scholarly journals scampy – A sub-halo clustering and abundance matching based python interface for painting galaxies on the dark matter halo/sub-halo hierarchy

2020 ◽  
Vol 498 (2) ◽  
pp. 2095-2113
Author(s):  
Tommaso Ronconi ◽  
Andrea Lapi ◽  
Matteo Viel ◽  
Alberto Sartori
Keyword(s):  
Dark Matter ◽  
High Redshift ◽  
Object Oriented Programming ◽  
Dark Matter Halo ◽  
Extensive Documentation ◽  
Redshift Galaxy ◽  
Luminosity Functions ◽  
The Galaxy ◽  
Galaxy Population ◽  
Correlation Properties

ABSTRACT We present a computational framework for ‘painting’ galaxies on top of the dark matter halo/sub-halo hierarchy obtained from N-body simulations. The method we use is based on the sub-halo clustering and abundance matching (SCAM) scheme which requires observations of the 1- and 2-point statistics of the target (observed) population we want to reproduce. This method is particularly tailored for high redshift studies and thereby relies on the observed high-redshift galaxy luminosity functions and correlation properties. The core functionalities are written in C++ and exploit Object Oriented Programming, with a wide use of polymorphism, to achieve flexibility and high computational efficiency. In order to have an easily accessible interface, all the libraries are wrapped in python and provided with an extensive documentation. We validate our results and provide a simple and quantitative application to reionization, with an investigation of physical quantities related to the galaxy population, ionization fraction, and bubble size distribution. The library is publicly available at https://github.com/TommasoRonconi/scampy with full documentation and examples at https://scampy.readthedocs.io.

scholarly journals The impact of scatter in the galaxy UV luminosity to halo mass relation on Ly α visibility during the epoch of reionization

2020 ◽  
Vol 495 (4) ◽  
pp. 3602-3613 ◽  
Author(s):  
Lily R Whitler ◽  
Charlotte A Mason ◽  
Keven Ren ◽  
Mark Dijkstra ◽  
Andrei Mesinger ◽  
...  
Keyword(s):  
Dark Matter ◽  
High Redshift ◽  
Neutral Hydrogen ◽  
Dark Matter Halo ◽  
Mass Relation ◽  
Lyman Alpha ◽  
Redshift Galaxy ◽  
The Galaxy ◽  
Improved Model ◽  
The Impact

ABSTRACT The reionization of hydrogen is closely linked to the first structures in the Universe, so understanding the timeline of reionization promises to shed light on the nature of these early objects. In particular, transmission of Lyman alpha (Ly α) from galaxies through the intergalactic medium (IGM) is sensitive to neutral hydrogen in the IGM, so can be used to probe the reionization timeline. In this work, we implement an improved model of the galaxy UV luminosity to dark matter halo mass relation to infer the volume-averaged fraction of neutral hydrogen in the IGM from Ly α observations. Many models assume that UV-bright galaxies are hosted by massive dark matter haloes in overdense regions of the IGM, so reside in relatively large ionized regions. However, observations and N-body simulations indicate that scatter in the UV luminosity–halo mass relation is expected. Here, we model the scatter (though we assume the IGM topology is unaffected) and assess the impact on Ly α visibility during reionization. We show that UV luminosity–halo mass scatter reduces Ly α visibility compared to models without scatter, and that this is most significant for UV-bright galaxies. We then use our model with scatter to infer the neutral fraction, $\overline{x}_{\mathrm{ H}\,{\small I}}$, at z ∼ 7 using a sample of Lyman-break galaxies in legacy fields. We infer $\overline{x}_{\mathrm{ H}\,{\small I}} = 0.55_{-0.13}^{+0.11}$ with scatter, compared to $\overline{x}_{\mathrm{ H}\,{\small I}} = 0.59_{-0.14}^{+0.12}$ without scatter, a very slight decrease and consistent within the uncertainties. Finally, we place our results in the context of other constraints on the reionization timeline and discuss implications for future high-redshift galaxy studies.

scholarly journals Is the dark-matter halo spin a predictor of galaxy spin and size?

