- ID:
- ivo://CDS.VizieR/J/A+AS/120/257
- Title:
- Ionized gas velocity in 6 galaxies
- Short Name:
- J/A+AS/120/257
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report observations of the velocity field of the ionized gas in the nearby ellipticals NGC 1453, NGC 2974, NGC 3962, NGC 4636, NGC 6868 and NGC 7097. This is part of an ESO Key Programme intended to derive the mass distribution of elliptical galaxies and to investigate the possible presence of dark matter. All galaxy spectra are characterized by LINER-type emission. The derived gas kinematics confirm the picture of a regular gaseous disk structure with ordered rotation. The gas velocity dispersion profiles decline rapidly from a high central value in the range of =~150 to =~250km/s.
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1802. Ionized nebulae in M31
- ID:
- ivo://CDS.VizieR/J/A+AS/92/625
- Title:
- Ionized nebulae in M31
- Short Name:
- J/A+AS/92/625
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Deep CCD imagery in H{alpha} and [SII] is presented of the major spiral arms of M31 with particular attention given to the data reduction and the analysis of the [SII]/H{alpha} flux ratios. A diffuse ionized gas noted in the images is analyzed which shows higher [SII]/H{alpha} ratios, and 967 discrete nebulae are listed with gray-scale images, finding charts, and absolute fluxes. The differential H-alpha luminosity function is found to have a slope of -0.95 for brighter objects and flattens out below a critical level. The curve is shown to correspond to the point at which single-star ionization accounts for the H{alpha} luminosities and is consistent with previous observations. The catalog of objects and fluxes is the largest existing sample of this type, and the unresolved objects in the sample are considered to be planetary nebulae.
- ID:
- ivo://CDS.VizieR/J/ApJ/510/104
- Title:
- Ionizing Stars of Extragalactic H II Regions
- Short Name:
- J/ApJ/510/104
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Medium-resolution spectra from 3650 to 10000 {AA} are presented for 96 giant H II regions distributed in 20 spiral galaxies. In order to interpret the data, we have calculated two separate grids of photoionization models, adopting single-star atmospheres (Kurucz) and star clusters synthesized with different initial mass functions (IMFs) as ionizing sources. Additional models were computed with more recent non-LTE stellar atmospheres, in order to check the effects of different stellar ionizing fluxes. We use the radiation softness parameter {eta}'=([O II]/[O III])/([S II]/[S III]) of Vilchez & Pagel (1988MNRAS.231..257V) to test for a metallicity dependence of the effective temperatures of the ionizing stars. Our results are consistent with a significant decrease in mean stellar temperatures of the ionizing stars with increasing metallicity. The magnitude of the effect, combined with the behavior of the He I {lambda}5876/H{beta} ratio, suggest a smaller upper mass limit for star formation at abundances higher than solar, even when considering the effects of metallicity on stellar evolution and atmospheric line blanketing. However, the exact magnitudes of the stellar temperature and IMF variations are dependent on the choice of stellar atmosphere and evolution models used, as well as on uncertainties in the nebular abundance scale at high metallicities. Our results also constrain the systematic behavior of the ionization parameter and the N/O ratio in extragalactic H II regions. The observed spectral sequences are inconsistent with current stellar evolution models, which predict a luminous, hot W-R stellar population in evolved H II regions older than 2-3 Myr. This suggests either that the hardness of the emitted Lyman continuum spectrum has been overestimated in the models or that some mechanism disrupts the H II regions before the W-R phases become important.
- ID:
- ivo://CDS.VizieR/J/AJ/159/216
- Title:
- Ions density in the CGM of low mass galaxy groups
- Short Name:
- J/AJ/159/216
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We explore how environment affects the metallicity of the circumgalactic medium (CGM) using 13 low-mass galaxy groups (two to five galaxies) at <z_abs_>=0.25 identified near background quasars. Using quasar spectra from the Hubble Space Telescope/Cosmic Origins Spectrograph (HST/COS) and from Keck/High Resolution Echelle Spectrometer (Keck/HIRES) or the Very Large Telescope/Ultraviolet and Visual Echelle Spectrograph (VLT/UVES), we measure column densities of or determine limits on CGM absorption lines. We use a Markov Chain Monte Carlo approach with Cloudy to estimate metallicities of cool (T~104K) CGM gas within groups and compare them to CGM metallicities of 47 isolated galaxies. Both group and isolated CGM metallicities span a wide range (-2<[Si/H]<0), where the mean group (-0.54{pm}0.22) and isolated (-0.77{pm}0.14) CGM metallicities are similar. Group and isolated environments have similar distributions of HI column densities as a function of impact parameter. However, contrary to isolated galaxies, we do not find an anticorrelation between HI column density and the nearest group galaxy impact parameter. We additionally divided the groups by member luminosity ratios (i.e., galaxy-galaxy and galaxy-dwarf groups). While there was no significant difference in their mean metallicities, a modest increase in sample size should allow one to statistically identify a higher CGM metallicity in galaxy-dwarf groups compared to galaxy-galaxy groups. We conclude that either environmental effects have not played an important role in the metallicity of the CGM at this stage and expect that this may only occur when galaxies are strongly interacting or merging or that some isolated galaxies have higher CGM metallicities due to past interactions. Thus, environment does not seem to be the cause of the CGM metallicity bimodality.
