scholarly journals The atomic hydrogen content of the post-reionization Universe

2020 ◽  
Vol 493 (4) ◽  
pp. 5434-5455 ◽  
Author(s):  
Marta Spinelli ◽  
Anna Zoldan ◽  
Gabriella De Lucia ◽  
Lizhi Xie ◽  
Matteo Viel
Keyword(s):  
Galaxy Formation ◽  
Shot Noise ◽  
Atomic Hydrogen ◽  
Mass Function ◽  
Limiting Factor ◽  
History Plays ◽  
Local Universe ◽  
Intensity Mapping ◽  
The One ◽  
Halo Occupation Distribution

ABSTRACT We present a comprehensive analysis of atomic hydrogen (H i) properties using a semi-analytical model of galaxy formation and N-body simulations covering a large cosmological volume at high resolution. We examine the H i mass function and the H i density, characterizing both their redshift evolution and their dependence on hosting halo mass. We analyse the H i content of dark matter haloes in the local Universe and up to redshift z = 5, discussing the contribution of different galaxy properties. We find that different assembly history plays a crucial role in the scatter of this relation. We propose new fitting functions useful for constructing mock H i maps with halo occupation distribution techniques. We investigate the H i clustering properties relevant for future 21 cm intensity mapping (IM) experiments, including the H i bias and the shot-noise level. The H i bias increases with redshift and it is roughly flat on the largest scales probed. The scale dependence is found at progressively larger scales with increasing redshift, apart from a dip feature at z = 0. The shot-noise values are consistent with the ones inferred by independent studies, confirming that shot noise will not be a limiting factor for IM experiments. We detail the contribution from various galaxy properties on the H i power spectrum and their relation to the halo bias. We find that H i poor satellite galaxies play an important role at the scales of the one-halo term. Finally, we present the 21 cm signal in redshift space, a fundamental prediction to be tested against data from future radio telescopes such as Square Kilometre Array.

scholarly journals Extracting H i astrophysics from interferometric Intensity Mapping

2021 ◽  
Author(s):  
Zhaoting Chen ◽  
Laura Wolz ◽  
Marta Spinelli ◽  
Steven G Murray
Keyword(s):  
Galaxy Formation ◽  
Shot Noise ◽  
Large Scale ◽  
Neutral Hydrogen ◽  
Mass Function ◽  
Small Scale ◽  
Number Density ◽  
Model Framework ◽  
Intensity Mapping ◽  
Cent Level

Abstract We present a new halo model of neutral hydrogen (H i) calibrated to galaxy formation simulations at redshifts z ∼ 0.1 and z ∼ 1.0 which we employ to investigate the constraining power of interferometric H i Intensity Mapping on H i astrophysics. We demonstrate that constraints on the small-scale H i power spectrum can break the degeneracy between the H i density $\Omega _{\rm H\, \rm \small {I}}$ and the H i bias $b_{\rm H\, \rm \small {I}}$. For z ∼ 0.1, we forecast that an accurate measurement of $\Omega _{\rm H\, \rm \small {I}}$ up to 6 per cent level precision and the large scale H i bias $b_{\rm H\, \rm \small {I}}^0$ up to 1 per cent level precision can be achieved using Square Kilometre Array (SKA) pathfinder data from MeerKAT and ASKAP. We also propose a new description of the H i shot noise in the halo model framework in which a scatter of the relation between the H i mass of galaxies and their host halo mass is taken into account. Furthermore, given the number density of H i galaxies above a certain H i mass threshold, future surveys will also be able to constrain the H i Mass Function using only the H i shot noise. This will lead to constraints at the 10 per cent level using the standard Schechter function. This technique will potentially provide a new way of measuring the H i Mass Function, independent from existing methods. We predict that the SKA will be able to further improve the low redshift constraints by a factor of three, as well as pioneering measurements of H i astrophysics at higher redshifts.

scholarly journals The cosmic atomic hydrogen mass density as a function of mass and galaxy hierarchy from spectral stacking

