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861. Obscured AGN at z~0.5-1 in the CDFS
ID:
ivo://CDS.VizieR/J/ApJ/740/37
Title:
Obscured AGN at z~0.5-1 in the CDFS
Short Name:
J/ApJ/740/37
Date:
21 Oct 2021
Publisher:
CDS
Description:
We identify a numerically significant population of heavily obscured AGNs at z~0.5-1 in the Chandra Deep Field-South (CDF-S) and Extended Chandra Deep Field-South by selecting 242 X-ray undetected objects with infrared-based star-formation rates (SFRs) substantially higher (a factor of 3.2 or more) than their SFRs determined from the UV after correcting for dust extinction. An X-ray stacking analysis of 23 candidates in the central CDF-S region using the 4Ms Chandra data reveals a hard X-ray signal with an effective power-law photon index of {Gamma}=0.6^+0.3^_-0.4_, indicating a significant contribution from obscured AGNs. Based on Monte Carlo simulations, we conclude that 74%+/-25% of the selected galaxies host obscured AGNs, within which ~95% are heavily obscured and ~80% are Compton-thick (CT; N_H_>1.5x10^24^cm^-2^).
862. Obscured AGNs in XMM deep survey in CDF-S
ID:
ivo://CDS.VizieR/J/A+A/556/A114
Title:
Obscured AGNs in XMM deep survey in CDF-S
Short Name:
J/A+A/556/A114
Date:
21 Oct 2021
Publisher:
CDS
Description:
Accretion onto supermassive black holes is believed to occur mostly in obscured active galactic nuclei (AGN). Such objects are proving rather elusive in surveys of distant galaxies, including those at X-ray energies. Our main goal is to determine whether the revised IRAC criteria of Donley et al. (2012ApJ...748..142D; objects with an infrared (IR) power-law spectral shape), are effective at selecting X-ray type-2 AGN (i.e., absorbed N_H_>10^22^cm^-2^). We present the results from the X-ray spectral analysis of 147 AGN selected by cross-correlating the highest spectral quality ultra-deep XMM-Newton and the Spitzer/IRAC catalogues in the Chandra Deep Field South. Consequently it is biased towards sources with high S/N X-ray spectra. In order to measure the amount of intrinsic absorption in these sources, we adopt a simple X-ray spectral model that includes a power-law modified by intrinsic absorption at the redshift of each source and a possible soft X-ray component.
863. Observation of Ser FIRS 1 at 230GHz
ID:
ivo://CDS.VizieR/J/ApJ/707/103
Title:
Observation of Ser FIRS 1 at 230GHz
Short Name:
J/ApJ/707/103
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present the first results of a program to characterize the disk and envelope structure of typical Class 0 protostars in nearby low-mass star-forming regions. We use Spitzer Infrared Spectrograph (IRS) mid-infrared spectra, high-resolution Combined Array for Research in Millimeter-wave Astronomy (CARMA) 230GHz continuum imaging, and two-dimensional radiative transfer models to constrain the envelope structure, as well as the size and mass of the circumprotostellar disk in Serpens FIRS 1. The primary envelope parameters (centrifugal radius, outer radius, outflow opening angle, and inclination) are well constrained by the spectral energy distribution (SED), including Spitzer IRAC and MIPS photometry, IRS spectra, and 1.1mm Bolocam photometry. These together with the excellent uv-coverage (4.5-500k{lambda}) of multiple antenna configurations with CARMA allow for a robust separation of the envelope and a resolved disk. The SED of Serpens FIRS 1 is best fit by an envelope with the density profile of a rotating, collapsing spheroid with an inner (centrifugal) radius of approximately 600AU, and the millimeter data by a large resolved disk with M_disk_~1.0M_{sun}_ and R_disk_~300AU.
864. Observations of SiO masers
ID:
ivo://CDS.VizieR/J/ApJ/669/446
Title:
Observations of SiO masers
Short Name:
J/ApJ/669/446
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present the results of SiO millimeter line observations of a sample of known SiO maser sources covering a wide dust temperature range. A cold part of the sample was selected from the SiO maser sources found in our recent SiO maser survey of cold dusty objects. The aim of the present research is to investigate the causes of the correlation between infrared colors and SiO maser intensity ratios among different transition lines. In particular, the correlation between infrared colors and SiO maser intensity ratio among the J=1-0 v=1, 2, and 3 lines are our main concern in this paper. We observed in total 75 SiO maser sources with the Nobeyama 45m telescope quasi-simultaneously in the SiO J=1-0 v=0, 1, 2, 3, 4 and J=2-1 v=1, 2 lines. We also observed the sample in the ^29^SiO J=1-0 v=0 and J=2-1 v=0 lines, ^30^SiO J=1-0 v=0 line, and the H_2_O 61,6-52,3 line.
865. Observed red supergiants in the inner Galaxy
ID:
ivo://CDS.VizieR/J/ApJ/822/L5
Title:
Observed red supergiants in the inner Galaxy
Short Name:
J/ApJ/822/L5
Date:
21 Oct 2021
Publisher:
CDS
Description:
In this Letter, we present a search for Galactic red supergiant stars (RSGs) in the direction of the inner Galaxy. A total of 94 targets selected from the 2MASS (Cat. VII/233) and GLIMPSE I North (Benjamin et al. 2003, Cat. II/293; Churchwell et al. 2009PASP..121..213C) catalogs - via their blue extinction-free Q1 and Q2 colors - were spectroscopically observed at infrared wavelengths (in the H- and K-bands at R~1000), and an extraordinary high detection rate of RSGs (>61%) was found. We identified spectroscopically 58 RSGs, based on their flat continua and large equivalent widths of the CO-band at 2.293 {mu}m (EW>45 {AA}). This increase corresponds to about 25% of previously known RSGs in the Galactic region 10{deg}<l<60{deg}, -1.1{deg}<b<1.1{deg}. In order to confirm the location of the new RSGs in the inner Galaxy, distances were estimated for a subsample of 47 stars with the clump method and found to range from 3.6+/-0.4 to 8.6+/-0.7 kpc. The large new sample will allow us to investigate Galactic metallicity gradients as a function of galactocentric distances and azimuthal angles. Such information is currently an highly disputed issue to constrain models of Galaxy formation and evolution.