2019 ◽  
Vol 488 (4) ◽  
pp. 4801-4815 ◽  
Author(s):  
Fangzhou Jiang ◽  
Avishai Dekel ◽  
Omer Kneller ◽  
Sharon Lapiner ◽  
Daniel Ceverino ◽  
...  
Keyword(s):  
Dark Matter ◽  
Angular Momentum ◽  
High Redshift ◽  
General Relation ◽  
Retention Factor ◽  
Dark Matter Halo ◽  
High Redshift Galaxies ◽  
The Galaxy ◽  
One To One ◽  
Analytic Models

ABSTRACT The similarity between the distributions of spins for galaxies (λgal) and for dark-matter haloes (λhalo), indicated both by simulations and observations, is naively interpreted as a one-to-one correlation between the spins of a galaxy and its host halo. This is used to predict galaxy sizes in semi-analytic models via Re ≃ fjλhaloRvir, where Re is the half-mass radius of the galaxy, fj is the angular momentum retention factor, and Rvir is the halo radius. Using two suites of zoom-in cosmological simulations, we find that λgal and the λhalo of its host halo are in fact barely correlated, especially at z ≥ 1, in line with previous indications. Since the spins of baryons and dark matter are correlated at accretion into Rvir, the null correlation in the end reflects an anticorrelation between fj and λhalo, which can arise from mergers and a ‘wet compaction’ phase that many high-redshift galaxies undergo. It may also reflect that unrepresentative small fractions of baryons are tapped to the galaxies. The galaxy spin is better correlated with the spin of the inner halo, but this largely reflects the effect of the baryons on the halo. While λhalo is not a useful predictor for Re, our simulations reproduce a general relation of the form of Re = ARvir, in agreement with observational estimates. We find that the relation becomes tighter with A = 0.02(c/10)−0.7, where c is the halo concentration, which in turn introduces a dependence on mass and redshift.

scholarly journals Quasars at intermediate redshift are not special; but they are often satellites

2021 ◽  
Vol 504 (1) ◽  
pp. 857-870
Author(s):  
Shadab Alam ◽  
Nicholas P Ross ◽  
Sarah Eftekharzadeh ◽  
John A Peacock ◽  
Johan Comparat ◽  
...  
Keyword(s):  
Dark Matter ◽  
Galaxy Formation ◽  
Dark Matter Halo ◽  
Stellar Objects ◽  
The Galaxy ◽  
Quasi Stellar Objects ◽  
Satellite Galaxies ◽  
Emission Line Galaxies ◽  
Galaxy Population ◽  
Red Galaxies

ABSTRACT Understanding the links between the activity of supermassive black holes (SMBHs) at the centres of galaxies and their host dark matter haloes is a key question in modern astrophysics. The final data release of the SDSS-IV eBOSS provides the largest contemporary spectroscopic sample of galaxies and quasi-stellar objects (QSOs). Using this sample and covering the redshift interval z = 0.7–1.1, we have measured the clustering properties of the eBOSS QSOs, emission-line galaxies (ELGs), and luminous red galaxies (LRGs). We have also measured the fraction of QSOs as a function of the overdensity defined by the galaxy population. Using these measurements, we investigate how QSOs populate and sample the galaxy population, and how the host dark-matter haloes of QSOs sample the underlying halo distribution. We find that the probability of a galaxy hosting a QSO is independent of the host dark matter halo mass of the galaxy. We also find that about 60 per cent of eBOSS QSOs are hosted by LRGs and about 20–40 per cent of QSOs are hosted by satellite galaxies. We find a slight preference for QSOs to populate satellite galaxies over central galaxies. This is connected to the host halo mass distribution of different types of galaxies. Based on our analysis, QSOs should be hosted by a very broad distribution of haloes, and their occurrence should be modulated only by the efficiency of galaxy formation processes.

scholarly journals Spectral energy distribution similarity of the local galaxies and the 3.6 μm selected galaxies from the Spitzer Extended Deep Survey

