- ID:
- ivo://CDS.VizieR/IX/43
- Title:
- 1SXPS Swift X-ray telescope point source catalogue
- Short Name:
- IX/43
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the 1SXPS (Swift-XRT Point Source) catalogue of 151,524 X-ray point-sources detected by the Swift-XRT in 8 years of operation. The catalogue covers 1905 square degrees distributed approximately uniformly on the sky. We analyze the data in two ways. First we consider all observations individually, for which we have a typical sensitivity of ~3e-13 erg.cm^-2^s^-1` (0.3-10 keV). Then we co-add all data covering the same location on the sky: these images have a typical sensitivity of ~9e-14 erg cm^-2^s^-1^ (0.3-10 keV). Our sky coverage is nearly 2.5 times that of 3XMM-DR4, although the catalog is a factor of ~1.5 less sensitive. The median position error is 5.5" (90% confidence), including systematics. Our source detection method improves on that used in previous XRT catalogues and we report >68,000 new X-ray sources. The goals and observing strategy of the Swift satellite allow us to probe source variability on multiple timescales, and we find ~30,000 variable objects in our catalog. For every source we give positions, fluxes, time series (in four energy bands and two hardness ratios), estimates of the spectral properties, spectra and spectral fits for the brightest sources, and variability probabilities in multiple energy bands and timescales.
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- ID:
- ivo://CDS.VizieR/IX/58
- Title:
- 2SXPS Swift X-ray telescope point source catalogue
- Short Name:
- IX/58
- Date:
- 22 Feb 2022
- Publisher:
- CDS
- Description:
- We present the 2SXPS (Swift-XRT Point Source) catalog, containing 206,335 point sources detected by the Swift X-ray Telescope (XRT) in the 0.3-10 keV energy range. This catalog represents a significant improvement over 1SXPS, with double the sky coverage (now 3,790deg^2^), and several significant improvements in source detection and classification. In particular, we present for the first time techniques to model the effect of stray light - significantly reducing the number of spurious sources detected. These techniques will be very important for future, large effective area X-ray mission such as the forthcoming Athena X-ray observatory. We also present a new model of the XRT point spread function, and a method for correctly localising and characterising piled up sources. We provide light curves - in four energy bands, two hardness ratios and two binning timescales -- for every source, and from these deduce that over 80,000 of the sources in 2SXPS are variable in at least one band or hardness ratio. The catalog data can be queried or downloaded via a bespoke web interface at https://www.swift.ac.uk/2SXPS, via HEASARC, or in Vizier (IX/58)
- ID:
- ivo://CDS.VizieR/J/A+A/452/975
- Title:
- Temporal variability of Cygnus X-1
- Short Name:
- J/A+A/452/975
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present results of fitting power density spectra from archived Rossi X-ray Timing Explorer (RXTE) data of the source Cygnus X-1. The data cover the observations of the source during 1996-2003, and all spectral states are included.
- ID:
- ivo://CDS.VizieR/J/MNRAS/458/56
- Title:
- TeV gamma-ray blazar X-ray spectral studies
- Short Name:
- J/MNRAS/458/56
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- This work is a summary of the X-ray spectral studies of 29TeV (10^12^eV, tera-electron-volt) {gamma}-ray emitting blazars observed with Swift/XRT, especially focusing on sources for which the X-ray regime allows us to study the low- and the high-energy ends of the particle distribution function. Variability studies require simultaneous coverage, ideally sampling different flux states of each source. This is achieved using X-ray observations by disentangling the high-energy end of the synchrotron emission and the low-energy end of the Compton emission, which are produced by the same electron population. We focused on a sample of 29 TeV {gamma}-ray emitting blazars with the best signal-to-noise X-ray observations collected with Swift/XRT in the energy range 0.3-10keV during 10yr of Swift/XRT operations. We investigate the X-ray spectral shapes and the effects of different corrections for neutral hydrogen absorption and decompose the synchrotron and inverse Compton components. For five sources (3C 66A, S5 0716+714, W Comae, 4C +21.35 and BL Lacertae) a superposition of both components is observed in the X-ray band, permitting simultaneous, time-resolved studies of both ends of the electron distribution. The analysis of multi-epoch observations revealed that the break energy of the X-ray spectrum varies only by a small factor with flux changes. Flux variability is more pronounced in the synchrotron domain (high-energy end of the electron distribution) than in the Compton domain (low-energy end of the electron distribution). The spectral shape of the Compton domain is stable, while the flux of the synchrotron domain is variable. These changes cannot be described by simple variations of the cut-off energy, suggesting that the high-energy end of the electron distribution is not generally well described by cooling only.
