scholarly journals A prediction about the age of thick discs as a function of the stellar mass of the host galaxy

2021 ◽  
Vol 645 ◽  
pp. L13
Author(s):  
S. Comerón
Keyword(s):  
Stellar Mass ◽  
Host Galaxy ◽  
Formation Mechanisms ◽  
Lenticular Galaxies ◽  
Thick Disc ◽  
Minor Mergers ◽  
Stellar Masses ◽  
S0 Galaxies ◽  
Mass Functions

One of the suggested thick disc formation mechanisms is that they were born quickly and in situ from a turbulent clumpy disc. Subsequently, thin discs formed slowly within them from leftovers of the turbulent phase and from material accreted through cold flows and minor mergers. In this Letter, I propose an observational test to verify this hypothesis. By combining thick disc and total stellar masses of edge-on galaxies with galaxy stellar mass functions calculated in the redshift range of z ≤ 3.0, I derived a positive correlation between the age of the youngest stars in thick discs and the stellar mass of the host galaxy; galaxies with a present-day stellar mass of ℳ⋆(z = 0) < 1010 ℳ⊙ have thick disc stars as young as 4 − 6 Gyr, whereas the youngest stars in the thick discs of Milky-Way-like galaxies are ∼10 Gyr old. I tested this prediction against the scarcely available thick disc age estimates, all of them are from galaxies with ℳ⋆(z = 0) ≳ 1010 ℳ⊙, and I find that field spiral galaxies seem to follow the expectation. On the other hand, my derivation predicts ages that are too low for the thick discs in lenticular galaxies, indicating a fast early evolution for S0 galaxies. I propose the idea of conclusively testing whether thick discs formed quickly and in situ by obtaining the ages of thick discs in field galaxies with masses of ℳ⋆(z = 0) ∼ 109.5 ℳ⊙ and by checking whether they contain ∼5 Gyr-old stars.

scholarly journals Kinematics of the outskirts of S0 galaxies from PNe and GCs

2016 ◽  
Vol 11 (S321) ◽  
pp. 290-290
Author(s):  
A. Cortesi ◽  
C. Mendes de Oliveira
Keyword(s):  
Galaxy Formation ◽  
Globular Clusters ◽  
Velocity Dispersion ◽  
Spiral Galaxies ◽  
Formation Mechanisms ◽  
Stellar Kinematics ◽  
Lenticular Galaxies ◽  
Star Forming ◽  
Flat Rotation Curves ◽  
S0 Galaxies

AbstractThe stellar kinematics of the discs of S0 galaxies (as obtained using planetary nebulae, PNe, and integrated stellar light data) is comparable to that of spiral galaxies, with similar flat rotation curves and falling velocity dispersion profiles, but they present a larger amount of random motions. The only other tracer available to probe the kinematics of individual early-type galaxies are globular clusters (GCs). GCs’ formation is intimately connected to a galaxy major star forming event(s) and GCs are, therefore, good proofs of galaxy formation histories. We directly compare a sample of PNe, GCs, and stellar velocities out to 4 effective radii, in the S0 galaxies NGC 2768 and NGC 1023. In particular, we test a new method for studying GC properties and we find that these two lenticular galaxies are consistent with being formed through different formation mechanisms.

scholarly journals Bar rejuvenation in S0 galaxies?

2020 ◽  
Vol 495 (4) ◽  
pp. 4548-4556
Author(s):  
Sudhanshu Barway ◽  
Kanak Saha
Keyword(s):  
Star Formation ◽  
Spiral Galaxies ◽  
Theoretical Studies ◽  
Tidal Interactions ◽  
Colour Measurements ◽  
Induce Star Formation ◽  
Minor Mergers ◽  
Stellar Masses ◽  
S0 Galaxies ◽  
Intermediate Density

ABSTRACT Based on the colour measurements from a multiband, multicomponent 2D decompositions of S0 and spiral galaxies using SDSS images, we found that bars are bluer in S0 galaxies compared to the spiral galaxies. Most of the S0s in our sample have stellar masses ∼L* galaxies. The environment might have played an important role as most of the S0s with bluer bars are in the intermediate-density environment. The possibility of minor mergers and tidal interactions that occurs frequently in the intermediate-density environment might have caused either a bar to form and/or induce star formation in the barred region of S0 galaxies. The underlying discs show the usual behaviour being redder in S0s compared to spiral galaxies while the bulges are red and old for both S0 and spiral galaxies. The finding of bluer bars in S0 galaxies is a puzzling issue and poses an interesting question at numerical and theoretical studies most of which shows that the bars are long-lived structures with old stellar populations.

