- ID:
- ivo://CDS.VizieR/J/ApJ/831/145
- Title:
- 6Ms Chandra long-term analyses of AGNs
- Short Name:
- J/ApJ/831/145
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We perform long-term (~15 years, observed-frame) X-ray variability analyses of the 68 brightest radio-quiet active galactic nuclei (AGNs) in the 6Ms Chandra Deep Field-South survey; the majority are in the redshift range of 0.6-3.1, providing access to penetrating rest-frame X-rays up to ~10-30keV. Of the 68 sources, 24 are optical spectral type I AGNs, and the rest (44) are type II AGNs. The timescales probed in this work are among the longest for X-ray variability studies of distant AGNs. Photometric analyses reveal widespread photon flux variability: 90% of AGNs are variable above a 95% confidence level, including many X-ray obscured AGNs and several optically classified type II quasars. We characterize the intrinsic X-ray luminosity (L_X_) and absorption (N_H_) variability via spectral fitting. Most (74%) sources show L_X_ variability; the variability amplitudes are generally smaller for quasars. A Compton-thick candidate AGN shows variability of its high-energy X-ray flux, indicating the size of reflecting material to be <~0.3pc. L_X_ variability is also detected in a broad absorption line quasar. The N_H_ variability amplitude for our sample appears to rise as time separation increases. About 16% of sources show N_H_ variability. One source transitions from an X-ray unobscured to obscured state, while its optical classification remains type I; this behavior indicates the X-ray eclipsing material is not large enough to obscure the whole broad-line region.
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- ID:
- ivo://CDS.VizieR/J/A+A/373/63
- Title:
- M31 second ROSAT PSPC survey
- Short Name:
- J/A+A/373/63
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- This paper reports the results of the analysis of the second ROSAT PSPC survey of M 31 performed in summer 1992. We compare our results with those of the first survey, already published in Supper et al. (1997, Cat. <J/A+A/317/328>). Within the ~10.7deg^2^ field of view, 396 individual X-ray sources are detected in the second survey data, of which 164 are new detections. When combined with the first survey, this result in a total of 560 X-ray sources in the field of M 31. Their (0.1keV-2.0keV) fluxes range from 7x10^-15^erg/cm^2^/s to 7.6x10^-12^erg/cm^2^/s, and of these 560 sources, 55 are tentatively identified with foreground stars, 33 with globular clusters, 16 with supernova remnants, and 10 with radio sources and galaxies (including M 32). A comparison with the results of the Einstein M 31 survey reveals 491 newly detected sources, 11 long term variable sources, and 7 possible transient sources. Comparing the two ROSAT surveys, we come up with 34 long term variable sources and 8 transient candidates.
- ID:
- ivo://CDS.VizieR/J/ApJ/919/18
- Title:
- 1.75 Ms Ultra Narrow Deep Field Catalogue
- Short Name:
- J/ApJ/919/18
- Date:
- 07 Dec 2021
- Publisher:
- CDS
- Description:
- The present catalog summaries the results of a survey carried out on one of the deepest X-ray field observed by the XMM-Newton satellite. The survey is made by 13 observations taken over 2 years with a total exposure time of 1.75Ms (1.372Ms for flare-filtered) in a field of 30'x30' around the blazar 1ES 1553+113. Using a conservative threshold of Maximum Likelihood significance of ML>=6, we detected 301 X-ray point-sources, for which we derived positions, fluxes at different bands and hardness ratios. Thanks to an optical follow-up by the Gran Telescopio Canarias (GTC) over the same field in u'g'r'i'z' bands, we obtained an optical source list of 43,068 elements with photometric redshift. We cross correlated this optical source list and an infrared catalog obtained by WISE with photometric measurements in the W1, W2, W3 and W4 bands, with our X-ray catalog. We identified optical/IR counterpart candidates for our X-ray sources and we estimated their X-ray luminosities, redshift distribution, X-ray/optical flux ratio and absolute magnitudes. Additionally, we identify a subset of 204 AGNs, for which we classified as: Quasar, Seyfert galaxies and Low Luminous AGNs (LLAGNs), based on their luminosities.
- ID:
- ivo://CDS.VizieR/J/ApJ/610/247
- Title:
- M31 supersoft and quasi-soft X-ray sources
- Short Name:
- J/ApJ/610/247
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report on very soft X-ray sources (VSSs) in M31. In a survey that was most sensitive to soft sources in four 8'x8' regions covered by Chandra's ACIS-S S3 CCD, we find 33 VSSs that appear to belong to M31. Fifteen VSSs have spectral characteristics mirroring the supersoft X-ray sources studied in the Magellanic Clouds and Milky Way (kT_eff_<=100eV); we therefore call these "classical" supersoft sources, or simply supersoft sources (SSSs). Eighteen VSSs may have either small (<10%) hard components or slightly higher effective temperatures (but still less than 350eV). We refer to these VSSs as quasi-soft sources (QSSs).
