scholarly journals Early-type galaxy density profiles from IllustrisTNG – I. Galaxy correlations and the impact of baryons

2019 ◽  
Vol 491 (4) ◽  
pp. 5188-5215 ◽  
Author(s):  
Yunchong Wang ◽  
Mark Vogelsberger ◽  
Dandan Xu ◽  
Shude Mao ◽  
Volker Springel ◽  
...  
Keyword(s):  
Dark Matter ◽  
Stellar Mass ◽  
High Mass ◽  
Total Power ◽  
Total Density ◽  
Early Type ◽  
Density Profiles ◽  
Low Mass ◽  
Stellar Masses ◽  
The Impact

ABSTRACT We explore the isothermal total density profiles of early-type galaxies (ETGs) in the IllustrisTNG simulation. For the selected 559 ETGs at z = 0 with stellar masses $10^{10.7}\, \mathrm{M}_{\odot } \leqslant M_{\ast } \leqslant 10^{11.9}\, \mathrm{M}_{\odot }$, the total power-law slope has a mean of 〈γ′〉 = 2.011 ± 0.007 and a scatter of $\sigma _{\gamma ^{\prime }} = 0.171$ over the radial range 0.4–4 times the stellar half-mass radius. Several correlations between γ′ and galactic properties including stellar mass, effective radius, stellar surface density, central velocity dispersion, central dark matter fraction, and in situ-formed stellar mass ratio are compared to observations and other simulations, revealing that IllustrisTNG reproduces many correlation trends, and in particular, γ′ is almost constant with redshift below z = 2. Through analysing IllustrisTNG model variations, we show that black hole kinetic winds are crucial to lowering γ′ and matching observed galaxy correlations. The effects of stellar winds on γ′ are subdominant compared to active galactic nucleus (AGN) feedback, and differ due to the presence of AGN feedback from previous works. The density profiles of the ETG dark matter haloes are well described by steeper than NFW profiles, and they are steeper in the full physics (FP) run than their counterparts in the dark matter-only (DMO) run. Their inner density slopes anticorrelate (remain constant) with the halo mass in the FP (DMO) run, and anticorrelate with the halo concentration parameter c200 in both the types of runs. The dark matter haloes of low-mass ETGs are contracted whereas high-mass ETGs are expanded, suggesting that variations in the total density profile occur through the different halo responses to baryons.

scholarly journals Early-type galaxy density profiles from IllustrisTNG – II. Evolutionary trend of the total density profile

2019 ◽  
Vol 490 (4) ◽  
pp. 5722-5738 ◽  
Author(s):  
Yunchong Wang ◽  
Mark Vogelsberger ◽  
Dandan Xu ◽  
Xuejian Shen ◽  
Shude Mao ◽  
...  
Keyword(s):  
Density Profile ◽  
Total Density ◽  
Evolutionary Trend ◽  
Early Type ◽  
Low Mass ◽  
Statistical Sample ◽  
Stellar Masses ◽  
Mass Dependent ◽  
Kinetic Mode ◽  
The Impact

ABSTRACT We study the evolutionary trend of the total density profile of early-type galaxies (ETGs) in IllustrisTNG. To this end, we trace ETGs from z = 0 to 4 and measure the power-law slope γ′ of the total density profile for their main progenitors. We find that their slopes γ′ steepen on average during z ∼ 4–2, then becoming shallower until z = 1, after which they remain almost constant, aside from a residual trend of becoming shallower towards z = 0. We also compare to a statistical sample of ETGs at different redshifts, selected based on their luminosity profiles and stellar masses. Due to different selection effects, the average slopes of the statistical samples follow a modified evolutionary trend. They monotonically decrease since z = 3, and after z ≈ 1, they remain nearly invariant with a mild increase towards z = 0. These evolutionary trends are mass dependent for both samples, with low-mass galaxies having in general steeper slopes than their more massive counterparts. Galaxies that transitioned to ETGs more recently have steeper mean slopes as they tend to be smaller and more compact at any given redshift. By analysing the impact of mergers and AGN feedback on the progenitors’ evolution, we conjecture a multiphase path leading to isothermality in ETGs: dissipation associated with rapid wet mergers tends to steepen γ′ from z = 4 to 2, whereas subsequent AGN feedback (especially in the kinetic mode) makes γ′ shallower again from z = 2 to 1. Afterwards, passive evolution from z = 1 to 0, mainly through gas-poor mergers, mildly decreases γ′ and maintains the overall mass distribution close to isothermal.

