scholarly journals Testing dark matter halo properties using self-similarity

2020 ◽  
Author(s):  
M Leroy ◽  
L Garrison ◽  
D Eisenstein ◽  
M Joyce ◽  
S Maleubre
Keyword(s):  
Dark Matter ◽  
Particle Number ◽  
Percent Level ◽  
Mass Function ◽  
Dark Matter Halo ◽  
Self Similarity ◽  
Good Convergence ◽  
Scale Free ◽  
Point Correlation ◽  
Mass Functions

Abstract We use self-similarity in N-body simulations of scale-free models to test for resolution dependence in the mass function and two-point correlation functions of dark matter halos. We use 10243 particle simulations performed with Abacus, and compare results obtained with two halo finders: friends-of-friends (fof) and Rockstar. The fof mass functions show a systematic deviation from self-similarity which is explained by resolution dependence of the fof mass assignment previously reported in the literature. Weak evidence for convergence is observed only starting from halos of several thousand particles, and mass functions are overestimated by at least as much as $20-25\%$ for halos of 50 particles. The mass function of the default Rockstar halo catalog (with bound virial spherical overdensity mass), on the other hand, shows good convergence from of order 50 to 100 particles per halo, with no detectable evidence at the few percent level of any systematic dependence for larger particle number. Tests show that the mass unbinding procedure in Rockstar is the key factor in obtaining this much improved resolution. Applying the same analysis to the halo-halo two point correlation function, we find again strong evidence for convergence only for Rockstar halos, at separations sufficiently large so that halos do not overlap. At these separations we can exclude dependence on resolution at the $5-10\%$ level once halos have of order 50 to 100 particles. At smaller separations results are not converged even at significantly larger particle number, and bigger simulations would be required to establish the resolution required for convergence.

scholarly journals The normalization and slope of the dark matter (sub-)halo mass function on sub-galactic scales

2020 ◽  
Vol 493 (1) ◽  
pp. 1268-1276
Author(s):  
Andrew J Benson
Keyword(s):  
Dark Matter ◽  
Gravitational Lensing ◽  
Cold Dark Matter ◽  
Mass Range ◽  
Mass Function ◽  
Matter Content ◽  
Dark Matter Halo ◽  
Halo Masses ◽  
Near Future ◽  
Mass Functions

ABSTRACT Simulations of cold dark matter make robust predictions about the slope and normalization of the dark matter halo and subhalo mass functions on small scales. Recent observational advances utilizing strong gravitational lensing have demonstrated the ability of this technique to place constraints on these quantities on subgalactic scales corresponding to dark matter halo masses of 106–$10^9\, \mathrm{M}_\odot$. On these scales the physics of baryons, which make up around 17 per cent of the matter content of the Universe but which are not included in pure dark matter N-body simulations, are expected to affect the growth of structure and the collapse of dark matter haloes. In this work, we develop a semi-analytic model to predict the amplitude and slope of the dark matter halo and subhalo mass functions on subgalactic scales in the presence of baryons. We find that the halo mass function is suppressed by up to 25 per cent, and the slope is modified, ranging from −1.916 to −1.868 in this mass range. These results are consistent with current measurements, but differ sufficiently from the expectations for a dark matter only universe that it may be testable in the near future.

scholarly journals Modelling Galaxy Populations in the Era of Big Data

2014 ◽  
Vol 10 (S306) ◽  
pp. 304-306
Author(s):  
S. G. Murray ◽  
C. Power ◽  
A. S. G. Robotham
Keyword(s):  
Dark Matter ◽  
Big Data ◽  
Open Source ◽  
Recent Work ◽  
Mass Function ◽  
Dark Matter Halo ◽  
Square Kilometre Array ◽  
Galaxy Surveys ◽  
Software Frameworks ◽  
Galaxy Populations

AbstractThe coming decade will witness a deluge of data from next generation galaxy surveys such as the Square Kilometre Array and Euclid. How can we optimally and robustly analyse these data to maximise scientific returns from these surveys? Here we discuss recent work in developing both the conceptual and software frameworks for carrying out such analyses and their application to the dark matter halo mass function. We summarise what we have learned about the HMF from the last 10 years of precision CMB data using the open-source HMFcalc framework, before discussing how this framework is being extended to the full Halo Model.

scholarly journals HMFcalc: An online tool for calculating dark matter halo mass functions

2013 ◽  
Vol 3-4 ◽  
pp. 23-34 ◽  
Author(s):  
S.G. Murray ◽  
C. Power ◽  
A.S.G. Robotham
Keyword(s):  
Dark Matter ◽  
Dark Matter Halo ◽  
Online Tool ◽  
Mass Functions

scholarly journals Survey of gravitationally-lensed objects in HSC imaging (SuGOHI)