2020 ◽  
Vol 493 (2) ◽  
pp. 1587-1595 ◽  
Author(s):  
Wenkai Hu ◽  
Barbara Catinella ◽  
Luca Cortese ◽  
Lister Staveley-Smith ◽  
Claudia del P Lagos ◽  
...  
Keyword(s):  
Galaxy Formation ◽  
Atomic Hydrogen ◽  
Mass Density ◽  
Theoretical Models ◽  
Theoretical Work ◽  
Sloan Digital Sky Survey ◽  
Analytical Models ◽  
Local Universe ◽  
Satellite Galaxies ◽  
Stellar Masses

ABSTRACT We use spectral stacking to measure the contribution of galaxies of different masses and in different hierarchies to the cosmic atomic hydrogen (H i) mass density in the local Universe. Our sample includes 1793 galaxies at z < 0.11 observed with the Westerbork Synthesis Radio Telescope, for which Sloan Digital Sky Survey spectroscopy and hierarchy information are also available. We find a cosmic H i mass density of $\Omega _{\rm H\, \small {I} } = (3.99 \pm 0.54)\times 10^{-4} \, h_{70}^{-1}$ at 〈 z〉 = 0.065. For the central and satellite galaxies, we obtain $\Omega _{\rm H\, {\small {I}}}$ of $(3.51 \pm 0.49)\times 10^{-4} \, h_{70}^{-1}$ and $(0.90 \pm 0.16)\times 10^{-4} \, h_{70}^{-1}$, respectively. We show that galaxies above and below stellar masses of ∼109.3 M⊙ contribute in roughly equal measure to the global value of $\Omega _{\rm H\, \small {I} }$. While consistent with estimates based on targeted H i surveys, our results are in tension with previous theoretical work. We show that these differences are, at least partly, due to the empirical recipe used to set the partition between atomic and molecular hydrogen in semi-analytical models. Moreover, comparing our measurements with the cosmological semi-analytic models of galaxy formation Shark and GALFORM reveals gradual stripping of gas via ram pressure works better to fully reproduce the properties of satellite galaxies in our sample than strangulation. Our findings highlight the power of this approach in constraining theoretical models and confirm the non-negligible contribution of massive galaxies to the H i mass budget of the local Universe.

scholarly journals Mapping large-scale-structure evolution over cosmic times

2021 ◽  
Author(s):  
Marta B. Silva ◽  
Ely D. Kovetz ◽  
Garrett K. Keating ◽  
Azadeh Moradinezhad Dizgah ◽  
Matthieu Bethermin ◽  
...  
Keyword(s):  
Galaxy Formation ◽  
Large Scale ◽  
High Redshift ◽  
Formation Rate ◽  
Far Infrared ◽  
Large Scale Structure ◽  
Scale Structure ◽  
Structure Evolution ◽  
Intensity Mapping ◽  
Wide Range

AbstractThis paper outlines the science case for line-intensity mapping with a space-borne instrument targeting the sub-millimeter (microwaves) to the far-infrared (FIR) wavelength range. Our goal is to observe and characterize the large-scale structure in the Universe from present times to the high redshift Epoch of Reionization. This is essential to constrain the cosmology of our Universe and form a better understanding of various mechanisms that drive galaxy formation and evolution. The proposed frequency range would make it possible to probe important metal cooling lines such as [CII] up to very high redshift as well as a large number of rotational lines of the CO molecule. These can be used to trace molecular gas and dust evolution and constrain the buildup in both the cosmic star formation rate density and the cosmic infrared background (CIB). Moreover, surveys at the highest frequencies will detect FIR lines which are used as diagnostics of galaxies and AGN. Tomography of these lines over a wide redshift range will enable invaluable measurements of the cosmic expansion history at epochs inaccessible to other methods, competitive constraints on the parameters of the standard model of cosmology, and numerous tests of dark matter, dark energy, modified gravity and inflation. To reach these goals, large-scale structure must be mapped over a wide range in frequency to trace its time evolution and the surveyed area needs to be very large to beat cosmic variance. Only a space-borne mission can properly meet these requirements.

scholarly journals First Light And Reionization Epoch Simulations (FLARES) – I. Environmental dependence of high-redshift galaxy evolution

