- ID:
- ivo://CDS.VizieR/J/MNRAS/412/1853
- Title:
- Unidentified X-ray sources in XMM Slew Survey
- Short Name:
- J/MNRAS/412/1853
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present deep Swift follow-up observations of a sample of 94 unidentified X-ray sources from the XMM-Newton Slew Survey. The X-ray Telescope (XRT) on-board Swift detected 29 per cent of the sample sources; the flux limits for undetected sources suggest the bulk of the Slew Survey sources are drawn from one or more transient populations. We report revised X-ray positions for the XRT-detected sources, with typical uncertainties of 2.9 arcsec, reducing the number of catalogued optical matches to just a single source in most cases. We characterize the sources detected by Swift through their X-ray spectra and variability and via Ultraviolet-Optical Telescope photometry and using catalogued near-infrared, optical and radio observations of potential counterparts. Six sources can be associated with known objects and eight sources may be associated with unidentified ROSAT sources within the 3{sigma} error radii of our revised X-ray positions.
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- ID:
- ivo://CDS.VizieR/J/A+A/584/A103
- Title:
- Unified EoS for neutron stars
- Short Name:
- J/A+A/584/A103
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We derive a new equation of state (EoS) for neutron stars (NS) from the outer crust to the core based on modern microscopic calculations using the Argonne v18 potential plus three-body forces computed with the Urbana model. To deal with the inhomogeneous structures of matter in the NS crust, we use a recent nuclear energy density functional that is directly based on the same microscopic calculations, and which is able to reproduce the ground-state properties of nuclei along the periodic table. The EoS of the outer crust requires the masses of neutron-rich nuclei, which are obtained through Hartree-Fock-Bogoliubov calculations with the new functional when they are unknown experimentally. To compute the inner crust, Thomas-Fermi calculations in Wigner-Seitz cells are performed with the same functional. Existence of nuclear pasta is predicted in a range of average baryon densities between 0.067fm^-3^ and 0.0825fm^-3^, where the transition to the core takes place. The NS core is computed from the new nuclear EoS assuming non-exotic constituents (core of n-p-e-mu matter). In each region of the star, we discuss the comparison of the new EoS with previous EoSs for the complete NS structure, widely used in astrophysical calculations. The new microscopically derived EoS fulfills at the same time a NS maximum mass of 2 solar masses with a radius of 10km, and a 1.5 solar mass NS with a radius of 11.6km.
- ID:
- ivo://CDS.VizieR/J/ApJ/660/1072
- Title:
- Unified model of active galactic nuclei
- Short Name:
- J/ApJ/660/1072
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We assemble a sample composed of 243 nearby Seyfert galaxies with redshifts z<=0.05 to test the unification scheme. The sample contains 94 broad emission line Seyfert 1 galaxies (BLS1s), 44 narrow emission line Seyfert 1s (NLS1s), 36 X-ray-absorbed hidden broad line region Seyfert 2s (HBLR S2s), 42 X-ray-absorbed non-HBLR S2s, and 27 X-ray-unabsorbed Seyfert 2s (unabsorbed non-HBLR S2s and HBLR S2s). We find that (1) NLS1s have less massive black hole masses than BLS1s, (2) HBLR S2s have the same mass distribution of black holes as BLS1s, (3) absorbed non-HBLR S2s have less massive black holes than HBLR S2s, and (4) unabsorbed non-HBLR S2s have the most massive black holes.
