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24891. X-ray view of M33 after ROSAT
ID:
ivo://CDS.VizieR/J/A+A/373/438
Title:
X-ray view of M33 after ROSAT
Short Name:
J/A+A/373/438
Date:
21 Oct 2021
Publisher:
CDS
Description:
Table2 contains the catalogue of X-ray sources in M 33 detected in ROSAT observations. X-ray properties and results from cross-correlations with other catalogues are listed. The total number of sources is 184.
24892. X-ray view of NGC 2403 central region
ID:
ivo://CDS.VizieR/J/AJ/139/1066
Title:
X-ray view of NGC 2403 central region
Short Name:
J/AJ/139/1066
Date:
21 Oct 2021
Publisher:
CDS
Description:
Archival Chandra observations are used to study the X-ray emission associated with star formation in the central region of the nearby SAB(s)cd galaxy NGC 2403. The distribution of X-ray emission is compared to the morphology visible at other wavelengths using complementary Spitzer, Galaxy Evolution Explorer, and ground-based H{alpha} imagery.
24893. X-ray weak quasars from SDSS & Chandra
ID:
ivo://CDS.VizieR/J/ApJ/900/141
Title:
X-ray weak quasars from SDSS & Chandra
Short Name:
J/ApJ/900/141
Date:
02 Feb 2022 13:37:44
Publisher:
CDS
Description:
We investigate systematically the X-ray emission from type 1 quasars using a sample of 1825 Sloan Digital Sky Survey non-broad absorption line (non-BAL) quasars with Chandra archival observations. A significant correlation is found between the X-ray-to-optical power-law slope parameter ({alpha}_OX_) and the 2500{AA} monochromatic luminosity (L_2500{AA}_), and the X-ray weakness of a quasar is assessed via the deviation of its {alpha}_OX_ value from that expected from this relation. We demonstrate the existence of a population of non-BAL X-ray-weak quasars, and the fractions of quasars that are X-ray weak by factors of >=6 and >=10 are 5.8%+/-0.7% and 2.7%+/-0.5%, respectively. We classify X-ray-weak quasars (X-ray weak by factors of >=6) into three categories based on their optical spectral features: weak emission-line quasars (WLQs; CIV rest-frame equivalent width <16{AA}), red quasars ({Delta}(g-i)>0.2), and unclassified X-ray-weak quasars. The X-ray-weak fraction of 35_-9_^+12^% within the WLQ population is significantly higher than that within non-WLQs, confirming previous findings that WLQs represent one population of X-ray-weak quasars. The X-ray-weak fraction of 13_-3_^+5^% within the red quasar population is also considerably higher than that within the normal quasar population. The unclassified X-ray-weak quasars do not have unusual optical spectral features, and their X-ray weakness may be mainly related to quasar X-ray variability.
24894. XRB population synthesis models in 0<z<20 galaxies
ID:
ivo://CDS.VizieR/J/ApJ/766/19
Title:
XRB population synthesis models in 0<z<20 galaxies
Short Name:
J/ApJ/766/19
Date:
21 Oct 2021
Publisher:
CDS
Description:
Emission from X-ray binaries (XRBs) is a major component of the total X-ray luminosity of normal galaxies, so X-ray studies of high-redshift galaxies allow us to probe the formation and evolution of XRBs on very long timescales (~10Gyr). In this paper, we present results from large-scale population synthesis models of binary populations in galaxies from z=0 to ~20. We use as input into our modeling the Millennium II Cosmological Simulation and the updated semi-analytic galaxy catalog by Guo et al. (2011MNRAS.413..101G) to self-consistently account for the star formation history (SFH) and metallicity evolution of each galaxy. We run a grid of 192 models, varying all the parameters known from previous studies to affect the evolution of XRBs. We use our models and observationally derived prescriptions for hot gas emission to create theoretical galaxy X-ray luminosity functions (XLFs) for several redshift bins. Models with low common envelope efficiencies, a 50% twins mass ratio distribution, a steeper initial mass function exponent, and high stellar wind mass-loss rates best match observational results from Tzanavaris & Georgantopoulos, though they significantly underproduce bright early-type and very bright (L_x_>10^41^) late-type galaxies. These discrepancies are likely caused by uncertainties in hot gas emission and SFHs, active galactic nucleus contamination, and a lack of dynamically formed low-mass XRBs. In our highest likelihood models, we find that hot gas emission dominates the emission for most bright galaxies. We also find that the evolution of the normal galaxy X-ray luminosity density out to z=4 is driven largely by XRBs in galaxies with X-ray luminosities between 10^40^ and 10^41^erg/s.
