اشترك بالحزمة الذهبية واحصل على وصول غير محدود شمرا أكاديميا
تسجيل مستخدم جديدOn the (Lack of) Evolution of the Stellar Mass Function of Massive Galaxies from $z$=1.5 to 0.4
64
0
0.0
(
0
)
اسأل ChatGPT حول البحث
ﻻ يوجد ملخص باللغة العربية
We study the evolution in the number density of the highest mass galaxies over $0.4<z<1.5$ (covering 9 Gyr). We use the Spitzer/HETDEX Exploratory Large-Area (SHELA) Survey, which covers 17.5 $mathrm{deg}^2$ with eight photometric bands spanning 0.3-4.5 $mu$m within the SDSS Stripe 82 field. This size produces the lowest counting uncertainties and cosmic variance yet for massive galaxies at $zsim1.0$. We study the stellar mass function (SMF) for galaxies with $log(M_ast/M_odot)>10.3$ using a forward-modeling method that fully accounts for statistical and systematic uncertainties on stellar mass. From $z$=0.4 to 1.5 the massive end of the SMF shows minimal evolution in its shape: the characteristic mass ($M^ast$) evolves by less than 0.1 dex ($pm$0.05 dex); the number density of galaxies with $log (M_ast/M_odot) >11$ stays roughly constant at $log (n/mathrm{Mpc}^{-3})$ $simeq$ $-$3.4 ($pm$0.05), then declines to $log (n/mathrm{Mpc}^{-3})$=$-$3.7 ($pm$0.05) at $z$=1.5. We discuss the uncertainties in the SMF, which are dominated by assumptions in the star formation history and details of stellar population synthesis models for stellar mass estimations. For quiescent galaxies, the data are consistent with no (or slight) evolution ($lesssim0.1$ dex) in the characteristic mass nor number density from $zsim 1.5$ to the present. This implies that any mass growth (presumably through dry mergers) of the quiescent massive galaxy population must balance the rate of mass losses from late-stage stellar evolution and the formation of quenching galaxies from the star-forming population. We provide a limit on this mass growth from $z=1.0$ to 0.4 of $Delta M_ast/M_astleq$ 45% (i.e., $simeq0.16$ dex) for quiescent galaxies more massive than $10^{11}$ $M_odot$.
قيم البحث
اقرأ أيضاً
Galaxy clusters are excellent probes to study the effect of environment on galaxy formation and evolution. Along with high-quality observational data, accurate cosmological simulations are required to improve our understanding of galaxy evolution in
these systems. In this work, we compare state-of-the-art observational data of massive galaxy clusters ($>10^{14} textrm{M}_{odot}$) at different redshifts ($0<z<1.5$) with predictions from the Hydrangea suite of cosmological hydrodynamic simulations of 24 massive galaxy clusters ($>10^{14} textrm{M}_{odot}$ at $z=0$). We compare three fundamental observables of galaxy clusters: the total stellar mass to halo mass ratio, the stellar mass function (SMF), and the radial mass density profile of the cluster galaxies. In the first two of these, the simulations agree well with the observations, albeit with a slightly too high abundance of $M_star lesssim 10^{10} textrm{M}_{odot}$ galaxies at $z gtrsim 1$. The NFW concentrations of cluster galaxies increase with redshift, in contrast to the decreasing dark matter halo concentrations. This previously observed behaviour is therefore due to a qualitatively different assembly of the smooth DM halo compared to the satellite population. Quantitatively, we however find a discrepancy in that the simulations predict higher stellar concentrations than observed at lower redshifts ($z<0.3$), by a factor of $approx$2. This may be due to selection bias in the simulations, or stem from shortcomings in the build-up and stripping of their inner satellite halo.
Spectral absorption features can be used to constrain the stellar initial mass function (IMF) in the integrated light of galaxies. Spectral indices used at low redshift are in the far red, and therefore increasingly hard to detect at higher and highe
r redshifts as they pass out of atmospheric transmission and CCD detector wavelength windows. We employ IMF-sensitive indices at bluer wavelengths. We stack spectra of red, quiescent galaxies around $z=0.4$, from the DEEP2 Galaxy Redshift Survey. The $z=0.4$ red galaxies have 2 Gyr average ages so that they cannot be passively evolving precursors of nearby galaxies. They are slightly enhanced in C and Na, and slightly depressed in Ti. Split by luminosity, the fainter half appears to be older, a result that should be checked with larger samples in the future. We uncover no evidence for IMF evolution between $z=0.4$ and now, but we highlight the importance of sample selection, finding that an SDSS sample culled to select archetypal elliptical galaxies at z$sim$0 is offset toward a more bottom heavy IMF. Other samples, including our DEEP2 sample, show an offset toward a more spiral galaxy-like IMF. All samples confirm that the reddest galaxies look bottom heavy compared with bluer ones. Sample selection also influences age-color trends: red, luminous galaxies always look old and metal-rich, but the bluer ones can be more metal-poor, the same abundance, or more metal-rich, depending on how they are selected.
