- ID:
- ivo://CDS.VizieR/J/ApJ/621/673
- Title:
- Line indices for 124 early-type galaxies
- Short Name:
- J/ApJ/621/673
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The aim of this paper is to set constraints on the epochs of early-type galaxy formation through the "archaeology" of the stellar populations in local galaxies. Using our models of absorption-line indices that account for variable abundance ratios, we derive ages, total metallicities, and element ratios of 124 early-type galaxies in high- and low-density environments. The data are analyzed by comparison with mock galaxy samples created through Monte Carlo simulations taking the typical average observational errors into account, in order to eliminate artifacts caused by correlated errors.
Number of results to display per page
Search Results
- ID:
- ivo://CDS.VizieR/J/MNRAS/448/1314
- Title:
- Line list for seven target PAndAS clusters
- Short Name:
- J/MNRAS/448/1314
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Detailed chemical abundances are presented for seven M31 outer halo globular clusters (with projected distances from M31 greater than 30 kpc), as derived from high-resolution integrated light spectra taken with the Hobby-Eberly Telescope. Five of these clusters were recently discovered in the Pan-Andromeda Archaeological Survey (PAndAS) - this paper presents the first determinations of integrated Fe, Na, Mg, Ca, Ti, Ni, Ba, and Eu abundances for these clusters. Four of the target clusters (PA06, PA53, PA54, and PA56) are metal poor ([Fe/H]< -1.5), {alpha}-enhanced (though they are possibly less {alpha}-enhanced than Milky Way stars at the 1{sigma} level), and show signs of star-to-star Na and Mg variations. The other three globular clusters (H10, H23, and PA17) are more metal rich, with metallicities ranging from [Fe/H]=-1.4 to -0.9. While H23 is chemically similar to Milky Way field stars, Milky Way globular clusters, and other M31 clusters, H10 and PA17, have moderately low [Ca/Fe], compared to Milky Way field stars and clusters. Additionally, PA17's high [Mg/Ca] and [Ba/Eu] ratios are distinct from Milky Way stars, and are in better agreement with the stars and clusters in the Large Magellanic Cloud. None of the clusters studied here can be conclusively linked to any of the identified streams from PAndAS; however, based on their locations, kinematics, metallicities, and detailed abundances, the most metal-rich PAndAS clusters H23 and PA17 may be associated with the progenitor of the Giant Stellar Stream, H10 may be associated with the SW cloud, and PA53 and PA56 may be associated with the eastern cloud.
- ID:
- ivo://CDS.VizieR/J/ApJ/795/165
- Title:
- Line ratios in z~2-3 galaxies from KBSS-MOSFIRE
- Short Name:
- J/ApJ/795/165
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present initial results of a deep near-IR spectroscopic survey covering the 15 fields of the Keck Baryonic Structure Survey using the recently commissioned MOSFIRE spectrometer on the Keck 1 telescope. We focus on a sample of 251 galaxies with redshifts 2.0<z<2.6, star formation rates (SFRs) 2<~SFR<~200 M_{sun}_/yr, and stellar masses 8.6<log(M_*_/M_{sun}_)<11.4, with high-quality spectra in both H- and K-band atmospheric windows. We show unambiguously that the locus of z~2.3 galaxies in the "BPT" nebular diagnostic diagram exhibits an almost entirely disjointed, yet similarly tight, relationship between the line ratios [N II] {lambda}6585/H{alpha} and [O III]/H{beta} as compared to local galaxies. Using photoionization models, we argue that the offset of the z~2.3 BPT locus relative to that at z~0 is caused by a combination of harder stellar ionizing radiation field, higher ionization parameter, and higher N/O at a given O/H compared to most local galaxies, and that the position of a galaxy along the z~2.3 star-forming BPT locus is surprisingly insensitive to gas-phase oxygen abundance. The observed nebular emission line ratios are most easily reproduced by models in which the net stellar ionizing radiation field resembles a blackbody with effective temperature T_eff_=50000-60000 K, the gas-phase oxygen abundances lie in the range 0.2<Z/Z_{sun}_<1.0, and the ratio of gas-phase N/O is close to the solar value. We critically assess the applicability at high redshift of commonly used strong line indices for estimating gas-phase metallicity, and consider the implications of the small intrinsic scatter of the empirical relationship between excitation-sensitive line indices and M_*_(i.e., the "mass-metallicity" relation) at z=~2.3.
