A5034807028- Cosmology and Gravitation Theories
- Galaxies: Formation, Evolution, Phenomena
- Dark Matter and Cosmic Phenomena
- Radio Astronomy Observations and Technology
- Astrophysics and Cosmic Phenomena
- Astronomy and Astrophysical Research
- Pulsars and Gravitational Waves Research
- Gamma-ray bursts and supernovae
- Scientific Research and Discoveries
- History and Developments in Astronomy
- Spanish Literature and Culture Studies
- Employment, Labor, and Gender Studies
- Astrophysical Phenomena and Observations
- Stellar, planetary, and galactic studies
- Superconducting and THz Device Technology
- Computational Physics and Python Applications
- Black Holes and Theoretical Physics
- Advertising and Communication Studies
- Geophysics and Gravity Measurements
- Historical and socio-economic studies of Spain and related regions
- Social Sciences and Policies
- Galician and Iberian cultural studies
- Urbanism, Landscape, and Tourism Studies
- Archaeological and Historical Studies
- Radio Wave Propagation Studies
The University of Texas at Austin
2023-2025
Center for Astrophysics Harvard & Smithsonian
2020-2024
Harvard University
2017-2021
Harvard University Press
2018-2021
IIT@Harvard
2019
Johns Hopkins University
2015-2017
Secretaría de Salud de Bogotá
1994
Connecticut College
1860
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...
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...
The International Gamma-Ray Astrophysics Laboratory ($INTEGRAL$) satellite has yielded unprecedented measurements of the soft gamma-ray spectrum our Galaxy. Here we use those to set constraints on dark matter (DM) that decays or annihilates into photons with energies $E\ensuremath{\approx}0.02--2\text{ }\text{ }\mathrm{MeV}$. First, revisit particle DM photon pairs. In particular, for decaying DM, find previous limits were overstated by roughly an order magnitude. Our new, conservative...
Abstract Recently, the Hydrogen Epoch of Reionization Array (HERA) has produced experiment’s first upper limits on power spectrum 21 cm fluctuations at z ∼ 8 and 10. Here, we use several independent theoretical models to infer constraints intergalactic medium (IGM) galaxies during epoch reionization from these limits. We find that IGM must have been heated above adiabatic-cooling threshold by 8, uncertainties about ionization radio background. Combining HERA with complementary observations...
Abstract We report the most sensitive upper limits to date on 21 cm epoch of reionization power spectrum using 94 nights observing with Phase I Hydrogen Epoch Reionization Array (HERA). Using similar analysis techniques as in previously reported limits, we find at 95% confidence that Δ 2 ( k = 0.34 h Mpc −1 ) ≤ 457 mK z 7.9 and 0.36 3496 10.4, an improvement by a factor 2.1 2.6, respectively. These are mostly consistent thermal noise over wide range after our data quality cuts, despite...
ABSTRACT The formation of the first galaxies during cosmic dawn and reionization (at redshifts z = 5–30), triggered last major phase transition our universe, as hydrogen evolved from cold neutral to hot ionized. 21-cm line will soon allow us map these milestones study that drove them. To aid in interpreting observations, we upgrade publicly available code 21cmFAST. We introduce a new, flexible parametrization additive feedback from: an inhomogeneous, H2-dissociating (Lyman–Werner; LW)...
The early-science observations made by the James Webb Space Telescope (JWST) have revealed an excess of ultramassive galaxy candidates that appear to challenge standard cosmological model (ΛCDM). Here, we argue any modifications ΛCDM can produce such galaxies in early Universe would also affect UV luminosity function (UV LF) inferred from Hubble (HST). LF covers same redshifts (z≈7–10) and host-halo masses (Mh≈1010–1012M⊙) as JWST candidates, but tracks star-formation rate rather than...
Abstract New James Webb Space Telescope (JWST) observations are revealing the first galaxies to be prolific producers of ionizing photons, which we argue gives rise a tension between different probes reionization. Over last two decades consensus has emerged where star-forming able generate enough photons drive reionization, given reasonable values for their number densities, efficiencies ξion (per unit UV luminosity), and escape fractions fesc. However, some new JWST infer high during...
