Science Verification
phase (SV), collecting data over 150 sq. deg. of sky. In this work we analyze
to what extent it is beneficial to supplement the analysis of DES data with CMB
lensing data... | Astrophysical Tests of Modified Gravity: Chameleon and similar (symmetron and dilation) theories of gravity can
exhibit new and interesting features on cosmological scales whilst screening
the modifications on small scales thereby satisfying solar system tests of
general relativity. This thesis explores the regime betw... |
Green Pea Galaxies and cohorts: Luminous Compact Emission-Line Galaxies
in the Sloan Digital Sky Survey: We present a large sample of 803 star-forming luminous compact galaxies
(LCGs) in the redshift range z = 0.02-0.63, selected from Data Release 7 of the
Sloan Digital Sky Survey (SDSS). The global properties of the... | On the Nature of Unconfirmed Supernovae: We study the nature of 39 unconfirmed supernovae (SNe) from the sky area
covered by the Sloan Digital Sky Survey (SDSS) Data Release 8 (DR8), using
available photometric and imaging data and intensive literature search. We
confirm that 21 objects are real SNe, 2 are Galactic sta... |
On the relativistic mass function and averaging in cosmology: The general relativistic description of cosmological structure formation is
an important challenge from both the theoretical and the numerical point of
views. In this paper we present a brief prescription for a general relativistic
treatment of structure for... | Cosmological Consequences of Exponential Gravity in Palatini Formalism: We investigate cosmological consequences of a class of exponential $f(R)$
gravity in the Palatini formalism. By using the current largest type Ia
Supernova sample along with determinations of the cosmic expansion at
intermediary and high-$z$ we imp... |
Erratum: Nonlinear spherical perturbations in quintessence models of
dark energy: We reported results of our study on non-linear spherical perturbations in
quintessence models of dark energy. In the process of some follow up studies we
discovered that a scaling factor in the code used for numerical calculations
that ... | Assessing the redshift evolution of massive black holes and their hosts: Motivated by recent observational results that focus on high redshift black
holes, we explore the effect of scatter and observational biases on the ability
to recover the intrinsic properties of the black hole population at high
redshift. We find ... |
Cosmological Magnetic Fields from Inflation and Backreaction: We study the backreaction problem in a mechanism of magnetogenesis from
inflation. In usual analysis, it has been assumed that the backreaction due to
electromagnetic fields spoils inflation once it becomes important. However,
there exists no justification f... | A Possible Detection of the Cosmic Antineutrino Background in the
Presence of Flavor Effects: Lusignoli and Vignati have recently pointed out that it is in principle
possible to directly detect the cosmic antineutrino background by using the
rather stable isotope holmium-163 as a target, which can decay into
dysprosi... |
The filling factor of intergalactic metals at redshift z=3: Observations of quasar absorption line systems reveal that the z=3
intergalactic medium (IGM) is polluted by heavy elements down to HI optical
depths tau_HI<<10. What is not yet clear, however, is what fraction of the
volume needs to be enriched by metals and ... | Non-Gaussian Probability Distribution for the CMB Angular Power Spectra?: This is my contribution to Proceedings of the International Workshop on
Cosmic Structure and Evolution, September 23-25, 2009, Bielefeld, Germany. In
my talk I presented some non-Gaussian features of the foreground reduced WMAP
five year full sky... |
On the possibility of braneworld quintessential inflation: We examine the possibility of achieving quintessential inflation, where the
same field serves as both inflaton and quintessence, in the context of a
five-dimensional braneworld. Braneworld cosmology provides an appropriate
environment as it permits inflation wi... | G2C2 I: Homogeneous SDSS photometry for Galactic GCs: We present $g^\prime$ and $z^\prime$ aperture photometry for 96 Galactic
Globular Clusters, making this the largest homogeneous catalog of photometry
for these objects in the SDSS filter system. For a subset of 56 clusters we
also provide photometry in $r^\prime$ an... |
Cosmology and Fundamental Physics and their Laboratory Astrophysics
Connections: The Decadal Survey of Astronomy and Astrophysics created five panels to
identify the science themes that would define the field's research frontiers in
the coming decade. I will describe the conclusions of one of these, the Panel
on Cosm... | Simulations of the Sunyaev-Zel'dovich Power Spectrum with AGN Feedback: We explore how radiative cooling, supernova feedback, cosmic rays and a new
model of the energetic feedback from active galactic nuclei (AGN) affect the
thermal and kinetic Sunyaev-Zel'dovich (SZ) power spectra. To do this, we use a
suite of hydrod... |
Cosmological Constraints from Measurements of Type Ia Supernovae
discovered during the first 1.5 years of the Pan-STARRS1 Survey: We present griz light curves of 146 spectroscopically confirmed Type Ia
Supernovae ($0.03 < z <0.65$) discovered during the first 1.5 years of the
Pan-STARRS1 Medium Deep Survey. The Pan-S... | Ultra-low frequency gravitational waves from cosmological and
astrophysical processes: Gravitational waves (GWs) at ultra-low frequencies (${\lesssim
100\,\mathrm{nHz}}$) are key to understanding the assembly and evolution of
astrophysical black hole (BH) binaries with masses $\sim
10^{6}-10^{9}\,M_\odot$ at low reds... |
Cosmology with massive neutrinos I: towards a realistic modeling of the
relation between matter, haloes and galaxies: By using a suite of large box-size N-body simulations that incorporate
massive neutrinos as an extra set of particles, we investigate the impact of
neutrino masses on the spatial distribution of dark ... | Pursuing the Amplitude of Tensor Mode Power Spectrum in Light of BICEP2: In this brief report, we try to constrain general parameterized forms of
scalar and tensor mode power spectra, $P_{s}(k)\equiv
A_s(k/k_0)^{n_s-1+\frac{1}{2}\alpha_s\ln(k/k_0)}$ and $P_{t}(k)\equiv
A_t(k/k_0)^{n_t+\frac{1}{2}\alpha_t\ln(k/k_0)}$ by... |
Turbulence Modelling and Stirring Mechanisms in the Cosmological
