scholarly journals A Self-Calibrating Halo-Based Group Finder: Application to SDSS

2021 ◽  
Vol 923 (2) ◽  
pp. 154
Author(s):  
Jeremy L. Tinker
Keyword(s):  
Mass Scale ◽  
Imaging Data ◽  
Star Forming ◽  
Deep Imaging ◽  
The Galaxy ◽  
Galaxy Sample ◽  
Low Mass ◽  
Massive Halos ◽  
Halo Masses ◽  
Clustering Data

Abstract We apply a new galaxy group-finder to the Main Galaxy Sample of the SDSS. This algorithm introduces new freedom to assign halos to galaxies that is self-calibrated by comparing the catalog to complementary data. These include galaxy clustering data and measurements of the total satellite luminosity from deep-imaging data. We present constraints on the galaxy-halo connection for star-forming and quiescent populations. The results of the self-calibrated group catalog differ in several key ways from previous group catalogs and halo-occupation analyses. The transition halo mass scale, where half of the halos contain quiescent central galaxies, is at M h ∼ 1012.4 h −1 M ⊙, significantly higher than other constraints. Additionally, the width of the transition from predominantly star-forming halos to quiescent halos occurs over a narrower range in halo mass. Quiescent central galaxies in low-mass halos are significantly more massive than star-forming centrals at the same halo mass, but this difference reverses above the transition halo mass. We find that the scatter in log M * at fixed M h is ∼0.2 dex for massive halos, in agreement with previous estimates, but rises sharply at lower halo masses. The halo masses assigned by the group catalog are in good agreement with weak-lensing estimates for star-forming and quiescent central galaxies. We discuss possible improvements to the algorithm made clear by this first application to data. The group catalog is made publicly available.

scholarly journals UV and NIR size of the low-mass field galaxies: the UV compact galaxies

2020 ◽  
Vol 633 ◽  
pp. A105 ◽  
Author(s):  
Cheng Cheng ◽  
Cong Kevin Xu ◽  
Lizhi Xie ◽  
Zhizheng Pan ◽  
Wei Du ◽  
...  
Keyword(s):  
Star Formation ◽  
Stellar Mass ◽  
Growth Mode ◽  
Massive Galaxies ◽  
Star Forming ◽  
The Galaxy ◽  
Galaxy Sample ◽  
Low Mass ◽  
Inside Out ◽  
Massive Galaxy

Context. Most of the massive star-forming galaxies are found to have “inside-out” stellar mass growth modes, which means the inner parts of the galaxies mainly consist of the older stellar population, while the star forming in the outskirt of the galaxy is still ongoing. Aims. The high-resolution HST images from Hubble Deep UV Legacy Survey and Cosmic Assembly Near-infrared Deep Extragalactic Legacy Survey projects with the unprecedented depth in both F275W and F160W bands are the perfect data sets to study the forming and formed stellar distribution directly. Methods. We selected the low redshift (0.05 <  zspec <  0.3) galaxy sample from the GOODS-North field where the HST F275W and F160W images are available. Then we measured the half light radius in F275W and F160W bands, which are the indicators of the star formation and stellar mass. Results. By comparing the F275W and F160W half light radius, we find the massive galaxies are mainly follow the “inside-out” growth mode, which is consistent with the previous results. Moreover, the HST F275W and F160W images reveal that some of the low-mass galaxies (< 108 M⊙) have the “outside-in” growth mode: their images show a compact UV morphology, implying an ongoing star formation in the galaxy centre, while the stars in the outskirts of the galaxies are already formed. The two modes transit smoothly at stellar mass range about 108 − 9 M⊙ with a large scatter. We also try to identify the possible neighbour massive galaxies from the SDSS data, which represent the massive galaxy sample. We find that all of the spec-z selected galaxies have no massive galaxy nearby. Thus the “outside-in” mode we find in the low-mass galaxies are not likely originated from the environment.

scholarly journals Constraining the scatter in the galaxy–halo connection at Milky Way masses

2020 ◽  
Vol 498 (4) ◽  
pp. 5080-5092 ◽  
Author(s):  
Jun-zhi Cao ◽  
Jeremy L Tinker ◽  
Yao-Yuan Mao ◽  
Risa H Wechsler
Keyword(s):  
Cross Correlation ◽  
Theoretical Models ◽  
Sloan Digital Sky Survey ◽  
Small Scale ◽  
Correlation Technique ◽  
Galaxy Groups ◽  
The Galaxy ◽  
Galaxy Sample ◽  
Low Mass ◽  
Halo Masses

