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17791. X-ray & MIR AGNs in Stripe 82 with eBOSS spectra
ID:
ivo://CDS.VizieR/J/ApJ/876/50
Title:
X-ray & MIR AGNs in Stripe 82 with eBOSS spectra
Short Name:
J/ApJ/876/50
Date:
21 Oct 2021
Publisher:
CDS
Description:
We report the results of a Sloan Digital Sky Survey IV eBOSS program to target X-ray sources and mid-infrared-selected Wide-field Infrared Survey Explorer (WISE) active galactic nucleus (AGN) candidates in a 36.8deg^2^ region of Stripe 82. About half this survey (15.6deg^2^) covers the largest contiguous portion of the Stripe 82 X-ray survey. This program represents the largest spectroscopic survey of AGN candidates selected solely by their WISE colors. We combine this sample with X-ray and WISE AGNs in the field identified via other sources of spectroscopy, producing a catalog of 4847 sources that is 82% complete to r~22. Based on X-ray luminosities or WISE colors, 4730 of these sources are AGNs, with a median sample redshift of z~1. About 30% of the AGNs are optically obscured (i.e., lack broad lines in their optical spectra). BPT analysis, however, indicates that 50% of the WISE AGNs at z<0.5 have emission line ratios consistent with star-forming galaxies, so whether they are buried AGNs or star-forming galaxy contaminants is currently unclear. We find that 61% of X-ray AGNs are not selected as mid-infrared AGNs, with 22% of X-ray AGNs undetected by WISE. Most of these latter AGNs have high X-ray luminosities (Lx>10^44^erg/s), indicating that mid-infrared selection misses a sizable fraction of the highest luminosity AGNs, as well as lower luminosity sources where AGN-heated dust is not dominating the mid-infrared emission. Conversely, ~58% of WISE AGNs are undetected by X-rays, though we do not find that they are preferentially redder than the X-ray-detected WISE AGNs.
17792. X-ray & MIR luminosities of the GBT galaxies
ID:
ivo://CDS.VizieR/J/ApJ/892/18
Title:
X-ray & MIR luminosities of the GBT galaxies
Short Name:
J/ApJ/892/18
Date:
19 Jan 2022 08:55:44
Publisher:
CDS
Description:
We present an investigation of the dependence of H_2_O maser detection rates and properties on the mid-IR active galactic nucleus (AGN) luminosity, L_AGN_, and the obscuring column density, N_H_, based on mid-IR and hard X-ray photometry. Based on spectral energy distribution fitting that allows for decomposition of the black hole accretion and star formation components in the mid-infrared, we show that the megamaser (disk maser) detection rate increases sharply for galaxies with 12{mu}m AGN luminosity L_12um_^AGN^ greater than 10^42^erg/s, from <~3% (<~2%) to ~12% (~5%). By using the ratio of the observed X-ray to mid-IR AGN luminosity as an indicator of N_H_, we also find that megamaser (disk maser) detection rates are boosted to 15% (7%) and 20% (9%) for galaxies with N_H_>=10^23^/cm^2^ and N_H_>=10^24^cm^-2^, respectively. Combining these column density cuts with a constraint for high L_12um_^AGN^ (>=10^42^erg/s) predicts further increases in the megamaser (disk maser) detection rates to 19% (8%) and 27% (14%), revealing unprecedented potential increases of the megamaser and disk maser detection rates by a factor of 7-15 relative to the current rates, depending on the chosen sample selection criteria. A noteworthy aspect of these new predictions is that the completeness rates are only compromised mildly, with the rates remaining at the level of ~95% (~50%) for sources with N_H_>=10^23^/cm^2^ (N_H_>=10^24^/cm^2^). Applying these selection methods to current X-ray AGN surveys predicts the detection of >~15 new megamaser disks.
17793. X-ray monitoring of M31 novae
ID:
ivo://CDS.VizieR/J/A+A/533/A52
Title:
X-ray monitoring of M31 novae
Short Name:
J/A+A/533/A52
Date:
21 Oct 2021
Publisher:
CDS
Description:
Context. Classical novae (CNe) represent the major class of supersoft X-ray sources (SSSs) in the central region of the galaxy M31. We performed a dedicated monitoring of the M31 central region with XMM-Newton and Chandra between Nov 2007 and Feb 2008 and between Nov 2008 and Feb 2009, respectively, to find SSS counterparts of CNe, determine the duration of their SSS phase, and derive physical outburst parameters. We systematically searched our data for X-ray counterparts of CNe, determined their X-ray light curves and characterised their spectra using blackbody fits and white dwarf (WD) atmosphere models. Additionally, we determined luminosity upper limits for all previously known X-ray emitting novae that are not detected any more and for all CNe in our field of view with optical outbursts between one year before the start of the X-ray monitoring (Oct 2006) and its end (Feb 2009).
