- 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}.
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- 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/MNRAS/330/547
- Title:
- Local galaxy ages and metallicities
- Short Name:
- J/MNRAS/330/547
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have assembled a catalogue of relative ages, metallicities and abundance ratios for about 150 local galaxies in field, group and cluster environments. The galaxies span morphological types from cD and ellipticals, to late-type spirals. Ages and metallicities were estimated from high-quality published spectral line indices using Worthey & Ottaviani (1997, Cat. <J/ApJS/111/377>) single stellar population evolutionary models. The identification of galaxy age as a fourth parameter in the fundamental plane (Forbes, Ponman & Brown, 1998ApJ...508L..43F) is confirmed by our larger sample of ages. We investigate trends between age and metallicity, and with other physical parameters of the galaxies, such as ellipticity, luminosity and kinematic anisotropy. We demonstrate the existence of a galaxy age-metallicity relation similar to that seen for local galactic disc stars, whereby young galaxies have high metallicity, while old galaxies span a large range in metallicities. We also investigate the influence of environment and morphology on the galaxy age and metallicity, especially the predictions made by semi-analytic hierarchical clustering models (HCM). We confirm that non-cluster ellipticals are indeed younger on average than cluster ellipticals as predicted by the HCM models. However we also find a trend for the more luminous galaxies to have a higher [Mg/Fe] ratio than the lower luminosity galaxies, which is opposite to the expectation from HCM models.
- ID:
- ivo://CDS.VizieR/J/MNRAS/451/2723
- Title:
- Low-redshift clusters in the SAMI Pilot Survey
- Short Name:
- J/MNRAS/451/2723
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Using new integral field observations of 106 galaxies in three nearby clusters, we investigate how the intrinsic scatter of the Fundamental Plane depends on the way in which the velocity dispersion and effective radius are measured. Our spatially resolved spectroscopy, combined with a cluster sample with negligible relative distance errors, allows us to derive a Fundamental Plane with minimal systematic uncertainties. From the apertures we tested, we find that velocity dispersions measured within a circular aperture with radius equal to one effective radius minimizes the intrinsic scatter of the Fundamental Plane. Using simple yet powerful Jeans dynamical models, we determine dynamical masses for our galaxies. Replacing luminosity in the Fundamental Plane with dynamical mass, we demonstrate that the resulting Mass Plane has further reduced scatter, consistent with zero intrinsic scatter. Using these dynamical models, we also find evidence for a possibly non-linear relationship between dynamical mass-to-light ratio and velocity dispersion.
- ID:
- ivo://CDS.VizieR/J/A+A/599/A76
- Title:
- L-{sigma} relation for HII galaxies
- Short Name:
- J/A+A/599/A76
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The correlation between emission-line luminosity (L) and profile-width ({sigma}) for HII galaxies provides a powerful method to measure the distances to galaxies over a wide range of redshifts. In this paper, we use SDSS spectrophotometry to explore the systematics of the correlation using the [OIII]5007 lines instead of H{alpha} or H{beta} to measure luminosities and line widths. We also examine possible systematic effects involved in measuring the profile-widths and the luminosities through different apertures. We find that the green L-{sigma} relation, defined using [OIII]5007 luminosities, is significantly more sensitive than H{beta} to the effects of age and the physical conditions of the nebulae, which more than offsets the advantage of the higher strength of the [OIII]5007 lines. We then explore the possibility of mixing [OIII]5007 profile-widths with SDSS H{beta} luminosities using the Hubble constant H_0_ to quantify the possible systematic effects. We find the mixed L(H{beta})-{sigma}_[OIII]_ relation to be at least as powerful as the canonical L-{sigma} relation as a distance estimator, and we show that evolutionary corrections do not change the slope and the scatter of the correlation and, therefore, do not bias the L-{sigma} distance indicator at high redshifts. Locally, however, the luminosities of the giant HII regions that provide the zero-point calibrators are sensitive to evolutionary corrections and may bias the Hubble constant if their mean ages, as measured by the equivalent widths of H{beta}, are significantly different from the mean age of the HII galaxies. Using a small sample of 16 ad-hoc zero point calibrators we obtain a value of H_0_=66.4^+5.0^_-4.5_km/s/Mpc for the Hubble constant, which is fully consistent with the best modern determinations, and which is not biased by evolutionary corrections.
- ID:
- ivo://CDS.VizieR/J/ApJ/852/72
- Title:
- Luminosity functions of tidal disruption flares
- Short Name:
- J/ApJ/852/72
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The tidal disruption of a star by a massive black hole is expected to yield a luminous flare of thermal emission. About two dozen of these stellar tidal disruption flares (TDFs) may have been detected in optical transient surveys. However, explaining the observed properties of these events within the tidal disruption paradigm is not yet possible. This theoretical ambiguity has led some authors to suggest that optical TDFs are due to a different process, such as a nuclear supernova or accretion disk instabilities. Here we present a test of a fundamental prediction of the tidal disruption event scenario: a suppression of the flare rate due to the direct capture of stars by the black hole. Using a recently compiled sample of candidate TDFs with black hole mass measurements, plus a careful treatment of selection effects in this flux-limited sample, we confirm that the dearth of observed TDFs from high-mass black holes is statistically significant. All the TDF impostor models we consider fail to explain the observed mass function; the only scenario that fits the data is a suppression of the rate due to direct captures. We find that this suppression can explain the low volumetric rate of the luminous TDF candidate ASASSN-15lh, thus supporting the hypothesis that this flare belongs to the TDF family. Our work is the first to present the optical TDF luminosity function. A steep power law is required to explain the observed rest-frame g-band luminosity, dN/dL_g_{propto}L_g_^-2.5^. The mean event rate of the flares in our sample is ~1x10^-4^galaxy^-1^/yr, consistent with the theoretically expected tidal disruption rate.
