- ID:
- ivo://CDS.VizieR/J/A+A/555/A65
- Title:
- X-ray variability of M31 central field
- Short Name:
- J/A+A/555/A65
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The central field of the Andromeda galaxy (M31) was monitored from 2006 to 2012 using the Chandra HRC-I detector (about 0.1-10keV energy range) with the main aim of detecting X-rays from optical novae. We present a systematic analysis of all X-ray sources found in the 41 nova monitoring observations, along with 23 M31 central field HRC-I observations available from the Chandra data archive starting in December 1999. Based on these observations, we studied the X-ray long-term variability of the source population and especially of X-ray binaries in M31. We created a catalogue of sources detected in the 64 available observations that adds up to a total exposure time of about 1Ms. To study the variability, we developed a processing pipeline to derive long-term Chandra HRC-I light curves for each source over the 13 years of observations. We also searched for extended X-ray sources in the merged images. We present a point-source catalogue containing 318 X-ray sources with detailed long-term variability information, 28 of which are published for the first time. The spatial and temporal resolution of the catalogue allows us to classify 115 X-ray binary candidates showing high X-ray variability or even outbursts, as well as 14 globular cluster X-ray binary candidates showing no significant variability. The analysis may suggest that outburst sources are less frequent in globular clusters than in the field of M31. We detected seven supernova remnants, one of which is a new candidate, and also resolved the first X-rays from a known radio supernova remnant. In addition to 33 known optical nova/X-ray source correlations, we discovered one previously unknown super-soft X-ray outburst and several new nova candidates. The catalogue contains a large sample of detailed long-term X-ray light curves in the M31 central field, which helps in understanding the X-ray population of our neighbouring spiral galaxy M31.
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1272. X-ray view of IC348
- ID:
- ivo://CDS.VizieR/J/A+A/537/A135
- Title:
- X-ray view of IC348
- Short Name:
- J/A+A/537/A135
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- IC348 is a nearby (~310pc), young (~2-3Myr) open cluster with >300 members identified from optical and infrared observations. We study the properties of the coronae of the young low-mass stars in IC348 combining X-ray and optical/infrared data. The four existing Chandra observations of IC348 are merged, thus providing a deeper and spatially more complete X-ray view than previous X-ray studies of the cluster. We have compiled a comprehensive catalog of IC348 members taking into account recent updates to the cluster census. Our data collection comprises fundamental stellar parameters, infrared excess indicating the presence of disks, Halpha emission as a tracer of chromospheric emission or accretion and mass accretion rates. We have detected 290 X-ray sources in four merged Chandra exposures, of which 187 are associated with known cluster members corresponding to a detection rate of ~60% for the cluster members of IC348 identified in optical/infrared studies. According to the most recent spectral classification of IC348 members only four of the X-ray sources are brown dwarfs (spectral type M6 and later). The detection rate is highest for diskless Class III stars and increases with stellar mass. This may be explained with higher X-ray luminosities for higher mass and later evolutionary stage that is evident in the X-ray luminosity functions. In particular, we find that for the lowest examined masses (0.1-0.25 Msun) there is a difference between the X-ray luminosity functions of accreting and non-accreting stars (classified on the basis of their Halpha emission strength) as well as those of disk-bearing and diskless stars (classified on the basis of the slope of the spectral energy distribution). These differences disappear for higher masses. This is related to our finding that the Lx/Lbol ratio is non-constant across the mass/luminosity sequence of IC348 with a decrease towards lower luminosity stars. Our analysis of an analogous stellar sample in the Orion Nebula Cluster suggests that the decline of Lx/Lbol for young stars at the low-mass end of the stellar sequence is likely universal.
- 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.
- 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.
- 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.