The 21-cm signal provides a novel avenue to measure the thermal state of Universe during cosmic dawn and reionization (redshifts <a:math xmlns:a="http://www.w3.org/1998/Math/MathML" display="inline"><a:mrow><a:mi>z</a:mi><a:mo>∼</a:mo><a:mn>5</a:mn><a:mi>–</a:mi><a:mn>30</a:mn></a:mrow></a:math>), thus probe energy injection from decaying or annihilating dark matter (DM). These DM processes are inherently inhomogeneous: both decay annihilation density-dependent, furthermore, fraction...
Abstract Recent JWST observations at z > 6 may imply galactic ionizing photon production above prior expectations. Under observationally motivated assumptions about escape fractions, these suggest a ~ 8–9 end to reionization, in tension with the < required by Ly α forest. In this work, we use radiative transfer simulations understand what different tell us when reionization ended and it started. We consider model that ends too early ( ≈ 8) alongside two more realistic scenarios 5: one...
Constraints to the parameters of inflation models are often derived assuming some plausible range for number---e.g., ${N}_{k}=46$ ${N}_{k}=60$---of $e$-folds that occurred between time our current observable Universe exited horizon and end inflation. However, number is, any specific inflaton potential, related an effective equation-of-state parameter ${w}_{\text{re}}$ temperature ${T}_{\text{re}}$, reheating. Although physics reheating is highly uncertain, there a finite reasonable values...
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...
The authors study cosmological intensity fluctuations in the Hydrogen 21-cm line as a promising future probe for primordial non-gaussianity, which is beyond CMB anisotropy sensitivity and would distinguish between different models of inflation. They extract intrinsic non-gaussian nature fluctuations, forecasting significantly increased sensitivity.
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...
The epoch of the formation first stars, known as cosmic dawn, has emerged a new arena in search for dark matter. In particular, claimed 21-cm detection exhibits deeper global absorption feature than expected, which could be caused by low baryonic temperature, and been interpreted sign electromagnetic interactions between baryons This hypothesis striking prediction: large temperature anisotropies sourced velocity-dependent cooling baryons. However, order to remain consistent with rest...
This brief code paper presents a new Python-wrapped version of the popular 21cm cosmology simulator, 21cmFAST. The version, v3+, maintains same core functionality previous versions 21cmFAST, but features simple and intuitive interface, great deal more flexibility. evolution represents work formalized collaboration, available publicly on GitHub, provides single point-of-reference for all future upgrades community-added features. In this paper, we describe usage some its features, provide...
Primordial black holes (PBHs), formed out of large overdensities in the early Universe, are a viable dark matter (DM) candidate over broad range masses. Ultra-light, asteroid-mass PBHs with masses around $10^{17}$ g particularly interesting as current observations allow them to constitute entire DM density. this mass emit $\sim$ MeV photons via Hawking radiation which can directly be detected by gamma ray telescopes, such upcoming AMEGO. In work we forecast how well an instrument sensitivity...
The distribution of matter fluctuations in our universe is key for understanding the nature dark and physics early cosmos. Different observables have been able to map this at large scales, corresponding wavenumbers $k\lesssim 10$ Mpc$^{-1}$, but smaller scales remain much less constrained. 21-cm line a promising tracer stellar formation, which took place small haloes (with masses $M\sim 10^6-10^8M_\odot$), formed out overdensities with as $k\approx100$ Mpc$^{-1}$. Here we forecast how well...
While astrophysical and cosmological probes provide a remarkably precise consistent picture of the quantity general properties dark matter, its fundamental nature remains one most significant open questions in physics. Obtaining more comprehensive understanding matter within next decade will require overcoming number theoretical challenges: groundwork for these strides is being laid now, yet much to be done. Chief among upcoming challenges establishing foundation needed harness full...
ABSTRACT The 21-cm signal holds the key to understanding first structure formation during cosmic dawn. Theoretical progress over last decade has focused on simulations of this signal, given non-linear and non-local relation between initial conditions observables (21 cm or reionization maps). Here, instead, we propose an effective fully analytical model for We take advantage exponential-like behaviour local star-formation rate density (SFRD) against densities at early times analytically find...