- ID:
- ivo://CDS.VizieR/J/PASJ/63/S677
- Title:
- MAXI/GSC catalog in high Galactic-latitude sky
- Short Name:
- J/PASJ/63/S677
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the first unbiased source catalog of the Monitor of All-sky X-ray Image (MAXI) mission at high Galactic latitudes (|b|>10{deg}), produced from the first 7-month data (2009 September 1 to 2010 March 31) of the Gas Slit Camera in the 4-10keV band. We have developed an analysis procedure to detect faint sources from the MAXI data, utilizing a maximum likelihood image fitting method, where the image response, background, and detailed observational conditions are taken into account. The catalog consists of 143 X-ray sources above the 7{sigma} significance level with a limiting sensitivity of ~1.5x10^-11^erg/cm^2^/s (1.2mCrab) in the 4-10keV band. Among them, we have identified 38 Galactic/LMC/SMC objects, 48 galaxy clusters, 39 Seyfert galaxies, 12 blazars, and 1 galaxy. Four other sources are confused with multiple objects, and one remains unidentified. The logN-logS relation of extragalactic objects is in good agreement with the HEAO-1 A-2 result, although the list of the brightest AGNs in the entire sky has significantly changed since that produced 30yr ago.
Number of results to display per page
Search Results
- ID:
- ivo://CDS.VizieR/J/PASJ/68/S32
- Title:
- MAXI/SSC catalog of X-ray sources in 0.7-7.0keV
- Short Name:
- J/PASJ/68/S32
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the first source catalog of the Solid-state Slit Camera (SSC) of the Monitor of All-sky X-ray Image (MAXI) mission on the International Space Station, using the 45-month data from 2010 August to 2014 April in the 0.7-7.0keV bands. Sources are searched for in two energy bands, 0.7-1.85keV (soft) and 1.85-7.0keV (hard), the limiting sensitivity of 3 and 4mCrab are achieved, and 140 and 138 sources are detected in the soft and hard energy bands, respectively. Combining the two energy bands, 170 sources are listed in the MAXI/SSC catalog. All but 2 sources are identified with 22 galaxies including AGNs, 29 cluster of galaxies, 21 supernova remnants, 75 X-ray binaries, 8 stars, 5 isolated pulsars, and 9 non-categorized objects. Comparing the soft-band fluxes at the brightest end in our catalog with the ROSAT survey, which was performed about 20 years ago, 10% of the cataloged sources are found to have changed flux since the ROSAT era.
- ID:
- ivo://CDS.VizieR/J/A+A/341/163
- Title:
- MBM 7 and MBM 55 X-ray sources
- Short Name:
- J/A+A/341/163
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The star formation capability of two molecular clouds at high galactic latitude (|b|>30{deg}) is investigated. Possible pre-main sequence stars in and around the translucent clouds MBM7 and MBM55 have been identified via their X-ray emission by inspecting ROSAT All-Sky Survey observations of the clouds and environs and ROSAT pointed observations of the high-density cores within the clouds. Follow-up optical spectroscopy of the stellar X-ray sources with V<=15.5mag was conducted with the 1.5-m Fred Lawrence Whipple Observatory telescope to identify standard signatures of pre-main sequence stars (LiI {lambda}6708{AA} absorption and H{alpha} emission). We found 11 stars which have lithium equivalent widths, W(Li), above our detection threshold. Three of the stars with lithium also have weak H{alpha} emission. Relative ages for the stars with lithium are estimated by their position on an W(Li) vs. T_eff_ diagram. A calibration derived from data for several clusters with known ages indicates that the stars are older than the translucent high-latitude clouds. This conclusion is supported by a comparison with theoretical evolutionary tracks of the stars from our sample for which we have distance measurements from Hipparcos. We find it is unlikely that any of the X-ray active, lithium-rich stars we identified have formed in the clouds in question. Theoretical and observational arguments support this conclusion and render unlikely the possibility that low-extinction translucent clouds are the sites of star formation.
- ID:
- ivo://CDS.VizieR/J/ApJ/577/738
- Title:
- M31 Chandra X-ray point sources
- Short Name:
- J/ApJ/577/738
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report on Chandra observations of the central region of M31. By combining eight Chandra ACIS-I observations taken between 1999 and 2001, we have identified 204 X-ray sources within the central ~17'x17' region of M31, with a detection limit of ~2x10^35^erg/s. Of these 204 sources, 22 are identified with globular clusters, two with supernova remnants, nine with planetary nebulae, and nine with supersoft sources. By comparing individual images, about 50% of the sources are variable on timescales of months. We also found 13 transients, with light curves showing a variety of shapes. We also extracted the energy spectra of the 20 brightest sources; they can be well fitted by a single power law with a mean photon index of 1.8. The spectral shapes of 12 sources are shown to be variable, suggesting that they went through state changes.
