scholarly journals SDSS-IV MaNGA: radial gradients in stellar population properties of early-type and late-type galaxies

2021 ◽  
Vol 502 (4) ◽  
pp. 5508-5527
Author(s):  
Taniya Parikh ◽  
Daniel Thomas ◽  
Claudia Maraston ◽  
Kyle B Westfall ◽  
Brett H Andrews ◽  
...  
Keyword(s):  
Stellar Population ◽  
Mass Range ◽  
Mass Relation ◽  
Individual Element ◽  
Late Type ◽  
Element Abundances ◽  
Entire Mass Range ◽  
Strong Gradient ◽  
Star Formation Histories ◽  
Absorption Features

ABSTRACT We derive ages, metallicities, and individual element abundances of early- and late-type galaxies (ETGs and LTGs) out to 1.5 Re. We study a large sample of 1900 galaxies spanning 8.6–11.3 log M/M⊙ in stellar mass, through key absorption features in stacked spectra from the SDSS-IV/MaNGA survey. We use mock galaxy spectra with extended star formation histories to validate our method for LTGs and use corrections to convert the derived ages into luminosity- and mass-weighted quantities. We find flat age and negative metallicity gradients for ETGs and negative age and negative metallicity gradients for LTGs. Age gradients in LTGs steepen with increasing galaxy mass, from −0.05 ± 0.11 log Gyr/Re for the lowest mass galaxies to −0.82 ± 0.08 log Gyr/Re for the highest mass ones. This strong gradient–mass relation has a slope of −0.70 ± 0.18. Comparing local age and metallicity gradients with the velocity dispersion σ within galaxies against the global relation with σ shows that internal processes regulate metallicity in ETGs but not age, and vice versa for LTGs. We further find that metallicity gradients with respect to local σ show a much stronger dependence on galaxy mass than radial metallicity gradients. Both galaxy types display flat [C/Fe] and [Mg/Fe], and negative [Na/Fe] gradients, whereas only LTGs display gradients in [Ca/Fe] and [Ti/Fe]. ETGs have increasingly steep [Na/Fe] gradients with local σ reaching 6.50 ± 0.78 dex/log km s−1 for the highest masses. [Na/Fe] ratios are correlated with metallicity for both galaxy types across the entire mass range in our sample, providing support for metallicity-dependent supernova yields.

scholarly journals STELLAR POPULATION MODELS AND INDIVIDUAL ELEMENT ABUNDANCES. II. STELLAR SPECTRA AND INTEGRATED LIGHT MODELS

2009 ◽  
Vol 694 (2) ◽  
pp. 902-923 ◽  
Author(s):  
Hyun-chul Lee ◽  
Guy Worthey ◽  
Aaron Dotter ◽  
Brian Chaboyer ◽  
Darko Jevremović ◽  
...  
Keyword(s):  
Stellar Population ◽  
Population Models ◽  
Individual Element ◽  
Stellar Spectra ◽  
Element Abundances

scholarly journals Near infrared spectroscopy and star-formation histories of 3 ≤ z ≤ 4 quiescent galaxies

2018 ◽  
Vol 618 ◽  
pp. A85 ◽  
Author(s):  
C. Schreiber ◽  
K. Glazebrook ◽  
T. Nanayakkara ◽  
G. G. Kacprzak ◽  
I. Labbé ◽  
...  
Keyword(s):  
Star Formation ◽  
Rest Frame ◽  
Stellar Population ◽  
Main Sequence ◽  
Near Infrared ◽  
Photometric Redshifts ◽  
Wide Range ◽  
Order Of Magnitude ◽  
Star Formation Histories ◽  
Absorption Features