scholarly journals How robustly can we constrain the low-mass end of the z ∼ 6−7 stellar mass function? The limits of lensing models and stellar population assumptions in the Hubble Frontier Fields

2020 ◽  
Vol 501 (2) ◽  
pp. 1568-1590
Author(s):  
Lukas J Furtak ◽  
Hakim Atek ◽  
Matthew D Lehnert ◽  
Jacopo Chevallard ◽  
Stéphane Charlot
Keyword(s):  
Star Formation ◽  
Mass Function ◽  
Stellar Mass ◽  
Star Formation History ◽  
Space Telescope ◽  
Formation History ◽  
Low Mass ◽  
Stellar Masses ◽  
Dust Attenuation ◽  
The Impact

ABSTRACT We present new measurements of the very low mass end of the galaxy stellar mass function (GSMF) at z ∼ 6−7 computed from a rest-frame ultraviolet selected sample of dropout galaxies. These galaxies lie behind the six Hubble Frontier Field clusters and are all gravitationally magnified. Using deep Spitzer/IRAC and Hubble Space Telescope imaging, we derive stellar masses by fitting galaxy spectral energy distributions and explore the impact of different model assumptions and parameter degeneracies on the resulting GSMF. Our sample probes stellar masses down to $M_{\star }\gt 10^{6}\, \text{M}_{\odot}$ and we find the z ∼ 6−7 GSMF to be best parametrized by a modified Schechter function that allows for a turnover at very low masses. Using a Monte Carlo Markov chain analysis of the GSMF, including accurate treatment of lensing uncertainties, we obtain a relatively steep low-mass end slope $\alpha \simeq -1.96_{-0.08}^{+0.09}$ and a turnover at $\log (M_T/\text{M}_{\odot})\simeq 7.10_{-0.56}^{+0.17}$ with a curvature of $\beta \simeq 1.00_{-0.73}^{+0.87}$ for our minimum assumption model with constant star formation history (SFH) and low dust attenuation, AV ≤ 0.2. We find that the z ∼ 6−7 GSMF, in particular its very low mass end, is significantly affected by the assumed functional form of the star formation history and the degeneracy between stellar mass and dust attenuation. For example, the low-mass end slope ranges from $\alpha \simeq -1.82_{-0.07}^{+0.08}$ for an exponentially rising SFH to $\alpha \simeq -2.34_{-0.10}^{+0.11}$ when allowing AV of up to 3.25. Future observations at longer wavelengths and higher angular resolution with the James Webb Space Telescope are required to break these degeneracies and to robustly constrain the stellar mass of galaxies on the extreme low-mass end of the GSMF.

scholarly journals Correlations between H α equivalent width and galaxy properties at z = 0.47: Physical or selection-driven?

2021 ◽  
Vol 503 (4) ◽  
pp. 5115-5133
Author(s):  
A A Khostovan ◽  
S Malhotra ◽  
J E Rhoads ◽  
S Harish ◽  
C Jiang ◽  
...  
Keyword(s):  
Star Formation ◽  
Equivalent Width ◽  
Luminosity Function ◽  
Mass Function ◽  
Stellar Mass ◽  
High Mass ◽  
Selection Effects ◽  
Star Formation Activity ◽  
Low Mass ◽  
Stellar Masses