Large-scale Structure: FEARLESS (Fluid mEchanics with Adaptively Refined Large Eddy SimulationS) is
a numerical scheme for modelling subgrid-scale turbulence in cosmological
adaptive mesh refinement simulations. In this contribution, the main features
o... | Generalised constraints on the curvature perturbation from primordial
black holes: Primordial black holes (PBHs) can form in the early Universe via the collapse
of large density perturbations. There are tight constraints on the abundance of
PBHs formed due to their gravitational effects and the consequences of their
... |
White dwarfs and revelations: We use the most recent, complete and independent measurements of masses and
radii of white dwarfs in binaries to bound the class of non-trivial modified
gravity theories, viable after GW170817/GRB170817, using its effect on the
mass-radius relation of the stars. We show that the uncertaint... | Mimetic DBI Inflation in Confrontation with Planck2018 data: We study mimetic gravity in the presence of a DBI-like term which is a
non-canonical setup of the scalar field's derivatives. We consider two general
cases with varying and constant sound speeds and construct the potentials for
both the DBI and Mimetic DBI mo... |
The ~0.9 mJy sample: A mid-infrared spectroscopic catalog of 150
infrared-luminous, 24 micron selected galaxies at 0.3<z<3.5: We present a catalog of mid-infrared (MIR) spectra of 150 infrared (IR)
luminous galaxies in the Spitzer extragalactic first look survey obtained with
IRS on board Spitzer. The sample is selec... | Massive star formation in Wolf-Rayet galaxies. III: Analysis of the O
and WR populations: (Abridged) We perform a comprehensive multiwavelength analysis of a sample of
20 starburst galaxies that show the presence of a substantial population of
Wolf-Rayet (WR) stars. In this paper we present the analysis of the O and ... |
Convergence of halo statistics: code comparison between Rockstar and
CompaSO using scale-free simulations: In this study, we perform a halo-finder code comparison between Rockstar and
CompaSO. Based on our previous analysis aiming at quantifying resolution of
$N$-body simulations by exploiting large (up to $N=4096^3$... | Growth of structure in interacting vacuum cosmologies: We examine the growth of structure in three different cosmological models
with interacting dark matter and vacuum energy. We consider the case of
geodesic dark matter with zero sound speed, where the relativistic growing mode
in comoving-synchronous gauge coincides... |
A multi-epoch spectroscopic study of the BAL quasar APM 08279+5255: I. C
IV absorption variability: Broad Absorption Lines indicate gas outflows with velocities from thousands
km/s to about 0.2 the speed of light, which may be present in all quasars and
may play a major role in the evolution of the host galaxy. The v... | Position-dependent power spectrum: a new observable in the large-scale
structure: We present a new observable, position-dependent power spectrum, to measure
the large-scale structure bispectrum in the squeezed configuration, where one
wavenumber is much smaller than the other two. The squeezed-limit bispectrum
measur... |
Measurement of the dispersion of radiation from a steady cosmological
source: The `missing baryons' of the near universe are believed to be principally in
a partially ionized state. Although passing electromagnetic waves are dispersed
by the plasma, the effect has hitherto not been utilized as a means of
detection be... | Adding helicity to inflationary magnetogenesis: The most studied mechanism of inflationary magnetogenesis relies on the
time-dependence of the coefficient of the gauge kinetic term
$F_{\mu\nu}\,{F}^{\mu\nu}$. Unfortunately, only extremely finely tuned versions
of the model can consistently generate the cosmological mag... |
Searching for large-scale structures around high-redshift radio galaxies
with Herschel: This paper presents the first results of a far-infrared search for
protocluster-associated galaxy overdensities using the SPIRE instrument
on-board the {\it Herschel} Space Observatory. Large ($\sim$400 arcmin$^{2}$)
fields surrou... | The UV Luminosity Function of star-forming galaxies via dropout
selection at redshifts z ~ 7 and 8 from the 2012 Ultra Deep Field campaign: We present a catalog of high redshift star-forming galaxies selected to lie
within the redshift range z ~ 7-8 using the Ultra Deep Field 2012 (UDF12), the
deepest near-infrared (... |
Generalized Non-Commutative Inflation: Non-commutative geometry indicates a deformation of the energy-momentum
dispersion relation $f(E)\equiv\frac{E}{pc}(\neq 1)$ for massless particles.
This distorted energy-momentum relation can affect the radiation dominated
phase of the universe at sufficiently high temperature. T... | Galaxies at z = 6 - 9 from the WFC3/IR imaging of the HUDF: We present the results of a systematic search for galaxies in the redshift
range z = 6 - 9, within the new, deep, near-infrared imaging of the Hubble
Ultra Deep Field provided by the Wide Field Camera 3 (WFC3) on HST. We have
performed full SED fitting to the ... |
The systematics of strong lens modeling quantified: the effects of
constraint selection and redshift information on magnification, mass, and
multiple image predictability: Until now, systematic errors in strong gravitational lens modeling have been
acknowledged but never been fully quantified. Here, we launch an in... | Microlensing of the broad line region in 17 lensed quasars: When an image of a strongly lensed quasar is microlensed, the different
components of its spectrum are expected to be differentially magnified owing to
the different sizes of the corresponding emitting region. Chromatic changes are
expected to be observed in t... |
Detailed abundance analysis from integrated high-dispersion
spectroscopy: Globular clusters in the Fornax Dwarf Spheroidal: Aims: We describe our newly developed approach to detailed abundance analysis
from integrated-light high-dispersion spectra of star clusters. As a pilot
project, we measure abundances of several... | LUCIFER@LBT view of star-forming galaxies in the cluster 7C 1756+6520 at
z~1.4: Galaxy clusters are key places to study the contribution of {\it nature}
(i.e. mass, morphology) and {\it nurture} (i.e.environment) in the formation
and evolution of galaxies. Recently, a number of clusters at z$>$1, i.e.
