scholarly journals The three causes of low-mass assembly bias

2020 ◽  
Vol 493 (4) ◽  
pp. 4763-4782 ◽  
Author(s):  
Philip Mansfield ◽  
Andrey V Kravtsov
Keyword(s):  
Large Scale ◽  
Mass Range ◽  
Small Mass ◽  
Formation Time ◽  
Gaussian Field ◽  
Physical Processes ◽  
Halo Formation ◽  
Low Mass ◽  
Mass Assembly ◽  
Halo Masses

ABSTRACT We present a detailed analysis of the physical processes that cause halo assembly bias – the dependence of halo clustering on proxies of halo formation time. We focus on the origin of assembly bias in the mass range corresponding to the hosts of typical galaxies and use halo concentration as our chief proxy of halo formation time. We also repeat our key analyses across a broad range of halo masses and for alternative formation time definitions. We show that splashback subhaloes are responsible for two-thirds of the assembly bias signal, but do not account for the entire effect. After splashback subhaloes have been removed, we find that the remaining assembly bias signal is due to a relatively small fraction ($\lesssim \!10{{\ \rm per\ cent}}$) of haloes in dense regions. We test a number of additional physical processes thought to contribute to assembly bias and demonstrate that the two key processes are the slowing of mass growth by large-scale tidal fields and by the high velocities of ambient matter in sheets and filaments. We also rule out several other proposed physical causes of halo assembly bias. Based on our results, we argue that there are three processes that modify the assembly bias of small-mass haloes arising from the properties of the primordial Gaussian field: large-scale tidal fields, gravitational heating due to the collapse of large-scale structures, and splashback subhaloes located outside the virial radius.

scholarly journals Deep inside low-mass stars

2008 ◽  
Vol 4 (S252) ◽  
pp. 163-174 ◽  
Author(s):  
Corinne Charbonnel ◽  
Suzanne Talon
Keyword(s):  
Large Scale ◽  
Main Sequence ◽  
Internal Gravity Waves ◽  
Transport Processes ◽  
Atomic Diffusion ◽  
Physical Processes ◽  
Low Mass Stars ◽  
Low Mass ◽  
Stellar Properties ◽  
The Impact

AbstractLow-mass stars exhibit, at all stages of their evolution, the signatures of complex physical processes that require challenging modeling beyond standard stellar theory. In this review, we recall the most striking observational evidences that probe the interaction and interdependence of various transport processes of chemicals and angular momentum in these objects. We then focus on the impact of atomic diffusion, large scale mixing due to rotation, and internal gravity waves on stellar properties on the main sequence and slightly beyond.

scholarly journals On the weak lensing masses of a new sample of galaxy groups

2021 ◽  
Author(s):  
Elizabeth J Gonzalez ◽  
Facundo Rodriguez ◽  
Manuel Merchán ◽  
Diego García Lambas ◽  
Martín Makler ◽  
...  
Keyword(s):  
Mass Range ◽  
Dark Matter Halo ◽  
Weak Lensing ◽  
Galaxy Groups ◽  
The Galaxy ◽  
Low Mass ◽  
Characteristic Group ◽  
Halo Masses ◽  
The Masses ◽  
Matching Techniques

Abstract Galaxy group masses are important to relate these systems with the dark matter halo hosts. However, deriving accurate mass estimates is particularly challenging for low-mass galaxy groups. Moreover, calibration of observational mass-proxies using weak-lensing estimates have been mainly focused on massive clusters. We present here a study of halo masses for a sample of galaxy groups identified according to a spectroscopic catalogue, spanning a wide mass range. The main motivation of our analysis is to assess mass estimates provided by the galaxy group catalogue derived through an abundance matching luminosity technique. We derive total halo mass estimates according to a stacking weak-lensing analysis. Our study allows to test the accuracy of mass estimates based on this technique as a proxy for the halo masses of large group samples. Lensing profiles are computed combining the groups in different bins of abundance matching mass, richness and redshift. Fitted lensing masses correlate with the masses obtained from abundance matching. However, when considering groups in the low- and intermediate-mass ranges, masses computed according to the characteristic group luminosity tend to predict higher values than the determined by the weak-lensing analysis. The agreement improves for the low-mass range if the groups selected have a central early-type galaxy. Presented results validate the use of mass estimates based on abundance matching techniques which provide good proxies to the halo host mass in a wide mass range.