We present Keck–MOSFIRE H and K spectra for a sample of 24 candidate quiescent galaxies at 3 < z < 4, identified from their rest-frame UVJ colors and photometric redshifts in the ZFOURGE and 3DHST surveys. With median integration times of one hour in H and five in K, we obtain spectroscopic redshifts for half of the sample, using either Balmer absorption lines or nebular emission lines. We confirm the high accuracy of the photometric redshifts for this spectroscopically-confirmed sample, with a median |Zphot − Zspec|/(1 + Zspec) of 1.2%. Two galaxies turn out to be dusty Hα emitters at lower redshifts (z < 2.5), and these are the only two detected in the sub-mm with ALMA. High equivalent-width [O III] emission is observed in two galaxies, contributing up to 30% of the K-band flux and mimicking the UVJ colors of an old stellar population. This implies a failure rate of only 20% for the UVJ selection at these redshifts. Lastly, Balmer absorption features are identified in four galaxies, among the brightest of the sample, confirming the absence of OB stars. We then modeled the spectra and photometry of all quiescent galaxies with a wide range of star-formation histories. We find specific star-formation rates (sSFR) lower than 0.15 Gyr−1 (a factor of ten below the main sequence) for all but one galaxy, and lower than 0.01 Gyr−1 for half of the sample. These values are consistent with the observed Hβ and [O II] luminosities, and the ALMA non-detections. The implied formation histories reveal that these galaxies have quenched on average 300 Myr prior to being observed, between z  =  3.5 and 5, and that half of their stars were formed by z ∼ 5.5 with a mean SFR ~ 300 M⊙ yr−1. We finally compared the UVJ selection to a selection based instead on the sSFR, as measured from the photometry. We find that galaxies a factor of ten below the main sequence are 40% more numerous than UVJ-selected quiescent galaxies, implying that the UVJ selection is pure but incomplete. Current models fail at reproducing our observations, and underestimate either the number density of quiescent galaxies by more than an order of magnitude, or the duration of their quiescence by a factor two. Overall, these results confirm the existence of an unexpected population of quiescent galaxies at z > 3, and offer the first insights on their formation histories.

scholarly journals Stellar Population Models and Individual Element Abundances. I. Sensitivity of Stellar Evolution Models

2007 ◽  
Vol 666 (1) ◽  
pp. 403-412 ◽  
Author(s):  
Aaron Dotter ◽  
Brian Chaboyer ◽  
Jason W. Ferguson ◽  
Hyun‐chul Lee ◽  
Guy Worthey ◽  
...  
Keyword(s):  
Stellar Evolution ◽  
Stellar Population ◽  
Population Models ◽  
Individual Element ◽  
Element Abundances

scholarly journals The SAMI Galaxy Survey: reconciling strong emission line metallicity diagnostics using metallicity gradients

2021 ◽  
Vol 502 (3) ◽  
pp. 3357-3373
Author(s):  
Henry Poetrodjojo ◽  
Brent Groves ◽  
Lisa J Kewley ◽  
Sarah M Sweet ◽  
Sebastian F Sanchez ◽  
...  
Keyword(s):  
Emission Line ◽  
Electron Temperature ◽  
Gas Phase ◽  
Mass Range ◽  
Accurate Method ◽  
Emission Lines ◽  
Mass Relation ◽  
Strong Emission ◽  
Data Release ◽  
Accurate Comparison

ABSTRACT We measure the gas-phase metallicity gradients of 248 galaxies selected from Data Release 2 of the SAMI Galaxy Survey. We demonstrate that there are large systematic discrepancies between the metallicity gradients derived using common strong emission line metallicity diagnostics. We determine which pairs of diagnostics have Spearman’s rank coefficients greater than 0.6 and provide linear conversions to allow the accurate comparison of metallicity gradients derived using different strong emission line diagnostics. For galaxies within the mass range 8.5 &lt; log (M/M⊙) &lt; 11.0, we find discrepancies of up to 0.11 dex/Re between seven popular diagnostics in the metallicity gradient–mass relation. We find a suggestion of a break in the metallicity gradient–mass relation, where the slope shifts from negative to positive, occurs between 9.5 &lt; log (M/M⊙) &lt; 10.5 for the seven chosen diagnostics. Applying our conversions to the metallicity gradient–mass relation, we reduce the maximum dispersion from 0.11 dex/Re to 0.02 dex/Re. These conversions provide the most accurate method of converting metallicity gradients when key emission lines are unavailable. We find that diagnostics that share common sets of emission line ratios agree best, and that diagnostics calibrated through the electron temperature provide more consistent results compared to those calibrated through photoionization models.