2021 ◽  
Vol 21 (10) ◽  
pp. 260
Author(s):  
Cheng Cheng ◽  
Jia-Sheng Huang ◽  
Hai Xu ◽  
Gao-Xiang Jin ◽  
Chuan He ◽  
...  
Keyword(s):  
High Redshift ◽  
Spectral Energy Distribution ◽  
Mass Function ◽  
Spectral Energy ◽  
Energy Distributions ◽  
Mid Infrared ◽  
Redshift Galaxy ◽  
The Galaxy ◽  
Deep Survey ◽  
Multi Wavelength

Abstract The Spitzer Extended Deep Survey (SEDS) as a deep and wide mid-infrared (MIR) survey project provides a sample of 500 000+ sources spreading 1.46 square degree and a depth of 26 AB mag (3σ). Combining with the previous available data, we build a PSF-matched multi-wavelength photometry catalog from u band to 8 μm. We fit the SEDS galaxies spectral energy distributions by the local galaxy templates. The results show that the SEDS galaxy can be fitted well, indicating the high redshift galaxy (z ∼ 1) shares the same templates with the local galaxies. This study would facilitate the further study of the galaxy luminosity and high redshift mass function.

scholarly journals Testing for Dark Matter in the Outskirts of Globular Clusters

2021 ◽  
Vol 922 (2) ◽  
pp. 104
Author(s):  
Raymond G. Carlberg ◽  
Carl J. Grillmair
Keyword(s):  
Dark Matter ◽  
Globular Clusters ◽  
High Probability ◽  
Velocity Dispersion ◽  
High Redshift ◽  
Dark Matter Halo ◽  
The Sun ◽  
Proper Motions ◽  
Preliminary Results ◽  
Galactic Background

Abstract The proper motions of stars in the outskirts of globular clusters are used to estimate cluster velocity dispersion profiles as far as possible within their tidal radii. We use individual color–magnitude diagrams to select high-probability cluster stars for 25 metal-poor globular clusters within 20 kpc of the Sun, 19 of which have substantial numbers of stars at large radii. Of the 19, 11 clusters have a falling velocity dispersion in the 3–6 half-mass radii range, 6 are flat, and 2 plausibly have a rising velocity dispersion. The profiles are all in the range expected from simulated clusters that started at high redshift in a zoom-in cosmological simulation. The 11 clusters with falling velocity dispersion profiles are consistent with no dark matter above the Galactic background. The six clusters with approximately flat velocity dispersion profiles could have local dark matter, but are ambiguous. The two clusters with rising velocity dispersion profiles are consistent with a remnant local dark matter halo, but need membership confirmation and detailed orbital modeling to further test these preliminary results.

scholarly journals The Dark Blue Compact Dwarf Galaxy NGC 2915

1997 ◽  
Vol 14 (1) ◽  
pp. 77-80 ◽  
Author(s):  
Gerhardt R. Meurer
Keyword(s):  
Dark Matter ◽  
Mass Distribution ◽  
Dwarf Galaxy ◽  
Dark Matter Halo ◽  
High Mass ◽  
Mass Star ◽  
Normal Galaxies ◽  
The Galaxy ◽  
Dark Blue ◽  
Blue Compact Dwarf Galaxy

AbstractRecent results on NGC 2915, the first blue compact dwarf galaxy to have its mass distribution modelled, are summarised. NGC 2915 is shown to have HI well beyond its detected optical extent. Its rotation curve is well determined and fit with maximum disk mass models. The dark matter halo dominates the mass distribution at nearly all radii, and has a very dense core compared to those of normal galaxies. High-mass star formation energises the HI in the centre of the galaxy, but appears to be maintained in viriai equilibrium with the dark matter halo. The implications of these results are briefly discussed.

scholarly journals Globular cluster ejection, infall, and the host dark matter halo of the Pegasus dwarf galaxy

2020 ◽  
Vol 492 (4) ◽  
pp. 5102-5120
Author(s):  
Ryan Leaman ◽  
Tomás Ruiz-Lara ◽  
Andrew A Cole ◽  
Michael A Beasley ◽  
Alina Boecker ◽  
...  
Keyword(s):  
Dark Matter ◽  
Relaxation Time ◽  
Density Profile ◽  
Globular Cluster ◽  
Dwarf Galaxy ◽  
Orbital Evolution ◽  
Dark Matter Halo ◽  
Host Galaxy ◽  
Structural Constraints ◽  
The Galaxy

