scholarly journals Disc stability and neutral hydrogen as a tracer of dark matter

2013 ◽  
Vol 429 (3) ◽  
pp. 2537-2549 ◽  
Author(s):  
Gerhardt R. Meurer ◽  
Zheng Zheng ◽  
W. J. G. de Blok
Keyword(s):  
Dark Matter ◽  
Neutral Hydrogen

scholarly journals Impact of dark matter models on the EoR 21-cm signal bispectrum

2020 ◽  
Vol 497 (3) ◽  
pp. 2941-2953 ◽  
Author(s):  
Anchal Saxena ◽  
Suman Majumdar ◽  
Mohd Kamran ◽  
Matteo Viel
Keyword(s):  
Dark Matter ◽  
Structure Formation ◽  
Cold Dark Matter ◽  
Power Spectra ◽  
Neutral Hydrogen ◽  
Cosmic Time ◽  
Lower Number ◽  
Neutral Fraction ◽  
Small Scales ◽  
Low Mass

ABSTRACT The nature of dark matter sets the timeline for the formation of first collapsed haloes and thus affects the sources of reionization. Here, we consider two different models of dark matter: cold dark matter (CDM) and thermal warm dark matter (WDM), and study how they impact the epoch of reionization (EoR) and its 21-cm observables. Using a suite of simulations, we find that in WDM scenarios, the structure formation on small scales gets suppressed, resulting in a smaller number of low-mass dark matter haloes compared to the CDM scenario. Assuming that the efficiency of sources in producing ionizing photons remains the same, this leads to a lower number of total ionizing photons produced at any given cosmic time, thus causing a delay in the reionization process. We also find visual differences in the neutral hydrogen (H i) topology and in 21-cm maps in case of the WDM compared to the CDM. However, differences in the 21-cm power spectra, at the same neutral fraction, are found to be small. Thus, we focus on the non-Gaussianity in the EoR 21-cm signal, quantified through its bispectrum. We find that the 21-cm bispectra (driven by the H i topology) are significantly different in WDM models compared to the CDM, even for the same mass-averaged neutral fractions. This establishes that the 21-cm bispectrum is a unique and promising way to differentiate between dark matter models, and can be used to constrain the nature of the dark matter in the future EoR observations.

scholarly journals Intensity mapping as a probe of axion dark matter

2020 ◽  
Vol 500 (3) ◽  
pp. 3162-3177
Author(s):  
Jurek B Bauer ◽  
David J E Marsh ◽  
Renée Hložek ◽  
Hamsa Padmanabhan ◽  
Alex Laguë
Keyword(s):  
Dark Matter ◽  
Power Spectrum ◽  
Neutral Hydrogen ◽  
Matrix Formalism ◽  
Intensity Mapping ◽  
Matter Power Spectrum ◽  
Wide Range ◽  
Non Linear ◽  
Order Of Magnitude ◽  
Magnitude Improvement

ABSTRACT We consider intensity mapping (IM) of neutral hydrogen (H i) in the redshift range 0 ≲ z ≲ 3 employing a halo model approach where H i is assumed to follow the distribution of dark matter (DM) haloes. If a portion of the DM is composed of ultralight axions, then the abundance of haloes is changed compared to cold DM below the axion Jeans mass. With fixed total H i density, $\Omega _{\rm H\, \rm {\small I}}$, assumed to reside entirely in haloes, this effect introduces a scale-independent increase in the H i power spectrum on scales above the axion Jeans scale, which our model predicts consistent with N-body simulations. Lighter axions introduce a scale-dependent feature even on linear scales due to its suppression of the matter power spectrum near the Jeans scale. We use the Fisher matrix formalism to forecast the ability of future H i surveys to constrain the axion fraction of DM and marginalize over astrophysical and model uncertainties. We find that a HIRAX-like survey is a very reliable IM survey configuration, being affected minimally by uncertainties due to non-linear scales, while the SKA1MID configuration is the most constraining as it is sensitive to non-linear scales. Including non-linear scales and combining a SKA1MID-like IM survey with the Simons Observatory CMB, the benchmark ‘fuzzy DM’ model with ma = 10−22 eV can be constrained at few per cent. This is almost an order of magnitude improvement over current limits from the Ly α forest. For lighter ULAs, this limit improves below 1 per cent, and allows the possibility to test the connection between axion models and the grand unification scale across a wide range of masses.

scholarly journals Bridging Galaxy Dynamics and Baryon Efficiency of 40 EDGE-CALIFA galaxies

