- ID:
- ivo://CDS.VizieR/J/ApJ/840/41
- Title:
- X-ray/UV Swift monitoring of NGC 4151
- Short Name:
- J/ApJ/840/41
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Swift monitoring of NGC 4151 with an ~6hr sampling over a total of 69days in early 2016 is used to construct light curves covering five bands in the X-rays (0.3-50keV) and six in the ultraviolet (UV)/optical (1900-5500{AA}). The three hardest X-ray bands (>2.5keV) are all strongly correlated with no measurable interband lag, while the two softer bands show lower variability and weaker correlations. The UV/optical bands are significantly correlated with the X-rays, lagging ~3-4days behind the hard X-rays. The variability within the UV/optical bands is also strongly correlated, with the UV appearing to lead the optical by ~0.5-1days. This combination of >~3day lags between the X-rays and UV and <~1day lags within the UV/optical appears to rule out the "lamp-post" reprocessing model in which a hot, X-ray emitting corona directly illuminates the accretion disk, which then reprocesses the energy in the UV/optical. Instead, these results appear consistent with the Gardner & Done (2017MNRAS.470.3591G) picture in which two separate reprocessings occur: first, emission from the corona illuminates an extreme-UV-emitting toroidal component that shields the disk from the corona; this then heats the extreme-UV component, which illuminates the disk and drives its variability.
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- 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/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.
- 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.
- 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.
- ID:
- ivo://CDS.VizieR/J/ApJ/788/105
- Title:
- XSTPS RR Lyrae in the north Galactic cap
- Short Name:
- J/ApJ/788/105
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a catalog of RR Lyrae stars (RRLs) observed by the Xuyi Schmidt Telescope Photometric Survey (XSTPS). The area we consider is located in the north Galactic cap, covering ~376.75 deg^2^ at RA~150{deg} and DE~27{deg} down to a magnitude limit of i~19. Using the variability information afforded by the multi-epoch nature of our XSTPS data, combined with colors from the Sloan Digital Sky Survey, we are able to identify candidate RRLs. We find 318 candidates, derive distances to them, and estimate the detection efficiency. The majority of our candidates have more than 12 observations, and for these we are able to calculate periods. These also allow us to estimate our contamination level, which we predict is between 30% and 40%. Finally, we use the sample to probe the halo density profile in the 9-49 kpc range and find that it can be well fitted by a double power law. We find good agreement between this model and the models derived for the south Galactic cap using the Watkins et al. (2009, J/MNRAS/398/1757) and Sesar et al. (2010, J/ApJ/708/717) RRL data sets, after accounting for possible contamination in our data set from Sagittarius stream members. We consider non-spherical double power-law models of the halo density profile and again find agreement with literature data sets, although we have limited power to constrain the flattening due to our small survey area. Much tighter constraints will be placed by current and future wide-area surveys, most notably ESA's astrometric Gaia mission. Our analysis demonstrates that surveys with a limited number of epochs can effectively be mined for RRLs. Our complete sample is provided as accompanying online material; as an example the first few entries of each electronic table are shown in the text.
8297. XX Cep BVRI light curves
- ID:
- ivo://CDS.VizieR/J/MNRAS/379/1665
- Title:
- XX Cep BVRI light curves
- Short Name:
- J/MNRAS/379/1665
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We obtained CCD photometric observations of the Algol-type semidetached binary XX Cephei (XX Cep) during 15 nights from 2002 September 17 to 2003 February 2, and also on 2005 January 21. Except for those data taken on the last night of the concentrated observing season, the 3881 measurements were obtained over an interval of only 106 nights. From these data, four new times of minimum light were calculated. The (O-C) diagram formed from all available timings, and thus the orbital period of the system, can be partly represented as a beat effect between two cyclical variations with different periods (P1'=42yr, P2'=181yr) and amplitudes (K1=0.015d, K2=0.103d), respectively. Both physical and non-physical interpretations of these cycles were investigated.
8298. 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/J/MNRAS/427/1517
- Title:
- XY And and UZ Vir light curves
- Short Name:
- J/MNRAS/427/1517
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a thorough analysis of multicolour CCD observations of two modulated RRab-type variables, XY And and UZ Vir. These Blazhko stars show relatively simple light-curve modulation with the usual multiplet structures in their Fourier spectra. One additional, independent frequency with linear-combination terms of the pulsation frequency is also detected in the residual spectrum of each of the two stars. The amplitude and phase relations of the triplet components are studied in detail. Most of the epoch-independent phase differences show a slight, systematic colour dependence. However, these trends have opposite signs in the two stars. The mean values of the global physical parameters and their changes with the Blazhko phase are determined, utilizing the inverse photometric method (IPM). The modulation properties and the IPM results are compared for the two variables. The pulsation period of XY And is the shortest when its pulsation amplitude is the highest, while UZ Vir has the longest pulsation period at this phase of the modulation. Despite this contrasting behaviour, the phase relations of the variations in their mean physical parameters are similar. These results do not agree with the predictions of the Blazhko model of Stothers.
8300. XY UMa BVRI light curves
- ID:
- ivo://CDS.VizieR/J/AJ/139/1801
- Title:
- XY UMa BVRI light curves
- Short Name:
- J/AJ/139/1801
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- New CCD photometric observations of the chromospherically active binary XY Ursae Majoris (XY UMa) were obtained every year since 2006. The light curves obtained in the late Spring of 2006 show obvious variations on a short timescale, while the light curves obtained in 2008 December do not. But both sets of light curves are markedly asymmetric, and were analyzed using the 2003 version of the Wilson-Devinney code with spot model. New absolute physical parameters are obtained.