ABSTRACT Recent photometric observations revealed a massive, extended (MGC ≳ 105 M⊙; Rh ∼ 14 pc) globular cluster (GC) in the central region (D3D ≲ 100 pc) of the low-mass (M* ∼ 5 × 106 M⊙) dwarf irregular galaxy Pegasus. This massive GC offers a unique opportunity to study star cluster inspiral as a mechanism for building up nuclear star clusters, and the dark matter (DM) density profile of the host galaxy. Here, we present spectroscopic observations indicating that the GC has a systemic velocity of ΔV = 3 ± 8 km s−1 relative to the host galaxy, and an old, metal-poor stellar population. We run a suite of orbital evolution models for a variety of host potentials (cored to cusped) and find that the GC’s observed tidal radius (which is ∼3 times larger than the local Jacobi radius), relaxation time, and relative velocity are consistent with it surviving inspiral from a distance of Dgal ≳ 700 pc (up to the maximum tested value of Dgal = 2000 pc). In successful trials, the GC arrives to the galaxy centre only within the last ∼1.4 ± 1 Gyr. Orbits that arrive in the centre and survive are possible in DM haloes of nearly all shapes, however to satisfy the GC’s structural constraints a galaxy DM halo with mass MDM ≃ 6 ± 2 × 109 M⊙, concentration c ≃ 13.7 ± 0.6, and an inner slope to the DM density profile of −0.9 ≤ γ ≤ −0.5 is preferred. The gas densities necessary for its creation and survival suggest the GC could have formed initially near the dwarf’s centre, but then was quickly relocated to the outskirts where the weaker tidal field permitted an increased size and relaxation time – with the latter preserving the former during subsequent orbital decay.

scholarly journals The gravitational force field of the Galaxy measured from the kinematics of RR Lyrae in Gaia

2019 ◽  
Vol 485 (3) ◽  
pp. 3296-3316 ◽  
Author(s):  
Christopher Wegg ◽  
Ortwin Gerhard ◽  
Marie Bieth
Keyword(s):  
Dark Matter ◽  
Dark Matter Halo ◽  
Galactic Centre ◽  
Gravitational Acceleration ◽  
Momentum Exchange ◽  
Acceleration Field ◽  
Rr Lyrae ◽  
Halo Stars ◽  
The Galaxy ◽  
Stellar Halo

Abstract From a sample of 15651 RR Lyrae with accurate proper motions in Gaia DR2, we measure the azimuthally averaged kinematics of the inner stellar halo between 1.5  and 20  kpc from the Galactic centre. We find that their kinematics are strongly radially anisotropic, and their velocity ellipsoid nearly spherically aligned over this volume. Only in the inner regions ${\lesssim } 5\, {\rm kpc}\,$ does the anisotropy significantly fall (but still with β > 0.25) and the velocity ellipsoid tilt towards cylindrical alignment. In the inner regions, our sample of halo stars rotates at up to $50\, {\rm km}\, {\rm s}^{-1}\,$, which may reflect the early history of the Milky Way, although there is also a significant angular momentum exchange with the Galactic bar at these radii. We subsequently apply the Jeans equations to these kinematic measurements in order to non-parametrically infer the azimuthally averaged gravitational acceleration field over this volume, and by removing the contribution from baryonic matter, measure the contribution from dark matter. We find that the gravitational potential of the dark matter is nearly spherical with average flattening $q_\Phi ={1.01 \pm 0.06\, }$ between 5 and 20 kpc, and by fitting parametric ellipsoidal density profiles to the acceleration field, we measure the flattening of the dark matter halo over these radii to be $q_\rho ={1.00 \pm 0.09\, }\!.$

scholarly journals The WIRCam Ultra Deep Survey (WUDS)

2018 ◽  
Vol 620 ◽  
pp. A51 ◽  
Author(s):  
R. Pelló ◽  
P. Hudelot ◽  
N. Laporte ◽  
Y. Mellier ◽  
H. J. McCracken ◽  
...  
Keyword(s):  
Luminosity Function ◽  
Formation Rate ◽  
Forthcoming Paper ◽  
Spectroscopic Studies ◽  
Photometric Redshifts ◽  
Near Ir ◽  
Luminosity Functions ◽  
The Galaxy ◽  
Deep Survey ◽  
Galaxy Population