- ID:
- ivo://irsa.ipac/USNO/Catalog/USNO-B1
- Title:
- United States Naval Observatory B1.0 Catalog
- Short Name:
- USNO-B1
- Date:
- 01 Oct 2018 20:27:21
- Publisher:
- NASA/IPAC Infrared Science Archive
- Description:
- This all-sky catalog, described in Monet et al. (2003), consists of positions, proper motions, magnitudes, and other measured quantities for 1,045,175,762 objects. The data were derived from digitizing scans of almost 7,500 photographic plates taken from various sky surveys during the interval from 1949 to 2002. The originating plate material includes five complete coverages of the northern sky and four of the southern sky. To be included in the catalog, an object must have been detected on two different surveys because isolated, single-survey detections are unreliable. For the earlier USNO-A catalog (which was essentially a two-color, one-epoch catalog), this meant that the object must have had detectable fluxes on both the red and blue plates, and this led to the exclusion of many faint objects with non-neutral colors. Also, the larger epoch difference in the southern survey coverage meant that objects with larger proper motions tended to be excluded. USNO-B1.0 attempts to fix both of these problems. An object detected in the same band at two epochs will be included in USNO-B1.0, as will objects that have significant proper motions, although it is still the case that objects with large motions and extreme colors may be omitted. The selection algorithm requires that spatially coincident detections must be made on any two of the surveys for an object to be classified as real and be included in the catalog. The catalog is expected to be complete down to V=21. Estimated positional accuracies are 0.2 arcsec, photographic magnitude accuracies are 0.3 mag, and the accuracy for distinguishing stars from non-stellar objects is 85%.
- ID:
- ivo://CDS.VizieR/J/ApJS/105/343
- Title:
- Universidad Complutense de Madrid list 2
- Short Name:
- J/ApJS/105/343
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- A low dispersion objective-prism survey for low-redshift emission-line galaxies (ELGs) is being carried out by the University Complutense de Madrid with the Schmidt telescope at the German-Spanish Observatory of Calar Alto (Almeria, Spain). A 4{deg} full aperture prism, which provides a dispersion of 1950{AA}/mm, and IIIa-F emulsion combination has been used to search for ELGs selected by the presence of H{alpha} emission in their spectra. A compilation of descriptions and positions, along with finding charts, is presented for 103 emission-line objects. This is the second list, which contains objects located in a region of the sky covering 201.4{deg}^2^ in seven fields near {alpha}=15h and {delta}=25{deg}.
- ID:
- ivo://CDS.VizieR/J/ApJS/122/415
- Title:
- Universidad Complutense de Madrid list 3
- Short Name:
- J/ApJS/122/415
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- A new low-dispersion objective-prism search for low-redshift (z<0.045) emission-line galaxies (ELGs) has been carried out by the Universidad Complutense de Madrid using the Schmidt Telescope at the Calar-Alto Observatory. This is a continuation of the UCM Survey, which was performed by visual selection of candidates in photographic plates via the presence of the H{alpha}+[N II]{lambda}6584 blend in emission. In making this new list we have applied an automatic procedure, fully developed by us, for selecting and analyzing ELG candidates on the digitized images obtained with the "Machine Automatique a Mesurer pour l'Astronomie" (MAMA). The analyzed region of the sky covers 189deg^2^ in nine fields near RA=14h and 17h, DE=25{deg}. The final sample contains 113 candidates. Special effort has been made to obtain a large amount of information directly from our uncalibrated plates by using several external calibrations. The parameters obtained for the ELG candidates allow us to study the statistical properties of the sample.
- ID:
- ivo://CDS.VizieR/J/ApJS/95/387
- Title:
- Universidad Complutense de Madrid list 1
- Short Name:
- J/ApJS/95/387
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- A low dispersion objective-prism survey for low-redshift emission-line galaxies (ELGs) is being carried out by the University Complutense de Madrid with the Schmidt telescope at the German-Spanish Observatory of Calar Alto (Almeria, Spain). A 4deg full aperture prism, which provides a dispersion of 1950A/mm, and IIIa-F emulsion combination has been used to search for ELGs selected by the presence of H{alpha} emission in their spectra. Our survey has proved to be able to recover objects already found by similar surveys with different techniques and, what is more important, to discover new objects not previously catalogued. A compilation of descriptions and positions, along with finding charts when necessary, is presented for 160 extragalactic emission-line objects. This is the first list, which contains objects located in a region of the sky covering 270deg^2^ in 10 fields near {alpha}=0h and {delta}=20deg.
