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1251. Ionizing Stars of Extragalactic H II Regions
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.
1252. Ions density in the CGM of low mass galaxy groups
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.
1253. IPHAS DR2 Source Catalogue
ID:
ivo://CDS.VizieR/II/321
Title:
IPHAS DR2 Source Catalogue
Short Name:
II/321
Date:
21 Oct 2021
Publisher:
CDS
Description:
The INT/WFC Photometric H-Alpha Survey of the Northern Galactic Plane (IPHAS) is a 1860 deg^2^ imaging survey of the Northern Milky Way at red visible wavelengths. It covers Galactic latitudes |b|<5{deg} and longitudes l=30 to 215{deg} in the broad-band r, i and narrow-band H-alpha filters using the Wide Field Camera (WFC) on the 2.5-m Isaac Newton Telescope (INT) in La Palma. IPHAS Data Release 2 (DR2) is the first quality-controlled and globally calibrated source catalogue derived from the survey, providing single-epoch photometry for 219 million unique sources across 92% of the footprint. The observations were carried out between 2003 and 2012 at a median seeing of 1.1 arcsec (sampled at 0.33 arcsec/pixel) and to a mean 5-sigma depth of 21.2 (r), 20.0 (i) and 20.3 (H-alpha). The photometric calibration is in the Vega magnitude system and carries an external precision of 0.03mag (root-mean-square error). The catalogue includes all the sources which have been detected at a signal-to-noise ratio of 5 or better in at least one band. Many applications will require a combination of quality criteria to be applied to avoid faint stars or confused sources. The choice of quality criteria tensions completeness against reliability, and hence depends on the requirements of a project. To aid users, the data release paper (arXiv:1406.4862) recommends two sets of quality criteria, named "a10" and "a10point", which should satisfy most projects. As a minimum, the "a10" criteria select objects which have been detected at the minimum level of 10-sigma in all bands, without being saturated. Additional constraints are provided by the "a10point" criteria, which require objects to be point sources free of blending, unaffected by nearby bright stars, as well as being unsaturated >10-sigma detections in all bands. Sources in both categories are flagged in the catalogue using the boolean columns a10 and a10point. Imaging and auxiliary data are available from the project website (www.iphas.org).
1254. IPHAS T Tauri candidates in IC 1396
ID:
ivo://CDS.VizieR/J/MNRAS/415/103
Title:
IPHAS T Tauri candidates in IC 1396
Short Name:
J/MNRAS/415/103
Date:
21 Oct 2021
Publisher:
CDS
Description:
The Isaac Newton Telescope (INT) Photometric H-Alpha Survey (IPHAS) is a 1800deg^2^ survey of the Northern Galactic Plane, reaching down to r'~21. We demonstrate how the survey can be used to (1) reliably select classical T Tauri star candidates and (2) constrain the mass accretion rates with an estimated relative uncertainty of 0.6dex. IPHAS is a necessary addition to spectroscopic surveys because it allows large and uniform samples of accretion rates to be obtained with a precise handle on the selection effects. We apply the method on a region of 7deg^2^ towards the HII region IC 1396 in Cepheus OB2 and identify 158 pre-main-sequence candidates with masses between 0.2 and 2.0M_{sun}_ and accretion rates between 10-9.2 and 10-7.0M_{sun}_/yr.
1255. IRAC Dark Field, ELAIS-N1 and ADF-S galaxies
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.
1256. IRAC identifications for 510 AEGIS20 radio sources
ID:
ivo://CDS.VizieR/J/ApJ/756/72
Title:
IRAC identifications for 510 AEGIS20 radio sources
Short Name:
J/ApJ/756/72
Date:
21 Oct 2021
Publisher:
CDS
Description:
Infrared 3.6-8{mu}m images of the Extended Groth Strip yield plausible counterpart identifications for all but one of 510 radio sources in the AEGIS20 S(1.4GHz)>50{mu}Jy sample. This is the first such deep sample that has been effectively 100% identified. Achieving the same identification rate at R band would require observations reaching R_AB_>27. Spectroscopic redshifts are available for 46% of the sample and photometric redshifts for an additional 47%. Almost all of the sources with 3.6{mu}m AB magnitudes brighter than 19 have spectroscopic redshifts z<1.1, while fainter objects predominantly have photometric redshifts with 1<~z<~3. Unlike more powerful radio sources that are hosted by galaxies having large stellar masses within a relatively narrow range, the AEGIS20 counterparts have stellar masses spanning more than a factor of 10 at z~1. The sources are roughly 10%-15% starbursts at z<~0.5 and 20%-25% active galactic nuclei mostly at z>1 with the remainder of uncertain nature.