The aim of this paper is to introduce the WIRCam Ultra Deep Survey (WUDS), a near-IR photometric survey carried out at the CFH Telescope in the field of the CFHTLS-D3 field (Groth Strip). WUDS includes four near-IR bands (Y, J, H and Ks) over a field of view of ∼400 arcmin2. The typical depth of WUDS data reaches between ∼26.8 in Y and J, and ∼26 in H and Ks (AB, 3σ in 1.3″ aperture), whereas the corresponding depth of the CFHTLS-D3 images in this region ranges between 28.6 and 29 in ugr, 28.2 in i and 27.1 in z (same S/N and aperture). The area and depth of this survey were specifically tailored to set strong constraints on the cosmic star formation rate and the luminosity function brighter or around L⋆ in the z ∼ 6 − 10 redshift domain, although these data are also useful for a variety of extragalactic projects. This first paper is intended to present the properties of the public WUDS survey in details: catalog building, completeness and depth, number counts, photometric redshifts, and global properties of the galaxy population. We have also concentrated on the selection and characterization of galaxy samples at z ∼ [4.5 − 7] in this field. For these purposes, we include an adjacent shallower area of ∼1260 arcmin2 in this region, extracted from the WIRCam Deep Survey (WIRDS), and observed in J, H and Ks bands. UV luminosity functions were derived at z ∼ 5 and z ∼ 6 taking advantage from the fact that WUDS covers a particularly interesting regime at intermediate luminosities, which allows a combined determination of M⋆ and Φ⋆ with increased accuracy. Our results on the luminosity function are consistent with a small evolution of both M⋆ and Φ⋆ between z = 5 and z = 6, irrespective of the method used to derive them, either photometric redshifts applied to blindly-selected dropout samples or the classical Lyman Break Galaxy color-preselected samples. Our results lend support to higher Φ⋆ determinations at z = 6 than usually reported. The selection and combined analysis of different galaxy samples at z ≥ 7 will be presented in a forthcoming paper, as well as the evolution of the UV luminosity function between z ∼ 4.5 and 9. WUDS is intended to provide a robust database in the near-IR for the selection of targets for detailed spectroscopic studies, in particular for the EMIR/GTC GOYA Survey.

scholarly journals Modelling a bright z = 6 galaxy at the faint end of the AGN luminosity function

2020 ◽  
Vol 494 (3) ◽  
pp. 3453-3463
Author(s):  
Maxime Trebitsch ◽  
Marta Volonteri ◽  
Yohan Dubois
Keyword(s):  
Black Hole ◽  
High Redshift ◽  
Galactic Nuclei ◽  
Stellar Populations ◽  
Star Forming ◽  
Relative Contribution ◽  
Lyman Break Galaxies ◽  
The Galaxy ◽  
Galaxy Population ◽  
High Redshift Universe

ABSTRACT Recent deep surveys have unravelled a population of faint active galactic nuclei (AGNs) in the high-redshift Universe, leading to various discussions on their nature and their role during the Epoch of Reionization. We use cosmological radiation hydrodynamics simulations of a bright galaxy at z ∼ 6 (${M_\star } \gtrsim 10^{10}\, {\rm M}_{\odot }$) hosting an actively growing supermassive black hole to study the properties of these objects. In particular, we study how the black hole and the galaxy coevolve and what is the relative contribution of the AGNs and of the stellar populations to the luminosity budget of the system. We find that the feedback from the AGN has no strong effect on the properties of the galaxy, and does not increase the total ionizing luminosity of the host. The average escape fraction of our galaxy is around $f_{\rm esc} \sim 5{{\ \rm per\ cent}}$. While our galaxy would be selected as an AGN in deep X-ray surveys, most of the ultraviolet (UV) luminosity is originating from stellar populations. This confirms that there is a transition in the galaxy population from star-forming galaxies to quasar hosts, with bright Lyman-break galaxies with MUV around −22 falling in the overlap region. Our results also suggest that faint AGNs do not contribute significantly to reionizing the Universe.

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