scholarly journals Kraken reveals itself – the merger history of the Milky Way reconstructed with the E-MOSAICS simulations

2020 ◽  
Vol 498 (2) ◽  
pp. 2472-2491 ◽  
Author(s):  
J M Diederik Kruijssen ◽  
Joel L Pfeffer ◽  
Mélanie Chevance ◽  
Ana Bonaca ◽  
Sebastian Trujillo-Gomez ◽  
...  
Keyword(s):  
Globular Clusters ◽  
Milky Way ◽  
Mass Range ◽  
Stellar Mass ◽  
Host Galaxies ◽  
Stellar Halo ◽  
Major Merger ◽  
Virial Mass ◽  
Minor Mergers ◽  
Stellar Masses

ABSTRACT Globular clusters (GCs) formed when the Milky Way experienced a phase of rapid assembly. We use the wealth of information contained in the Galactic GC population to quantify the properties of the satellite galaxies from which the Milky Way assembled. To achieve this, we train an artificial neural network on the E-MOSAICS cosmological simulations of the co-formation and co-evolution of GCs and their host galaxies. The network uses the ages, metallicities, and orbital properties of GCs that formed in the same progenitor galaxies to predict the stellar masses and accretion redshifts of these progenitors. We apply the network to Galactic GCs associated with five progenitors: Gaia-Enceladus, the Helmi streams, Sequoia, Sagittarius, and the recently discovered ‘low-energy’ GCs, which provide an excellent match to the predicted properties of the enigmatic galaxy ‘Kraken’. The five galaxies cover a narrow stellar mass range [M⋆ = (0.6–4.6) × 108 M⊙], but have widely different accretion redshifts ($\mbox{$z_{\rm acc}$}=0.57\!-\!2.65$). All accretion events represent minor mergers, but Kraken likely represents the most major merger ever experienced by the Milky Way, with stellar and virial mass ratios of $\mbox{$r_{M_\star }$}=1$:$31^{+34}_{-16}$ and $\mbox{$r_{M_{\rm h}}$}=1$:$7^{+4}_{-2}$, respectively. The progenitors match the z = 0 relation between GC number and halo virial mass, but have elevated specific frequencies, suggesting an evolution with redshift. Even though these progenitors likely were the Milky Way’s most massive accretion events, they contributed a total mass of only log (M⋆, tot/M⊙) = 9.0 ± 0.1, similar to the stellar halo. This implies that the Milky Way grew its stellar mass mostly by in-situ star formation. We conclude by organizing these accretion events into the most detailed reconstruction to date of the Milky Way’s merger tree.

scholarly journals Optimizing gravitational waves follow-up using galaxies stellar mass

2020 ◽  
Vol 492 (4) ◽  
pp. 4768-4779 ◽  
Author(s):  
J-G Ducoin ◽  
D Corre ◽  
N Leroy ◽  
E Le Floch
Keyword(s):  
Gravitational Wave ◽  
Stellar Mass ◽  
Host Galaxy ◽  
New Approach ◽  
Massive Galaxies ◽  
New Strategy ◽  
The Galaxy ◽  
Wave Event ◽  
Stellar Masses

ABSTRACT We present a new strategy to optimize the electromagnetic follow-up of gravitational wave triggers. This method is based on the widely used galaxy targeting approach where we add the stellar mass of galaxies in order to prioritize the more massive galaxies. We cross-matched the Galaxy List for the Advanced Detector Era (GLADE) galaxy catalogue with the AllWISE catalogue up to 400 Mpc with an efficiency of ∼93 per cent, and derived stellar masses using a mass-to-light ratio using the WISE1 band luminosity. We developed a new grade to rank galaxies combining their 3D localization probability associated with the gravitational wave event with the new stellar mass information. The efficiency of this new approach is illustrated with the GW170817 event, which shows that its host galaxy, NGC 4993, is ranked at the first place using this new method. The catalogue, named MANGROVE, is publicly available and the ranking of galaxies is automatically provided through a dedicated website for each gravitational wave event.

scholarly journals Strong dependence of Type Ia supernova standardization on the local specific star formation rate