- ID:
- ivo://CDS.VizieR/J/A+A/608/A68
- Title:
- TeV/non-TeV BL Lacs multi-lambda fluxes
- Short Name:
- J/A+A/608/A68
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have collected the most complete multi-wavelength (6.0-6.0E^-18^cm) dataset of very high energy (VHE) gamma-ray emitting (TeV) BL Lacs, which are the most numerous extragalactic VHE sources. Using significant correlations between different bands, we aim to identify the best TeV BL Lac candidates that can be discovered by the current and next generation of imaging air Cherenkovtelescopes. We formed five datasets from lower energy data, i.e. radio, mid-infrared, optical, X-rays, and GeV gamma-ray, and five VHE gamma-ray datasets to perform a correlation study between different bands and to construct the prediction method. The low energy datasets were averaged for individual sources, while the VHE gamma-ray data were divided into subsets according to the flux state of the source. We then looked for significant correlations and determined their best-fit parameters. Using the best-fit parameters we predicted the level of VHE gamma-ray flux for a sample of 182 BL Lacs, which have not been detected at TeV energies. We identified the most promising TeV BL Lac candidates based on the predicted VHE gamma-ray flux for each source. We found 14 significant correlations between radio, mid-infrared, optical, gamma-ray, and VHE gamma-ray bands. The correlation between optical and VHE gamma-ray luminosity is established for the first time. We attribute this to the more complete sample and more accurate handling of host galaxy flux in our work. We found nine BL Lac candidates whose predicted VHE gamma-ray flux is high enough for detection in less than 25 hours with current imaging air Cherenkov telescopes.
- ID:
- ivo://CDS.VizieR/J/ApJ/746/178
- Title:
- The augmented maxBCG cluster catalog
- Short Name:
- J/ApJ/746/178
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Reducing the scatter between cluster mass and optical richness is a key goal for cluster cosmology from photometric catalogs. We consider various modifications to the red-sequence-matched filter richness estimator of Rozo et al. (Paper I, 2009ApJ...703..601R) implemented on the maxBCG cluster catalog and evaluate the impact of these changes on the scatter in X-ray luminosity (L_X_) at fixed richness, using L_X_ from the ROSAT All-Sky Catalog as the best mass proxy available for the large area required. Most significantly, we find that deeper luminosity cuts can reduce the recovered scatter, finding that {sigma}_lnLx|{lambda}_=0.63+/-0.02 for clusters with M_500c_>~1.6x10^14^h^-1^_70_M_{sun}_. The corresponding scatter in mass at fixed richness is {sigma}_lnM|{lambda}_~0.2-0.3 depending on the richness, comparable to that for total X-ray luminosity. We find that including blue galaxies in the richness estimate increases the scatter, as does weighting galaxies by their optical luminosity. We further demonstrate that our richness estimator is very robust. Specifically, the filter employed when estimating richness can be calibrated directly from the data, without requiring a priori calibrations of the red sequence. We also demonstrate that the recovered richness is robust to up to 50% uncertainties in the galaxy background, as well as to the choice of photometric filter employed, so long as the filters span the 4000{AA} break of red-sequence galaxies. Consequently, our richness estimator can be used to compare richness estimates of different clusters, even if they do not share the same photometric data. Appendix A includes "easy-bake" instructions for implementing our optimal richness estimator, and we are releasing an implementation of the code that works with Sloan Digital Sky Survey data, as well as an augmented maxBCG catalog with the {lambda} richness measured for each cluster.
977. The BAX Database
- ID:
- ivo://CDS.VizieR/B/bax
- Title:
- The BAX Database
- Short Name:
- B/bax
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present BAX, Base de Donnees Amas de Galaxies X (http://bax.ast.obs-mip.fr), a multi-wavelength database dedicated to X-ray clusters and groups of galaxies allowing detailed information retrieval. BAX is designed to support astronomical research by providing access to published measurements of the main physical quantities and to the related bibliographic references: basic data stored in the database are cluster/group identifiers, equatorial coordinates, redshift, flux, X-ray luminosity (in the ROSAT band) and temperature, and links to additional linked parameters (in X-rays, such as spatial profile parameters, as well as SZ parameters of the hot gas, lensing measurements, and data at other wavelengths, such as optical and radio). The clusters and groups in BAX can be queried by the basic parameters as well as the linked parameters or combinations of these. We expect BAX to become an important tool for the astronomical community. BAX will optimize various aspects of the scientific analysis of X-ray clusters and groups of galaxies, from proposal planning to data collection, interpretation and publication, from both ground based facilities like MEGACAM (CFHT), VIRMOS (VLT) and space missions like XMM-Newton, Chandra and Planck.
