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1131. ASCA AGN optical identifications
ID:
ivo://CDS.VizieR/J/ApJS/148/275
Title:
ASCA AGN optical identifications
Short Name:
J/ApJS/148/275
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present the results of optical spectroscopic identifications of a bright subsample of 2-10keV hard X-ray-selected sources from the ASCA Medium Sensitivity Survey in the northern sky (AMSSn). The flux limit of the subsample is 3x10^-13^erg/s/cm^2^ in the 2-10keV band. All but one of the 87 hard X-ray-selected sources are optically identified, with AGNs (including broad-line AGNs, narrow-line AGNs, and three BL Lac objects), seven clusters of galaxies, and one galactic star. It is the largest complete sample of hard X-ray-selected AGNs at the bright flux limit. Amounts of absorption to their nuclei are estimated to be hydrogen column densities (NH) of up to 3x10^23^cm^-2^ from their X-ray spectra. Optical properties of X-ray absorbed AGNs with N_H_>1x10^22^cm^-2^ indicate the effects of dust absorption: at redshifts z<0.6, AGNs without broad H{beta} emission lines have significantly larger NH-values than AGNs with broad H{beta} emission lines. At z>0.6, the X-ray absorbed AGNs have a large hard X-ray to optical flux ratio (logf_2-10keV_/f_R_>+1). However, three X-ray absorbed z>0.6 AGNs show strong broad lines. In combination with hard X-ray-selected AGN samples from the ASCA Large Sky Survey, the ASCA Deep Survey in the Lockman Hole, and Chandra Deep Field North, the luminosity distributions of absorbed (N_H_>1x10^22^cm^-2^) and less-absorbed (N_H_<1x10^22^cm^-2^) AGNs are compared.
1132. ASCA Deep survey in Lockman Hole Field
ID:
ivo://CDS.VizieR/J/PASJ/53/445
Title:
ASCA Deep survey in Lockman Hole Field
Short Name:
J/PASJ/53/445
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present the results of deep observations of the Lockman Hole field with the ASCA SIS, covering 926arcmin^2^ in the 1-7keV energy range, with a sensitivity 3-5 times deeper than the previous ASCA larger area surveys. Utilizing the results of the ROSAT Ultra Deep survey, we have detected 32, 25, and 15 sources in the 1-7, 1-2, and 2-7keV bands, and only 4, 4, and 1 sources remain unidentified, respectively. The average hardness of the sources detected in the 1-7keV band with fluxes of between 10^-14^ and 10^-13^erg/cm^2^/s corresponds to a photon index of 1.65+/-0.10. Type-2 AGNs show significantly harder spectra than type-1s, which can be explained by absorption column densities of N_H_~10^22-23^cm^-2 at the source redshifts. Fifteen sources are detected in the hard-band (2-7keV), consisting of six type-1 AGNs, six type-2 AGNs, one star, one cluster of galaxies, and one unidentified source. Type-2 AGNs make up a major part of hard X-ray populations in the 2-7keV band at a flux level of 3x10^-14^erg/cm^2^/s (2-7 keV). The redshift distributions of type-1 and type-2 AGNs suggest a lack of high luminosity (optically-defined) type-2 AGNs with intrinsic N_H_<10^23^cm^-2, n the redshift range z~1-2 and/or with intrinsic luminosities larger than 3x10^44^erg/s (2-10keV at source frame).
1133. ASCA Galactic Plane Survey faint X-ray sources
ID:
ivo://CDS.VizieR/J/ApJS/134/77
Title:
ASCA Galactic Plane Survey faint X-ray sources
Short Name:
J/ApJS/134/77
Date:
21 Oct 2021
Publisher:
CDS
Description:
The X-ray emission from the central region of the Galactic plane, |l|<~45{deg} and |b|<~0.4{deg}, was studied in the 0.710keV energy band with a spatial resolution of ~3' with the Advanced Satellite for Cosmology and Astrophysics (ASCA) observatory. We developed a new analysis method for the ASCA data to resolve discrete sources from the extended Galactic ridge X-ray emission (GRXE). We successfully resolved 163 discrete sources with an X-ray flux down to 10^-12.5^ergs/cm^2^/s and determined the intensity variations of the GRXE as a function of the Galactic longitude with a spatial resolution of about 1{deg}.
1134. ASCA Large Sky Survey
ID:
ivo://CDS.VizieR/J/ApJ/518/656
Title:
ASCA Large Sky Survey
Short Name:
J/ApJ/518/656
Date:
21 Oct 2021
Publisher:
CDS
Description:
We carried out the first wide-area unbiased survey with the ASCA satellite in the 0.7-10keV band around a north Galactic-pole region covering a continuous area of 7deg^2^ (Large Sky Survey; LSS). To make the best use of ASCA's capabilities, we developed a new source-detection method in which the complicated detector responses are fully taken into account. Applying this method to the entire LSS data independently in the total (0.7-7keV), hard (2-10keV), and soft (0.7-2keV) bands, we detected 107 sources altogether, with sensitivity limits of 6x10^-14^ (0.7-7keV), 1x10^-13^ (2-10keV), and 2x10^-14^ergs/s/cm^2^ (0.7-2keV), respectively. A complete list of the detected sources is presented.