1257. 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.
1258. IRAS Observations of Large Optical Galaxies
ID:
ivo://CDS.VizieR/VII/109
Title:
IRAS Observations of Large Optical Galaxies
Short Name:
VII/109
Date:
21 Oct 2021
Publisher:
CDS
Description:
The catalogue reports the observations of 85 galaxies listed in RC2 with apparent blue light isophotal diameters (D25) greater than 8'; there are 83 corresponding maps (NGC 205 and M31 are in one field as are M81 and M82) listed in file "summary". The surface brightness maps have been written to tape in FITS format, as 83 sets of maps, each set consisting of an image and a noise map for each of the four IRAS wavelength bands, leading to 664 FITS images.
1259. IR-bright DOGs viewed with Subaru HSC
ID:
ivo://CDS.VizieR/J/ApJ/876/132
Title:
IR-bright DOGs viewed with Subaru HSC
Short Name:
J/ApJ/876/132
Date:
21 Oct 2021
Publisher:
CDS
Description:
We report on the optical properties of infrared (IR)-bright dust-obscured galaxies (DOGs) that are defined as (i-[22])_AB_>=7.0. Because supermassive black holes (SMBHs) in IR-bright DOGs are expected to be rapidly growing in the major-merger scenario, they provide useful clues for understanding the coevolution of SMBHs and their host galaxies. However, the optical properties of IR-bright DOGs remain unclear because the optical emission of a DOG is very faint. By combining ~105deg^2^ images of the optical, near-IR, and mid-IR data obtained from the Subaru Hyper Suprime-Cam (HSC) survey, the VISTA VIKING survey, and the Wide-field Infrared Survey Explorer all-sky survey, respectively, 571 IR-bright DOGs were selected. We found that IR-bright DOGs show a redder (g-z)_AB_ color than do other populations of dusty galaxies, such as ultraluminous IR galaxies (ULIRGs) at a similar redshift, with a significantly large dispersion. Among the selected DOGs, star formation (SF)-dominated DOGs show a relatively red color, while active galactic nucleus (AGN)-dominated DOGs show a rather blue color in optical. This result is consistent with the idea that the relative AGN contribution in the optical emission becomes more significant at a later stage in the major-merger scenario. We discovered eight IR-bright DOGs showing a significant blue excess in blue HSC bands. This blue excess can be interpreted as a leaked AGN emission that is either a directly leaking or a scattered AGN emission, as proposed for some blue-excess Hot DOGs in earlier studies.
1260. IR-bright MSX sources in the SMC with Spitzer/IRS
ID:
ivo://CDS.VizieR/J/ApJ/834/185
Title:
IR-bright MSX sources in the SMC with Spitzer/IRS
Short Name:
J/ApJ/834/185
Date:
21 Oct 2021
Publisher:
CDS
Description:
We have used the Infrared Spectrograph (IRS) on the Spitzer Space Telescope to observe stars in the Small Magellanic Cloud (SMC) selected from the Point Source Catalog of the Midcourse Space Experiment (MSX). We concentrate on the dust properties of the oxygen-rich evolved stars. The dust composition has smaller contributions from alumina compared to the Galaxy. This difference may arise from the lower metallicity in the SMC, but it could be a selection effect, as the SMC sample includes more stars that are brighter and thus more massive. The distribution of the SMC stars along the silicate sequence looks more like the Galactic sample of red supergiants than asymptotic giant branch stars (AGBs). While many of the SMC stars are definitively on the AGB, several also show evidence of hot bottom burning. Three of the supergiants show PAH emission at 11.3{mu}m. Two other sources show mixed chemistry, with both carbon-rich and oxygen-rich spectral features. One, MSX SMC 134, may be the first confirmed silicate/carbon star in the SMC. The other, MSX SMC 049, is a candidate post-AGB star. MSX SMC 145, previously considered a candidate OH/IR star, is actually an AGB star with a background galaxy at z=0.16 along the same line of sight. We consider the overall characteristics of all the MSX sources, the most infrared-bright objects in the SMC, in light of the higher sensitivity and resolution of Spitzer, and compare them with the object types expected from the original selection criteria. This population represents what will be seen in more distant galaxies by the upcoming James Webb Space Telescope (JWST). Color-color diagrams generated from the IRS spectra and the mid-infrared filters on JWST show how one can separate evolved stars from young stellar objects (YSOs) and distinguish among different classes of YSOs.