2020 ◽  
Vol 644 ◽  
pp. A176
Author(s):  
M. Rigault ◽  
V. Brinnel ◽  
G. Aldering ◽  
P. Antilogus ◽  
C. Aragon ◽  
...  
Keyword(s):  
Star Formation ◽  
Star Formation Rate ◽  
Strong Dependence ◽  
Formation Rate ◽  
Stellar Mass ◽  
Host Galaxy ◽  
Type Ia ◽  
Galaxy Environment ◽  
Stellar Masses ◽  
Ia Supernovae

As part of an on-going effort to identify, understand and correct for astrophysics biases in the standardization of Type Ia supernovae (SN Ia) for cosmology, we have statistically classified a large sample of nearby SNe Ia into those that are located in predominantly younger or older environments. This classification is based on the specific star formation rate measured within a projected distance of 1 kpc from each SN location (LsSFR). This is an important refinement compared to using the local star formation rate directly, as it provides a normalization for relative numbers of available SN progenitors and is more robust against extinction by dust. We find that the SNe Ia in predominantly younger environments are ΔY = 0.163 ± 0.029 mag (5.7σ) fainter than those in predominantly older environments after conventional light-curve standardization. This is the strongest standardized SN Ia brightness systematic connected to the host-galaxy environment measured to date. The well-established step in standardized brightnesses between SNe Ia in hosts with lower or higher total stellar masses is smaller, at ΔM = 0.119 ± 0.032 mag (4.5σ), for the same set of SNe Ia. When fit simultaneously, the environment-age offset remains very significant, with ΔY = 0.129 ± 0.032 mag (4.0σ), while the global stellar mass step is reduced to ΔM = 0.064  ±  0.029 mag (2.2σ). Thus, approximately 70% of the variance from the stellar mass step is due to an underlying dependence on environment-based progenitor age. Also, we verify that using the local star formation rate alone is not as powerful as LsSFR at sorting SNe Ia into brighter and fainter subsets. Standardization that only uses the SNe Ia in younger environments reduces the total dispersion from 0.142  ±  0.008 mag to 0.120  ±  0.010 mag. We show that as environment-ages evolve with redshift, a strong bias, especially on the measurement of the derivative of the dark energy equation of state, can develop. Fortunately, data that measure and correct for this effect using our local specific star formation rate indicator, are likely to be available for many next-generation SN Ia cosmology experiments.

Rapid build-up of the stellar content in the protocluster core SPT2349−56 at z  =  4.3

2021 ◽  
Author(s):  
Ryley Hill Scott Chapman ◽  
Kedar A Phadke ◽  
Manuel Aravena ◽  
Melanie Archipley ◽  
Matthew L N Ashby ◽  
...  
Keyword(s):  
Rest Frame ◽  
Imaging Finding ◽  
Mass Function ◽  
Stellar Mass ◽  
Spectral Energy ◽  
Formation Mechanisms ◽  
Stellar Content ◽  
Cluster Galaxy ◽  
Star Forming ◽  
Stellar Masses

Abstract The protocluster SPT2349−56 at z  =  4.3 contains one of the most actively star-forming cores known, yet constraints on the total stellar mass of this system are highly uncertain. We have therefore carried out deep optical and infrared observations of this system, probing rest-frame ultraviolet to infrared wavelengths. Using the positions of the spectroscopically-confirmed protocluster members, we identify counterparts and perform detailed source deblending, allowing us to fit spectral energy distributions in order to estimate stellar masses. We show that the galaxies in SPT2349−56 have stellar masses proportional to their high star-formation rates, consistent with other protocluster galaxies and field submillimetre galaxies (SMGs) around redshift 4. The galaxies in SPT2349−56 have on average lower molecular gas-to-stellar mass fractions and depletion timescales than field SMGs, although with considerable scatter. We construct the stellar-mass function for SPT2349−56 and compare it to the stellar-mass function of z  =  1 galaxy clusters, finding consistent shapes between the two. We measure rest-frame galaxy ultraviolet half-light radii from our HST-F160W imaging, finding that on average the galaxies in our sample are similar in size to typical star-forming galaxies at these redshifts. However, the brightest HST-detected galaxy in our sample, found near the luminosity-weighted centre of the protocluster core, remains unresolved at this wavelength. Hydrodynamical simulations predict that the core galaxies will quickly merge into a brightest cluster galaxy, thus our observations provide a direct view of the early formation mechanisms of this class of object.