ABSTRACT We develop and implement two new methods for constraining the scatter in the relationship between galaxies and dark matter haloes. These new techniques are sensitive to the scatter at low halo masses, making them complementary to previous constraints that are dependent on clustering amplitudes or rich galaxy groups, both of which are only sensitive to more massive haloes. In both of our methods, we use a galaxy group finder to locate central galaxies in the Sloan Digital Sky Survey main galaxy sample. Our first technique uses the small-scale cross-correlation of central galaxies with all lower mass galaxies. This quantity is sensitive to the satellite fraction of low-mass galaxies, which is in turn driven by the scatter between haloes and galaxies. The second technique uses the kurtosis of the distribution of line-of-sight velocities between central galaxies and neighbouring galaxies. This quantity is sensitive to the distribution of halo masses that contain the central galaxies at fixed stellar mass. Theoretical models are constructed using peak halo circular velocity, Vpeak, as our property to connect galaxies to haloes, and all comparisons between theory and observation are made after first passing the model through the group-finding algorithm. We parametrize scatter as a lognormal distribution in M* at fixed Vpeak, σ[M*|Vpeak]. The cross-correlation technique yields a constraint of σ[M*|Vpeak] = 0.27 ± 0.05 dex at a mean Vpeak of 168 km s−1, corresponding to a scatter in log M* at fixed Mh of σ[M*|Mh] = 0.38 ± 0.06 dex at $M_\text{h}=10^{11.8}\, \text{M}_\odot$. The kurtosis technique yields σ[M*|Vpeak] = 0.30 ± 0.03 at Vpeak = 209 km s−1, corresponding to σ[M*|Mh] = 0.34 ± 0.04 at $M_\text{h}=10^{12.2}\, \text{M}_\odot$. The values of σ[M*|Mh] are significantly larger than the constraints at higher masses, in agreement with the results of hydrodynamic simulations. This increase is only partly due to the scatter between Vpeak and Mh, and it represents an increase of nearly a factor of 2 relative to the values inferred from clustering and group studies at high masses.

scholarly journals Cosmic-Ray Driven Outflows to Mpc Scales from L* Galaxies

2020 ◽  
Author(s):  
Philip F Hopkins ◽  
T K Chan ◽  
Suoqing Ji ◽  
Cameron B Hummels ◽  
Dušan Kereš ◽  
...  
Keyword(s):  
Cosmic Ray ◽  
Plane Layer ◽  
Equilibrium Density ◽  
Pressure Gradients ◽  
Low Velocity ◽  
Star Forming ◽  
Stellar Feedback ◽  
Massive Halos ◽  
Halo Masses

Abstract We study the effects of cosmic rays (CRs) on outflows from star-forming galaxies in the circum and inter-galactic medium (CGM/IGM), in high-resolution, fully-cosmological FIRE-2 simulations (accounting for mechanical and radiative stellar feedback, magnetic fields, anisotropic conduction/viscosity/CR diffusion and streaming, and CR losses). We showed previously that massive (Mhalo ≳ 1011 M⊙), low-redshift (z ≲ 1 − 2) halos can have CR pressure dominate over thermal CGM pressure and balance gravity, giving rise to a cooler CGM with an equilibrium density profile. This dramatically alters outflows. Absent CRs, high gas thermal pressure in massive halos “traps” galactic outflows near the disk, so they recycle. With CRs injected in supernovae as modeled here, the low-pressure halo allows “escape” and CR pressure gradients continuously accelerate this material well into the IGM in “fast” outflows, while lower-density gas at large radii is accelerated in-situ into “slow” outflows that extend to &gt;Mpc scales. CGM/IGM outflow morphologies are radically altered: they become mostly volume-filling (with inflow in a thin mid-plane layer) and coherently biconical from the disk to &gt;Mpc. The CR-driven outflows are primarily cool (T ∼ 105 K) and low-velocity. All of these effects weaken and eventually vanish at lower halo masses (≲ 1011 M⊙) or higher redshifts (z ≳ 1 − 2), reflecting the ratio of CR to thermal+gravitational pressure in the outer halo. We present a simple analytic model which explains all of the above phenomena. We caution that these predictions may depend on uncertain CR transport physics.

scholarly journals The extended solar neighborhood: precision astrometry from the Pan-STARRS 1 3π Survey

2007 ◽  
Vol 3 (S248) ◽  
pp. 553-559 ◽  
Author(s):  
E. A. Magnier ◽  
M. Liu ◽  
D. G. Monet ◽  
K. C. Chambers
Keyword(s):  
Solar Neighborhood ◽  
Dynamical Structure ◽  
Nearby Star ◽  
Stellar Objects ◽  
Star Forming ◽  
Star Forming Regions ◽  
The Galaxy ◽  
Low Mass ◽  
Single Epoch ◽  
Insight Into