scholarly journals Dark Matter Haloes and Subhaloes

Galaxies ◽  
2019 ◽  
Vol 7 (4) ◽  
pp. 81 ◽  
Author(s):  
Jesús Zavala ◽  
Carlos S. Frenk
Keyword(s):  
Dark Matter ◽  
Large Scale ◽  
Cold Dark Matter ◽  
Background Radiation ◽  
Cosmic Background Radiation ◽  
Mass Range ◽  
Temperature Structure ◽  
N Body Problem ◽  
Central Regions ◽  
Low Mass

The development of methods and algorithms to solve the N-body problem for classical, collisionless, non-relativistic particles has made it possible to follow the growth and evolution of cosmic dark matter structures over most of the universe’s history. In the best-studied case—the cold dark matter or CDM model—the dark matter is assumed to consist of elementary particles that had negligible thermal velocities at early times. Progress over the past three decades has led to a nearly complete description of the assembly, structure, and spatial distribution of dark matter haloes, and their substructure in this model, over almost the entire mass range of astronomical objects. On scales of galaxies and above, predictions from this standard CDM model have been shown to provide a remarkably good match to a wide variety of astronomical data over a large range of epochs, from the temperature structure of the cosmic background radiation to the large-scale distribution of galaxies. The frontier in this field has shifted to the relatively unexplored subgalactic scales, the domain of the central regions of massive haloes, and that of low-mass haloes and subhaloes, where potentially fundamental questions remain. Answering them may require: (i) the effect of known but uncertain baryonic processes (involving gas and stars), and/or (ii) alternative models with new dark matter physics. Here we present a review of the field, focusing on our current understanding of dark matter structure from N-body simulations and on the challenges ahead.

scholarly journals The mass assembly of high-redshift black holes

2020 ◽  
Vol 500 (2) ◽  
pp. 2146-2158
Author(s):  
Olmo Piana ◽  
Pratika Dayal ◽  
Marta Volonteri ◽  
Tirthankar Roy Choudhury
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
High Redshift ◽  
Mass Range ◽  
Gas Content ◽  
Initial Growth ◽  
Black Hole Growth ◽  
Mass Assembly ◽  
Halo Masses ◽  
Gas Accretion

ABSTRACT We use the Delphi semi-analytic model to study the mass assembly and properties of high-redshift (z > 4) black holes over a wide mass range, $10^3 \lt M_{\rm bh}/{\rm \rm M_\odot }\lt 10^{10}$. Our black hole growth implementation includes a critical halo mass ($M_{\mathrm{ h}}^{\mathrm{ crit}}$) below which the black hole is starved and above which it is allowed to grow either at the Eddington limit or proportionally to the gas content of the galaxy. As a consequence, after an initial growth phase dominated by black hole mergers down to z ∼ 7 (9), supermassive black holes in z = 4 halo masses of $M_\mathrm{ h}|_{z=4} \sim 10^{11.75} \, (10^{13.4}) \, {\rm \rm M_\odot }$ mainly grow by gas accretion from the interstellar medium. In particular, we find that (i) while most of the accretion occurs in the major branch for $M_\mathrm{ h}|_{z=4} \sim 10^{11\!-\!12} \, {\rm \rm M_\odot }$ haloes, accretion in secondary branches plays a significant role in assembling the black hole mass in higher mass haloes ($M_\mathrm{ h}|_{z=4} \gtrsim 10^{12} \, {\rm \rm M_\odot }$); (ii) while the Eddington ratio increases with decreasing redshift for low-mass ($M_{\mathrm{ bh}} \lt 10^5 \, {\rm \rm M_\odot }$) black holes, it shows the opposite trend for larger masses. In addition, since the accretion rate depends on the gas mass present in the host halo, the duty cycle of the Eddington-limited accretion phase – which can last up to ≈650 Myr – is crucially linked to the joint assembly history of the black hole and its host halo.

scholarly journals Group connectivity in COSMOS: a tracer of mass assembly history

2019 ◽  
Vol 489 (4) ◽  
pp. 5695-5708 ◽  
Author(s):  
E Darragh Ford ◽  
C Laigle ◽  
G Gozaliasl ◽  
C Pichon ◽  
J Devriendt ◽  
...  
Keyword(s):  
Large Scale ◽  
Mass Range ◽  
High Mass ◽  
Large Field ◽  
Photometric Redshifts ◽  
Star Forming ◽  
Galaxy Groups ◽  
Hydrodynamical Simulation ◽  
Major Merger ◽  
Mass Assembly