- ID:
- ivo://CDS.VizieR/J/ApJ/609/735
- Title:
- M31 Chandra X-ray sources
- Short Name:
- J/ApJ/609/735
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have obtained 17 epochs of Chandra High Resolution Camera (HRC) snapshot images, each covering most of the M31 disk. The data cover a total baseline of ~2.5yr and contain a mean effective exposure of 17ks. We have measured the mean fluxes and long-term light curves for 166 objects detected in these data.
- ID:
- ivo://CDS.VizieR/J/A+A/534/A109
- Title:
- MCXC Meta-Catalogue X-ray galaxy Clusters
- Short Name:
- J/A+A/534/A109
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the compilation and properties of a meta-catalogue of X-ray detected clusters of galaxies, the MCXC. This very large catalogue is based on publicly available ROSAT All Sky Survey-based (NORAS, REFLEX, BCS, SGP, NEP, MACS, and CIZA) and serendipitous (160SD, 400SD, SHARC, WARPS, and EMSS) cluster catalogues. Data have been systematically homogenised to an overdensity of 500, and duplicate entries from overlaps between the survey areas of the individual input catalogues are carefully handled. The MCXC comprises 1743 clusters with virtually no duplicate entries. For each cluster the MCXC provides three identifiers, a redshift, coordinates, membership in the original catalogue, and standardised 0.1-2.4keV band luminosity L_500_, total mass M_500_, and radius R_500_. The meta-catalogue additionally furnishes information on overlaps between the input catalogues and the luminosity ratios when measurements from different surveys are available, and gives notes on individual objects.
- ID:
- ivo://CDS.VizieR/J/MNRAS/461/3443
- Title:
- M31 deepest Chandra catalogue of point sources
- Short Name:
- J/MNRAS/461/3443
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- This study represents the most sensitive Chandra X-ray point source catalogue of M31. Using 133 publicly available Chandra ACIS-I/S observations totalling ~1Ms, we detected 795 X-ray sources in the bulge, north-east, and south-west fields of M31, covering an area of ~=0.6deg^2^, to a limiting unabsorbed 0.5-8.0keV luminosity of ~10^34^erg/s. In the inner bulge, where exposure is approximately constant, X-ray fluxes represent average values because they were determined from many observations over a long period of time. Similarly, our catalogue is more complete in the bulge fields since monitoring allowed more transient sources to be detected. The catalogue was cross-correlated with a previous XMM-Newton catalogue of M31's D_25_ isophote consisting of 1948 X-ray sources, with only 979 within the field of view of our survey. We found 387 (49 per cent) of our Chandra sources (352 or 44 per cent unique sources) matched to within 5 arcsec of 352 XMM-Newton sources. Combining this result with matching done to previous Chandra X-ray sources we detected 259. new sources in our catalogue. We created X-ray luminosity functions (XLFs) in the soft (0.5-2.0keV) and hard (2.0-8.0keV) bands that are the most sensitive for any large galaxy based on our detection limits. Completeness-corrected XLFs show a break around ~=1.3x10^37^erg/s, consistent with previous work. As in past surveys, we find that the bulge XLFs are flatter than the disc, indicating a lack of bright high-mass X-ray binaries in the disc and an aging population of low-mass X-ray binaries in the bulge.