corresponding t... |
Ionization corrections in a multi-phase interstellar medium: Lessons
from a z~2 sub-DLA: We present a high resolution (FWHM=2.7 km/s), high S/N echelle spectrum for
the z = 2.26 QSO J2123-0050 and determine elemental abundances for the z = 2.06
sub-DLA in its line of sight. This high redshift sub-DLA has a complex
ki... | Effect of the Metallicity on the X-ray Emission from the Warm-Hot
Intergalactic Medium: Hydrodynamic simulations predict that a significant fraction of the gas in
the current Universe is in the form of high temperature, highly ionized plasma
emitting and absorbing primarily in the soft X-ray and UV bands, dubbed the
... |
Radio bursts from superconducting strings: We show that radio bursts from cusps on superconducting strings are linearly
polarized, thus, providing a signature that can be used to distinguish them
from astrophysical sources. We write the event rate of string-generated radio
transients in terms of observational variables... | Discovery of a compact gas-rich DLA galaxy at z = 2.2: evidences for a
starburst-driven outflow: We present the detection of Ly-alpha, [OIII] and H-alpha emission associated
with an extremely strong DLA system (N(HI) = 10^22.10 cm^-2) at z=2.207 towards
the quasar SDSS J113520-001053. This is the largest HI column de... |
The EGNoG Survey: Molecular Gas in Intermediate-Redshift Star-Forming
Galaxies: We present the Evolution of molecular Gas in Normal Galaxies (EGNoG) survey,
an observational study of molecular gas in 31 star-forming galaxies from z=0.05
to z=0.5, with stellar masses of (4-30)x10^10 M_Sun and star formation rates of
4... | CMB as a possible new tool to study the dark baryons in galaxies: Baryons constitute about 4% of our universe, but most of them are missing and
we do not know where and in what form they are hidden. This constitute the
so-called missing baryon problem. A possibility is that part of these baryons
are hidden in galactic ... |
Comparison between the Luminosity functions of X-ray and [OIII] selected
AGN: We investigate claims according to which the X-ray selection of AGN is not as
efficient compared to that based on [OIII] selection because of the effects of
X-ray absorption.We construct the predicted X-ray luminosity function both for
all ... | Cosmology With Axionic-quintessence Coupled with Dark Matter: We study the possibility of explaining the late time acceleration with an
axion field which is coupled with the dark matter sector of the energy budget
of the Universe. The axion field arises from the Ramond-Ramond sector of the
Type-IIB string theory. We st... |
Imprints of local lightcone projection effects on the galaxy bispectrum.
III Relativistic corrections from nonlinear dynamical evolution on
large-scales: The galaxy bispectrum is affected on equality scales and above by
relativistic observational effects, at linear and nonlinear order. These
lightcone effects inclu... | The Growth of Massive Black Holes in Galaxy Merger Simulations with
Feedback by Radiation Pressure: We study the growth of massive black holes (BH) in galaxies using smoothed
particle hydrodynamic simulations of major galaxy mergers with new
implementations of BH accretion and feedback. The effect of BH accretion on ... |
Intensity Mapping in the Presence of Foregrounds and Correlated
Continuum Emission: Intensity mapping has attracted significant interest as an approach to
measure the properties of the interstellar medium in typical galaxies at high
redshift. Intensity mapping measures the statistics of surface brightness as a
functi... | CFHT Legacy Ultraviolet Extension (CLUE): Witnessing Galaxy
Transformations up to 7 Mpc from Rich Cluster Cores: Using the optical data from the Wide component of the CFHT Legacy Survey, and
new ultraviolet data from GALEX, we study the colours and specific star
formation rates (SSFR) of ~100 galaxy clusters at 0.16<... |
Joint Cosmic Density Reconstruction from Photometric and Spectroscopic
Samples: We reconstruct the dark matter density field from spatially overlapping
spectroscopic and photometric redshift catalogs through a forward modelling
approach. Instead of directly inferring the underlying density field, we find
the best fit... | Dynamical Friction in a Fuzzy Dark Matter Universe: We present an in-depth exploration of the phenomenon of dynamical friction in
a universe where the dark matter is composed entirely of so-called Fuzzy Dark
Matter (FDM), ultralight bosons of mass $m\sim\mathcal{O}(10^{-22})\,$eV. We
review the classical treatment of d... |
Evidence for Shock-Shock Interaction in the Jet of CTA 102: We have found evidence for interaction between a standing and a traveling
shock in the jet of the blazar CTA 102. Our result is based in the study of the
spectral evolution of the turnover frequency-turnover flux density plane. The
radio/mm light curves were t... | The Weight of Emptiness: The Gravitational Lensing Signal of Stacked
Voids: The upcoming new generation of spectroscopic galaxy redshift surveys will
provide large samples of cosmic voids, the distinct, large underdense
structures in the universe. Combining these with future galaxy imaging surveys,
we study the prosp... |
Learning the Evolution of the Universe in N-body Simulations: Understanding the physics of large cosmological surveys down to small
(nonlinear) scales will significantly improve our knowledge of the Universe.