scholarly journals Evolution of the anti-truncated stellar profiles of S0 galaxies since z = 0.6 in the SHARDS survey

2018 ◽  
Vol 615 ◽  
pp. A26 ◽  
Author(s):  
Alejandro Borlaff ◽  
M. Carmen Eliche-Moral ◽  
John E. Beckman ◽  
Alexandre Vazdekis ◽  
Alejandro Lumbreras-Calle ◽  
...  
Keyword(s):  
Surface Brightness ◽  
Rest Frame ◽  
Structural Parameters ◽  
Stellar Mass ◽  
Scaling Relations ◽  
Local Universe ◽  
Lenticular Galaxies ◽  
Type Iii ◽  
S0 Galaxies ◽  
Stable Formation

Context. Anti-truncated lenticular galaxies (Type-III S0s) present tight scaling relations between their surface brightness photometric and structural parameters. Although several evolutionary models have been proposed for the formation of these structures, the observations of Type-III S0 galaxies are usually limited to the local Universe. Aims. We aim to compare the properties of Type-III discs in a sample of S0 galaxies at 0.2 < z < 0.6 with those of the local Universe. In this paper, we study the evolution of the photometric and structural scaling relations measured in the rest-frame R-band with z and the possible differences between the rest-frame (B − R) colours of the inner and outer disc profiles. Methods. We make use of a sample of 14 Type-III E/S0–S0 galaxies at 0.2 < z < 0.6 from the GOODS-N field identified and characterised in a previous paper. We study whether or not the correlations found in local Type-III S0 galaxies were present ~6 Gyr ago. We analyse the distribution of the surface brightness characteristic parameters (Rbreak, μbreak, hi, ho, μ0,i and μ0,o) as a function of the stellar mass and look to see if there is a significant change with z. We also derive their rest-frame (B − R) colour profiles. Finally, we compare these results with the predictions from a grid of SSP models. Results. We find that the inner and outer scale-lengths of Type-III S0 galaxies at 0.4 < z < 0.6 follow compatible trends and scaling relations with those observed in local S0 galaxies as a function of the break radius, Rbreak. We do not detect any significant differences between the location of Rbreak between z ~ 0.6 and z ~ 0 for a fixed stellar mass of the object, whereas the surface brightness at the break radius μbreak is ~1.5 mag arcsec-2 dimmer in the local Universe than at z ~ 0.6 for a fixed stellar mass. We find no significant differences in the (B − R) colour between the inner and outer profiles of the Type-III S0 galaxies at 0.2 < z < 0.6. Conclusions. In contrast to Type-II (down-bending) profiles, the anti-truncated surface brightness profiles of S0 galaxies present compatible Rbreak values and scaling relations during the last 6 Gyr. This result and the similarity of the colours of the inner and outer discs point to a highly scalable and stable formation process, probably more related to gravitational and dynamical processes than to the evolution of stellar populations.

scholarly journals Supernova host galaxies in the dark energy survey: I. Deep coadds, photometry, and stellar masses

2020 ◽  
Vol 495 (4) ◽  
pp. 4040-4060 ◽  
Author(s):  
P Wiseman ◽  
M Smith ◽  
M Childress ◽  
L Kelsey ◽  
A Möller ◽  
...  
Keyword(s):  
Dark Energy ◽  
High Redshift ◽  
High Mass ◽  
Host Galaxy ◽  
Formation Mechanisms ◽  
Atmospheric Conditions ◽  
Host Galaxies ◽  
Dark Energy Survey ◽  
Stellar Masses ◽  
Energy Survey

ABSTRACT The 5-yr Dark Energy Survey Supernova Programme (DES-SN) is one of the largest and deepest transient surveys to date in terms of volume and number of supernovae. Identifying and characterizing the host galaxies of transients plays a key role in their classification, the study of their formation mechanisms, and the cosmological analyses. To derive accurate host galaxy properties, we create depth-optimized coadds using single-epoch DES-SN images that are selected based on sky and atmospheric conditions. For each of the five DES-SN seasons, a separate coadd is made from the other four seasons such that each SN has a corresponding deep coadd with no contaminating SN emission. The coadds reach limiting magnitudes of order ∼27 in g band, and have a much smaller magnitude uncertainty than the previous DES-SN host templates, particularly for faint objects. We present the resulting multiband photometry of host galaxies for samples of spectroscopically confirmed type Ia (SNe Ia), core-collapse (CCSNe), and superluminous (SLSNe) as well as rapidly evolving transients (RETs) discovered by DES-SN. We derive host galaxy stellar masses and probabilistically compare stellar-mass distributions to samples from other surveys. We find that the DES spectroscopically confirmed sample of SNe Ia selects preferentially fewer high-mass hosts at high-redshift compared to other surveys, while at low redshift the distributions are consistent. DES CCSNe and SLSNe hosts are similar to other samples, while RET hosts are unlike the hosts of any other transients, although these differences have not been disentangled from selection effects.