- ID:
- ivo://CDS.VizieR/J/A+A/638/A20
- Title:
- M dwarfs X-ray activity and rotation relations
- Short Name:
- J/A+A/638/A20
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The relation of activity to rotation in M dwarfs is of high astrophysical interest because it provides observational evidence of the stellar dynamo, which is poorly understood for low-mass stars, especially in the fully convective regime. Previous studies have shown that the relation of X-ray activity to rotation consists of two different regimes: the saturated regime for fast-rotating stars and unsaturated regime for slowly rotating stars. The transition between the two regimes lies at a rotation period of ~10d. We present here a sample of 14 M dwarf stars observed with XMM-Newton and Chandra, for which we also computed rotational periods from Kepler Two-Wheel (K2) Mission light curves. We compiled X-ray and rotation data from the literature and homogenized all data sets to provide the largest uniform sample of M dwarfs (302 stars) for X-ray activity and rotation studies to date. We then fit the relation between LX-Prot using three different mass bins to separate partially and fully convective stars. We found a steeper slope in the unsaturated regime for fully convective stars and a nonconstant LX level in the saturated regime for all masses. In the LX/Lbol-R_O_ space we discovered a remarkable double gap that might be related to a discontinuous period evolution. Then we combined the evolution of Prot predicted by angular momentum evolution models with our new results on the empirical LX-Prot relation to provide an estimate for the age decay of X-ray luminosity. We compare predictions of this relationship with the actual X-ray luminosities of M stars with known ages from 100Myr to a few billion years. We find remarkably good agreement between the predicted LX and the observed values for partially convective stars. However, for fully convective stars at ages of a few billion years, the constructed LX-age relation overpredicts the X-ray luminosity because the angular momentum evolution model underpredicts the rotation period of these stars. Finally, we examine the effect of different parameterizations for the Rossby number (R_O_) on the shape of the activity-rotation relation in LX/Lbol-R_O_ space, and we find that the slope in the unsaturated regime and the location of the break point of the dual power-law depend sensitively on the choice of R_O_.
- ID:
- ivo://CDS.VizieR/J/A+A/530/A147
- Title:
- Megamaser detection in Seyfert galaxies
- Short Name:
- J/A+A/530/A147
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We revisit the relation between H_2_O maser detection rate and nuclear obscuration for a sample of 114 Seyfert galaxies, drawn from the CfA, 12um and IRAS F25/F60 catalogs. These sources have mid-infrared spectra from the Spitzer Space Telescope and they are searched for X-ray and [OIII] (5007{AA}) fluxes from the literature. We use the strength of the [OIV] (25.9um) emission line as tracer for the intrinsic AGN strength. After normalization by [OIV] the observed X-ray flux provides information about X-ray absorption. The distribution of X-ray/[OIV] flux ratios is significantly different for masers and non-masers: The maser detected Seyfert-2s (Sy 1.8-2.0) populate a distinct X-ray/[OIV] range which is, on average, about a factor four lower than the range of Seyfert-2 non-masers and about a factor of ten lower than the range of Seyfert-1s (Sy 1.0-1.5). Non-masers are almost equally distributed over the entire X-ray/[OIV] range. This provides evidence that high nuclear obscuration plays a crucial role for the probability of maser detection. Furthermore, after normalization with [OIV], we find a similar but weaker trend for the distribution of the maser detection rate with the absorption of the 7um dust continuum. This suggests that the obscuration of the 7um continuum occurs on larger spatial scales than that of the X-rays. Hence, in the AGN unified model, at moderate deviation from edge-on, the 7um dust absorption may occur without proportionate X-ray absorption. The absorption of [OIII] appears unrelated to maser detections. The failure to detect masers in obscured AGN is most likely due to insufficient observational sensitivity.
- ID:
- ivo://CDS.VizieR/J/A+A/637/A43
- Title:
- Membership in the Cepheus association
- Short Name:
- J/A+A/637/A43
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Young field stars are hardly distinguishable from older ones because their space motion rapidly mixes them with the stellar population of the Galactic plane.Nevertheless, a careful target selection allows for young stars to be spotted throughout the sky. We aim to identify additional sources associated with the four young comoving stars that we discovered towards the CO Cepheus void and to provide a comprehensive view of the Cepheus association. Based on multivariate analysis methods, we have built an extended sample of 193 young star candidates, which are the optical and infrared counterparts of ROSAT All-Sky Survey and XMM-Newton X-ray sources. From optical spectroscopic observations, we measured their radial velocity with the cross-correlation technique. We derived their atmospheric parameters and projected rotational velocity with the code ROTFIT. We applied the subtraction of inactive templates to measure the lithium equivalent width, from which we infer their lithium abundance and age. Finally, we studied their kinematics using the second Gaia data release. Our sample is mainly composed of young or active stars and multiple systems. We identify two distinct populations of young stars that are spatially and kinematically separated. Those with an age between 100 and 300Myr are mostly projected towards the Galactic plane. In contrast, 23 of the 37 sources younger than 30Myr are located in the CO Cepheus void, and 21 of them belong to the stellar kinematic group that we previously reported in this sky area. We report a total of 32 bona fide members and nine candidates for this nearby (distance=157+/-10pc) young (age=10-20Myr) stellar association. According to the spatial distribution of its members, the original cluster is already dispersed and partially mixed with the local population of the Galactic plane.