Large N-body simulations have been built to obtain predictions in the
non-linear regime. However, N-body simula... | Redshift Evolution in Black Hole-Bulge Relations: Testing CIV-based
Black Hole Masses: We re-examine claims of redshift evolution in black hole-bulge scaling
relations based on lensed quasars. In particular, we refine the black hole mass
estimates using measurements of Balmer lines from near-infrared spectroscopy
obt... |
The X-ray properties of typical high-redshift radio-loud quasars: We report spectral, imaging, and variability results from four new XMM-Newton
observations and two new Chandra observations of high-redshift (z > 4)
radio-loud quasars (RLQs). Our targets span lower, and more representative,
values of radio loudness than... | Constrained simulations of the local Universe with Modified Gravity: We present a methodology for constructing modified gravity (MG) constrained
simulations of the local Universe using positions and peculiar velocities from
the CosmicFlows data set. Our analysis focuses on the following MG models: the
normal branch of ... |
Revisiting the VOS model for monopoles: We revisit the physical properties of global and local monopoles and discuss
their implications in the dynamics of monopole networks. In particular, we
review the Velocity-dependent One-Scale (VOS) model for global and local
monopoles and propose physically motivated changes to i... | The Ysz--Yx Scaling Relation as Determined from Planck and Chandra: SZ clusters surveys like Planck, the South Pole Telescope, and the Atacama
Cosmology Telescope, will soon be publishing several hundred SZ-selected
systems. The key ingredient required to transport the mass calibration from
current X-ray selected clust... |
Weak Lensing Effect on CMB in the Presence of a Dipole Anisotropy: We investigate weak lensing effect on cosmic microwave background (CMB) in
the presence of dipole anisotropy. The approach of flat-sky approximation is
considered. We determine the functions $\sigma_0^2$ and $\sigma_2^2$ that
appear in expressions of th... | Mixed constraints to inflationary models: We show how to constrain inflationary models and reheating by using mixed
constraints. In particular we study the physics of the reheating phase after
inflation from observational constraints to the inflationary stage. We show
that it is possible to determine $\omega$, the equa... |
Constraints on the Optical Depth to Reionization from Balloon-Borne CMB
Measurements: We assess the uncertainty with which a balloon-borne experiment, nominally
called Tau Surveyor ($\tau S$), can measure the optical depth to reionization
$\sigma(\tau)$ with given realistic constraints of instrument noise and
foregro... | Gaussian Process Reconstruction of Reionization History: We reconstruct the history of reionization using Gaussian process regression.
Using the UV luminosity data compilation from Hubble Frontiers Fields we
reconstruct the redshift evolution of UV luminosity density and thereby the
evolution of the source term in the ... |
The X-ray luminous cluster underlying the z = 1.04 quasar PKS1229-021: We present a 100 ks Chandra observation studying the extended X-ray emission
around the powerful z=1.04 quasar PKS1229-021. The diffuse cluster X-ray
emission can be traced out to ~15 arcsec (~120 kpc) radius and there is a drop
in the calculated ha... | The multi-stream flows and the dynamics of the cosmic web: A new numerical technique to identify the cosmic web is proposed. It is based
on locating multi-stream flows, i.e. the places where the velocity field is
multi-valued. The method is local in Eulerian space, simple and computaionally
efficient. This technique us... |
Galaxy Kinematics with VIRUS-P: The Dark Matter Halo of M87: We present 2-D stellar kinematics of M87 out to R = 238" taken with the
integral field spectrograph VIRUS-P. We run a large set of axisymmetric,
orbit-based dynamical models and find clear evidence for a massive dark matter
halo. While a logarithmic parameter... | Dynamical Mass Measurements of Contaminated Galaxy Clusters Using
Machine Learning: We study dynamical mass measurements of galaxy clusters contaminated by
interlopers and show that a modern machine learning (ML) algorithm can predict
masses by better than a factor of two compared to a standard scaling relation
appro... |
Stellar Population and Kinematic Profiles in Spiral Bulges & Disks:
Population Synthesis of Integrated Spectra: We present a detailed study of the stellar populations (SPs) and kinematics
of the bulge and inner disk regions of eight nearby spiral galaxies (Sa-Sd)
based on deep Gemini/GMOS data. The long-slit spectra ... | Contemporary gravitational waves from primordial black holes: Stochastic background of gravitational waves (GW) generated by the
interactions between primordial black holes (PBH) in the early universe and by
PBH evaporation is considered. If PBHs dominated in the cosmological energy
density prior to their evaporation, ... |
Varying alpha from N-body Simulations: We have studied the Bekenstein-Sandvik-Barrow-Magueijo (BSBM) model for the
spatial and temporal variations of the fine structure constant, alpha, with the
aid of full N-body simulations which explicitly and self-consistently solve for
the scalar field driving the alpha-evolution.... | Primordial black hole formation processes with full numerical relativity: See thesis for complete abstract.
