- ID:
- ivo://CDS.VizieR/J/PAZh/30/946
- Title:
- Unidentified cometary emission lines
- Short Name:
- J/PAZh/30/946
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We discuss the possible nature of unidentified cometary emission lines. We propose a model of the ice particles in cometary halos as a mixture of frozen polycyclic aromatic hydrocarbons (PAHs) and acyclic hydrocarbons. We describe the general properties of frozen hydrocarbon particles (FHPs) and suggest interpreting some of the unidentified cometary emission lines as the photoluminescence of FHPs. We compare the position of quasi-lines in the spectrum of Comet 122P/de Vico with the position of quasi-lines in the photoluminescence spectrum of PAHs that were dissolved in acyclic hydrocarbons at a temperature of 77K and that constituted a polycrystalline solution. We estimated the detectability of FHP photoluminescence in cometary spectra.
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- ID:
- ivo://CDS.VizieR/J/ApJS/207/4
- Title:
- Unidentified {gamma}-ray sources. III. Radio
- Short Name:
- J/ApJS/207/4
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- About one-third of the {gamma}-ray sources listed in the second Fermi Large Area Telescope catalog (2FGL) have no firmly established counterpart at lower energies and so are classified as unidentified {gamma}-ray sources (UGSs). Here, we propose a new approach to find candidate counterparts for the UGSs based on the 325 MHz radio survey performed with the Westerbork Synthesis Radio Telescope in the northern hemisphere. First, we investigate the low-frequency radio properties of blazars, the largest known population of {gamma}-ray sources; then we search for sources with similar radio properties combining the information derived from the Westerbork Northern Sky Survey (WENSS, Rengelink et al. 1997, Cat. J/A+AS/124/259; superseded by Cat. VIII/62) with those of the NRAO Very Large Array Sky Survey (NVSS, Condon et al. 1998, Cat. VIII/65). We present a list of candidate counterparts for 32 UGSs with at least one counterpart in the WENSS. We also performed an extensive research in the literature to look for infrared and optical counterparts of the {gamma}-ray blazar candidates selected using the low-frequency radio observations to confirm their nature. On the basis of our multifrequency research, we identify 23 new {gamma}-ray blazar candidates out of the 32 UGSs investigated. Comparison with previous results on the UGSs is also presented. Finally, we speculate on the advantages of using low-frequency radio observations to associate UGSs and to search for {gamma}-ray pulsar candidates.
- ID:
- ivo://CDS.VizieR/J/ApJS/209/9
- Title:
- Unidentified gamma-ray sources. IV. X-ray
- Short Name:
- J/ApJS/209/9
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- A significant fraction (~30%) of the high-energy {gamma}-ray sources listed in the second Fermi Large Area Telescope (LAT) catalog are still of unknown origin, having not yet been associated with counterparts at lower energies. To investigate the nature of these enigmatic sources, we present an extensive search of X-ray sources lying in the positional uncertainty region of a selected sample of these unidentified gamma-ray sources (UGSs) that makes use of all available observations performed by the Swift X-ray Telescope before 2013 March 31, available for 205 UGSs. To detect the fainter sources, we merged all the observations covering the Fermi LAT positional uncertainty region at a 95% level of confidence of each UGS. This yields a catalog of 357 X-ray sources, finding candidate X-ray counterparts for ~70% of the selected sample. In particular, 25% of the UGSs feature a single X-ray source within their positional uncertainty region, while 45% have multiple X-ray sources. For each X-ray source, we also looked in the corresponding Swift UVOT merged images for optical and ultraviolet counterparts, also performing source photometry. We found ultraviolet-optical correspondences for ~70% of the X-ray sources. We searched several major radio, infrared, optical, and ultraviolet surveys for possible counterparts within the positional error of the sources in the X-ray catalog to obtain additional information on their nature. Applying the kernel density estimation technique to infrared colors of Wide-Field Infrared Survey Explorer counterparts of our X-ray sources we select six {gamma}-ray blazar candidates. In addition, comparing our results with previous analyses, we select 11 additional {gamma}-ray blazar candidates.
- ID:
- ivo://CDS.VizieR/J/A+A/405/999
- Title:
- Unidentified infrared bands (UIR)
- Short Name:
- J/A+A/405/999
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a set of 6-12{mu}m ISOPHOT-S spectra of the general interstellar medium of the Milky Way. This part of the spectrum is dominated by a series of strong, wide emission features commonly called the Unidentified Infrared Bands (UIR). The sampled area covers the inner Milky Way from l=-60{deg} to +60{deg} with a ten-degree step in longitude and nominal latitudes b=0{deg}, +/-1{deg}. For each grid position the actual observed direction was selected from IRAS 100{mu}m maps to minimize contamination by point sources and molecular clouds.
- 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.
- 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://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.