2020 ◽  
Vol 500 (2) ◽  
pp. 2127-2145
Author(s):  
Christopher C Lovell ◽  
Aswin P Vijayan ◽  
Peter A Thomas ◽  
Stephen M Wilkins ◽  
David J Barnes ◽  
...  
Keyword(s):  
Galaxy Evolution ◽  
Galaxy Formation ◽  
Dynamic Range ◽  
High Redshift ◽  
Formation Rate ◽  
Mass Function ◽  
Distribution Functions ◽  
Large Area ◽  
Composite Distribution ◽  
Environmental Dependence

ABSTRACT We introduce the First Light And Reionisation Epoch Simulations (FLARES), a suite of zoom simulations using the EAGLE model. We resimulate a range of overdensities during the Epoch of Reionization (EoR) in order to build composite distribution functions, as well as explore the environmental dependence of galaxy formation and evolution during this critical period of galaxy assembly. The regions are selected from a large $(3.2 \, \mathrm{cGpc})^{3}$ parent volume, based on their overdensity within a sphere of radius 14 h−1 cMpc. We then resimulate with full hydrodynamics, and employ a novel weighting scheme that allows the construction of composite distribution functions that are representative of the full parent volume. This significantly extends the dynamic range compared to smaller volume periodic simulations. We present an analysis of the galaxy stellar mass function (GSMF), the star formation rate distribution function (SFRF), and the star-forming sequence (SFS) predicted by FLARES, and compare to a number of observational and model constraints. We also analyse the environmental dependence over an unprecedented range of overdensity. Both the GSMF and the SFRF exhibit a clear double-Schechter form, up to the highest redshifts (z = 10). We also find no environmental dependence of the SFS normalization. The increased dynamic range probed by FLARES will allow us to make predictions for a number of large area surveys that will probe the EoR in coming years, carried out on new observatories such as Roman and Euclid.

scholarly journals The Bimodality of Galaxy Populations Revisited Through Spectral Synthesis

2006 ◽  
Vol 2 (S235) ◽  
pp. 139-139
Author(s):  
L. Sodré ◽  
A. Mateus ◽  
R. Cid Fernandes ◽  
G. Stasińska ◽  
W. Schoenell ◽  
...  
Keyword(s):  
Galaxy Formation ◽  
Spectral Synthesis ◽  
Synthesis Method ◽  
Local Universe ◽  
Massive Galaxies ◽  
Star Forming ◽  
The Galaxy ◽  
Galaxy Populations ◽  
Galaxy Population ◽  
Stellar Masses

AbstractWe revisit the bimodality of the galaxy population seen in the local universe. We address this issue in terms of physical properties of galaxies, such as mean stellar ages and stellar masses, derived from the application of a spectral synthesis method to galaxy spectra from the SDSS. We show that the mean light-weighted stellar age of galaxies presents the best description of the bimodality seen in the galaxy population. The stellar mass has an additional role since most of the star-forming galaxies present in the local universe are low-mass galaxies. Our results give support to the existence of a ‘downsizing’ in galaxy formation, where nowadays massive galaxies tend to have stellar populations older than those found in less massive objects.

scholarly journals Intensity mapping cross-correlations II: HI halo models including shot noise

2018 ◽  
Vol 484 (1) ◽  
pp. 1007-1020 ◽  
Author(s):  
L Wolz ◽  
S G Murray ◽  
C Blake ◽  
J S Wyithe
Keyword(s):  
Shot Noise ◽  
Intensity Mapping ◽  
Cross Correlations

scholarly journals The NIBLES bivariate luminosity–H I mass distribution function revised using Arecibo follow-up observations

2020 ◽  
Vol 642 ◽  
pp. A175
Author(s):  
Z. Butcher ◽  
W. van Driel ◽  
S. Schneider
Keyword(s):  
Mass Distribution ◽  
Radio Telescope ◽  
Luminosity Function ◽  
Mass Function ◽  
Bivariate Analysis ◽  
Dimensional Distribution ◽  
Low Mass ◽  
The One ◽  
Mass Distribution Function