scholarly journals Comparing galaxy clustering in Horizon-AGN simulated light-cone mocks and VIDEO observations

2019 ◽  
Vol 490 (4) ◽  
pp. 5043-5056 ◽  
Author(s):  
P W Hatfield ◽  
C Laigle ◽  
M J Jarvis ◽  
J Devriendt ◽  
I Davidzon ◽  
...  
Keyword(s):  
Light Cone ◽  
Spectral Energy Distribution ◽  
Cosmic Time ◽  
Stellar Mass ◽  
Spectral Energy ◽  
Mass Ratio ◽  
Distribution Fitting ◽  
Low Mass ◽  
Stellar Masses ◽  
Mass Functions

ABSTRACT Hydrodynamical cosmological simulations have recently made great advances in reproducing galaxy mass assembly over cosmic time – as often quantified from the comparison of their predicted stellar mass functions to observed stellar mass functions from data. In this paper, we compare the clustering of galaxies from the hydrodynamical cosmological simulated light-cone Horizon-AGN to clustering measurements from the VIDEO survey observations. Using mocks built from a VIDEO-like photometry, we first explore the bias introduced into clustering measurements by using stellar masses and redshifts derived from spectral energy distribution fitting, rather than the intrinsic values. The propagation of redshift and mass statistical and systematic uncertainties in the clustering measurements causes us to underestimate the clustering amplitude. We then find that clustering and halo occupation distribution (HOD) modelling results are qualitatively similar in Horizon-AGN and VIDEO. However, at low stellar masses, Horizon-AGN underestimates the observed clustering by up to a factor of ∼3, reflecting the known excess stellar mass to halo mass ratio for Horizon-AGN low-mass haloes, already discussed in previous works. This reinforces the need for stronger regulation of star formation in low-mass haloes in the simulation. Finally, the comparison of the stellar mass to halo mass ratio in the simulated catalogue, inferred from angular clustering, to that directly measured from the simulation validates HOD modelling of clustering as a probe of the galaxy–halo connection.

scholarly journals Stellar masses of giant clumps in CANDELS and simulated galaxies using machine learning

2020 ◽  
Vol 499 (1) ◽  
pp. 814-835
Author(s):  
Marc Huertas-Company ◽  
Yicheng Guo ◽  
Omri Ginzburg ◽  
Christoph T Lee ◽  
Nir Mandelker ◽  
...  
Keyword(s):  
Galaxy Evolution ◽  
Gravitational Lensing ◽  
High Redshift ◽  
Mass Function ◽  
Stellar Mass ◽  
Star Forming ◽  
Mixture Density ◽  
Distant Galaxies ◽  
Stellar Masses

ABSTRACT A significant fraction of high redshift star-forming disc galaxies are known to host giant clumps, whose nature and role in galaxy evolution are yet to be understood. In this work, we first present a new method based on neural networks to detect clumps in galaxy images. We use this method to detect clumps in the rest-frame optical and UV images of a complete sample of ∼1500 star forming galaxies at 1 &lt; z &lt; 3 in the CANDELS survey as well as in images from the VELA zoom-in cosmological simulations. We show that observational effects have a dramatic impact on the derived clump properties leading to an overestimation of the clump mass up to a factor of 10, which highlights the importance of fair comparisons between observations and simulations and the limitations of current HST data to study the resolved structure of distant galaxies. After correcting for these effects with a mixture density network, we estimate that the clump stellar mass function follows a power law down to the completeness limit (107 solar masses) with the majority of the clumps being less massive than 109 solar masses. This is in better agreement with recent gravitational lensing based measurements. The simulations explored in this work overall reproduce the shape of the observed clump stellar mass function and clumpy fractions when confronted under the same conditions, although they tend to lie in the lower limit of the confidence intervals of the observations. This agreement suggests that most of the observed clumps are formed in situ.

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