Primordial black holes (PBHs) can form in the early universe, and there are
several mass windows in which their abundance today may be large enough to
comprise a significant part of the dark matter density. Add... |
Fingerprinting Dark Energy II: weak lensing and galaxy clustering tests: The characterization of dark energy is a central task of cosmology. To go
beyond a cosmological constant, we need to introduce at least an equation of
state and a sound speed and consider observational tests that involve
perturbations. If dark ene... | LIGO gravitational wave detection, primordial black holes and the
near-IR cosmic infrared background anisotropies: LIGO's discovery of a gravitational wave from two merging black holes (BHs)
of similar masses rekindled suggestions that primordial BHs (PBHs) make up the
dark matter (DM). If so, PBHs would add a Poisso... |
A Measurement of Gravitational Lensing of the Cosmic Microwave
Background Using SPT-3G 2018 Data: We present a measurement of gravitational lensing over 1500 deg$^2$ of the
Southern sky using SPT-3G temperature data at 95 and 150 GHz taken in 2018. The
lensing amplitude relative to a fiducial Planck 2018 $\Lambda$CDM... | Spectator Higgs, large-scale gauge fields and the non-minimal coupling
to gravity: Even if the Higgs field does not affect the evolution of the background
geometry, its massive inhomogeneities induce large-scale gauge fields whose
energy density depends on the slow-roll parameters, on the effective scalar
mass and, l... |
Information gains from Monte Carlo Markov Chains: In this paper, we present a novel method for computing the relative entropy
as well as the expected relative entropy using an MCMC chain. The relative
entropy from information theory can be used to quantify differences in
posterior distributions of a pair of experiments... | Unified Superfluid Dark Sector: We present a novel theory of a unified dark sector, where late-time cosmic
acceleration emerges from the dark matter superfluid framework. The system is
described by a superfluid mixture consisting of two distinguishable states with
a small energy gap, such as the ground state and an exc... |
Current and Future Constraints on Primordial Magnetic Fields: We present new limits on the amplitude of potential primordial magnetic
fields (PMFs) using temperature and polarization measurements of the cosmic
microwave background (CMB) from Planck, BICEP2/Keck Array, POLARBEAR, and
SPTpol. We reduce twofold the 95% CL... | Structure formation in large-volume cosmological simulations of fuzzy
dark matter: Impact of the non-linear dynamics: An ultra-light bosonic particle of mass around $10^{-22}\,\mathrm{eV}/c^2$ is
of special interest as a dark matter candidate, as it both has particle physics
motivations, and may give rise to notable ... |
A quasi-molecular mechanism of formation of hydrogen in the early
Universe -- a scheme of calculation: In our recent papers (Kereslidze et all 2019a, 2021) a non-standard
quasi-molecular mechanism was suggested and applied to treat the cosmological
recombination. It was assumed that in the pre-recombination stage of ... | Real-space density profile reconstruction of stacked voids: We present a non-parametric, model-independent method to reconstruct the
spherical density profiles of void stacks in real space, without redshift-space
distortions. Our method uses the expected spherical symmetry of stacked voids
to build the shape of the sph... |
All about baryons: revisiting SIDM predictions at small halo masses: We use cosmological hydrodynamic simulations to consistently compare the
assembly of dwarf galaxies in both $\Lambda$ dominated, Cold (CDM) and
Self--Interacting (SIDM) dark matter models. The SIDM model adopts a constant
cross section of 2 $cm^{2}/g$... | Structure Formation and the Global 21-cm Signal in the Presence of
Coulomb-like Dark Matter-Baryon Interactions: Many compelling dark matter (DM) scenarios feature Coulomb-like interactions
between DM particles and baryons, in which the cross section for elastic
scattering scales with relative particle velocity as $v... |
The rates and time-delay distribution of multiply imaged supernovae
behind lensing clusters: Time delays of gravitationally lensed sources can be used to constrain the
mass model of a deflector and determine cosmological parameters. We here
present an analysis of the time-delay distribution of multiply imaged sources... | Cosmology and the Korteweg-de Vries Equation: The Korteweg-de Vries (KdV) equation is a non-linear wave equation that has
played a fundamental role in diverse branches of mathematical and theoretical
physics. In the present paper, we consider its significance to cosmology. It is
found that the KdV equation arises in a ... |
Using Observations of Distant Quasars to Constrain Quantum Gravity: Aims. The small-scale nature of spacetime can be tested with observations of
distant quasars. We comment on a recent paper by Tamburini et al. (A&A, 533,
71) which claims that Hubble Space Telescope observations of the most distant
quasars place severe... | Dark Before Light: Testing the Cosmic Expansion History through the
Cosmic Microwave Background: The cosmic expansion history proceeds in broad terms from a radiation
dominated epoch to matter domination to an accelerated, dark energy dominated
epoch. We investigate whether intermittent periods of acceleration are po... |
Evidence for anisotropy of cosmic acceleration: Observations reveal a `bulk flow' in the local Universe which is faster and
extends to much larger scales than is expected around a typical observer in the
standard $\Lambda$CDM cosmology. This is expected to result in a
scale-dependent dipolar modulation of the accelerat... | The Two Phases of Galaxy Formation: Cosmological simulations of galaxy formation appear to show a two-phase
character with a rapid early phase at z>2 during which in-situ stars are formed
within the galaxy from infalling cold gas followed by an extended phase since
z<3 during which ex-situ stars are primarily accreted.... |
Effect of Mask Regions on Weak Lensing Statistics: Sky masking is unavoidable in wide-field weak lensing observations. We study
how masks affect the measurement of statistics of matter distribution probed by
weak gravitational lensing. We first use 1000 cosmological ray-tracing
simulations to examine in detail the impa... | Kinetic decoupling of WIMPs: analytic expressions: We present a general expression for the values of the average kinetic energy
and of the temperature of kinetic decoupling of a WIMP, valid for any
cosmological model. We show an example of the usage of our solution when the
Hubble rate has a power-law dependence on tem... |
Beyond Assembly Bias: Exploring Secondary Halo Biases for Cluster-size
Haloes: Secondary halo bias, commonly known as 'assembly bias,' is the dependence of
halo clustering on a halo property other than mass. This prediction of the
Lambda-Cold Dark Matter cosmology is essential to modelling the galaxy
distribution to ... | A conceptual problem for non-commutative inflation and the new approach
for non-relativistic inflationary equation of state: In a previous paper, we connected the phenomenological non-commutative
inflation of Alexander, Brandenberger and Magueijo (2003) and Koh S and
Brandenberger (2007) with the formal representatio... |