We reliably extend the stellar mass-size relation over $0.2leq z leq2$ to low stellar mass galaxies by combining the depth of Hubble Frontier Fields (HFF) with the large volume covered by CANDELS. Galaxies are simultaneously modelled in multiple band
s using the tools developed by the MegaMorph project, allowing robust size (i.e., half-light radius) estimates even for small, faint, and high redshift galaxies. We show that above 10$^7$M$_odot$, star-forming galaxies are well represented by a single power law on the mass-size plane over our entire redshift range. Conversely, the stellar mass-size relation is steep for quiescent galaxies with stellar masses $geq 10^{10.3}$M$_odot$ and flattens at lower masses, regardless of whether quiescence is selected based on star-formation activity, rest-frame colours, or structural characteristics. This flattening occurs at sizes of $sim1$kpc at $zleq1$. As a result, a double power law is preferred for the stellar mass-size relation of quiescent galaxies, at least above 10$^7$M$_odot$. We find no strong redshift dependence in the slope of the relation of star-forming galaxies as well as of high mass quiescent galaxies. We also show that star-forming galaxies with stellar masses $geq$10$^{9.5}$M$_odot$ and quiescent galaxies with stellar masses $geq10^{10.3}$M$_odot$ have undergone significant size growth since $zsim2$, as expected; however, low mass galaxies have not. Finally, we supplement our data with predominantly quiescent dwarf galaxies from the core of the Fornax cluster, showing that the stellar mass-size relation is continuous below 10$^7$M$_odot$, but a more complicated functional form is necessary to describe the relation.
Utilising optical and near-infrared broadband photometry covering $> 5,{rm deg}^2$ in two of the most well-studied extragalactic legacy fields (COSMOS and XMM-LSS), we measure the galaxy stellar mass function (GSMF) between $0.1 < z < 2.0$. We explor
e in detail the effect of two source extraction methods (SExtractor and ProFound) in addition to the inclusion/exclusion of Spitzer IRAC 3.6 and 4.5$mu$m photometry when measuring the GSMF. We find that including IRAC data reduces the number of massive ($log_{10}(M/M_odot) > 11.25$) galaxies found due to improved photometric redshift accuracy, but has little effect on the more numerous lower-mass galaxies. We fit the resultant GSMFs with double Schechter functions down to $log_{10}(M/M_odot)$ = 7.75 (9.75) at z = 0.1 (2.0) and find that the choice of source extraction software has no significant effect on the derived best-fit parameters. However, the choice of methodology used to correct for the Eddington bias has a larger impact on the high-mass end of the GSMF, which can partly explain the spread in derived $M^*$ values from previous studies. Using an empirical correction to model the intrinsic GSMF, we find evidence for an evolving characteristic stellar mass with $delta log_{10}(M^*/M_odot)/delta z$ = $-0.16pm0.05 , (-0.11pm0.05)$, when using SExtractor (ProFound). We argue that with widely quenched star formation rates in massive galaxies at low redshift ($z<0.5$), additional growth via mergers is required in order to sustain such an evolution to a higher characteristic mass.
We utilize deep near-infrared survey data from the UltraVISTA fourth data release (DR4) and the VIDEO survey, in combination with overlapping optical and Spitzer data, to search for bright star-forming galaxies at $z gtrsim 7.5$. Using a full photome
tric redshift fitting analysis applied to the $sim 6,{rm deg}^2$ of imaging searched, we find 27 Lyman-break galaxies (LBGs), including 20 new sources, with best-fitting photometric redshifts in the range $7.4 < z < 9.1$. From this sample we derive the rest-frame UV luminosity function (LF) at $z = 8$ and $z = 9$ out to extremely bright UV magnitudes ($M_{rm UV} simeq -23$) for the first time. We find an excess in the number density of bright galaxies in comparison to the typically assumed Schechter functional form derived from fainter samples. Combined with previous studies at lower redshift, our results show that there is little evolution in the number density of very bright ($M_{rm UV} sim -23$) LBGs between $z simeq 5$ and $zsimeq 9$. The tentative detection of an LBG with best-fit photometric redshift of $z = 10.9 pm 1.0$ in our data is consistent with the derived evolution. We show that a double power-law fit with a brightening characteristic magnitude ($Delta M^*/Delta z simeq -0.5$) and a steadily steepening bright-end slope ($Delta beta/Delta z simeq -0.5$) provides a good description of the $z > 5$ data over a wide range in absolute UV magnitude ($-23 < M_{rm UV} < -17$). We postulate that the observed evolution can be explained by a lack of mass quenching at very high redshifts in combination with increasing dust obscuration within the first $sim 1 ,{rm Gyr}$ of galaxy evolution.
سجل دخول لتتمكن من نشر تعليقات
التعليقات
جاري جلب التعليقات
سجل دخول لتتمكن من متابعة معايير البحث التي قمت باختيارها