ABSTRACT The H α equivalent width (EW) is an observational proxy for specific star formation rate (sSFR) and a tracer of episodic, bursty star-formation activity. Previous assessments show that the H α EW strongly anticorrelates with stellar mass as M−0.25 similar to the sSFR – stellar mass relation. However, such a correlation could be driven or even formed by selection effects. In this study, we investigate how H α EW distributions correlate with physical properties of galaxies and how selection biases could alter such correlations using a z = 0.47 narrow-band-selected sample of 1572 H α emitters from the Ly α Galaxies in the Epoch of Reionization (LAGER) survey as our observational case study. The sample covers a 3 deg2 area of COSMOS with a survey comoving volume of 1.1 × 105 Mpc3. We assume an intrinsic EW distribution to form mock samples of H α emitters and propagate the selection criteria to match observations, giving us control on how selection biases can affect the underlying results. We find that H α EW intrinsically correlates with stellar mass as W0∝M−0.16 ± 0.03 and decreases by a factor of ∼3 from 107 M⊙ to 1010 M⊙, while not correcting for selection effects steepens the correlation as M−0.25 ± 0.04. We find low-mass H α emitters to be ∼320 times more likely to have rest-frame EW>200 Å compared to high-mass H α emitters. Combining the intrinsic W0–stellar mass correlation with an observed stellar mass function correctly reproduces the observed H α luminosity function, while not correcting for selection effects underestimates the number of bright emitters. This suggests that the W0–stellar mass correlation when corrected for selection effects is physically significant and reproduces three statistical distributions of galaxy populations (line luminosity function, stellar mass function, EW distribution). At lower stellar masses, we find there are more high-EW outliers compared to high stellar masses, even after we take into account selection effects. Our results suggest that high sSFR outliers indicative of bursty star formation activity are intrinsically more prevalent in low-mass H α emitters and not a byproduct of selection effects.

scholarly journals The co-evolution of total density profiles and central dark matter fractions in simulated early-type galaxies

2016 ◽  
Vol 464 (3) ◽  
pp. 3742-3756 ◽  
Author(s):  
Rhea-Silvia Remus ◽  
Klaus Dolag ◽  
Thorsten Naab ◽  
Andreas Burkert ◽  
Michaela Hirschmann ◽  
...  
Keyword(s):  
Dark Matter ◽  
Total Density ◽  
Early Type ◽  
Density Profiles

scholarly journals Massive Elliptical Galaxies: BH Scouring or a Bottom-Heavy IMF?

2014 ◽  
Vol 10 (S311) ◽  
pp. 36-39
Author(s):  
Jens Thomas ◽  
Roberto Saglia ◽  
Ralf Bender ◽  
Peter Erwin ◽  
Maximilian Fabricius
Keyword(s):  
Dark Matter ◽  
Power Law ◽  
Milky Way ◽  
Elliptical Galaxies ◽  
Stellar Mass ◽  
Initial Mass Function ◽  
Early Type ◽  
Stellar Masses ◽  
Kinematical Data ◽  
The Imf

AbstractWe present indirect constraints on the stellar initial-mass-function (IMF) in nine massive elliptical galaxies with σ ≈ 300 km/s, via a comparison of dynamical and stellar-population based stellar masses. We use adaptive-optics assisted, high resolution kinematical data from the SINFONI Search for Supermassive Black Holes that allow us to constrain the dynamical stellar mass-to-light ratio in the very centre of each galaxy. Hence we measure the IMF in a galaxy region where the stellar mass dominates over dark matter, minimising any potential degeneracy between the two mass components. In six of our galaxies – those which have depleted stellar cores – we find an IMF consistent with the one measured in the Milky-Way via direct star counts. The three remaining, power-law galaxies have instead stellar masses about a factor of two times larger than expected from a Milky-Way type IMF, indicating either a more bottom-heavy IMF (like, e.g., the Salpeter IMF) or a dark-matter distribution that is degenerate with the stellar mass down to the very centres of these galaxies. The bottom-light IMF in our core galaxies is surprising in view of previous studies that suggested a systematic IMF variation where early-type galaxies with σ ≈ 300 km/s have a Salpeter or even more dwarf-dominated IMF. Core galaxies are particularly important since their unique central orbital structure offers an independent crosscheck for the dynamical models. Our models with a bottom-light IMF are consistent with the distribution of orbits predicted by SMBH-binary core-formation models. This indicates that spatially well resolved central kinematical data are important for determining unbiased dynamical stellar mass-to-light ratios. Our results imply either that the IMF in massive galaxies varies over a wider range than previously anticipated, and is not the same in core and power-law ellipticals, or else that there are systematic variations in the distribution of dark matter among massive early-type galaxies.

scholarly journals The quantity of dark matter in early-type galaxies and its relation to the environment

2019 ◽  
Vol 488 (1) ◽  
pp. 1320-1331 ◽  
Author(s):  
A Nigoche-Netro ◽  
G Ramos-Larios ◽  
P Lagos ◽  
E de la Fuente ◽  
A Ruelas-Mayorga ◽  
...  
Keyword(s):  
Dark Matter ◽  
Surface Brightness ◽  
Stellar Mass ◽  
Sloan Digital Sky Survey ◽  
Early Type ◽  
Dynamical Mass ◽  
Redshift Range ◽  
Sky Survey ◽  
The Impact ◽  
Mass Functions