Variable partial covering and a relativistic iron line in NGC 1365: We present a complete analysis of the hard X-ray (2-10 keV) properties of the
Seyfert galaxy NGC 1365, based on a 60 ks XMM-Newton observation performed in
January 2004. The two main results are: 1) We detect an obscuring cloud with
N_H~3.5x10^23 cm^(-... | The Dark Side of QSO Formation at High Redshifts: Observed high-redshift QSOs, at z~6, may reside in massive dark matter (DM)
halos of more than 10^{12} Msun and are thus expected to be surrounded by
overdense regions. In a series of 10 constrained simulations, we have tested
the environment of such QSOs. Comparing the... |
The Magellanic Bridge as a DLA System: Physical Properties of Cold Gas
toward PKS0312-770: We measure the physical properties of a local multi-component absorption-line
system at V_sol ~ 200 km/s toward the quasar PKS0312-770 behind the Magellanic
Bridge (MB) using Hubble Space Telescope STIS spectroscopy in conjunct... | The connection between radio halos and cluster mergers and the
statistical properties of the radio halo population: We discuss the statistical properties of the radio halo population in galaxy
clusters. Radio bi-modality is observed in galaxy clusters: a fraction of
clusters host giant radio halos while the majority ... |
Measurement of a Cosmographic Distance Ratio with Galaxy and CMB Lensing: We measure the gravitational lensing shear signal around dark matter halos
hosting CMASS galaxies using light sources at $z\sim 1$ (background galaxies)
and at the surface of last scattering at $z\sim 1100$ (the cosmic microwave
background). The ... | A Method for Individual Source Brightness Estimation in Single- and
Multi-band Data: We present a method of reliably extracting the flux of individual sources
from sky maps in the presence of noise and a source population in which number
counts are a steeply falling function of flux. The method is an extension of a
s... |
Dynamics of entropy perturbations in assisted dark energy with mixed
kinetic terms: We study dynamics of entropy perturbations in the two-field assisted dark
energy model. Based on the scenario of assisted dark energy, in which one
scalar field is subdominant compared with the other in the early epoch, we show
that t... | Imprints of the Early Universe on Axion Dark Matter Substructure: Despite considerable experimental progress large parts of the axion-like
particle (ALP) parameter space remain difficult to probe in terrestrial
experiments. In some cases, however, small-scale structure of the ALP dark
matter (DM) distribution is strong... |
Exponents of non-linear clustering in scale-free one dimensional
cosmological simulations: One dimensional versions of cosmological N-body simulations have been shown
to share many qualitative behaviours of the three dimensional problem. They can
resolve a large range of time and length scales, and admit exact numeri... | SCG0018-4854: a young and dynamic compact group I. Kinematical analysis: Compact groups of galaxies are in particular good laboratories for studying
galaxy interactions and their effects on the evolution of galaxies due to their
high density and low velocity dispersion. SCG0018-4854 is a remarkably high
galaxy density ... |
Cosmology based on $f(R)$ gravity with ${\cal O}(1)$ eV sterile neutrino: We address the cosmological role of an additional ${\cal O}(1)$ eV sterile
neutrino in modified gravity models. We confront the present cosmological data
with predictions of the FLRW cosmological model based on a variant of $f(R)$
modified gravit... | The Atacama Cosmology Telescope: Dusty Star-Forming Galaxies and Active
Galactic Nuclei in the Southern Survey: We present a catalog of 191 extragalactic sources detected by the Atacama
Cosmology Telescope (ACT) at 148 GHz and/or 218 GHz in the 2008 Southern
survey. Flux densities span 14-1700 mJy, and we use source ... |
Quantized fields and gravitational particle creation in f(R) expanding
universes: The problem of cosmological particle creation for a spatially flat,
homogeneous and isotropic Universes is discussed in the context of f(R)
theories of gravity. Different from cosmological models based on general
relativity theory, it i... | Detectability of Small-Scale Dark Matter Clumps with Pulsar Timing
Arrays: We examine the capability of pulsar timing arrays (PTAs) to detect very
small-scale clumps of dark matter (DM), which are a natural outcome of the
standard cold dark matter (CDM) paradigm. A clump streaming near the Earth or a
pulsar induces a... |
Anthropic Bounds on Lambda from the No-Boundary Quantum State: We show that anthropic selection emerges inevitably in the general framework
for prediction in quantum cosmology. There the predictions of anthropic
reasoning depend on the prior implied by the universe's quantum state. To
illustrate this we compute the pro... | Evidence of patchy hydrogen reionization from an extreme Ly$α$
trough below redshift six: We report the discovery of an extremely long ($\sim$110 Mpc/$h$) and dark
($\tau_{\rm eff} \gtrsim 7$) Ly$\alpha$ trough extending down to $z \simeq 5.5$
towards the $z_{\rm em} \simeq 6.0$ quasar ULAS J0148+0600. We use these n... |
Overconfidence in Photometric Redshift Estimation: We describe a new test of photometric redshift performance given a
spectroscopic redshift sample. This test complements the traditional comparison
of redshift {\it differences} by testing whether the probability density
functions $p(z)$ have the correct {\it width}. We... | Measurement on the cosmic curvature using the Gaussian process method: Inflation predicts that the Universe is spatially flat. The Planck 2018
measurements of the cosmic microwave background anisotropy favour a spatially
closed universe at more than 2$\sigma$ confidence level. We use model
independent methods to study ... |
Zoomed high-resolution simulations of Multi-coupled Dark Energy: cored
galaxy density profiles at high redshift: We perform for the first time high-resolution zoom-in re-simulations of
individual halos in the context of the Multi-coupled Dark Energy (McDE)
scenario, which is characterised by the existence of two dist... | Reconciling cosmic dipolar tensions with a gigaparsec void: Recent observations indicate a $4.9\sigma$ tension between the CMB and quasar
dipoles. This tension challenges the cosmological principle. We propose that if
we live in a gigaparsec scale void, the CMB and quasar dipolar tension can be
reconciled. This is beca... |
The size of the Universe according to the Poincare dodecahedral space
hypothesis: One of the FLRW models that best fits the WMAP sky maps of the CMB is the
Poincare dodecahedral space. The optimal fit of this model to WMAP data was
recently found using an optimal cross-correlation method, but the systematic
error in ... | Black hole variability and the star formation-AGN connection: Do all
star-forming galaxies host an AGN?: We investigate the effect of active galactic nucleus (AGN) variability on the
observed connection between star formation and black hole accretion in
extragalactic surveys. Recent studies have reported relatively w... |
A model independent measure of the large scale curvature of the Universe: Cosmological distances as a function of redshift depend on the effective
curvature density via the effect on the geometrical path of photons from large
scale spatial curvature and its effect on the expansion history, H(z).