- ID:
- ivo://CDS.VizieR/J/ApJ/591/53
- Title:
- I photometry of Cl 0024+16
- Short Name:
- J/ApJ/591/53
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We describe a new wide-field Hubble Space Telescope survey of the galaxy cluster Cl 0024+16 (z~0.4) consisting of a sparsely sampled mosaic of 39 Wide Field Planetary Camera 2 images that extends to a cluster radius of ~5Mpc. Together with extensive ground-based spectroscopy taken from the literature, augmented with over a hundred newly determined redshifts, this unique data set enables us to examine environmental influences on the properties of cluster members from the inner core to well beyond the virial radius (~1.7Mpc). We catalog photometric measures for 22000 objects to I>~25 and assign morphological types for 2181 to I=22.5, of which 195 are spectroscopically confirmed cluster members.
- ID:
- ivo://CDS.VizieR/J/AJ/116/2728
- Title:
- I photometry of early-type galaxies
- Short Name:
- J/AJ/116/2728
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- As part of a project to compare the fundamental plane and Tully-Fisher distance scales, we present here I-band CCD photometry for 636 early-type galaxies in eight clusters and groups of galaxies. These are the A262, A1367, Coma (A1656), A2634, Cancer and Pegasus Clusters, and the NGC 383 and NGC 507 Groups. Sample selection, cluster properties, and cluster membership assignment criteria are discussed. We present photometric parameters that are used in the fundamental plane relation, the effective radius r_e_, and the effective surface brightness {mu}_e_, as derived from a r^1/4^ fit to the observed radial photometric profile of each galaxy. A comparison with similar data found in the literature for the Coma Cluster shows that large systematic uncertainties can be introduced in the measurement of r_e_ and {mu}_e_ by the particular method used to derive those parameters. However, the particular combination of these two parameters that enters in the fundamental plane relation is a quantity that can be measured with high accuracy.
- ID:
- ivo://CDS.VizieR/J/AJ/132/2159
- Title:
- IRAC counterparts of 6cm galaxies in EGS
- Short Name:
- J/AJ/132/2159
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- A new 6cm survey of almost 0.6deg^2^ to a limit of 0.55mJy/beam (10sigma) finds 37 isolated radio sources and seven radio-source pairs (not necessarily physical companions). Infrared Array Camera (IRAC) counterparts are identified for at least 92% of the radio sources within the area of deep IRAC coverage, which includes 31 isolated sources and six pairs. This contrasts with an identification rate of <74% to R<23.95 in visible light. Eight of the IRAC galaxies have power-law spectral energy distributions, implying that the mid-infrared emission comes from a powerful active galactic nucleus (AGN). The remaining 26 IRAC galaxies show stellar emission in the mid-infrared, probably in most of these galaxies because the stellar emission is bright enough to outshine an underlying AGN.
- ID:
- ivo://CDS.VizieR/J/MNRAS/472/4259
- Title:
- IRAC Dark Field, ELAIS-N1 and ADF-S galaxies
- Short Name:
- J/MNRAS/472/4259
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the first detailed analysis of three extragalactic fields (IRAC Dark Field, ELAIS-N1, ADF-S) observed by the infrared satellite, AKARI, using an optimised data analysis toolkit specifically for the processing of extragalactic point sources. The InfaRed Camera (IRC) on AKARI complements the Spitzer space telescope via its comprehensive coverage between 8-24{mu}m filling the gap between the Spitzer IRAC and MIPS instruments.
- ID:
- ivo://CDS.VizieR/J/ApJ/642/158
- Title:
- IRAC flux densities in IC2163 and NGC2207
- Short Name:
- J/ApJ/642/158
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- IC 2163 and NGC 2207 are interacting galaxies that have been well studied at optical and radio wavelengths and simulated in numerical models to reproduce the observed kinematics and morphological features. Spitzer IRAC and MIPS observations reported here show over 200 bright clumps from young star complexes. The brightest IR clump is a morphologically peculiar region of star formation in the western arm of NGC 2207. This clump, which dominates the H{alpha} and radio continuum emission from both galaxies, accounts for ~12% of the total 24{mu}m flux. Nearly half of the clumps are regularly spaced along some filamentary structure, whether in the starburst oval of IC 2163 or in the thin spiral arms of NGC 2207.
1810. IRAC/MUSYC SIMPLE survey
- ID:
- ivo://CDS.VizieR/J/ApJ/727/1
- Title:
- IRAC/MUSYC SIMPLE survey
- Short Name:
- J/ApJ/727/1
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the Spitzer IRAC/MUSYC Public Legacy Survey in the Extended CDF-South (SIMPLE), which consists of deep IRAC observations covering the ~1600arcmin^2^ area surrounding GOODS-S. The limiting magnitudes of the SIMPLE IRAC mosaics typically are 23.8, 23.6, 21.9, and 21.7, at 3.6um, 4.5um, 5.8um, and 8.0um, respectively (5{sigma} total point source magnitudes in AB). The SIMPLE IRAC images are combined with the 10'x15' GOODS IRAC mosaics in the center. We give detailed descriptions of the observations, data reduction, and properties of the final images, as well as the detection and photometry methods used to build a catalog. Using published optical and near-infrared data from the Multiwavelength Survey by Yale-Chile (MUSYC), we construct an IRAC-selected catalog, containing photometry in UBVRIz'JHK, [3.6um], [4.5um], [5.8um], and [8.0um]. The catalog contains 43,782 sources with S/N>5 at 3.6um, 19,993 of which have 13-band photometry. We compare this catalog to the publicly available MUSYC and FIREWORKS catalogs and discuss the differences. Using a high signal-to-noise sub-sample of 3391 sources with ([3.6]+[4.5])/2<21.2, we investigate the star formation rate history of massive galaxies out to z~1.8. We find that at z~1.8 at least 30+/-7% of the most massive galaxies (M*>10^11^M_{sun}_) are passively evolving, in agreement with earlier results from surveys covering less area.