1135. ASCA sources in the SMC
ID:
ivo://CDS.VizieR/J/PASJ/55/161
Title:
ASCA sources in the SMC
Short Name:
J/PASJ/55/161
Date:
21 Oct 2021
Publisher:
CDS
Description:
We made 22 observations on the Small Magellanic Cloud (SMC) and covered full regions of the main body and the eastern wing by the end of the ASCA mission. We detected 106 discrete sources with a criterion of S/N>5 and performed systematic analyses on all of the sources. We determined the source positions with an ~40" error radius (90% confidence) for sources detected in the central 20' radius of the GIS. We detected coherent pulsations from 17 sources. Among them, eight were newly discovered during this study. We classified most of these pulsars as X-ray binary pulsars (XBPs) based on their properties, such as the flux variability and the existence of an optical counterpart. We detected X-ray emission from eight supernova remnants (SNRs). Based on these ASCA results and further information from ROSAT, SAX, RXTE, CGRO, Chandra, and XMM-Newton, we compiled comprehensive catalogues of discrete X-ray sources in the Small Magellanic Cloud.
1136. ASC Gaia Attitude Star Catalog
ID:
ivo://CDS.VizieR/VI/145
Title:
ASC Gaia Attitude Star Catalog
Short Name:
VI/145
Date:
21 Oct 2021
Publisher:
CDS
Description:
The ASC is a compilation produced for the Gaia mission. We have combined data from the following catalogs or datasets to produce a homogenous list of positions, proper motions, photometry in a blue and red band and estimates of the magnitudes in the Gaia G and G_RVS bands: Tycho2, UCAC4, Hipparcos, PPMXL, GSC2.3 and Sky2000. Originally ASC sources were selected from the Initial Gaia Source List (IGSL, <A HREF="http://cdsarc.u-strasbg.fr/cgi-bin/Cat?I/324">I/324</A>). However, here we produce a cleaner catalog starting from the bright source catalogs and using the following criteria: 1) The candidate must be in the Tycho2, UCAC4, Hipparcos or Sky2000 catalog. 2) The Gaia G magnitude must be brighter than 13.4. 3) The star must be isolated from other objects of similar magnitudes 4) The object must not be in the Washington Double Star catalog 5) If a healpix 6th region has more than 1000 objects the magnitude limit is reduced to reduce the number of objects in that region. Since the ASC was produced independently from the IGSL using different procedures there is not a direct 1 to 1 match between ASC and IGSL entries. We have matched the ASC to the IGSL and found that 9 out of the 8 million entries do not have a clear match. Since there may still remain ambiguous matches in the 8 million matched objects, we decided to assign the sourceIDs of the IGSL with the adjustment that the runningnumber is equal to the IGSL runningnumber + 320000. Included Catalogs: Tycho2, UCAC4, Sky2000, HIPPARCOS for candidates and the PPMXL, GSC2.3 were used to calculating magnitudes.
1137. AS CrB BVRI light curves
ID:
ivo://CDS.VizieR/J/other/NewA/51.1
Title:
AS CrB BVRI light curves
Short Name:
J/other/NewA/51.
Date:
21 Oct 2021
Publisher:
CDS
Description:
The first high-precision BVRI light curves of the eclipsing binary AS CrB were presented and were analyzed by the 2015 version of the W-D code. It is found that AS CrB is an extreme mass-ratio, deep contact binary with a fill-out factor of f=59.6+/-2.5% and a mass ratio of q=0.172+/-0.008q=0.172+/-0.008. Based on the photometric solution and the Dartmouth isochrones model, the masses, radii, and luminosities of the components are estimated as follows: M_1_=1.25+/-0.15M_{sun}_, M_1_=1.25+/-0.15M_{sun}_, M_2_=0.21+/-0.06M_{sun}_, M_2_=0.21+/-0.06M_{sun}_, R_1_=1.40+/-0.07R_{sun}_, R_1_=1.40+/-0.07R_{sun}_, R_2_=0.67+/-0.04R_{sun}_, R_2_=0.67+/-0.04R_{sun}_, L_1_=3.2+/-0.2L_{sun}_, L_1_=3.2+/-0.2L_{sun}_, and L_2_=0.72+/-0.04L_{sun}_, L_2_=0.72+/-0.04L_{sun}_, with an estimated distance 459+/-42pc. These uncertainties mainly come from the errors of the color used to estimate the temperature of the primary star. By investigating all of the available times of light minima, it is found that the Observed-Calculated [(O-C)(O-C)] curve shows a long-term period increase, with a rate of dP/dt=+(3.46+/-0.01)x10^-7^dP/dt=+(3.46+/-0.01)x10^-7^day/year. As an extreme mass-ratio contact binary, AS CrB may merge into a single star, such as an FK Com-type star or a blue straggler, because of the orbital instability.