- ID:
- ivo://CDS.VizieR/J/ApJ/691/1862
- Title:
- Line-strength indices for 74 early-type galaxies
- Short Name:
- J/ApJ/691/1862
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present line-strength measurements for 74 early-type galaxies in the core of the Coma cluster reaching down to velocity dispersions, {sigma}, of 30km/s. The index-{sigma} relations for our sample, including galaxies with {sigma}<100km/s (low-{sigma}), differ in shape depending on which index is used. We note two types of relations for the metallic indices: one showing a break in the slope around ~100km/s and another group with strong linear relations between an index and log {sigma}. We find no connection between the behavior of index-{sigma} relations with either {alpha}- or Fe-peak elements. However, we find indications that the relations are tighter for indices which do not depend on the microturbulent velocities of stellar atmospheres.
- ID:
- ivo://CDS.VizieR/J/A+A/395/431
- Title:
- Line-strength indices for 148 early-type galaxies
- Short Name:
- J/A+A/395/431
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have derived high quality line-strength indices and velocity dispersions for a sample of 148 early-type galaxies in different environments. The wavelength region covered by the observations (lambda~4600 to 6600{AA}) includes the Lick/IDS indices Hbeta, Mg_1_, Mg_2_, Mgb, Fe5015, Fe5270, Fe5335, Fe5406, Fe5709, Fe5782, NaD, TiO_1_ and TiO_2_. The data are intended to address possible differences of the stellar populations of early-type galaxies in low- and high-density environments. This paper describes the sample properties, explains the data reduction and presents the complete list of all the measurements. Most galaxies of the sample (85%) had no previous measurements of any Lick/IDS indices and for 30% of the galaxies we present first-time determinations of their velocity dispersions. Special care is taken to identify galaxies with emission lines. We found that 62 per cent of the galaxies in the sample have emission lines, as measured by the equivalent width of the [0III]5007{AA} line, EW[OIII]~>~0.3{AA}.
- ID:
- ivo://CDS.VizieR/J/A+A/453/493
- Title:
- Line-strength indices in IC 4200
- Short Name:
- J/A+A/453/493
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Optical spectroscopy, imaging and radio observations of the galaxy IC 4200 are analysed in order to determine the formation history of the galaxy. The two tables available contain informations extracted from the long-slit spectra of IC 4200. The spectra were taken with ESO/NTT/EMMI mounted on the NTT on 12 July 2004, as described in Sec. 3.2 and in Table 4 of the paper. tablec1.dat contains informations on the stellar and ionised-gas kinematics along the optical major and minor axis of the galaxy. The stellar kinematics was determined by fitting Bruzual & Charlot (2003MNRAS.344.1000B) stellar populations synthesis models to the low-S/N 1D bins extracted from the 2D spectrum of IC 4200 (Sec. 3.2.1). The kinematics of the ionised gas was determined by fitting single Gaussians to the Halpha emission line; for this purpose we used IRAF.NOAO.ONEDSPEC.SPLOT. tablec2.dat contains the values of the Lick/IDS indices measured along the optical major and minor axis of IC 4200. The values given are corrected for the effect of velocity dispersion and shifted to the Lick/IDS system.