17794. X-ray monitoring of M31 novae
ID:
ivo://CDS.VizieR/J/A+A/563/A2
Title:
X-ray monitoring of M31 novae
Short Name:
J/A+A/563/A2
Date:
21 Oct 2021
Publisher:
CDS
Description:
Classical novae (CNe) represent the major class of supersoft X-ray sources (SSSs) in the central region of our neighbouring galaxy M 31. We performed a dedicated monitoring of the M 31 central region, which aimed to detect SSS counterparts of CNe, with XMM-Newton and Chandra between Nov and Mar of the years 2009/10, 2010/11, and 2011/12. We systematically searched our data for X-ray counterparts of CNe and determined their X-ray light curves and also their spectral properties in the case of XMM-Newton data. Additionally, we determined luminosity upper limits for all previously known X-ray emitting novae, which are not detected anymore, and for all CNe in our field of view with recent optical outbursts.
17795. X-ray monitoring of optical novae in M31
ID:
ivo://CDS.VizieR/J/A+A/465/375
Title:
X-ray monitoring of optical novae in M31
Short Name:
J/A+A/465/375
Date:
21 Oct 2021
Publisher:
CDS
Description:
Optical novae have recently been identified as the major class of supersoft X-ray sources in M 31 based on ROSAT and early XMM-Newton and Chandra observations. This paper reports on a search for X-ray counterparts of optical novae in M 31 based on archival Chandra HRC-I and ACIS-I as well as XMM-Newton observations of the galaxy center region obtained from July 2004 to February 2005. We systematically determine X-ray brightness or upper limit for counterparts of all known optical novae with outbursts between November 2003 to the end of the X-ray coverage. In addition, we determine the X-ray brightnesses for counterparts of four novae with earlier outbursts. For comparison with the X-ray data we created a catalogue of optical novae in M 31 based on our own nova search programs and on all novae reported in the literature. We collected all known properties and named the novae consistently following the CBAT scheme. We detect eleven out of 34 novae within a year after the optical outburst in X-rays. While for eleven novae we detect the end of the supersoft source phase, seven novae are still bright more than 1200, 1600, 1950, 2650, 3100, 3370 and 3380d after outburst. One nova is detected to turn on 50d, another 200d after outburst. Three novae unexpectedly showed short X-ray outbursts starting within 50d after the optical outburst and lasting only two to three months. The X-ray emission of several of the novae can be characterized as supersoft from hardness ratios and/or X-ray spectra or by comparing HRC-I count rates with ACIS-I count rates or upper limits. The number of detected optical novae at supersoft X-rays is much higher than previously estimated (>30%). We use the X-ray light curves to estimate the burned masses of the White Dwarf and of the ejecta.
17796. X-ray/NIR correlation for early-type galaxies
ID:
ivo://CDS.VizieR/J/MNRAS/367/627
Title:
X-ray/NIR correlation for early-type galaxies
Short Name:
J/MNRAS/367/627
Date:
21 Oct 2021
Publisher:
CDS
Description:
The relation between X-ray luminosity and near-infrared (NIR) luminosity for early-type galaxies has been examined. NIR luminosities should provide a superior measure of stellar mass compared to optical luminosities used in previous studies, especially if there is significant star formation or dust present in the galaxies. However, we show that the X-ray-NIR relations are remarkably consistent with the X-ray-optical relations. This indicates that the large scatter of the relations is dominated by scatter in the X-ray properties of early-type galaxies, and is consistent with early-types consisting of old, quiescent stellar populations. We have investigated scatter in terms of environment, surface brightness profile, Mg2, H{beta}, H{gamma} line strength indices, spectroscopic age and nuclear H{alpha} emission.
17797. X-ray obs. and membership probabilities of M37
ID:
ivo://CDS.VizieR/J/ApJ/809/161
Title:
X-ray obs. and membership probabilities of M37
Short Name:
J/ApJ/809/161
Date:
21 Oct 2021
Publisher:
CDS
Description:
Empirical calibrations of the stellar age-rotation-activity relation (ARAR) rely on observations of the co-eval populations of stars in open clusters. We used the Chandra X-ray Observatory to study M37, a 500-Myr-old open cluster that has been extensively surveyed for rotation periods (P_rot_). M37 was observed almost continuously for five days, for a total of 440.5ks, to measure stellar X-ray luminosities (L_X_), a proxy for coronal activity, across a wide range of masses. The cluster's membership catalog was revisited to calculate updated membership probabilities from photometric data and each star's distance to the cluster center. The result is a comprehensive sample of 1699 M37 members: 426 with P_rot_, 278 with X-ray detections, and 76 with both. We calculate Rossby numbers, R_0_=P_rot_/{tau}, where {tau} is the convective turnover time, and ratios of the X-ray-to-bolometric luminosity, L_X_/L_bol_, to minimize mass dependencies in our characterization of the rotation-coronal activity relation at 500Myr. We find that fast rotators, for which R_0_<0.09+/-0.01, show saturated levels of activity, with log(L_X_/L_bol_)=-3.06+/-0.04. For R_0_>=0.09+/-0.01, activity is unsaturated and follows a power law of the form R_0_^{beta}^, where {beta}=-2.03^+0.17^_-1.14_. This is the largest sample available for analyzing the dependence of coronal emission on rotation for a single-aged population, covering stellar masses in the range 0.4-1.3M_{sun}_, P_rot_ in the range 0.4-12.8 days, and L_X_ in the range 10^28.4-30.5^erg/s. Our results make M37 a new benchmark open cluster for calibrating the ARAR at ages of ~500Myr.