- ID:
- ivo://CDS.VizieR/J/A+A/647/A195
- Title:
- Unknown active galactic nuclei study
- Short Name:
- J/A+A/647/A195
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We collect data at all frequencies for the new sources classified as unknown active galactic nuclei (AGNs) in the latest Burst Alert Telescope all-sky hard X-ray catalog. Focusing on the 36 sources with measured redshift, we compute their spectral energy distribution (SED) from radio to {gamma}-rays with the aim to classify these objects. We apply emission models that attempt to reproduce the obtained SEDs, including: (i) a standard thin accretion disk together with an obscuring torus and a X-ray corona; (ii) a two temperature thick advection-dominated flow; (iii) an obscured AGN model, accounting for absorption along the line of sight at kiloelectronvolt energies and in the optical band; and (iv) a phenomenological model to describe the jet emission in blazar-like objects. We integrate the models with the SWIRE template libraries to account for the emission of the host galaxy. For every source we found a good agreement between data and our model. Considering that the sources were selected in the hard X-ray band, which is rather unaffected by absorption, we expected and found a large fraction of absorbed radio-quiet AGNs (31 out of 36) and some additional rare radio-loud sources (5 out of 36), since the jet emission in hard X-rays is important for aligned jets owing to the boost produced by the beaming effect. With our work we can confirm the hypothesis that a number of galaxies, whose optical spectra lack AGN emission features, host an obscured active nucleus. The approach we used proved to be efficient in rapidly identifying objects, which commonly used methods were not able to classify.
- ID:
- ivo://CDS.VizieR/J/ApJ/856/85
- Title:
- Unlocking CO depletion in protoplanetary disks. I.
- Short Name:
- J/ApJ/856/85
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- CO is commonly used as a tracer of the total gas mass in both the interstellar medium and in protoplanetary disks. Recently, there has been much debate about the utility of CO as a mass tracer in disks. Observations of CO in protoplanetary disks reveal a range of CO abundances, with measurements of low CO to dust mass ratios in numerous systems. One possibility is that carbon is removed from CO via chemistry. However, the full range of physical conditions conducive to this chemical reprocessing is not well understood. We perform a systematic survey of the time dependent chemistry in protoplanetary disks for 198 models with a range of physical conditions. We vary dust grain size distribution, temperature, comic-ray and X-ray ionization rates, disk mass, and initial water abundance, detailing what physical conditions are necessary to activate the various CO depletion mechanisms in the warm molecular layer. We focus our analysis on the warm molecular layer in two regions: the outer disk (100au) well outside the CO snowline and the inner disk (19au) just inside the midplane CO snowline. After 1Myr, we find that the majority of models have a CO abundance relative to H_2_ less than 10^-4^ in the outer disk, while an abundance less than 10^-5^ requires the presence of cosmic-rays. Inside the CO snowline, significant depletion of CO only occurs in models with a high cosmic-ray rate. If cosmic-rays are not present in young disks, it is difficult to chemically remove carbon from CO. Additionally, removing water prior to CO depletion impedes the chemical processing of CO. Chemical processing alone cannot explain current observations of low CO abundances. Other mechanisms must also be involved.
- ID:
- ivo://CDS.VizieR/J/AJ/157/211
- Title:
- Unresolved binaries in TESS with speckle imaging
- Short Name:
- J/AJ/157/211
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Transiting Exoplanet Survey Satellite (TESS) is conducting a two-year wide-field survey searching for transiting exoplanets around nearby bright stars that will be ideal for follow-up characterization. To facilitate studies of planet compositions and atmospheric properties, accurate and precise planetary radii need to be derived from the transit light curves. Since 40%-50% of exoplanet host stars are in multiple star systems, however, the observed transit depth may be diluted by the flux of a companion star, causing the radius of the planet to be underestimated. High angular resolution imaging can detect companion stars that are not resolved in the TESS Input Catalog, or by seeing-limited photometry, to validate exoplanet candidates and derive accurate planetary radii. We examine the population of stellar companions that will be detectable around TESS planet candidate host stars, and those that will remain undetected, by applying the detection limits of speckle imaging to the simulated host star populations of Sullivan et al. (2015, J/ApJ/809/77) and Barclay et al. (2018, J/ApJS/239/2). By detecting companions with contrasts of {Delta}m~<7-9 and separations of ~0.02"-1.2", speckle imaging can detect companion stars as faint as early M stars around A-F stars and stars as faint as mid-M around G-M stars, as well as up to 99% of the expected binary star distribution for systems located within a few hundred parsecs.