- ID:
- ivo://CDS.VizieR/J/MNRAS/474/3324
- Title:
- Multicomponent matched filter test
- Short Name:
- J/MNRAS/474/3324
- Date:
- 02 Mar 2022 00:06:44
- Publisher:
- CDS
- Description:
- We describe a multicomponent matched filter (MCMF) cluster confirmation tool designed for the study of large X-ray source catalogues produced by the upcoming X-ray all-sky survey mission eROSITA. We apply the method to confirm a sample of 88 clusters with redshifts 0.05<z<0.8 in the recently published 2RXS catalogue from the ROSAT All-Sky Survey (RASS) over the 208 deg^2^ region overlapped by the Dark Energy Survey (DES) Science Verification (DES-SV) data set. In our pilot study, we examine all X-ray sources, regardless of their extent. Our method employs a multicolour red sequence (RS) algorithm that incorporates the X-ray count rate and peak position in determining the region of interest for follow-up and extracts the positionally and colour-weighted optical richness {lambda}_MCMF_ as a function of redshift for each source. Peaks in the {lambda}_MCMF_-redshift distribution are identified and used to extract photometric redshifts, richness and uncertainties. The significances of all optical counterparts are characterized using the distribution of richnesses defined along random lines of sight. These significances are used to extract cluster catalogues and to estimate the contamination by random superpositions of unassociated optical systems. The delivered photometric redshift accuracy is {delta}z/(1+z)=0.010. We find a well-defined X-ray luminosity-{lambda}_MCMF_ relation with an intrinsic scatter of {delta}ln({lambda}_MCMF_|Lx)=0.21. Matching our catalogue with the DES-SV redMaPPer catalogue yields good agreement in redshift and richness estimates; comparing our catalogue with the South Pole Telescope (SPT) selected clusters shows no inconsistencies. SPT clusters in our data set are consistent with the high-mass extension of the RASS-based {lambda}_MCMF_-mass relation.
- ID:
- ivo://CDS.VizieR/J/other/RMxAA/35.187
- Title:
- Multifrequency catalog of LINERs
- Short Name:
- J/other/RMxAA/35
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the first Catalog of Low Ionization Emission Line Galaxies (LINERs or Liners, which is the simplest name, and which we shall adopt in what follows). The Catalog "MCL" (Multifrequency Catalog of Liners), contains 476 entries and contains both broad-band and monochromatic emission data (ranging from radio to X-ray frequencies) of colors, and other data compiled from the literature and various data bases, as indicated in the references. Most of the galaxies can be considered "pure" Liners on the basis of the Veilleux & Osterbrock (1987ApJS...63..295V) classification as suggested by Ho, Filippenko, & Sargent (1997ApJS..112..315H). However, a considerable number of transition (Liners-H II or Liners-Starburst) objects are also included. One of the open questions, is whether Liners should be considered as a class of galaxies (like Seyfert galaxies for instance) or rather, as an heterogeneous group of objects. We believe the study of Liners as a group is very interesting, precisely because they very likely represent a transition between non-thermal and starburst activity, and probably also between "active" and "non- active" galaxies. This catalog may be used as a basis for statistical research. A preliminary discussion of the main statistical properties of Liners, in the range from radio to X-ray frequencies, is given here.
- ID:
- ivo://CDS.VizieR/J/A+AS/106/303
- Title:
- Multifrequency observations of ROSAT sources
- Short Name:
- J/A+AS/106/303
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report on results of multifrequency radio continuum observations with the Effelsberg 100-m telescope of 234 radio sources which have counterparts in the ROSAT all-sky survey. Observations have been made at 21 cm, 11 cm, 6 cm and 2.8 cm wavelength in the flux density range above 20 mJy. We have determined the spectrum, size, linear polarization and improved positions of these sources. We give the statistical properties of the ROSAT selected radio sources and compare them with results from unbiased radio source surveys so far available.
- ID:
- ivo://CDS.VizieR/J/A+A/573/A76
- Title:
- Multifrequency study of NL Seyfert 1 galaxies
- Short Name:
- J/A+A/573/A76
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- High-energy {gamma}-rays, which are produced by powerful relativistic jets, are usually associated with blazars and radio galaxies. In the current active galactic nuclei (AGN) paradigm, such jets are almost exclusively launched from massive elliptical galaxies. Recently, however, Fermi/LAT detected {gamma}-rays from a few narrow-line Seyfert 1 galaxies and thus confirmed the presence of relativistic jets in them. Since NLS1 galaxies are assumed to be young evolving AGN, they offer a unique opportunity to study the production of relativistic jets in late-type galaxies. Our aim is to estimate by which processes the emission of various kinds is produced in NLS1 galaxies and to study how emission properties are connected to other intrinsic AGN properties. We have compiled the so far largest multiwavelength database of NLS1 sources. This allowed us to explore correlations between different wavebands and source properties using, for example, Pearson and Spearman correlations and principal component analysis. We did this separately for radio-loud and radio-quiet sources.
- ID:
- ivo://CDS.VizieR/J/other/Ser/166.13
- Title:
- Multi-frequency study of the Pavo field
- Short Name:
- J/other/Ser/166.
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We test the prediction of Hamilton and Helfand (<A HREF="http://simbad.cds.unistra.fr/simbad/sim-ref?bibcode=1993ApJ...418...55H%201993ApJ...418...55H">1993ApJ...418...55H 1993ApJ...418...55H</A>) that faint radio selected galaxies are a new class contributing to the diffuse X-ray background (XRB) radiation. The test is based on the correlation of X-ray, optical and radio positions for sources detected in ROSAT (S<SUB>0.08–2.4keV</SUB>>6x10<SUP>–15</SUP>erg/s/cm<SUP>2</SUP>, 69 sources) and ATCA (S<SUB>1.42GHz</SUB>>250uJy, 93 sources) observations of the Einstein Pavo field. A total of six ATCA radio sources inside the inner ring of the ROSAT image are located within 10" of the ROSAT X-ray positions, with one associated by random chance.
- ID:
- ivo://CDS.VizieR/J/MNRAS/414/3084
- Title:
- Multi-waveband analysis of 12um galaxies
- Short Name:
- J/MNRAS/414/3084
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a multi-waveband analysis of a 126-galaxy sub-sample of the 12um galaxy sample (12MGS), for which we have carried out a detailed X-ray spectral analysis in a previous paper. We determine the activity class of the galaxies by way of optical-line ratio diagnostics and characterize the optical classes by their X-ray, 12um and [OIII] luminosities and X-ray spectral properties.