2019 ◽  
Vol 630 ◽  
pp. A71 ◽  
Author(s):  
Alessandro Sonnenfeld ◽  
Anton T. Jaelani ◽  
James Chan ◽  
Anupreeta More ◽  
Sherry H. Suyu ◽  
...  
Keyword(s):  
Dark Matter ◽  
Gravitational Lensing ◽  
Mass Function ◽  
Initial Mass Function ◽  
Dark Matter Halo ◽  
Open Problems ◽  
Massive Galaxies ◽  
Spatially Resolved ◽  
Stellar Masses ◽  
The Imf

Context. The determination of the stellar initial mass function (IMF) of massive galaxies is one of the open problems in cosmology. Strong gravitational lensing is one of the few methods that allow us to constrain the IMF outside of the Local Group. Aims. The goal of this study is to statistically constrain the distribution in the IMF mismatch parameter, defined as the ratio between the true stellar mass of a galaxy and that inferred assuming a reference IMF, of massive galaxies from the Baryon Oscillation Spectroscopic Survey (BOSS) constant mass (CMASS) sample. Methods. We took 23 strong lenses drawn from the CMASS sample, measured their Einstein radii and stellar masses using multi-band photometry from the Hyper Suprime-Cam survey, then fitted a model distribution for the IMF mismatch parameter and dark matter halo mass to the whole sample. We used a prior on halo mass from weak lensing measurements and accounted for strong lensing selection effects in our model. Results. Assuming a Navarro Frenk and White density profile for the dark matter distribution, we infer a value μIMF = −0.04 ± 0.11 for the average base-10 logarithm of the IMF mismatch parameter, defined with respect to a Chabrier IMF. A Salpeter IMF is in tension with our measurements. Conclusions. Our results are consistent with a scenario in which the region of massive galaxies where the IMF normalisation is significantly heavier than that of the Milky Way is much smaller than the scales 5 − 10 kpc probed by the Einstein radius of the lenses in our sample, as recent spatially-resolved studies of the IMF in massive galaxies suggest.

scholarly journals A flexible analytic model of cosmic variance in the first billion years

2020 ◽  
Vol 499 (2) ◽  
pp. 2401-2415
Author(s):  
A C Trapp ◽  
Steven R Furlanetto
Keyword(s):  
Dark Matter ◽  
Star Formation ◽  
Luminosity Function ◽  
Large Scale ◽  
High Redshift ◽  
Mass Function ◽  
Dark Matter Halo ◽  
Analytic Model ◽  
Stellar Feedback ◽  
High Redshift Universe

ABSTRACT Cosmic variance is the intrinsic scatter in the number density of galaxies due to fluctuations in the large-scale dark matter density field. In this work, we present a simple analytic model of cosmic variance in the high-redshift Universe (z ∼ 5–15). We assume that galaxies grow according to the evolution of the halo mass function, which we allow to vary with large-scale environment. Our model produces a reasonable match to the observed ultraviolet (UV) luminosity functions in this era by regulating star formation through stellar feedback and assuming that the UV luminosity function is dominated by recent star formation. We find that cosmic variance in the UV luminosity function is dominated by the variance in the underlying dark matter halo population, and not by differences in halo accretion or the specifics of our stellar feedback model. We also find that cosmic variance dominates over Poisson noise for future high-z surveys except for the brightest sources or at very high redshifts (z ≳ 12). We provide a linear approximation of cosmic variance for a variety of redshifts, magnitudes, and survey areas through the public python package galcv. Finally, we introduce a new method for incorporating priors on cosmic variance into estimates of the galaxy luminosity function and demonstrate that it significantly improves constraints on that important observable.

scholarly journals A systematic search for galaxy proto-cluster cores at z ∼ 2

2019 ◽  
Vol 15 (S359) ◽  
pp. 166-167
Author(s):  
Makoto Ando ◽  
Kazuhiro Shimasaku ◽  
Rieko Momose
Keyword(s):  
Dark Matter ◽  
Galaxy Formation ◽  
Clustering Analysis ◽  
Mass Function ◽  
Stellar Mass ◽  
Dark Matter Halo ◽  
Massive Galaxies ◽  
The Galaxy ◽  
Mass Assembly ◽  
Cluster Cores

AbstractA proto-cluster core is the most massive dark matter halo (DMH) in a given proto-cluster. To reveal the galaxy formation in core regions, we search for proto-cluster cores at z ˜ 2 in ˜1.5deg2 of the COSMOS field. Using pairs of massive galaxies (log (M*/Mʘ) ≥ 11) as tracers of cores, we find 75 candidate cores. A clustering analysis and the extended Press-Schechter model show that their descendant mass at z = 0 is consistent with Fornax-like or Virgo-like clusters. Moreover, using the IllustrisTNG simulation, we confirm that pairs of massive galaxies are good tracers of DMHs massive enough to be regarded as proto-cluster cores. We then derive the stellar mass function and the quiescent fraction for member galaxies of the 75 candidate cores. We find that stellar mass assembly and quenching are accelerated as early as z ˜ 2 in proto-cluster cores.

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