24895. XRBs and star clusters in NGC 4449
ID:
ivo://CDS.VizieR/J/ApJ/741/86
Title:
XRBs and star clusters in NGC 4449
Short Name:
J/ApJ/741/86
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present 23 candidate X-ray binaries with luminosities down to 1.8x10^36^erg/s, in the nearby starburst galaxy NGC 4449, from observations totaling 105ks taken with the ACIS-S instrument on the Chandra Space Telescope. We determine count rates, luminosities, and colors for each source, and perform spectral fits for sources with sufficient counts. We also compile a new catalog of 129 compact star clusters in NGC 4449 from high-resolution, multi-band optical images taken with the Hubble Space Telescope, doubling the number of clusters known in this galaxy. The UBVI, H{alpha} luminosities of each cluster are compared with predictions from stellar evolution models to estimate their ages and masses. We find strong evidence for a population of very young massive, black hole binaries, which comprise nearly 50% of the detected X-ray binaries in NGC 4449. Approximately a third of these remain within their parent star clusters, which formed {tau}<=6-8Myr ago, while others have likely been ejected from their parent clusters. We also find evidence for a population of somewhat older X-ray binaries, including both supergiant and Be-binaries, which appear to be associated with somewhat older {tau}~100-400Myr star clusters, and one X-ray binary in an ancient ({tau}~10Gyr) globular cluster. Our results suggest that detailed information on star clusters can significantly improve constraints on X-ray binary populations in star-forming galaxies.
24896. XRISM Master Catalog
ID:
ivo://nasa.heasarc/xrismmastr
Title:
XRISM Master Catalog
Short Name:
XRISMMASTR
Date:
14 Feb 2025
Publisher:
NASA/GSFC HEASARC
Description:
The X-Ray Imaging and Spectroscopy Mission (XRISM) is an international mission led by Institute of Space and Astronautical Science (ISAS) of Japan Aerospace Exploration Agency (JAXA). XRISM was launched on 2023 September 6 (UT) into a near-circular orbit with an apogee of ~575 km, an inclination of ~31 degrees, and an orbital period of about 96 minutes. During the performance verification (PV) phase, targets selected by the XRISM science team are being observed. Subsequently, it will become a general observatory with annual call for proposals open to all astronomers. XRISM has two co-aligned instruments that are used concurrently: Resolve, a soft X-ray spectrometer, and Xtend, a wide field-of-view imager. Resolve uses an X-ray microcalorimeter with ~5 eV spectral resolution withs a 3x3 arcmin field of view. It is currently operating with the Gate Valve closed, which limits its effective bandpass to 1.7-12 keV. Xtend is an X-ray CCD instrument with a 38 x 38 arcmin&lt;sup&gt;2&lt;/sup&gt; field of view. This table contains a list of observations that have taken place as well as those that have been accepted and planned. The latter includes pre-approved targets for TOO observations and priority C targets whose observations are not guaranteed. This database table is based on information supplied by the XRISM Science Data Center at NASA/GSFC. It is updated automatically on a regular basis. This is a service provided by NASA HEASARC .
24897. X-shaped radio galaxies from FIRST
ID:
ivo://CDS.VizieR/J/ApJS/245/17
Title:
X-shaped radio galaxies from FIRST
Short Name:
J/ApJS/245/17
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present a catalog of 290 "winged" or X-shaped radio galaxies (XRGs) extracted from the latest (2014 December 17) data release of the "Very Large Array Faint Images of the Radio Sky at Twenty centimeter". We have combined these radio images with their counterparts in the TIFR GMRT sky survey at 150MHz, in an attempt to identify any low surface brightness radio emission present in these sources. This has enabled us to assemble a sample of 106 "strong" XRG candidates and 184 "probable" XRG candidates whose XRG designation needs to be verified by further observations. The present sample of 290 XRG candidates is almost twice as large as the number of XRGs currently known. Twenty-five of our 290 XRG candidates (9 "strong" and 16 "probable") are identified as quasars. Double-peaked narrow emission lines are seen in the optical spectra of three of the XRG candidates (two "strong" and one "probable"). Nearly 90% of the sample is located in the FR II domain of the Owen-Ledlow diagram. A few of the strong XRG candidates have a rather flat radio spectrum (spectral index {alpha} flatter than -0.3) between 150MHz and 1.4GHz, or between 1.4 and 5GHz. Since this is not expected for lobe-dominated extragalactic radio sources (like nearly all known XRGs), these sources are particularly suited for follow-up radio imaging and near-simultaneous measurement of the radio spectrum.