We present a modified optical luminosity–H I mass bivariate luminosity function based on H I line observations from the Nançay Interstellar Baryons Legacy Extragalactic Survey (NIBLES), including data from our new, four times more sensitive follow-up H I line observations obtained with the Arecibo radio telescope. The follow-up observations were designed to probe the underlying H I mass distribution of the NIBLES galaxies that were undetected or marginally detected in H I at the Nançay Radio Telescope. Our total follow-up sample consists of 234 galaxies, and it spans the entire luminosity and color range of the parent NIBLES sample of 2600 nearby (900 <  cz <  12 000 km s−1) SDSS galaxies. We incorporated the follow-up data into the bivariate analysis by scaling the NIBLES undetected fraction by an Arecibo-only distribution. We find the resulting increase in low H I mass-to-light ratio densities to be about 10% for the bins −1.0 ≤ log(MHI/M⊙/Lr/L⊙) ≤ −0.5, which produces an increased H I mass function (HIMF) low mass slope of α = −1.14 ± 0.07, being slightly shallower than the values of −1.35 ± 0.05 obtained by recent blind H I surveys. Applying the same correction to the optically corrected bivariate luminosity function from our previous paper produces a larger density increase of about 0.5 to 1 dex in the lowest H I mass-to-light ratio bins for a given luminosity while having a minimal effect on the resulting HIMF low mass slope, which still agrees with blind survey HIMFs. This indicates that while low H I-mass-to-light ratio galaxies do not contribute much to the one-dimensional HIMF, their inclusion has a significant impact on the densities in the two-dimensional distribution.

Tyranny and Usurpation

2019 ◽  
Author(s):  
Doyeeta Majumder
Keyword(s):  
Sixteenth Century ◽  
Political Thought ◽  
The Political ◽  
History Plays ◽  
Elizabethan Drama ◽  
Political Drama ◽  
English Stage ◽  
The One ◽  
Tragic Drama ◽  
Law Making

This book examines the fraught relationship between the sixteenth-century formulations of the theories of sovereign violence, tyranny and usurpation and the manifestations of these ideas on the contemporary English stage. It will attempt to trace an evolution of the poetics of English and Scottish political drama through the early, middle, and late decades of the sixteenth-century in conjunction with developments in the political thought of the century, linking theatre and politics through the representations of the problematic figure of the usurper or, in Machiavellian terms, the ‘New Prince’. While the early Tudor morality plays are concerned with the legitimate monarch who becomes a tyrant, the later historical and tragic drama of the century foregrounds the figure of the illegitimate monarch who is a tyrant by default. On the one hand the sudden proliferation of usurpation plots in Elizabethan drama and the transition from the legitimate tyrant to the usurper tyrant is linked to the dramaturgical shift from the allegorical morality play tradition to later history plays and tragedies, and on the other it is reflective of a poetic turn in political thought which impelled political writers to conceive of the state and sovereignty as a product of human ‘poiesis’, independent of transcendental legitimization. The poetics of political drama and the emergence of the idea of ‘poiesis’ in the political context merge in the figure of the nuove principe: the prince without dynastic claims who creates his sovereignty by dint of his own ‘virtu’ and through an act of law-making violence.

Water Access in the Fight Against Poverty

2013 ◽  
pp. 315-325
Author(s):  
Diego Azqueta ◽  
Álvaro Montoya
Keyword(s):  
Water Footprint ◽  
Positive Impact ◽  
Rural Poverty ◽  
Critical Issue ◽  
Limiting Factor ◽  
Multiple Use ◽  
Potential Conflict ◽  
Access To Water ◽  
Tourist Development ◽  
The One

Rural poverty in underdeveloped countries is a critical issue. A fair amount of literature exists examining the conditions of pro-poor tourism development, as well as different ways to fight it. However, in some cases, and because of the existence of a limiting factor, a potential incompatibility between tourist development and other strategies can emerge, as well as the need to compare relative efficiency. An example of this potential conflict is the one posed by tourist development and the Multiple Use of Water Services strategy (MUS) to alleviate rural poverty. In this case, the limiting constraint is access to water. This paper analyses the impacts, direct and indirect, on poverty levels, of tourist development and MUS. the authors examine the Quindío Region in Colombia, where the MUS strategy is being implemented and where an ambitious tourist development plan may open social conflict regarding water supply. The results of this analysis shows that, even if the MUS strategy has a greater positive impact on poverty alleviation, in terms of income and employment generated per unit of water, its water footprint, contrary to expectations, is much higher than the one corresponding to the tourist sector. This may jeopardize its future development, calling for a more balanced approach.

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