A5035557169- Cosmology and Gravitation Theories
- Galaxies: Formation, Evolution, Phenomena
- Radio Astronomy Observations and Technology
- Dark Matter and Cosmic Phenomena
- Astronomy and Astrophysical Research
- Astrophysics and Cosmic Phenomena
- Pulsars and Gravitational Waves Research
- Gamma-ray bursts and supernovae
- Geophysics and Gravity Measurements
- Superconducting and THz Device Technology
- Stellar, planetary, and galactic studies
- Particle physics theoretical and experimental studies
- Computational Physics and Python Applications
- Mechanics and Biomechanics Studies
- History and Developments in Astronomy
- Black Holes and Theoretical Physics
- Astrophysical Phenomena and Observations
- Scientific Research and Discoveries
- Neutrino Physics Research
- Solar and Space Plasma Dynamics
- Astrophysics and Star Formation Studies
- Adaptive optics and wavefront sensing
- Relativity and Gravitational Theory
- Spectroscopy and Laser Applications
- Advanced Thermodynamic Systems and Engines
Ben-Gurion University of the Negev
2019-2025
Johns Hopkins University
2014-2020
Max Planck Institute for Astronomy
2019
Max Planck Society
2019
Bakke Graduate University
2019
The University of Texas at Austin
2012-2015
Tel Aviv University
2007-2012
We consider the possibility that black-hole (BH) binary detected by LIGO may be a signature of dark matter. Interestingly enough, there remains window for masses 20M_{⊙}≲M_{bh}≲100M_{⊙} where primordial black holes (PBHs) constitute If two BHs in galactic halo pass sufficiently close, they radiate enough energy gravitational waves to become gravitationally bound. The bound will rapidly spiral inward due emission radiation and ultimately merge. Uncertainties rate such events arise from our...
This book lays out the scientific goals to be addressed by next-generation ground-based cosmic microwave background experiment, CMB-S4, envisioned consist of dedicated telescopes at South Pole, high Chilean Atacama plateau and possibly a northern hemisphere site, all equipped with new superconducting cameras. CMB-S4 will dramatically advance cosmological studies crossing critical thresholds in search for B-mode polarization signature primordial gravitational waves, determination number...
Primordial black holes (PBHs) have long been a candidate for the elusive dark matter (DM), and remain poorly constrained in $\ensuremath{\sim}20--100\text{ }\text{ }{M}_{\ensuremath{\bigodot}}$ mass range. PBH binaries were recently suggested as possible source of LIGO's first detections. In this paper, we thoroughly revisit existing estimates merger rate binaries. We compute probability distribution orbital parameters formed early Universe, accounting tidal torquing by all other PBHs, well...
The possibility that part of the dark matter is made massive compact halo objects (MACHOs) remains poorly constrained over a wide range masses, and especially in 20-100 M_{⊙} window. We show strong gravitational lensing extragalactic fast radio bursts (FRBs) by MACHOs masses larger than ∼20 would result repeated FRBs with an observable time delay. Strong FRB lens mass M_{L} induces two images, separated typical delay ∼few×(M_{L}/30 M_{⊙}) msec. Considering expected detection rate upcoming...
Following the first two annual intensity mapping workshops at Stanford in March 2016 and Johns Hopkins June 2017, we report on recent advances theory, instrumentation observation that were presented these meetings some of opportunities challenges identified looking forward. With preliminary detections CO, [CII], Lya low-redshift 21cm, a host experiments set to go online next few years, field is rapidly progressing all fronts, with great anticipation for flood new exciting results. This...
The search for the curl component (B mode) in cosmic microwave background (CMB) polarization induced by inflationary gravitational waves is described. canonical single-field slow-roll model of inflation presented, and we explain quantum production primordial density perturbations waves. It shown how these then give rise to CMB. We describe geometric decomposition CMB pattern into a curl-free (E show explicitly that induce B modes. discuss modes lensing Galactic foregrounds both are...
Measurements of weak gravitational lensing at low redshifts ($z\lesssim 0.5-1$), quantified by the parameter $S_8$, favor weaker matter clustering than that expected from standard $\Lambda$CDM cosmological model with parameters determined cosmic microwave background (CMB) measurements. However, amplitude higher redshifts, as probed CMB, is consistent $\Lambda$CDM. This apparent paradox suggests a connection between $S_8$ tension and transition to dark-energy domination. Here we show can be...
We investigate the hypothesis that Coulomb-type interactions between dark matter (DM) and baryons explain anomalously low 21 cm brightness-temperature minimum at redshift $z\ensuremath{\sim}17$ was recently measured by EDGES experiment. In particular, we reassess validity of scenario where a small fraction total DM is millicharged, focusing on newly derived constraints from Planck 2015 cosmic microwave background (CMB) data. Crucially, CMB power spectrum sensitive to DM--baryon scattering if...