- ID:
- ivo://CDS.VizieR/J/A+A/362/799
- Title:
- The BeppoSAX 2-10 keV Survey
- Short Name:
- J/A+A/362/799
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the results of a 2-10keV BeppoSAX survey based on 140 high galactic latitude MECS fields, 12 of which are deep exposures of ``blank'' parts of the sky. The limiting sensitivity is 5x10^-14^erg/cm^2^/s where about 25% of the Cosmic X-ray Background (CXB) is resolved into discrete sources. The logN-logS function, built with a statistically complete sample of 177 sources, is steep and in good agreement with the counts derived from ASCA surveys.
- ID:
- ivo://CDS.VizieR/J/ApJS/195/10
- Title:
- The CDF-S survey: 4Ms source catalogs
- Short Name:
- J/ApJS/195/10
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present source catalogs for the 4Ms Chandra Deep Field-South (CDF-S), which is the deepest Chandra survey to date and covers an area of 464.5arcmin^2^. We provide a main Chandra source catalog, which contains 740 X-ray sources that are detected with wavdetect at a false-positive probability threshold of 10^-5^ in at least one of three X-ray bands (0.5-8keV, full band; 0.5-2keV, soft band; and 2-8keV, hard band) and also satisfy a binomial-probability source-selection criterion of P<0.004 (i.e., the probability of sources not being real is less than 0.004); this approach is designed to maximize the number of reliable sources detected. A total of 300 main-catalog sources are new compared to the previous 2Ms CDF-S main-catalog sources. We determine X-ray source positions using centroid and matched-filter techniques and obtain a median positional uncertainty of ~0.42". We also provide a supplementary catalog, which consists of 36 sources that are detected with wavdetect at a false-positive probability threshold of 10^-5^, satisfy the condition of 0.004<P<0.1, and have an optical counterpart with R<24. Multiwavelength identifications, basic optical/infrared/radio photometry, and spectroscopic/photometric redshifts are provided for the X-ray sources in the main and supplementary catalogs. Seven hundred sixteen (~97%) of the 740 main-catalog sources have multiwavelength counterparts, with 673 (~94% of 716) having either spectroscopic or photometric redshifts. Basic analyses of the X-ray and multiwavelength properties of the sources indicate that >75% of the main-catalog sources are active galactic nuclei (AGNs); of the 300 new main-catalog sources, about 35% are likely normal and starburst galaxies, reflecting the rise of normal and starburst galaxies at the very faint flux levels uniquely accessible to the 4Ms CDF-S.
- ID:
- ivo://CDS.VizieR/B/chandra
- Title:
- The Chandra Archive Log
- Short Name:
- B/chandra
- Date:
- 07 Mar 2022 06:17:49
- Publisher:
- CDS
- Description:
- The Chandra X-Ray Observatory (CXO) is a high-resolution (< 0.5 arcsecond) X-ray telescope with a suite of advanced imaging and spectroscopic instruments. The Observatory was successfully launched by NASA's Space Shuttle Columbia on July 23, 1999. Chandra was designed to provide order-of-magnitude advances over previous X-ray astronomy missions with regards to spatial and spectral resolution. The High Resolution Mirror Assembly (HRMA) produces images with a half-power diameter (HPD) of the point spread function (PSF) of < 0.5 arcsec. Chandra has two focal plane science instruments, i) The Advanced CCD Imaging Spectrometer (ACIS), and ii) The High Resolution Camera (HRC). ACIS is comprised of two CCD arrays, a 4-chip array, ACIS-I ; and a 6-chip array, ACIS-S . ACIS-I was designed for CCD imaging and spectrometry; ACIS-S can be used both for CCD imaging spectrometry and also for high-resolution spectroscopy in conjunction with the HETG grating. A mix of ACIS-S and ACIS-I chips (up to six) may be used for imaging observations. The HRC is comprised of two microchannel plate (MCP ) imaging detectors: the HRC-I designed for wide-field imaging; and, HRC-S designed to serve as a readout for the LETG . The grating systems consist of the Low Energy Transmission Grating (LETG) and the High Energy Transmission Grating (HETG). The HETG , when operated with the HRMA and the ACIS-S , forms the High-Energy Transmission Grating Spectrometer (HETGS ) for high resolution spectroscopy . The HETGS achieves resolving power up to 1000 in the band between 0.4 keV and 10.0 keV. The LETG when operated with the HRC-S , forms the Low Energy Transmission Grating Spectrometer (LETGS ). The LETGS provides the highest spectral resolution on Chandra at low (0.08 - 0.2 keV) energies. This catalogue is a copy of the Chandra Observation Catalog from the Chandra Data Archive (CDA) which is part of the Chandra X-Ray Observatory Science Center (CXC) which is operated for NASA by the Smithsonian Astrophysical Observatory.