ABSTRACT We study the behaviour of the dynamical and stellar mass inside the effective radius of early-type galaxies (ETGs) as a function of environment considering Newtonian dynamics, different surface-brightness profiles, different initial mass functions (IMF), and different redshift ranges. We use several samples of ETGs – ranging from 19 000 to 98 000 objects – from the ninth data release of the Sloan Digital Sky Survey. We assume that any difference between the dynamical and stellar mass is due to dark matter and/or a non-universal IMF. The main results, considering samples in the redshift range 0.0024 ≤ z ≤ 0.35, are as follows: (i) the amount of dark matter inside ETGs depends on the environment; (ii) ETGs in low-density environments span a wider dark matter range than ETGs in dense environments; (iii) the amount of dark matter inside ETGs in the most dense environments will be less than approximately 55–75 per cent of the dynamical mass; (iv) the accurate value of this upper limit depends on the impact of the IMF on the stellar mass estimation; (v) in the case of an ETG sample which is approximately complete for log(MVirial/MSun) > 10.5 and in the redshift range 0.04 ≤ z ≤ 0.08, we find that the amount of dark matter in the most dense environments will be less than approximately 60–65 per cent of the dynamical mass.

scholarly journals SDSS-IV MaNGA: Internal mass distributions and orbital structures of early-type galaxies and their dependence on environment

2019 ◽  
Author(s):  
Yunpeng Jin ◽  
Ling Zhu ◽  
R J Long ◽  
Shude Mao ◽  
Lan Wang ◽  
...  
Keyword(s):  
Dark Matter ◽  
Major Axis ◽  
Mass Range ◽  
Stellar Mass ◽  
Effective Radius ◽  
High Mass ◽  
Internal Mass ◽  
Early Type ◽  
Internal Structures ◽  
The Individual

Abstract In our earlier 2019 paper, we evaluated the reliability of Schwarzschild’s orbit-superposition dynamical modelling method in estimating the internal mass distribution, intrinsic stellar shapes and orbit distributions of early-type galaxies (ETGs) taken from the Illustris cosmological simulation. We now apply the same techniques to galaxies taken from the integral-field survey Mapping Nearby Galaxies with APO (MaNGA), using a sample of 149 ETGs in the mass range of 109.90 ∼ 1011.80M⊙ and made up of 105 central and 44 satellite galaxies. We find that low-mass ETGs with log (M*/M⊙) < 11.1 have an average dark matter fraction of ∼0.2 within one effective radius Re, tend to be oblate-like, and are dominated by rotation about their minor axis. High-mass ETGs with log (M*/M⊙) > 11.1 have an average dark matter fraction of ∼0.4 within one effective radius Re, tend to be prolate-like, and are dominated by rotation about their major axis and by centrophilic orbits. The changes of internal structures within one Re are dominated by the total stellar mass of the individual galaxies. We find no differences of internal structures between central and satellite ETGs for the same stellar masses. However, for similar stellar mass and colour distributions, we find that ETGs more prolate-like, or with more hot orbits, tend to have higher close neighbour counts at rp ∼ 40 kpc.

scholarly journals Stellar masses calibrated with micro-lensed quasars

2014 ◽  
Vol 10 (S311) ◽  
pp. 96-99
Author(s):  
Paul L. Schechter ◽  
Jeffrey A. Blackburne ◽  
David Pooley ◽  
Joachim Wambsganss
Keyword(s):  
Gravitational Potential ◽  
Brown Dwarfs ◽  
Stellar Mass ◽  
Calibration Factor ◽  
Early Type ◽  
Individual Stars ◽  
Red Dwarfs ◽  
Low Mass ◽  
Spectroscopic Signatures ◽  
Stellar Masses

AbstractWe measure the stellar mass surface densities of early type galaxies by observing the micro-lensing of macro-lensed quasars caused by individual stars, including stellar remnants, brown dwarfs and red dwarfs too faint to produce photometric or spectroscopic signatures. Our method measures the graininess of the gravitational potential, in contrast to methods that decompose a smooth total gravitational potential into two smooth components, one stellar and one dark. We find the median likelihood value for the calibration factor $\cal F$ by which Salpeter stellar masses (with a low mass cutoff of 0.1 M⊙) must be multiplied is 1.23, with a one sigma confidence range of 0.77 < $\cal F$ < 2.10.