1276. XXL Survey. DR2
- ID:
- ivo://CDS.VizieR/IX/52
- Title:
- XXL Survey. DR2
- Short Name:
- IX/52
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the second data release (DR2) of the XXL Survey, contextually with the appearance of a second A&A special issue dedicated to XXL. This intermediate release includes the following catalogues and data: The X-ray point source catalogue (3XLSS) and the associated multiwavelength catalogues in the XXL-N and XXL-s areas (XXL paper XXVII). The same paper also provides the list of XMM pointings used, and a supplementary catalogue of redshifts obtained with the AAOmega spectrograph in the XXL-S area. The XXL-365-GC galaxy cluster catalogue (XXL paper XX) with the complete subset of clusters for which the selection function is well determined plus all X-ray clusters which are, to date, spectroscopically confirmed. The ATCA 2.1 GHz radio source catalogue in the XXL-S area (XXL paper XXVIII), together with the catalogue of ther optical and near infrared counterparts (XXL paper XXVI). The GMRT 610 MHz radio source catalogue in the XXL-N area (XXL paper XXIX). FITS images of the XXL-North field: continuum radio mosaic from observations with the Giant Meterwave Radio Telescope (GMRT) at 610MHz, and the corresponding noise map. A complete spectrophotometric sample of galaxies within X-ray detected, optically spectroscopically confirmed groups and clusters (G&C), including also field objects, in the XXL-N area (XXL paper XXII). The list of brightest cluster galaxies (BCGs) in the XXL-N area (XXL paper XXVIII). FITS images of the two radio galaxies described in XXL paper XXXIV. ATCA XXL-S source classification data (XXL paper XXXVI) http://sci.esa.int/xmm-newton/60686-tracing-the-universe-x-ray-survey-\ supports-standard-cosmological-model/ List of XXL DR2 papers: XVI. The clustering of X-ray selected galaxy clusters at z~0.3 XVII. X-ray and Sunyaev-Zel'dovich properties of the redshift 2.0 galaxy cluster XLSSC 122 XVIII. ATCA 2.1 GHz radio source catalogue and source counts for the XXL-South field XIX. A realistic population of simulated X-ray AGN: Comparison of models with observations XX. The 365 cluster catalogue XXI. The environment and clustering of X-ray AGN in the XXL-South field XXII. The XXL-North spectrophotometric sample and galaxy stellar mass function in X-ray detected groups and clusters XXIII. The mass scale of XXL clusters from ensemble spectroscopy XXIV. The final detection pipeline XXV. Cosmological analysis of the C1 cluster number counts XXVI. Optical and near infrared identification of the ATCA 2.1 GHz radio sources in the XXL-S field XXVII. The 3XLSS point source catalogue XXVIII. Galaxy luminosity functions of the XXL-N clusters XXIX. GMRT 610 MHz continuum observations XXX. Characterisation of the XLSSsC N01 supercluster and analysis of the galaxy stellar populations XXXI. Classification and host galaxy properties of 2.1 GHz ATCA XXL-S radio sources XXXII. Spatial clustering of the XXL-S AGN XXXIII. Chandra constraints on the AGN contamination of z > 1 XXL galaxy clusters XXXIV. Double irony in XXL-North. A tale of two radio galaxies in a supercluster at z = 0.14 XXXV. The role of cluster mass in AGN activity XXXVI. Evolution and black hole feedback of high-excitation and low-excitation radio galaxies in XXL-S
- ID:
- ivo://CDS.VizieR/IX/49
- Title:
- XXL Survey: First results
- Short Name:
- IX/49
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The quest for the cosmological parameters that describe our universe continues to motivate the scientific community to undertake very large survey initiatives across the electromagnetic spectrum. Over the past two decades, the Chandra and XMM-Newton observatories have sup- ported numerous studies of X-ray-selected clusters of galaxies, active galactic nuclei (AGNs), and the X-ray background. The present paper is the first in a series reporting results of the XXL-XMM survey; it comes at a time when the Planck mission results are being finalised. We present the XXL Survey, the largest XMM programme totaling some 6.9Ms to date and involving an international consortium of roughly 100 members. The XXL Survey covers two extragalactic areas of 25deg^2^ each at a point-source sensitivity of ~5x10^-15^erg/s/cm^2^ in the [0.5-2]keV band (completeness limit). The survey's main goals are to provide constraints on the dark energy equation of state from the space-time distribution of clusters of galaxies and to serve as a pathfinder for future, wide-area X-ray missions. We review science objectives, including cluster studies, AGN evolution, and large-scale structure, that are being conducted with the support of approximately 30 follow-up programmes. List of XXL papers: I. Scientific motivations - XMM-Newton observing plan - Follow-up observations and simulation programme. II. The bright cluster sample: catalogue and luminosity function. III. Luminosity-temperature relation of the bright cluster sample. IV. Mass-temperature relation of the bright cluster sample. VI. The 1000 brightest X-ray point sources. VII. A supercluster of galaxies at z = 0.43. VIII. MUSE characterisation of intracluster light in a z~0.53 cluster of galaxies. IX. Optical overdensity and radio continuum analysis of a supercluster at z=0.43. X. K-band luminosity - weak-lensing mass relation for groups and clusters of galaxies. XI. ATCA 2.1 GHz continuum observations. XII. Optical spectroscopy of X-ray-selected clusters and the frequency of AGN in superclusters. XIII. Baryon content of the bright cluster sample. XIV. AAOmega redshifts for the southern XXL field.