ABSTRACT Cosmic filaments are the channel through which galaxy groups assemble their mass. Cosmic connectivity, namely the number of filaments connected to a given group, is therefore expected to be an important ingredient in shaping group properties. The local connectivity is measured in COSMOS around X-ray-detected groups between redshift 0.5 and 1.2. To this end, large-scale filaments are extracted using the accurate photometric redshifts of the COSMOS2015 catalogue in two-dimensional slices of thickness 120 comoving Mpc centred on the group’s redshift. The link between connectivity, group mass, and the properties of the brightest group galaxy (BGG) is investigated. The same measurement is carried out on mocks extracted from the light-cone of the hydrodynamical simulation Horizon-AGN in order to control systematics. More massive groups are on average more connected. At fixed group mass in low-mass groups, BGG mass is slightly enhanced at high connectivity, while in high-mass groups BGG mass is lower at higher connectivity. Groups with a star-forming BGG have on average a lower connectivity at given mass. From the analysis of the Horizon-AGN simulation, we postulate that different connectivities trace different paths of group mass assembly: at high group mass, groups with higher connectivity are more likely to have grown through a recent major merger, which might be in turn the reason for the quenching of the BGG. Future large-field photometric surveys, such as Euclid and LSST, will be able to confirm and extend these results by probing a wider mass range and a larger variety of environment.

scholarly journals Light elements as diagnostics on the structure and evolution of low-mass stars

2009 ◽  
Vol 5 (S268) ◽  
pp. 365-374 ◽  
Author(s):  
Suzanne Talon ◽  
Corinne Charbonnel
Keyword(s):  
Gravity Waves ◽  
Large Scale ◽  
Internal Gravity Waves ◽  
Light Elements ◽  
Physical Processes ◽  
Low Mass Stars ◽  
Low Mass ◽  
Lithium Depletion ◽  
The Impact

AbstractLow-mass stars exhibit, at all stages of their evolution, the signatures of complex physical processes that require challenging modelling beyond standard stellar theory. In this review, we focus on lithium depletion in low-mass stars. After disecting the Li dip, we discuss how large scale mixing due to rotation and internal gravity waves may interact to explain this feature. We also briefly discuss the impact that is expected on Population II stars.

scholarly journals An optical observational cluster mass function at z ∼ 1 with the ORELSE survey

2021 ◽  
Vol 502 (3) ◽  
pp. 3942-3954
Author(s):  
D Hung ◽  
B C Lemaux ◽  
R R Gal ◽  
A R Tomczak ◽  
L M Lubin ◽  
...  
Keyword(s):  
Monte Carlo ◽  
Large Scale ◽  
Near Infrared ◽  
Function Analysis ◽  
Voronoi Tessellation ◽  
Cosmological Parameters ◽  
Mass Range ◽  
Mass Function ◽  
Cluster Mass ◽  
Theoretical Mass

ABSTRACT We present a new mass function of galaxy clusters and groups using optical/near-infrared (NIR) wavelength spectroscopic and photometric data from the Observations of Redshift Evolution in Large-Scale Environments (ORELSE) survey. At z ∼ 1, cluster mass function studies are rare regardless of wavelength and have never been attempted from an optical/NIR perspective. This work serves as a proof of concept that z ∼ 1 cluster mass functions are achievable without supplemental X-ray or Sunyaev-Zel’dovich data. Measurements of the cluster mass function provide important contraints on cosmological parameters and are complementary to other probes. With ORELSE, a new cluster finding technique based on Voronoi tessellation Monte Carlo (VMC) mapping, and rigorous purity and completeness testing, we have obtained ∼240 galaxy overdensity candidates in the redshift range 0.55 < z < 1.37 at a mass range of 13.6 < log (M/M⊙) < 14.8. This mass range is comparable to existing optical cluster mass function studies for the local universe. Our candidate numbers vary based on the choice of multiple input parameters related to detection and characterization in our cluster finding algorithm, which we incorporated into the mass function analysis through a Monte Carlo scheme. We find cosmological constraints on the matter density, Ωm, and the amplitude of fluctuations, σ8, of $\Omega _{m} = 0.250^{+0.104}_{-0.099}$ and $\sigma _{8} = 1.150^{+0.260}_{-0.163}$. While our Ωm value is close to concordance, our σ8 value is ∼2σ higher because of the inflated observed number densities compared to theoretical mass function models owing to how our survey targeted overdense regions. With Euclid and several other large, unbiased optical surveys on the horizon, VMC mapping will enable optical/NIR cluster cosmology at redshifts much higher than what has been possible before.