2015 ◽  
Vol 11 (S315) ◽  
Author(s):  
Veselina Kalinova ◽  
Dario Colombo ◽  
Erik Rosolowsky
Keyword(s):  
Dark Matter ◽  
Neutral Hydrogen ◽  
Expansion Method ◽  
Mass Range ◽  
Stellar Mass ◽  
Molecular Gas ◽  
Galaxy Dynamics ◽  
Circular Velocity ◽  
Hydrogen Mass ◽  
Stellar Kinematic

AbstractWe apply the Jeans Axisymmetric Multi-Gaussian Expansion method to the stellar kinematic maps of 40 Sa–Sd EDGE-CALIFA galaxies and derive their circular velocity curves (CVCs). The CVCs are classified using the Dynamical Classification method developed in Kalinova et al. (2015). We also calculate the observational baryon efficiency, OBE, where M*/Mb=M*/(M*+MHI+MH2) of the galaxies using their stellar mass, total neutral hydrogen mass and total molecular gas from CO luminosities. Slow-rising, Flat and Round-peaked CVC types correspond to specific OBEs, stellar and dark matter (DM) halo mass values, while the Sharp-peaked CVCs span in the whole DM halo mass range of 1011-1014M⊙.

scholarly journals Probing ultra-light axion dark matter from 21 cm tomography using Convolutional Neural Networks

2022 ◽  
Vol 2022 (01) ◽  
pp. 020
Author(s):  
Cristiano G. Sabiu ◽  
Kenji Kadota ◽  
Jacobo Asorey ◽  
Inkyu Park
Keyword(s):  
Dark Matter ◽  
Temperature Field ◽  
Brightness Temperature ◽  
Neutral Hydrogen ◽  
Mass Range ◽  
Training Data ◽  
Small Scale ◽  
Axion Mass ◽  
Density Perturbations ◽  
Square Kilometer Array

Abstract We present forecasts on the detectability of Ultra-light axion-like particles (ULAP) from future 21 cm radio observations around the epoch of reionization (EoR). We show that the axion as the dominant dark matter component has a significant impact on the reionization history due to the suppression of small scale density perturbations in the early universe. This behavior depends strongly on the mass of the axion particle. Using numerical simulations of the brightness temperature field of neutral hydrogen over a large redshift range, we construct a suite of training data. This data is used to train a convolutional neural network that can build a connection between the spatial structures of the brightness temperature field and the input axion mass directly. We construct mock observations of the future Square Kilometer Array survey, SKA1-Low, and find that even in the presence of realistic noise and resolution constraints, the network is still able to predict the input axion mass. We find that the axion mass can be recovered over a wide mass range with a precision of approximately 20%, and as the whole DM contribution, the axion can be detected using SKA1-Low at 68% if the axion mass is M X < 1.86 × 10-20 eV although this can decrease to M X < 5.25 × 10-21 eV if we relax our assumptions on the astrophysical modeling by treating those astrophysical parameters as nuisance parameters.

scholarly journals Beyond ΛCDM with H i intensity mapping: robustness of cosmological constraints in the presence of astrophysics

2020 ◽  
Vol 496 (4) ◽  
pp. 4115-4126 ◽  
Author(s):  
Stefano Camera ◽  
Hamsa Padmanabhan
Keyword(s):  
Dark Matter ◽  
Modified Gravity ◽  
Cosmological Parameters ◽  
Neutral Hydrogen ◽  
Temperature Fluctuations ◽  
Dark Matter Halo ◽  
Cosmological Constraints ◽  
Intensity Mapping ◽  
Standard Cosmological Model ◽  
First Time

ABSTRACT Mapping the unresolved intensity of the 21-cm emission of neutral hydrogen (H i) is now regarded as one the most promising tools for cosmological investigation in the coming decades. Here, we investigate, for the first time, extensions of the standard cosmological model, such as modified gravity and primordial non-Gaussianity, taking self-consistently into account. The present constraints on the astrophysics of H i clustering in the treatment of the brightness temperature fluctuations. To understand the boundaries within which results thus obtained can be considered reliable, we examine the robustness of cosmological parameter estimation performed via studies of 21-cm intensity mapping, against our knowledge of the astrophysical processes leading to H i clustering. Modelling of astrophysical effects affects cosmological observables through the relation linking the overall H i mass in a bound object, to the mass of the underlying dark matter halo that hosts it. We quantify the biases in estimates of standard cosmological parameters and those describing modified gravity and primordial non-Gaussianity that are obtained if one misconceives the slope of the relation between H i mass and halo mass, or the lower virial velocity cut-off for a dark matter halo to be able to host H i. Remarkably, we find that astrophysical uncertainties will not affect searches for primordial non-Gaussianity – one of the strongest science cases for H i intensity mapping – despite the signal being deeply linked to the H i bias.