scholarly journals MASS DISTRIBUTION OF DARK MATTER HALO AND SCALE EVOLUTION OF EARLY TYPE GALAXIES

2020 ◽  
Vol 6 (334) ◽  
pp. 91-98
Author(s):  
D. Kairatkyzy ◽  
◽  
H. C. Quevedo ◽  
◽  
◽  
...  
Keyword(s):  
Dark Matter ◽  
Star Formation ◽  
Galaxy Formation ◽  
Stellar Mass ◽  
Dark Matter Halo ◽  
High Mass ◽  
Galactic Halos ◽  
Mass Relation ◽  
Early Type ◽  
Survival Fraction

In this paper we use two suites of ultra-high resolution N-body simulations Phoenix and Aquarius Projects to study the assembly history of sub-halos and its dependence on host halo mass. We found that more massive haloes have more progenitors, which is in contrast with former works because they counted dynamical progenitors repeatedly. Less massive halos have larger fraction of dynamical progenitors than more massive ones. The typical accretion time depends strongly on host halo mass. Progenitors of galactic halos are accreted at higher redshift than that of cluster halos. Once these progenitors orbit their primary systems, they rapidly lose their original mass but not their identifiers. Most of the progenitors are able to survive to present day. At given redshift, the survival fraction of accreted sub-halos is independent of host halo mass, while sub-halos in high mass halos lost more mass. In the second part, we use a semi-analytical galaxy formation model compiled on a Millennium Simulation to study the size evolution of massive early-type galaxies from redshift z = 2 to present days. We find that the model we used is able to well reproduce the amplitude and slope of size-mass relation, as well as its evolution. The amplitude of this relation reflects the typical compactness of dark matter halos at the time when most stars are formed. This link between size and star formation epoch is propagated in through galaxy combinations. Minor combinations are increasingly important with increasing present day stellar mass for galaxies more massive than 1011.4M⊙. At lower masses, major combinations are more important. In situ star formation contributes more to the size growth than it does to stellar mass growth. Similar to former works, we find that minor combinations dominate the subsequent growth both in stellar mass and in size for early formed early-type galaxies.

scholarly journals The formation of ultradiffuse galaxies in the RomulusC galaxy cluster simulation

2020 ◽  
Vol 497 (3) ◽  
pp. 2786-2810 ◽  
Author(s):  
M Tremmel ◽  
A C Wright ◽  
A M Brooks ◽  
F Munshi ◽  
D Nagai ◽  
...  
Keyword(s):  
Dark Matter ◽  
Stellar Evolution ◽  
Dwarf Galaxies ◽  
Galaxy Cluster ◽  
High Mass ◽  
Tidal Interactions ◽  
Low Surface Brightness ◽  
Low Mass ◽  
Tidal Heating ◽  
Low Surface Brightness Galaxies

ABSTRACT We study the origins of 122 ultradiffuse galaxies (UDGs) in the Romulus c zoom-in cosmological simulation of a galaxy cluster (M200 = 1.15 × 1014 M⊙), one of the only such simulations capable of resolving the evolution and structure of dwarf galaxies (M⋆ &lt; 109 M⊙). We find broad agreement with observed cluster UDGs and predict that they are not separate from the overall cluster dwarf population. UDGs in cluster environments form primarily from dwarf galaxies that experienced early cluster in-fall and subsequent quenching due to ram pressure. The ensuing dimming of these dwarf galaxies due to passive stellar evolution results in a population of very low surface brightness galaxies that are otherwise typical dwarfs. UDGs and non-UDGs alike are affected by tidal interactions with the cluster potential. Tidal stripping of dark matter, as well as mass-loss from stellar evolution, results in the adiabatic expansion of stars, particularly in the lowest mass dwarfs. High-mass dwarf galaxies show signatures of tidal heating while low-mass dwarfs that survive until z = 0 typically have not experienced such impulsive interactions. There is little difference between UDGs and non-UDGs in terms of their dark matter haloes, stellar morphology, colours, and location within the cluster. In most respects cluster UDG and non-UDGs alike are similar to isolated dwarf galaxies, except for the fact that they are typically quenched.

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