Cosmological time, howe... | Understanding the non-linear clustering of high redshift galaxies: We incorporate the non-linear clustering of dark matter halos, as modelled by
Jose et al. (2016) into the halo model to better understand the clustering of
Lyman break galaxies (LBGs) in the redshift range $z=3-5$. We find that, with
this change, the pr... |
Reionization of the Intergalactic Medium: After recombination the cosmic gas was left in a cold and neutral state.
However, as the first stars and black holes formed within early galactic
systems, their UV and X-ray radiation induced a gradual phase transition of the
intergalactic gas into the warm and ionized state we... | Testing f(R) gravity with the simulated data of gravitational waves from
the Einstein Telescope: In this paper we analyze the implications of gravitational waves (GWs) as
standard sirens on the modified gravity models by using the third-generation
gravitational wave detector, i.e., the Einstein Telescope. Two viable ... |
Bayesian evidence of non-standard inflation: isocurvature perturbations
and running spectral index: Bayesian model comparison penalizes models with more free parameters that are
allowed to vary over a wide range, and thus offers the most robust method to
decide whether some given data require new parameters. In this ... | Mid-Infrared Variability from the Spitzer Deep, Wide-Field Survey: We use the multi-epoch, mid-infrared Spitzer Deep, Wide-Field Survey to
investigate the variability of 474,179 objects in 8.1 deg^2 of the NDWFS Bootes
field. We perform a Difference Image Analysis of the four available epochs
between 2004 and 2008, foc... |
New Constraints on variations of the fine structure constant from CMB
anisotropies: We demonstrate that recent measurements of Cosmic Microwave Background
temperature and polarization anisotropy made by the ACBAR, QUAD and BICEP
experiments substantially improve the cosmological constraints on possible
variations of ... | On the amount of peculiar velocity field information in supernovae from
LSST and beyond: Peculiar velocities introduce correlations between supernova magnitudes,
which implies that the supernova Hubble diagram residual carries information on
both the matter power spectrum at the present time and its growth rate. By a... |
Full-sky bispectrum in redshift space for 21cm intensity maps: We compute the tree-level bispectrum of 21cm intensity mapping after
reionisation. We work in the directly observable angular and redshift space,
focusing on equal-redshift correlations and thin redshift bins, for which the
lensing contribution is negligibl... | Gauge invariance and non-Gaussianity in Inflation: We clarify the role of gauge invariance for the computation of quantum
non-Gaussian correlators in inflation. A gauge invariant generating functional
for n-point functions is given and the special status of the spatially flat
gauge is pointed out. We also comment on th... |
Spectroscopic failures in photometric redshift calibration: cosmological
biases and survey requirements: We use N-body-spectro-photometric simulations to investigate the impact of
incompleteness and incorrect redshifts in spectroscopic surveys to photometric
redshift training and calibration and the resulting effects... | The Atacama Cosmology Telescope: Cosmology from Galaxy Clusters Detected
via the Sunyaev-Zel'dovich Effect: We present constraints on cosmological parameters based on a sample of
Sunyaev-Zel'dovich-selected galaxy clusters detected in a millimeter-wave
survey by the Atacama Cosmology Telescope. The cluster sample use... |
Mass Accretion and its Effects on the Self-Similarity of Gas Profiles in
the Outskirts of Galaxy Clusters: Galaxy clusters exhibit remarkable self-similar behavior which allows us to
establish simple scaling relationships between observable quantities and
cluster masses, making galaxy clusters useful cosmological pro... | Effect of Priomordial non-Gaussianities on Galaxy Clusters Scaling
Relations: Galaxy clusters are a valuable source of cosmological information. Their
formation and evolution depends on the underlying cosmology and on the
statistical nature of the primordial density fluctuations. In this work we
investigate the impac... |
MILCANN : A neural network assessed tSZ map for galaxy cluster detection: We present the first combination of thermal Sunyaev-Zel'dovich (tSZ) map with
a multi-frequency quality assessment of the sky pixels based on Artificial
Neural Networks (ANN) aiming at detecting tSZ sources from sub-millimeter
observations of the... | A Hybrid Deep Learning Approach to Cosmological Constraints From Galaxy
Redshift Surveys: We present a deep machine learning (ML)-based technique for accurately
determining $\sigma_8$ and $\Omega_m$ from mock 3D galaxy surveys. The mock
surveys are built from the AbacusCosmos suite of $N$-body simulations, which
comp... |
Scalar perturbations in cosmological models with quark nuggets: In this paper we consider the Universe at the late stage of its evolution and
deep inside the cell of uniformity. At these scales, the Universe is filled
with inhomogeneously distributed discrete structures (galaxies, groups and
clusters of galaxies). Supp... | Non-congruent Phase Transitions in Cosmic Matter and in the Laboratory: Non-congruence appears to be the most general form of phase transition in
cosmic matter and in the laboratory. In terrestrial applications
noncongruencemeans coexistence of phases with different chemical composition in
systems consisting of two (or... |
Probing the cool ISM in galaxies via 21cm HI absorption: Recent targeted studies of associated HI absorption in radio galaxies are
starting to map out the location, and potential cosmological evolution, of the
cold gas in the host galaxies of Active Galactic Nuclei (AGN). The observed 21
cm absorption profiles often sh... | The cosmological dependence of halo and galaxy assembly bias: One of the main predictions of excursion set theory is that the clustering of
dark matter haloes only depends on halo mass. However, it has been long
established that the clustering of haloes also depends on other properties,
including formation time, concen... |
Measuring the Inflaton Coupling in the CMB: We study the perspectives to extract information about the microphysical
parameters that governed the reheating process after cosmic inflation from CMB
data. We identify conditions under which the inflaton coupling to other fields
can be constrained for a given model of infla... | Feedback and the Structure of Simulated Galaxies at redshift z=2: We study the properties of simulated high-redshift galaxies using
cosmological N-body/gasdynamical runs from the OverWhelmingly Large Simulations
(OWLS) project. The runs contrast several feedback implementations of varying
effectiveness: from no-feedbac... |
Blazars in hard X-rays: Although blazars are thought to emit most of their luminosity in the
gamma-ray band, there are subclasses of them very prominent in hard X-rays.