866. OB stars extinction based in IR photometry
ID:
ivo://CDS.VizieR/J/AcA/43/209
Title:
OB stars extinction based in IR photometry
Short Name:
J/AcA/43/209
Date:
21 Oct 2021
Publisher:
CDS
Description:
The paper presents an extensive survey of interstellar extinction curves derived from the near IR photometric measurements of early type stars belonging to our Galaxy. This survey is more extensive and deeper than any other one, based on spectral data. The IR magnitudes of about 500 O and B type stars with E(B-V)>=0.05 were selected from literature. The IR color excesses are determined with the aid of "artificial standards". The results indicate that the extinction law changes from place to place. The mean galactic extinction curve in the near IR is very similar in different directions and changes very little from the value R=3.10+/-0.05 obtained in this paper.
867. OCCAM. IV. Open cluster abundances using APOGEE DR16
ID:
ivo://CDS.VizieR/J/AJ/159/199
Title:
OCCAM. IV. Open cluster abundances using APOGEE DR16
Short Name:
J/AJ/159/199
Date:
21 Oct 2021
Publisher:
CDS
Description:
The Open Cluster Chemical Abundances and Mapping (OCCAM) survey aims to constrain key Galactic dynamical and chemical evolution parameters by the construction of a large, comprehensive, uniform, infrared-based spectroscopic data set of hundreds of open clusters. This fourth contribution from the OCCAM survey presents analysis using Sloan Digital Sky Survey/APOGEE DR16 of a sample of 128 open clusters, 71 of which we designate to be "high quality" based on the appearance of their color-magnitude diagram. We find the APOGEE DR16 derived [Fe/H] abundances to be in good agreement with previous high-resolution spectroscopic open cluster abundance studies. Using the high-quality sample, we measure Galactic abundance gradients in 16 elements, and find evolution of some of the [X/Fe] gradients as a function of age. We find an overall Galactic [Fe/H] versus Rgc gradient of -0.068{+-}0.001dex/kpc over the range of 6<Rgc<13.9kpc; however, we note that this result is sensitive to the distance catalog used, varying as much as 15%. We formally derive the location of a break in the [Fe/H] abundance gradient as a free parameter in the gradient fit for the first time. We also measure significant Galactic gradients in O, Mg, S, Ca, Mn, Cr, Cu, Na, Al, and K, some of which are measured for the first time. Our large sample allows us to examine four well-populated age bins in order to explore the time evolution of gradients for a large number of elements and comment on possible implications for Galactic chemical evolution and radial migration.
868. OH maser emission from IRAS sources
ID:
ivo://CDS.VizieR/J/A+A/327/755
Title:
OH maser emission from IRAS sources
Short Name:
J/A+A/327/755
Date:
21 Oct 2021
Publisher:
CDS
Description:
A high-sensitivity search for water maser emission at 22.2 GHz has been performed on a sample of 91 IRAS point sources at high-latitudes. The aim of the survey is to verify if these clouds are capable of star formation as indicated by the presence of water masers. The sample is based on the recent work of Magnani et al. (1995ApJS...96..159M) who have identified 192 infrared objects from the IRAS Faint Source Survey possibly associated with translucent clouds at galactic latitudes |b|>=30{deg}. These IRAS sources have far-infrared colours typical of young stellar objects and pre-main-sequence stars and thus provide a starting list for further studies about their actual nature. H_2_O maser emission is a good diagnostic of the presence of dense gas and of recent star formation. We did not find water maser emission at a level of 0.2-0.5Jy (3{sigma}) in any of the 91 objects. The negative result indicates that these high-latitude sources do not represent potential sites of star formation, consistent with the fact that most high-latitude molecular clouds do not appear gravitationally bound.
869. OH maser IRAS and MSX observations
ID:
ivo://CDS.VizieR/J/ApJS/155/595
Title:
OH maser IRAS and MSX observations
Short Name:
J/ApJS/155/595
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present OH maser observations at 1612, 1665, 1667, and 1720MHz for 86 likely post-asymptotic giant branch (post-AGB) stars selected from a survey of 1612MHz maser sources in the Galactic plane. The observations were taken with the Parkes Telescope and the Australia Telescope Compact Array between 2002 September and 2003 August. We redetected all 86 sources at 1612MHz, while 27 sources were detected at 1665MHz and 45 at 1667MHz. One source was redetected at 1720MHz. We present a classification scheme for the maser profiles and show that 25% of sources in our sample are likely to have asymmetric or bipolar outflows.
870. OH megamasers at z>0.1. III
ID:
ivo://CDS.VizieR/J/AJ/124/100
Title:
OH megamasers at z>0.1. III
Short Name:
J/AJ/124/100
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present the final results from the Arecibo Observatory OH megamaser survey. We discuss in detail the properties of the remaining 18 OH megamasers detected in the survey, including three redetections. We place upper limits on the OH emission from 85 nondetections and examine the properties of 25 ambiguous cases for which the presence or absence of OH emission could not be determined. The complete survey has discovered 50 new OH megamasers (OHMs) in (ultra)luminous infrared galaxies ([U]LIRGs), which doubles the sample of known OHMs and increases the sample at z>0.1 sevenfold.