scholarly journals Morphology of E+A Galaxies in CL0016+16 (z=0.54)

1996 ◽  
Vol 171 ◽  
pp. 469-469
Author(s):  
Gregory Wirth ◽  
Paola Belloni
Keyword(s):  
Concentration Index ◽  
Quantitative Measure ◽  
Type Systems ◽  
Emission Lines ◽  
Galaxy Mergers ◽  
Late Type ◽  
Distant Cluster ◽  
Ram Pressure ◽  
Absorption Features

We present new results on the morphology of member galaxies in the distant cluster C10016+16 from HST images (WFCl). Based on narrow multiband ground-based photometry and spectra obtained with the Keck 10 m telescope we identify 7 new cluster members which appear to have strong Balmer absorption features but no detectable emission lines, doubling the number of such galaxies previously observed with HST in this cluster. These candidate E+A galaxies have been identified in other distant clusters, but the morphology of this population has appeared bulge-like in AC114 (Couch et al., 1994, ApJ 430, 107) and disk-like or irregular and interacting in C10939+47 and C10016+16 (Wirth et al., 1994 ApJ 435, L105). By means of the image concentration index as a quantitative measure of morphology we show that our enlarged sample of E+A objects in C10016+16 now contains some galaxies resembling bulge systems as well as the previously-identified disk-like objects. The observed heterogeneity suggests that both galaxy mergers (rapidly resulting in an r1/4 profile) and ram-pressure stripping of isolated late-type systems may originate E+A objects.

scholarly journals Twins born in different environments? Nuclei of two dSphs: isolated galaxy KKS3 and E269-66, a close neighbor of NGC5128

2015 ◽  
Vol 12 (S316) ◽  
pp. 349-350
Author(s):  
Margarita Sharina ◽  
Alexei Kniazev ◽  
Igor Karachentsev
Keyword(s):  
Globular Clusters ◽  
Massive Star ◽  
Stellar Population ◽  
Central Star ◽  
Close Neighbor ◽  
Dwarf Spheroidal Galaxies ◽  
Star Forming ◽  
Star Formation Histories ◽  
Massive Clusters ◽  
Centaurus A

AbstractWe present the results of age, metallicity and radial velocity determination for central massive globular clusters (GCs) in dwarf spheroidal galaxies: KKs3 and ESO269-66. KKS3 is a unique isolated galaxy. ESO269-66 is a close neighbor of the giant S0 Centaurus A. The results contribute to the knowledge about the origin of massive star clusters and their host dSphs. The structure and star formation histories of the two dwarf galaxies look rather similar. Both of them have experienced several star-forming events. The most recent ones occurred 1-2 Gyr ago, and most powerful bursts happened 12-14 Gyrs ago. Our analysis has shown that both GCs appear to be 1-2 Gyr younger and 0.1-0.3 dex more metal-rich than the most ancient metal-poor stars in the host dSphs. We examine signatures of multiple stellar population in the GCs using our data. Since central star-forming bursts were extended in time, the massive clusters might be considered as nuclei of the galaxies.

scholarly journals Substructure in Dwarf Galaxies

2004 ◽  
Vol 21 (4) ◽  
pp. 379-381
Author(s):  
Matthew Coleman
Keyword(s):  
Dark Matter ◽  
Star Formation ◽  
Large Scale ◽  
Stellar Population ◽  
Milky Way ◽  
Dwarf Galaxies ◽  
Tidal Interaction ◽  
Kinematic Evolution ◽  
Dark Material ◽  
Star Formation Histories