These are the best candidates to be studied by Simbol-X. They are at the
extremes of the blazar sequence, having very small or very high jet powers. Th... | Fuzzy Dark Matter Dynamics and the Quasiparticle Hypothesis: Dark matter may be composed of ultra-light bosons whose de Broglie wavelength
in galaxies is of order 1 kpc. The standard model for this fuzzy dark matter
(FDM) is a complex scalar field that obeys the Schr\"odinger-Poisson equations.
The wavelike nature of F... |
A survey of lens spaces and large-scale CMB anisotropy: The cosmic microwave background (CMB) anisotropy possesses the remarkable
property that its power is strongly suppressed on large angular scales. This
observational fact can naturally be explained by cosmological models with a
non-trivial topology. The paper focus... | Testing the theory of gravity with DESI: estimators, predictions and
simulation requirements: Shortly after its discovery, General Relativity (GR) was applied to predict
the behavior of our Universe on the largest scales, and later became the
foundation of modern cosmology. Its validity has been verified on a range o... |
Cosmic voids and the kinetic analysis. II. Link to Hubble tension: We consider a principal problem, that of the possible dominating role of
self-consistent gravitational interaction in the formation of cosmic
structures: voids and their walls in the local Universe. It is in the context
of the Hubble tension as a possib... | Detecting the Cold Spot as a Void with the Non-Diagonal Two-Point
Function: The anomaly in the Cosmic Microwave Background known as the "Cold Spot" could
be due to the existence of an anomalously large spherical (few hundreds Mpc/h
radius) underdense region, called a "Void" for short. Such a structure would
have an i... |
Supermassive Black Holes from Ultra-Strongly Self-Interacting Dark
Matter: We consider the cosmological consequences if a small fraction ($f\lesssim
0.1$) of the dark matter is ultra-strongly self-interacting, with an elastic
self-interaction cross-section per unit mass $\sigma\gg1\ \mathrm{cm^{2}/g}$.
This possibili... | Weak Lensing Minima and Peaks: Cosmological Constraints and the Impact
of Baryons: We present a novel statistic to extract cosmological information in weak
lensing data: the lensing minima. We also investigate the effect of baryons on
the cosmological constraints from peak and minimum counts. Using the
\texttt{Massiv... |
IDCS J1426.5+3508: Cosmological implications of a massive, strong
lensing cluster at Z = 1.75: The galaxy cluster IDCS J1426.5+3508 at z = 1.75 is the most massive galaxy
cluster yet discovered at z > 1.4 and the first cluster at this epoch for which
the Sunyaev-Zel'Dovich effect has been observed. In this paper we r... | Numerically reconstructing the geometry of the Universe from data: We give an outline of an algorithm designed to reconstruct the background
cosmological metric within the class of spherically symmetric dust universes
that may include a cosmological constant. Luminosity and age data are used to
derive constraints on th... |
Primordial non-Gaussianities: This contribution gives an overview on primordial non-Gaussianities from a
theoretical perspective. After presenting a general formalism to describe
nonlinear cosmological perturbations, several classes of models, illustrated
with examples, are discussed: multi-field inflation with non-sta... | Testing cosmic opacity with the combination of strongly lensed and
unlensed supernova Ia: In this paper, we present a scheme to investigate the opacity of the Universe
in a cosmological-model-independent way, with the combination of current and
future measurements of type Ia supernova sample and galactic-scale strong... |
Testing black hole no-hair theorem with OJ287: We examine the ability to test the black hole no-hair theorem at the 10%
level in this decade using the binary black hole in OJ287. In the test we
constrain the value of the dimensionless parameter q that relates the scaled
quadrupole moment and spin of the primary black h... | Structure formation in a nonlocally modified gravity model: We study a nonlocally modified gravity model proposed by Deser and Woodard
which gives an explanation for current cosmic acceleration. By deriving and
solving the equations governing the evolution of the structure in the Universe,
we show that this model predi... |
Constraining the Statistics of Population III Binaries: We perform a cosmological simulation in order to model the growth and
evolution of Population III (Pop III) stellar systems in a range of host
minihalo environments. A Pop III multiple system forms in each of the ten
minihaloes, and the overall mass function is to... | Directional axion detection: We develop a formalism to describe extensions of existing axion haloscope
designs to those that possess directional sensitivity to incoming dark matter
axion velocities. The effects are measurable if experiments are designed to
have dimensions that approach the typical coherence length for ... |
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