AbstractThe Pan-STARRS pathfinding telescope PS1 will begin a major set of surveys starting in 2008, and lasting for 3.5 years. One of these, the PS1 3π Survey, will repeatedly observe the entire sky north of −30 degrees, visiting every position 12 times in each of 5 filters. With single-epoch astrometry of 10 milliarcseconds, these observations will yield parallaxes for stars within 100 pc and proper motions out to several hundred pc. The result will be an unprecedented view on nearby stellar populations and insight into the dynamical structure of the local portions of the Galaxy. One exciting science product will be a volume-limited sample of nearby low-mass objects including thousands of L dwarfs, hundreds of T dwarfs, and perhaps even cooler sub-stellar objects. Another project will use proper-motion measurements to improve the membership of nearby star forming regions.

scholarly journals Search for gas accretion imprints in voids: II. The galaxy Ark 18 as a result of a dwarf-dwarf merger

2021 ◽  
Author(s):  
Evgeniya S Egorova ◽  
Oleg V Egorov ◽  
Alexei V Moiseev ◽  
Anna S Saburova ◽  
Kirill A Grishin ◽  
...  
Keyword(s):  
Complex Structure ◽  
Disc Galaxy ◽  
Star Forming ◽  
Galaxy Type ◽  
The Galaxy ◽  
Depth Study ◽  
Multi Wavelength ◽  
Low Mass ◽  
Formation And Evolution ◽  
Gas Accretion

Abstract The low-mass low-surface brightness (LSB) disc galaxy Arakelian 18 (Ark 18) resides in the Eridanus void and because of its isolation represents an ideal case to study the formation and evolution mechanisms of such a galaxy type. Its complex structure consists of an extended blue LSB disc and a bright central elliptically-shaped part hosting a massive off-centered star-forming clump. We present the in-depth study of Ark 18 based on observations with the SCORPIO-2 long-slit spectrograph and a scanning Fabry-Perot interferometer at the Russian 6-m telescope complemented by archival multi-wavelength images and SDSS spectra. Ark 18 appears to be a dark matter dominated gas-rich galaxy without a radial metallicity gradient. The observed velocity field of the ionised gas is well described by two circularly rotating components moderately inclined with respect to each other and a possible warp in the outer disc. We estimated the age of young stellar population in the galaxy centre to be ∼140 Myr, while the brightest star-forming clump appears to be much younger. We conclude that the LSB disc is likely the result of a dwarf–dwarf merger with a stellar mass ratio of the components at least ∼5:1 that occurred earlier than 300 Myr ago. The brightest star forming clump was likely formed later by accretion of a gas cloud.

scholarly journals On the universality of void density profiles

2014 ◽  
Vol 11 (S308) ◽  
pp. 551-554
Author(s):  
E. Ricciardelli ◽  
V. Quilis ◽  
J. Varela
Keyword(s):  
Dark Energy ◽  
Internal Structure ◽  
Density Profile ◽  
Matter Distribution ◽  
Density Profiles ◽  
Massive Galaxies ◽  
The Galaxy ◽  
Galaxy Sample ◽  
Low Mass ◽  
Void Radius

AbstractThe massive exploitation of cosmic voids for precision cosmology in the upcoming dark energy experiments, requires a robust understanding of their internal structure, particularly of their density profile. We show that the void density profile is insensitive to the void radius both in a catalogue of observed voids and in voids from a large cosmological simulation. However, the observed and simulated voids display remarkably different profile shapes, with the former having much steeper profiles than the latter. We ascribe such difference to the dependence of the observed profiles on the galaxy sample used to trace the matter distribution. Samples including low-mass galaxies lead to shallower profiles with respect to the samples where only massive galaxies are used, as faint galaxies live closer to the void centre. We argue that galaxies are biased tracers when used to probe the matter distribution within voids.

scholarly journals SDSS-IV MaNGA: environmental dependence of gas metallicity gradients in local star-forming galaxies

2019 ◽  
Vol 489 (1) ◽  
pp. 1436-1450 ◽  
Author(s):  
Jianhui Lian ◽  
Daniel Thomas ◽  
Cheng Li ◽  
Zheng Zheng ◽  
Claudia Maraston ◽  
...  
Keyword(s):  
Star Formation ◽  
Galaxy Formation ◽  
Cold Dark Matter ◽  
Star Forming ◽  
Spatially Resolved ◽  
The Galaxy ◽  
Low Mass ◽  
Satellite Galaxies ◽  
Galaxy Environment ◽  
Gas Accretion