AbstractRecent years have seen a series of large-scale photometric surveys with the aim of detecting substructure in nearby dwarf galaxies. Some of these objects display a varying distribution of each stellar population, reflecting their star formation histories. Also, dwarf galaxies are dominated by dark matter, therefore luminous substructure may represent a perturbation in the underlying dark material. Substructure can also be the effect of tidal interaction, such as the disruption of the Sagittarius dSph by the Milky Way. Therefore, substructure in dwarf galaxies manifests the stellar, structural, and kinematic evolution of these objects.

scholarly journals Optical spectral characterization of the TeV extreme blazar 2WHSP J073326.7+515354

2020 ◽  
Vol 494 (4) ◽  
pp. 6036-6042
Author(s):  
J Becerra González ◽  
J A Acosta-Pulido ◽  
R Clavero
Keyword(s):  
Stellar Population ◽  
Gamma Ray ◽  
Velocity Dispersion ◽  
Optical Emission ◽  
Absolute Magnitude ◽  
Brightness Distribution ◽  
Host Galaxy ◽  
Mass Relation ◽  
Relativistic Jets

ABSTRACT The emission from the relativistic jets in blazars usually outshines their host galaxies, challenging the determination of their distances and the characterization of the stellar population. The situation becomes more favourable in the case of the extreme blazars (EHBLs), for which the bulk of the emission of the relativistic jets is emitted at higher energies, unveiling the optical emission from the host galaxy. The distance determination is fundamental for the study of the intrinsic characteristics of the blazars, especially to estimate the intrinsic gamma-ray spectra distorted due to the interaction with the extragalactic background light. In this work, we report on the properties of 2WHSP J073326.7+515354 host galaxy in the optical band, which is one of the few EHBLs detected at TeV energies. We present the first measurement of the distance of the source, z = 0.065 04 ± 0.000 02 (velocity dispersion $\sigma =237 \pm 9\, \mathrm{km s^{-1}}$). We also perform a detailed study of the stellar population of its host galaxy. We find that the mass-weighted mean stellar age is $11.72\pm 0.06\, \mathrm{Gyr}$ and the mean metallicity [M/H] = 0.159 ± 0.016. In addition, a morphological study of the host galaxy is also carried out. The surface brightness distribution is modelled by a composition of a dominant classical bulge (Re = 3.77 ± 1 arcsec or equivalently 4.74 kpc) plus an unresolved source which corresponds to the active nucleus. The black hole mass is estimated using both the mass relation with the velocity dispersion and the absolute magnitude from the bulge yielding comparable results: $(4.8\pm 0.9)\times 10^8$ and $(3.7\pm 1.0)\times 10^8\, \mathrm{ M}_{\odot }$, respectively.

scholarly journals Studies of the Planetary Nebulae in NGC 5128

2003 ◽  
Vol 209 ◽  
pp. 593-593
Author(s):  
J. R. Walsh ◽  
G. H. Jacoby ◽  
R. F. Peletier ◽  
N. A. Walton
Keyword(s):  
Planetary Nebula ◽  
Surface Density ◽  
Stellar Population ◽  
Elliptical Galaxy ◽  
Small Distance ◽  
Star Formation History ◽  
Stellar Photometry ◽  
Element Abundances ◽  
Formation History ◽  
Low Mass

As the nearest large elliptical galaxy, NGC 5128 is ideal for planetary nebula studies. Its size, favourable aspect, small distance and reddening allow low mass stellar evolution in a whole galaxy to be surveyed. The surface density and properties of the PN can be compared with stars of various ages, metallicities and components (bulge, halo). The PN provide the α-element abundances whilst stellar photometry is calibrated against Fe/H; applied to the same stellar population, the PN abundances can be related to those of the stars. Gradients and non-radial trends in the abundance can be mapped using spectral observations of a large number of PN, allowing star formation history to be studied.

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