Quasar host galaxies and environments in the GAMA survey

2019 ◽  
Vol 15 (S356) ◽  
pp. 170-170
Author(s):  
Jari Kotilainen
Keyword(s):  
Galaxy Evolution ◽  
Large Scale ◽  
Group Membership ◽  
Host Galaxy ◽  
Host Galaxies ◽  
Cluster Group ◽  
First Results ◽  
Triggering Mechanisms ◽  
Mass Assembly

AbstractWe present first results from our study of the host galaxies and environments of quasars in Galaxy And Mass Assembly (GAMA), a multiwavelength photometric and spectroscopic survey for ∼300,000 galaxies over ∼300 deg2, to a limiting magnitude of r ∼ 20 mag. We use a GAIA-selected sample of ∼350 quasars at z < 0.3 in GAMA. For all the quasars, we determine all surrounding GAMA galaxies and measure their star formation (SF) rate and SF history, and the host galaxy morphology and group membership of the quasars. As a comparison sample of inactive galaxies, we use 1000 subsets of galaxies in GAMA, matched in redshift and galaxy stellar mass to the quasars. We find that quasar activity does not depend on the large-scale environment (cluster/group/void), although quasars tend to prefer satellite location in their environment. Compared to inactive galaxies, quasars are preferentially hosted in bulge-dominated galaxies and have higher SF rates, both overall and averaged over the last 10 and 100 Myr. Quasars also have shorter median SF timescales, shorter median time since the last SF burst, and higher metallicity than inactive galaxies. We discuss these results in terms of triggering mechanisms of the quasar activity and the role of quasars in galaxy evolution.

scholarly journals Small Mass but Strong Information: Diagnostic Ions Provide Crucial Clues to Correctly Identify Histone Lysine Modifications

Proteomes ◽  
2021 ◽  
Vol 9 (2) ◽  
pp. 18
Author(s):  
Alaa Hseiky ◽  
Marion Crespo ◽  
Sylvie Kieffer-Jaquinod ◽  
François Fenaille ◽  
Delphine Pflieger
Keyword(s):  
Amino Acid ◽  
Small Mass ◽  
Mass Region ◽  
Amino Acid Sequences ◽  
Lysine Modification ◽  
Lysine Residues ◽  
Two Factors ◽  
Low Mass ◽  
Diagnostic Ions

(1) Background: The proteomic analysis of histones constitutes a delicate task due to the combination of two factors: slight variations in the amino acid sequences of variants and the multiplicity of post-translational modifications (PTMs), particularly those occurring on lysine residues. (2) Methods: To dissect the relationship between both aspects, we carefully evaluated PTM identification on lysine 27 from histone H3 (H3K27) and the artefactual chemical modifications that may lead to erroneous PTM determination. H3K27 is a particularly interesting example because it can bear a range of PTMs and it sits nearby residues 29 and 31 that vary between H3 sequence variants. We discuss how the retention times, neutral losses and immonium/diagnostic ions observed in the MS/MS spectra of peptides bearing modified lysines detectable in the low-mass region might help validate the identification of modified sequences. (3) Results: Diagnostic ions carry key information, thereby avoiding potential mis-identifications due to either isobaric PTM combinations or isobaric amino acid-PTM combinations. This also includes cases where chemical formylation or acetylation of peptide N-termini artefactually occurs during sample processing or simply in the timeframe of LC-MS/MS analysis. Finally, in the very subtle case of positional isomers possibly corresponding to a given mass of lysine modification, the immonium and diagnostic ions may allow the identification of the in vivo structure.

scholarly journals Multiwavelength Modeling the SED of Strongly Interacting Binaries

2011 ◽  
Vol 7 (S282) ◽  
pp. 65-66
Author(s):  
Augustin Skopal
Keyword(s):  
Physical Parameters ◽  
X Rays ◽  
Physical Processes ◽  
Short Contribution ◽  
Composite Spectrum ◽  
X Ray ◽  
Strongly Interacting ◽  
Low Mass ◽  
X Ray Binaries

AbstractThe spectrum of strongly interacting binaries, as for example, high and low mass X-ray binaries, symbiotic (X-ray) binaries and/or classical and recurrent novae, consists of more components of radiation contributing from hard X-rays to radio wavelengths. To understand the basic physical processes responsible for the observed spectrum we have to disentangle the composite spectrum into its individual components, i.e. to determine their physical parameters. In this short contribution I demonstrate the method of modeling the multiwavelength SED on the example of the extragalactic super-soft X-ray source RX J0059.1-7505 (LIN 358).

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