ABSTRACT Within the standard model of hierarchical galaxy formation in a Λ cold dark matter universe, the environment of galaxies is expected to play a key role in driving galaxy formation and evolution. In this paper, we investigate whether and how the gas metallicity and the star formation surface density (ΣSFR) depend on galaxy environment. To this end, we analyse a sample of 1162 local, star-forming galaxies from the galaxy survey Mapping Nearby Galaxies at APO (MaNGA). Generally, both parameters do not show any significant dependence on environment. However, in agreement with previous studies, we find that low-mass satellite galaxies are an exception to this rule. The gas metallicity in these objects increases while their ΣSFR decreases slightly with environmental density. The present analysis of MaNGA data allows us to extend this to spatially resolved properties. Our study reveals that the gas metallicity gradients of low-mass satellites flatten and their ΣSFR gradients steepen with increasing environmental density. By extensively exploring a chemical evolution model, we identify two scenarios that are able to explain this pattern: metal-enriched gas accretion or pristine gas inflow with varying accretion time-scales. The latter scenario better matches the observed ΣSFR gradients, and is therefore our preferred solution. In this model, a shorter gas accretion time-scale at larger radii is required. This suggests that ‘outside–in quenching’ governs the star formation processes of low-mass satellite galaxies in dense environments.

scholarly journals Star-forming, rotating spheroidal galaxies in the GAMA and SAMI surveys

2019 ◽  
Vol 489 (2) ◽  
pp. 2830-2843 ◽  
Author(s):  
Amanda J Moffett ◽  
Steven Phillipps ◽  
Aaron S G Robotham ◽  
Simon P Driver ◽  
Malcolm N Bremer ◽  
...  
Keyword(s):  
Stellar Population ◽  
Elliptical Galaxies ◽  
High Resolution Imaging ◽  
Detailed Structure ◽  
Star Forming ◽  
The Galaxy ◽  
Low Mass ◽  
Resolution Imaging ◽  
Mass Assembly ◽  
Integral Field

ABSTRACT The Galaxy And Mass Assembly (GAMA) survey has morphologically identified a class of ‘Little Blue Spheroid’ (LBS) galaxies whose relationship to other classes of galaxies we now examine in detail. Considering a sample of 868 LBSs, we find that such galaxies display similar but not identical colours, specific star formation rates, stellar population ages, mass-to-light ratios, and metallicities to Sd-Irr galaxies. We also find that LBSs typically occupy environments of even lower density than those of Sd-Irr galaxies, where ∼65 per cent of LBS galaxies live in isolation. Using deep, high-resolution imaging from VST KiDS and the new Bayesian, 2D galaxy profile modelling code profit, we further examine the detailed structure of LBSs and find that their Sérsic indices, sizes, and axial ratios are compatible with those of low-mass elliptical galaxies. We then examine SAMI Galaxy survey integral field emission line kinematics for a subset of 62 LBSs and find that the majority (42) of these galaxies display ordered rotation with the remainder displaying disturbed/non-ordered dynamics. Finally, we consider potential evolutionary scenarios for a population with this unusual combination of properties, concluding that LBSs are likely formed by a mixture of merger and accretion processes still recently active in low-redshift dwarf populations. We also infer that if LBS-like galaxies were subjected to quenching in a rich environment, they would plausibly resemble cluster dwarf ellipticals.

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 Insights on bar quenching from a multiwavelength analysis: The case of Messier 95

2019 ◽  
Vol 621 ◽  
pp. L4 ◽  
Author(s):  
K. George ◽  
P. Joseph ◽  
C. Mondal ◽  
S. Subramanian ◽  
A. Subramaniam ◽  
...  
Keyword(s):  
Star Formation ◽  
Molecular Hydrogen ◽  
Stellar Population ◽  
Major Axis ◽  
Nuclear Region ◽  
Imaging Data ◽  
Physical Processes ◽  
Star Forming ◽  
The Galaxy ◽  
Barred Spiral Galaxy

The physical processes related to the effect of bars in the quenching of star formation in the region between the nuclear/central sub-kiloparsec region and the ends of the bar (bar region) of spiral galaxies is not fully understood. It is hypothesized that the bar can either stabilize the gas against collapse, inhibiting star formation, or efficiently consume all the available gas, leaving no fuel for further star formation. We present a multiwavelength study using the archival data of an early-type barred spiral galaxy, Messier 95, which shows signatures of suppressed star formation in the bar region. Using optical, ultraviolet (UV), infrared, CO, and HI imaging data we study the pattern of star formation progression and stellar/gas distribution, and try to provide insights into the process responsible for the observed pattern. The FUV–NUV pixel colour map reveals a cavity devoid of UV flux in the bar region that matches the length of the bar, which is ∼4.2 kpc. The central nuclear region of the galaxy shows a blue colour clump and along the major axis of the stellar bar the colour progressively becomes redder. Based on a comparison to single stellar population models, we show that the region of galaxy along the major axis of the bar, unlike the region outside the bar, is comprised of stellar populations with ages ≥350 Myr; there is a star-forming clump in the centre of younger ages of ∼150 Myr. Interestingly the bar region is also devoid of neutral and molecular hydrogen but has an abundant molecular hydrogen present at the nuclear region of the galaxy. Our results are consistent with a picture in which the stellar bar in Messier 95 is redistributing the gas by funnelling gas inflows to nuclear region, thus making the bar region devoid of fuel for star formation.

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