- ID:
- ivo://CDS.VizieR/J/ApJ/459/110
- Title:
- Line strengths and gradients in S0 galaxies
- Short Name:
- J/ApJ/459/110
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Line strengths and their gradients in Mg, Fe, and HBeta have been determined for a sample of 20 S0 galaxies in order to study the stellar populations of their bulges and disks and to investigate their relationship to elliptical galaxies. Data are also presented for the elliptical galaxy NGC 1700 and the E/S0 NGC 3585. We find that S0 galaxies generally follow a similar, though possibly steeper, relationship between central Mg_2 line strength and central velocity dispersion as found for elliptical galaxies. The S0 galaxies show no dependence between Fe line strengths and central velocity dispersion -- similar to the behavior observed in elliptical galaxies. The central Mg/Fe ratios in the luminous S0 galaxies show an overabundance of Mg to Fe with respect to solar element ratios. The magnitudes of the Mg and Fe line-strength gradients within the galaxies are found to be correlated, i.e., objects with steep Mg gradients have correspondingly large Fe gradients. We infer bulge and disk gradients for the nine most edge-on galaxies for which we have both major- and minor-axis profiles. The metal line strengths decrease with radius along the major and minor axes in the bulge-dominated central regions. At larger radii, however, the major-axis metal line strength profiles flatten while the minor-axis bulge profiles fall to lower values. Representative color maps in B-R are presented that display a separation between bulge and disk colors corresponding to the metal line strength profiles. Based on our Mg_2 profiles, the average metal gradient found in the disks of our sub-sample is Delta[Fe/H]/Delta(r/h)=-0.08+/-0.06, which corresponds to a reduction in the mean metallicity of the disk stellar population by <~15% per disk scale length (h). These shallow metallicity gradients are approximately a factor of 2-3 smaller than those derived for the disks of late-type spiral galaxies from H II regions and are consistent with previous investigations that showed a trend for disk metallicity gradients to decrease toward earlier Hubble types. As inferred from our Mg and Fe line strengths, the mean size of the bulge metallicity gradients is Delta[Fe/H]/Delta(log r)=-0.7+/-0.4, which is steeper than typical elliptical galaxy gradients. Our findings do not support formation scenarios in which bulges formed either from heated disk material at late times after disk formation or through dissipationless stellar merging, as neither process includes mechanisms for producing the observed metallicity gradients. Our observations are better explained in terms of formation via dissipative collapse (or merging) at early times.
- ID:
- ivo://CDS.VizieR/J/ApJ/527/573
- Title:
- Line Strengths in Elliptical Galaxies
- Short Name:
- J/ApJ/527/573
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have restudied line-strength gradients of 80 elliptical galaxies. Typical metallicity gradients of elliptical galaxies are {delta}[Fe/H]/{delta}log(r){=~}-0.3, which is flatter than the gradients predicted by monolithic collapse simulations. The metallicity gradients do not correlate with any physical properties of galaxies, including central and mean metallicities, central velocity dispersions {sigma}_0_, absolute B magnitudes M_B_, absolute effective radii R_e_, and dynamical masses of galaxies. By using the metallicity gradients, we have calculated mean stellar metallicities for individual ellipticals. Typical mean stellar metallicities are <[Fe/H]> {=~} -0.3 and range from <[Fe/H]>{=~}-0.8 to +0.3, which is contrary to what Gonzalez & Gorgas (1996) claimed; the mean metallicities of ellipticals are not universal. The mean metallicities correlate well with {sigma}_0{sigma}_ and dynamical masses, though relations for M_B_ and R_e_ include significant scatters.
- ID:
- ivo://CDS.VizieR/J/AJ/135/2424
- Title:
- Line strengths of early-type galaxies
- Short Name:
- J/AJ/135/2424
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- In this paper we present measurements of velocity dispersions and Lick indices for 509 galaxies in the local universe, based on high signal-to-noise, long-slit spectra obtained with the 1.52m ESO telescope at La Silla.
- ID:
- ivo://CDS.VizieR/J/A+A/462/81
- Title:
- L_IR_-T_dust_ relation in galaxies
- Short Name:
- J/A+A/462/81
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- IRAS observations show the existence of a correlation between the infrared luminosity L_IR_ and dust temperature T_d_ in star-forming galaxies, in which larger L_IR_ leads to higher dust temperature. The L_IR_-T_d_ relation is commonly seen as reflecting the increase in dust temperature in galaxies with higher star formation rate (SFR). Even though the correlation shows a significant amount of dispersion, a unique relation has been commonly used to construct spectral energy distributions (SEDs) of galaxies in distant universe studies, such as source number counting or photometric redshift determination. In this work, we introduce a new parameter, namely the size of the star-forming region r_IR_ and lay out the empirical and modelled relation between the global parameters L_IR_, T_d_ and r_IR_ of IR-bright non-AGN galaxies.