24898. X-shaped radio sources. II. New redshifts
ID:
ivo://CDS.VizieR/J/ApJS/181/548
Title:
X-shaped radio sources. II. New redshifts
Short Name:
J/ApJS/181/548
Date:
21 Oct 2021
Publisher:
CDS
Description:
We reported optical spectroscopic observations of X-shaped radio sources with the Hobby-Eberly Telescope and Multiple-Mirror Telescope, focused on the sample of candidates from the FIRST survey presented in Paper I (Cheung, 2007, Cat. <J/AJ/133/2097>). A total of 27 redshifts were successfully obtained, 21 of which are new, including a newly identified candidate source of this type which is presented here. With these observations, the sample of candidates from the previous paper is over 50% spectroscopically identified. Two new broad emission-lined X-shaped radio sources are revealed, while no emission lines were detected in about one-third of the observed sources; a detailed study of the line properties is deferred to a future paper. Finally, to explore their relation to the Fanaroff-Riley division, the radio luminosities and host galaxy absolute magnitudes of a spectroscopically identified sample of 50 X-shaped radio galaxies are calculated to determine their placement in the Owen-Ledlow plane.
24899. "X-shaped" radio sources. II. Sample properties
ID:
ivo://CDS.VizieR/J/ApJ/852/48
Title:
"X-shaped" radio sources. II. Sample properties
Short Name:
J/ApJ/852/48
Date:
21 Oct 2021
Publisher:
CDS
Description:
In an earlier paper, we presented Jansky Very Large Array multi-frequency, multi-array continuum imaging of a unique sample of low-axial ratio radio galaxies. In this paper, the second in the series, we examine the images to learn the phenomenology of how the off-axis emission relates to the main radio source. Inversion-symmetric offset emission appears to be bimodal and to originate from one of two strategic locations: outer ends of radio lobes (outer-deviation) or from inner ends (inner-deviation). The latter sources are almost always associated with edge-brightened sources. With S- and Z-shaped sources being a subset of outer-deviation sources, this class lends itself naturally to explanations involving black hole axis precession. Our data allow us to present a plausible model for the more enigmatic inner-deviation sources with impressive wings; as for outer-deviation sources these too require black hole axis shifts, although they also require plasma backflows into relic channels. Evolution in morphology over time relates the variety in structures in inner-deviation sources including XRGs. With features such as non- collinearities, central inner-S "spine," corresponding lobe emission peaks, double and protruding hotspots not uncommon, black hole axis precession, drifts, or flips could be active in a significant fraction of radio sources with prominent off-axis emission. At least 4% of radio galaxies appear to undergo black hole axis rotation. Quasars offer a key signature for recognizing rotating axes. With a rich haul of sources that have likely undergone axis rotation, our work shows the usefulness of low-axial ratio sources in pursuing searches for binary supermassive black holes.
24900. "X-shaped" radio sources. I. VLA imaging
ID:
ivo://CDS.VizieR/J/ApJ/852/47
Title:
"X-shaped" radio sources. I. VLA imaging
Short Name:
J/ApJ/852/47
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present archival and Jansky Very Large Array multi-frequency multi-array radio continuum imaging of a unique sample of 100 radio sources that have been selected to be candidate "X-shaped" radio galaxies (XRGs). The archival data were calibrated in AIPS (Bridle & Greisen 1994, NRAO AIPS Memo 87) and imaged using DIFMAP (Shepherd+ 1994BAAS...26..987S), while the new Very Large Array data were calibrated and imaged in CASA (McMullin+ 2007ASPC..376..127M). No attempt was made to re-image the archival data in CASA. Altogether we present images of 95 of the 100 sources. These observations give us the opportunity to study radio sources with synchrotron plasma that is significantly offset from the main radio axis and therefore to open a window into investigations of physical mechanisms responsible for depositing the plasma in off-axis regions. Here, we present the technical details of the observations and all of the total intensity images, while in subsequent papers we use them to examine critically various models for the formation of XRGs. Spectral index and linear polarization information is also presented and analyzed in further papers in this series.

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