- ID:
- ivo://CDS.VizieR/J/A+A/551/A142
- Title:
- 7 year Swift-XRT point source catalog (1SWXRT)
- Short Name:
- J/A+A/551/A142
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Swift satellite is a multi-wavelength observatory specifically designed for gamma-ray burst (GRB) astronomy that is operational since 2004. Swift is also a very flexible multi-purpose facility that supports a wide range of scientific fields such as active galactic nuclei, supernovae, cataclysmic variables, Galactic transients, active stars and comets. The Swift X-ray Telescope (XRT) has collected more than 150Ms of observations in its first seven years of operations. The purpose of this work is to present to the scientific community the list of all the X-ray point sources detected in XRT imaging data taken in photon counting mode during the first seven years of Swift operations. All these point-like sources, excluding the Gamma-Ray Bursts (GRB), will be stored in a catalog publicly available (1SWXRT). We consider all the XRT observations with exposure time longer than 500 s taken in the period 2005-2011. Data were reduced and analyzed with standard techniques and a list of detected sources for each observation was produced. A careful visual inspection was performed to remove extended, spurious and piled-up sources. Finally, positions, count rates, fluxes and the corresponding uncertainties were computed.
- ID:
- ivo://CDS.VizieR/J/A+AS/124/449
- Title:
- Young stars south of Taurus-Auriga
- Short Name:
- J/A+AS/124/449
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present results of intermediate resolution spectroscopy of 131 optical counterparts to 115 ROSAT All-Sky Survey X-ray sources south of the Taurus-Auriga dark cloud complex. These objects have been selected as candidate young stars from a total of 1084 ROSAT sources in a ~300 square degree area. We identify 30 objects as low-mass PMS stars on the basis of the LiI{lambda}6708{AA} doublet in their spectrum, a signature of their young age. All these stars have a spectral type later than F7 and show spectral characteristics typical of weak-line and post-T Tauri stars. The presence of young objects several parsecs away from the regions of ongoing star formation is discussed in the light of the current models of T Tauri dispersal.
- ID:
- ivo://CDS.VizieR/J/ApJ/762/88
- Title:
- Young stellar kinematic group candidate members
- Short Name:
- J/ApJ/762/88
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a new method based on a Bayesian analysis to identify new members of nearby young kinematic groups. The analysis minimally takes into account the position, proper motion, magnitude, and color of a star, but other observables can be readily added (e.g., radial velocity, distance). We use this method to find new young low-mass stars in the {beta} Pictoris and AB Doradus moving groups and in the TW Hydrae, Tucana-Horologium, Columba, Carina, and Argus associations. Starting from a sample of 758 mid-K to mid-M (K5V-M5V) stars showing youth indicators such as H{alpha} and X-ray emission, our analysis yields 214 new highly probable low-mass members of the kinematic groups analyzed. One is in TW Hydrae, 37 in {beta} Pictoris, 17 in Tucana-Horologium, 20 in Columba, 6 in Carina, 50 in Argus, 32 in AB Doradus, and the remaining 51 candidates are likely young but have an ambiguous membership to more than one association. The false alarm rate for new candidates is estimated to be 5% for {beta} Pictoris and TW Hydrae, 10% for Tucana-Horologium, Columba, Carina, and Argus, and 14% for AB Doradus. Our analysis confirms the membership of 58 stars proposed in the literature. Firm membership confirmation of our new candidates will require measurement of their radial velocity (predicted by our analysis), parallax, and lithium 6708{AA} equivalent width. We have initiated these follow-up observations for a number of candidates, and we have identified two stars (2MASSJ01112542+1526214, 2MASSJ05241914-1601153) as very strong candidate members of the {beta} Pictoris moving group and one strong candidate member (2MASSJ05332558-5117131) of the Tucana-Horologium association; these three stars have radial velocity measurements confirming their membership and lithium detections consistent with young age.