17798. X-ray observations of CG 12
ID:
ivo://CDS.VizieR/J/ApJ/673/331
Title:
X-ray observations of CG 12
Short Name:
J/ApJ/673/331
Date:
21 Oct 2021
Publisher:
CDS
Description:
The mysterious high Galactic latitude cometary globule CG 12 has been observed with the ACIS detector on board the Chandra X-Ray Observatory. We detect 128 X-ray sources, of which half are likely young stars formed within the globule's head. This new population of >~50 T Tauri stars and one new embedded protostar is far larger than the previously reported few intermediate-mass and two protostellar members of the cloud.
17799. X-Ray Observations of Compact Group Galaxies
ID:
ivo://nasa.heasarc/hcgxrbs
Title:
X-Ray Observations of Compact Group Galaxies
Short Name:
HCGXRBS
Date:
01 Nov 2024
Publisher:
NASA/GSFC HEASARC
Description:
This catalog presents the study of a sample of 15 compact groups (CGs) observed with Chandra/ACIS, Swift/UVOT and Spitzer/IRAC-MIPS for which archival data exist, allowing the authors to obtain SFRs, stellar masses, sSFRs and X-ray fluxes and luminosities for individual, off-nuclear point sources, which they summed to obtain total X-ray luminosities originating in off-nuclear point sources in a galaxy. Details on the Swift and Spitzer observations and data for systems in this sample can be found in Tzanavaris et al. (2010ApJ...716..556T) and Lenkic et al. (2016MNRAS.459.2948L). For Chandra/ACIS observations, see Tzanavaris et al. (2014ApJS..212....9T) and Desjardins et al. (2013ApJ...763..121D; 2014ApJ...790..132D). The authors obtained total galaxy X-ray luminosities, L&lt;sub&gt;X&lt;/sub&gt;, originating from individually detected point sources in a sample of 47 galaxies in 15 compact groups of galaxies (CGs). For the great majority of the galaxies, they found that the detected point sources most likely are local to their associated galaxy, and are thus extragalactic X-ray binaries (XRBs) or nuclear active galactic nuclei (AGNs). For spiral and irregular galaxies, they found that, after accounting for AGNs and nuclear sources, most CG galaxies are either within the +/- 1 sigma scatter of the Mineo et al. L&lt;sub&gt;X&lt;/sub&gt;-star formation rate (SFR) correlation or have higher L&lt;sub&gt;X&lt;/sub&gt; than predicted by this correlation for their SFR. These &quot;excesses&quot; may be due to low metallicities and high interaction levels. For elliptical and S0 galaxies, after accounting for AGNs and nuclear sources, most CG galaxies were found to be consistent with the Boroson et al. L&lt;sub&gt;X&lt;/sub&gt;-stellar mass correlation for low-mass XRBs, with larger scatter, likely due to residual effects such as AGN activity or hot gas. Assuming non-nuclear sources are low- or high-mass XRBs, the authors used appropriate XRB luminosity functions to estimate the probability that stochastic effects can lead to such extreme L&lt;sub&gt;X&lt;/sub&gt; values. They found that, although stochastic effects do not in general appear to be important, for some galaxies there is a significant probability that high L&lt;sub&gt;X&lt;/sub&gt; values can be observed due to strong XRB variability. This table was created by the HEASARC in May 2019 based upon the &lt;a href="https://cdsarc.cds.unistra.fr/ftp/cats/J/ApJ/817/95"&gt;CDS Catalog J/ApJ/817/95&lt;/a&gt; file table3.dat This is a service provided by NASA HEASARC .
17800. X-ray observations of galactic Supernova Remnants
ID:
ivo://CDS.VizieR/J/ApJS/73/781
Title:
X-ray observations of galactic Supernova Remnants
Short Name:
J/ApJS/73/781
Date:
21 Oct 2021
Publisher:
CDS
Description:
This paper summarizes the observations of Galactic supernova remnants with the imaging detectors of the Einstein Observatory. X-ray surface brightness contours of 47 remnants are shown together with gray-scale pictures. Count rates for these remnants have been derived and are listed for the HRI, IPC, and MPC detectors.

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