scholarly journals Luminosity Bias. II. The Cosmic Web of the First Stars

2013 ◽  
Vol 30 ◽  
Author(s):  
R. Barkana
Keyword(s):  
Dark Matter ◽  
Galaxy Formation ◽  
Relative Velocity ◽  
Large Scale ◽  
Neutral Hydrogen ◽  
Unique Form ◽  
Velocity Difference ◽  
First Stars ◽  
Formation And Evolution ◽  
The Universe

AbstractUnderstanding the formation and evolution of the first stars and galaxies represents one of the most exciting frontiers in astronomy. Since the universe was filled with neutral hydrogen at early times, the most promising method for observing the epoch of the first stars is using the prominent 21-cm spectral line of the hydrogen atom. Current observational efforts are focused on the reionisation era (cosmic age t ~ 500 Myr), with earlier times considered much more challenging. However, the next frontier of even earlier galaxy formation (t ~ 200 Myr) is emerging as a promising observational target. This is made possible by a recently noticed effect of a significant relative velocity between the baryons and dark matter at early times. The velocity difference suppresses star formation, causing a unique form of early luminosity bias. The spatial variation of this suppression enhances large-scale clustering and produces a prominent cosmic web on 100 comoving Mpc scales in the 21-cm intensity distribution. This structure makes it much more feasible for radio astronomers to detect these early stars, and should drive a new focus on this era, which is rich with little-explored astrophysics.

scholarly journals The Epoch of Reionization in Warm Dark Matter Scenarios

2021 ◽  
Author(s):  
M. Romanello ◽  
N. Menci ◽  
M. Castellano
Keyword(s):  
Dark Matter ◽  
Galaxy Formation ◽  
Volume Fraction ◽  
Power Spectra ◽  
Neutral Hydrogen ◽  
Wave Model ◽  
Hydrogen Ionization ◽  
Uv Photons ◽  
Initial Power ◽  
Mass Dependent

In this paper we investigate how the Reionization process is affected by early galaxy formation in different cosmological scenarios. We use a semi-analytic model with suppressed initial power spectra to obtain the UV Luminosity Function in thermal Warm Dark Matter and sterile neutrino cosmologies. We retrace the ionization history of intergalactic medium with hot stellar emission only, exploiting fixed and mass-dependent photons escape fraction (fesc). For each cosmology, we find an upper limit to fixed fesc, which guarantees the completion of the process at z&amp;lt;6.7. The analysis is tested with two limit hypothesis on high-z ionized hydrogen volume fraction, comparing our predictions with observational results. We then implement a blast-wave model, which explains the genesis of UV photons escape fraction in the context of feedback and co-evolution between galaxies and Active Galactic Nuclei. Including the AGNs contribution, we find that the neutral hydrogen ionization is almost complete at z&amp;lt;7, with a weak dependence on initial gaseous ionized fraction and accretion UV spectral slope.

scholarly journals Multiwavelength analysis of low surface brightness galaxies to study possible dark matter signature

2020 ◽  
Author(s):  
Pooja Bhattacharjee ◽  
Pratik Majumdar ◽  
Mousumi Das ◽  
Subinoy Das ◽  
Partha S Joarder ◽  
...  
Keyword(s):  
Dark Matter ◽  
Surface Brightness ◽  
Neutral Hydrogen ◽  
Indirect Detection ◽  
Large Area ◽  
Very Large Array ◽  
Dwarf Spheroidal Galaxies ◽  
Optical Images ◽  
Low Surface Brightness ◽  
Lsb Galaxies

Abstract Low Surface Brightness (LSB) galaxies have very diffuse, low surface density stellar disks which appear faint in optical images. They are very rich in neutral hydrogen (HI) gas, which extends well beyond the stellar disks. Their extended HI rotation curves and stellar disks indicate that they have very massive dark matter (DM) halos compared to normal bright galaxies. Hence, LSB galaxies may represent valuable laboratories for the indirect detection of DM. In this paper, we search for WIMP annihilation signatures in four LSB galaxies and present an analysis of nearly nine years of data from the Fermi Large Area Telescope (LAT). Above 500 MeV, no excess emission was detected from the LSB galaxies. We obtain constraints on the DM cross-section for different annihilation channels, for both individual and stacked targets. In addition to this, we use radio data from the Very Large Array (VLA) radio telescope in order to derive DM constraints, following a multiwavelength approach. The constraints obtained from the four considered LSB galaxies are nearly 3 orders of magnitude weaker than the predicted limits for the thermal relic abundances and the combined limits achieved from Fermi-LAT observations of dwarf spheroidal galaxies. Finally, we discuss the possibility of detecting emission from LSB galaxies using the upcoming ground-based γ-ray and radio observatories, namely the Cherenkov Telescope Array (CTA) and the Square Kilometre Array (SKA).

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