- ID:
- ivo://CDS.VizieR/J/MNRAS/389/1074
- Title:
- LX-{sigma} relation of galaxy clusters
- Short Name:
- J/MNRAS/389/1074
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We use the ROSAT All-Sky Survey to study the X-ray properties of a sample of 625 groups and clusters of galaxies selected from the Sloan Digital Sky Survey. We stack clusters with similar velocity dispersions and investigate whether their average X-ray luminosities and surface brightness profiles vary with the radio activity level of their central galaxies. We find that at a given value of {sigma}, clusters with a central radio active galactic nucleus (AGN) have more concentrated X-ray surface brightness profiles, larger central galaxy masses and higher X-ray luminosities than clusters with radio-quiet central galaxies. The enhancement in X-ray luminosity is more than a factor of 2, is detected with better than 6{sigma} significance and cannot be explained by X-ray emission from the radio AGN itself. This difference is largely due to a subpopulation of radio-quiet, high velocity dispersion clusters with low-mass central galaxies. These clusters are underluminous at X-ray wavelengths when compared to otherwise similar clusters where the central galaxy is radio-loud, more massive, or both.
- ID:
- ivo://CDS.VizieR/J/AJ/154/113
- Title:
- Magellan/M2FS spectroscopy of Abell 267
- Short Name:
- J/AJ/154/113
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report the results of a pilot program to use the Magellan/M2FS spectrograph to survey the galactic populations and internal kinematics of galaxy clusters. For this initial study, we present spectroscopic measurements for 223 quiescent galaxies observed along the line of sight of the galaxy cluster Abell 267 (z~0.23). We develop a Bayesian method for modeling the integrated light from each galaxy as a simple stellar population, with free parameters that specify the redshift (v_los_/c) and characteristic age, metallicity ([Fe/H]), alpha-abundance ([{alpha}/Fe]), and internal velocity dispersion ({sigma}_int_) for individual galaxies. Parameter estimates derived from our 1.5hr observation of A267 have median random errors of {sigma}_Vlos_=20km/s, {sigma}_Age_=1.2Gyr, {sigma}_[Fe/H]_=0.11dex, {sigma}_[{alpha}/Fe]_=0.07dex, and {sigma}_{sigma}int_=20km/s. In a companion paper, we use these results to model the structure and internal kinematics of A267.
- ID:
- ivo://CDS.VizieR/J/A+A/474/783
- Title:
- Main galaxy groups from SDSS-DR5
- Short Name:
- J/A+A/474/783
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We investigate the correlations between galaxy properties and environment. From the main galaxy sample of the SDSS Data Release 5, we have extracted 11 163 groups at the linking length R_0_=0.2x({bar}n)^-1/3^=1.97Mpc (where {bar}n is the mean number density of galaxies) by the three-dimensional friends-of-friends (FOF) algorithm, where {bar}n is the mean galaxy density, and compare basic properties of member galaxies of main galaxy groups with those of the main galaxy sample and isolated galaxies in each redshift bin.
- ID:
- ivo://CDS.VizieR/J/MNRAS/476/1765
- Title:
- MaNGA E and S galaxies properties
- Short Name:
- J/MNRAS/476/1765
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We perform full spectrum fitting stellar population analysis and Jeans Anisotropic modelling of the stellar kinematics for about 2000 early-type galaxies (ETGs) and spiral galaxies from the MaNGA DR14 sample. Galaxies with different morphologies are found to be located on a remarkably tight mass plane which is close to the prediction of the virial theorem, extending previous results for ETGs. By examining an inclined projection ('the mass-size' plane), we find that spiral and early-type galaxies occupy different regions on the plane, and their stellar population properties (i.e. age, metallicity, and stellar mass-to-light ratio) vary systematically along roughly the direction of velocity dispersion, which is a proxy for the bulge fraction. Galaxies with higher velocity dispersions have typically older ages, larger stellar mass-to-light ratios and are more metal rich, which indicates that galaxies increase their bulge fractions as their stellar populations age and become enriched chemically. The age and stellar mass-to-light ratio gradients for low-mass galaxies in our sample tend to be positive (centre<outer), while the gradients for most massive galaxies are negative. The metallicity gradients show a clear peak around velocity dispersion log_10_{sigma}_e_~=2.0, which corresponds to the critical mass ~3x10^10^M_{sun}_ of the break in the mass-size relation. Spiral galaxies with large mass and size have the steepest gradients, while the most massive ETGs, especially above the critical mass M_crit_>=2x 10^11^M_{sun}_, where slow rotator ETGs start dominating, have much flatter gradients. This may be due to differences in their evolution histories, e.g. mergers.