1138. A search for accreting young companions
ID:
ivo://CDS.VizieR/J/A+A/622/A156
Title:
A search for accreting young companions
Short Name:
J/A+A/622/A156
Date:
21 Oct 2021
Publisher:
CDS
Description:
In recent years, our understanding of giant planet formation progressed substantially. There have even been detections of a few young protoplanet candidates still embedded in the circumstellar disks of their host stars. The exact physics that describes the accretion of material from the circumstellar disk onto the suspected circumplanetary disk and eventually onto the young, forming planet is still an open question. We seek to detect and quantify observables related to accretion processes occurring locally in circumstellar disks, which could be attributed to young forming planets. We focus on objects known to host protoplanet candidates and/or disk structures thought to be the result of interactions with planets. We analyzed observations of six young stars and their surrounding environments with the SPHERE/ZIMPOL instrument on the Very Large Telescope (VLT) in the H{alpha} filter (656nm) and a nearby continuum filter (644.9nm). We redetect the known accreting M-star companion HD142527 B with the highest published signal to noise to date in both H{alpha} and the continuum. No other companions are detected. We analyzed observations of six young stars (age 3.5-10Myr) and their surrounding environments with the SPHERE/ZIMPOL instrument on the Very Large Telescope (VLT) in the H{alpha}filter (656nm) and a nearby continuum filter (644.9nm). We applied several point spread function (PSF) subtraction techniques to reach the highest possible contrast near the primary star, specifically investigating regions where forming companions were claimed or have been suggested based on observed disk morphology.
1139. A search for Compact High-Velocity Clouds
ID:
ivo://CDS.VizieR/J/A+A/391/159
Title:
A search for Compact High-Velocity Clouds
Short Name:
J/A+A/391/159
Date:
21 Oct 2021
Publisher:
CDS
Description:
An automated search is applied to the Leiden/Dwingeloo HI Survey (LDS) for high-velocity clouds north of Dec.=-28{deg}. From the general catalog we extract a sample of relatively small (less than about 8{deg}) and isolated high-velocity clouds, CHVCs: anomalous-velocity HI clouds which are sharply bounded in angular extent with no kinematic or spatial connection to other HI features down to a limiting column density of 1.5x10^18cm^-2. Unambiguously isolated objects are given the "CHVC" designation, while those with some degree of ambiguity in this classification or designated "CHVC:" or "CHVC?". The vast majority of features show diffuse connections at low column densities with the extended HVC complexes and are simply designated as "HVC" features. The automated search algorithm has been applied to the HIPASS and to the Leiden/Dwingeloo data sets. The results from the LDS are described here; Putman et al. (2002, Cat. <J/AJ/123/873>) describe application of this algorithm to the HIPASS material. Only those catalog entries which have and additional ID listed have been confirmed in independent data.
1140. A search for double-peaked AGNs in AGES
ID:
ivo://CDS.VizieR/J/ApJ/777/64
Title:
A search for double-peaked AGNs in AGES
Short Name:
J/ApJ/777/64
Date:
21 Oct 2021
Publisher:
CDS
Description:
Dual supermassive black holes (SMBHs) with kiloparsec-scale separations in merger-remnant galaxies are informative tracers of galaxy evolution, but the avenue for identifying them in large numbers for such studies is not yet clear. One promising approach is to target spectroscopic signatures of systems where both SMBHs are fueled as dual active galactic nuclei (AGNs), or where one SMBH is fueled as an offset AGN. Dual AGNs may produce double-peaked narrow AGN emission lines, while offset AGNs may produce single-peaked narrow AGN emission lines with line-of-sight velocity offsets relative to the host galaxy. We search for such dual and offset systems among 173 Type 2 AGNs at z<0.37 in the AGN and Galaxy Evolution Survey (AGES), and we find two double-peaked AGNs and five offset AGN candidates. When we compare these results to a similar search of the DEEP2 Galaxy Redshift Survey and match the two samples in color, absolute magnitude, and minimum velocity offset, we find that the fraction of AGNs that are dual SMBH candidates increases from z=0.25 to z=0.7 by a factor of ~6 (from 2/70 to 16/91, or 2.9_-1.9_^+3.6^% to 18_-5_^+5^%). This may be associated with the rise in the galaxy merger fraction over the same cosmic time. As further evidence for a link with galaxy mergers, the AGES offset and dual AGN candidates are tentatively ~3 times more likely than the overall AGN population to reside in a host galaxy that has a companion galaxy (from 16/173 to 2/7, or 9_-2_^+3^% to 29_-19_^+26^%). Follow-up observations of the seven offset and dual AGN candidates in AGES will definitively distinguish velocity offsets produced by dual SMBHs from those produced by narrow-line region kinematics, and will help sharpen our observational approach to detecting dual SMBHs.