We explore the effects of elastic scattering between dark matter and baryons on 21-cm signal during ages. In particular, we consider a dark-matter--baryon interaction with cross section form $\ensuremath{\sigma}={\ensuremath{\sigma}}_{0}{v}^{\ensuremath{-}4}$, in which case effect drag force baryon fluids grows time. show that, as opposed to what was previously thought, this heats up due relative velocity baryons. This creates an additional source fluctuations, can potentially make...
We perform an improved cosmic microwave background (CMB) analysis to search for dark matter--proton scattering with a momentum-transfer cross section of the form ${\ensuremath{\sigma}}_{0}{v}^{n}$ $n=\ensuremath{-}2$ and $n=\ensuremath{-}4$. In particular, we present new robust prescription incorporating relative bulk velocity between matter baryon fluids into standard linear Boltzmann calculation. Using iterative procedure, self-consistently include effects velocities in cosmology which...
We forecast the scientific capabilities to improve our understanding of cosmic inflation CORE, a proposed CMB space satellite submitted in response ESA fifth call for medium-size mission opportunity. The CORE will map anisotropies temperature and polarization 19 frequency channels spanning range 60-600 GHz. have an aggregate noise sensitivity $1.7 \mu$K$\cdot \,$arcmin angular resolution 5' at 200 explore impact telescope size on science return by making forecasts several instrumental...
It was recently suggested that the merger of $\ensuremath{\sim}30\text{ }\text{ }{M}_{\ensuremath{\bigodot}}$ primordial black holes (PBHs) may provide a significant number events in gravitational-wave observatories over next decade, if they make up an appreciable fraction dark matter. Here we show measurement eccentricities inspiralling binary can be used to distinguish these binaries from those produced by more traditional astrophysical mechanisms. These PBH are formed on highly eccentric...
We examine how future gravitational-wave measurements from merging black holes (BHs) can be used to infer the shape of black-hole mass function, with important implications for study star formation and evolution properties binary BHs. model function as a power law, inherited stellar initial introduce lower upper cutoff parameterizations in order probe minimum maximum BH masses allowed by evolution, respectively. initially focus on heavier each binary, minimize dependence. Taking into account...
The discrepancy between early-Universe inferences and direct measurements of the Hubble constant, known as tension, recently became a pressing subject in high precision cosmology. As result, large variety theoretical models have been proposed to relieve this tension. In work we analyze conformally coupled modified gravity (CCMG) model an evolving gravitational constant due coupling scalar field Ricci scalar, which becomes active around matter-radiation equality, required for solutions...
We investigate a possible method for determining the progenitors of black-hole (BH) mergers observed via their gravitational wave (GW) signal. argue that measurements cross-correlation GW events with overlapping galaxy catalogs may provide an additional tool in if BH trace stellar mass Universe, as would be expected from end points evolution. If, on other hand, BHs are primordial origin, has been recently suggested, merging preferentially hosted by lower biased objects and thus have luminous...
Large-amplitude density perturbations may have collapsed during the radiation dominated epoch of Universe to form primordial black holes (PBHs). There are several constraints abundance PBHs that stem from evaporation or gravitational effects. Due connection between and formation PBHs, on present-day can be translated into limits curvature power spectrum. We introduce new observational forecasted amplitude spectrum incorporate in our analysis uncertainties critical overdensity for collapse...
Primordial black holes (PBHs) have long been suggested as a candidate for making up some or all of the dark matter in Universe. Most theoretically possible mass range PBH has ruled out with various null observations expected signatures their interaction standard astrophysical objects. However, current constraints are significantly less robust 20 M_sun < M_PBH 100 window, which received much attention recently, following detection merging estimated masses ~30 by LIGO and suggestion that these...
We present a study of the feasibility an intensity-mapping survey targeting 115 GHz CO(1-0) rotational transition at $z\sim3$. consider four possible models and estimate spatial angular power spectra CO fluctuations predicted by each them. The frequency bandwidths most proposed intensity mapping spectrographs are too small to use Limber approximation calculate spectrum, so we alternative method for calculating spectrum. span two orders magnitude in signal amplitude, there is significant...
Line-intensity mapping (LIM) provides a promising way to probe cosmology, reionization and galaxy evolution. However, its sensitivity cosmology astrophysics at the same time is also nuisance. Here we develop comprehensive framework for modelling LIM power spectrum, which includes redshift space distortions Alcock-Paczynski effect. We then identify isolate degeneracies with so that they can be marginalized over. study gains of using multipole expansion anisotropic providing an accurate...
Our current understanding of the Universe is established through pristine measurements structure in cosmic microwave background (CMB) and distribution shapes galaxies tracing large scale (LSS) Universe. One key ingredient that underlies cosmological observables field sources observed assumed to be initially Gaussian with high precision. Nevertheless, a minimal deviation from Gaussianityis perhaps most robust theoretical prediction models explain Universe; itis necessarily present even...
Inflation may provide unique insight into the physics at highest available energy scales that cannot be replicated in any realistic terrestrial experiment. Features primordial power spectrum are generically predicted a wide class of models inflation and its alternatives, observationally one most overlooked channels for finding evidence non-minimal inflationary models. Constraints from observations cosmic microwave background cover widest range feature frequencies, but sensitive constraints...