- ID:
- ivo://CDS.VizieR/J/MNRAS/416/1135
- Title:
- Unbiased sample of CSS and GPS
- Short Name:
- J/MNRAS/416/1135
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Compact Steep Spectrum (CSS) and Gigahertz Peaked Spectrum (GPS) sources are classes of compact, powerful, extragalactic objects. These sources are thought to be the earliest stages in the evolution of radio galaxies, capturing the ignition (or, in some cases, re-ignition) of the active galactic nucleus. As well as serving as probes of the early stages of large-scale radio sources, these sources are good, stable, amplitude calibrators for radio telescopes. We present an unbiased flux density limited (>1.5Jy at 2.7GHz) catalogue of these objects in the Southern hemisphere, including tabulated data, radio spectra, and where available, optical images and measurements. The catalogue contains 26 sources, consisting of two new candidates and 15 known CSS sources, and nine known GPS sources. We present new Australia Telescope Compact Array (ATCA) data on 10 of these 26 sources, and data on a further 42 sources which were excluded from our final sample. This bright sample will serve as a reference sample for comparison with subsequent faint (mJy level) samples of CSS and GPS candidates currently being compiled.
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- ID:
- ivo://CDS.VizieR/J/A+A/342/881
- Title:
- Uncertainties in r-abundance distribution
- Short Name:
- J/A+A/342/881
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Tables 1&2 correspond to the first estimate of the error factors affecting the {beta} decay rates of highly ionized heavy atoms in stellar environments. The uncertainties in the stellar {beta}-decay and EC rates strongly depend on the relevance of the experimentally unknown transitions at a given temperature and density and the reliability of their evaluated probability. To estimate the temperature- and density-dependent errors on the {beta}-decay rates, we have reiterated the Yokoi & Takahashi (1987, At. Data Nucl. Data Tables 36, 375) calculation with unknown transition rates modified by a typical error value of log(ft)=+/-0.5 (Takahashi 1998, private communication). No transition faster than log(ft)=5 is permitted in this error calculation. Newly measured transition probabilities, e.g. the allowed transition in the ^187^Re bound-state {beta}-decay (Bosch et al., 1996PhRvL..77.5190B), have been considered. Minimum and maximum error factors around the published rates of Yokoi & Takahashi (1987) are given in Tables 1 and 2 at temperatures 1<=T_8_<=4 and electronic densities (expressed in terms of 10^26^cm^-3^ of 1<=N_e_<=30. When the density-dependence does not affect the final uncertainty factor by more than 0.10 between the N_e_=1 and 3 cases, only values at N_e_=10 are given in the tables. Note that an increase of transition probability by log(ft)=0.5 gives rise to an increase of the final rate by a maximum value of 3.16. This maximum variation is obtained for many rates. The derived error factors are used in parametric s-process calculations within the canonical multi-event model to estimate their impact on the predicted s-abundance distribution and the resulting uncertainties on the solar r-abundance distribution.
- ID:
- ivo://CDS.VizieR/J/ApJ/798/54
- Title:
- "Under-massive" black hole candidates
- Short Name:
- J/ApJ/798/54
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Several recent papers have reported on the occurrence of active galactic nuclei (AGNs) containing undermassive black holes relative to a linear scaling relation between black hole mass (M_bh_) and host spheroid stellar mass (M_sph,*_). However, dramatic revisions to the M_bh_-M_sph,*_ and M_bh_-L_sph_ relations, based on samples containing predominantly inactive galaxies, have recently identified a new steeper relation at M_bh_<~(2-10)x10^8^M_{sun}_, roughly corresponding to M_sph,*_<~(0.3-1)x10^11^M_{sun}_. We show that this steeper, quadratic-like M_bh_-M_sph,*_ relation defined by the Sersic galaxies, i.e., galaxies without partially depleted cores, roughly tracks the apparent offset of the AGN having 10^5^<~M_bh_/M_{sun}_<~0.5x10^8^. That is, these AGNs are not randomly offset with low black hole masses, but also follow a steeper (nonlinear) relation. As noted by Busch et al. (2014, J/A+A/561/A140), confirmation or rejection of a possible AGN offset from the steeper M_bh_-M _sph,*_ relation defined by the Sersic galaxies will benefit from improved stellar mass-to-light ratios for the spheroids hosting these AGNs. Several implications for formation theories are noted. Furthermore, reasons for possible under- and overmassive black holes, the potential existence of intermediate mass black holes (<10^5^M_{sun}_), and the new steep (black hole)-(nuclear star cluster) relation, M_bh_{propto}M_nc_^2.7+/-0.7^, are also discussed.
22034. UniDAM results
- ID:
- ivo://CDS.VizieR/J/A+A/604/A108
- Title:
- UniDAM results
- Short Name:
- J/A+A/604/A108
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Galactic archaeology, the study of the formation and evolution of the Milky Way by reconstructing its past from its current constituents, requires precise and accurate knowledge of stellar parameters for as many stars as possible. To achieve this, a number of large spectroscopic surveys have been undertaken and are still ongoing. So far consortia carrying out the different spectroscopic surveys have used different tools to determine stellar parameters of stars from their derived effective temperatures, surface gravities, and metallicities; the parameters can be combined with photometric, astrometric, interferometric, or asteroseismic information. Here we aim to homogenise the stellar characterisation by applying a unified tool to a large set of publicly available spectrophotometric data. We used spectroscopic data from a variety of large surveys combined with infrared photometry from 2MASS and AllWISE and compared these in a Bayesian manner with PARSEC isochrones to derive probability density functions (PDFs) for stellar masses, ages, and distances. We treated PDFs of pre-helium-core burning, helium-core burning, and post helium-core burning solutions as well as different peaks in multimodal PDFs (i.e. each unimodal sub-PDF) of the different evolutionary phases separately. For over 2.5 million stars we report mass, age, and distance estimates for each evolutionary phase and unimodal sub-PDF. We report Gaussian, skewed, Gaussian, truncated Gaussian, modified truncated exponential distribution or truncated Student's t-distribution functions to represent each sub-PDF, allowing us to reconstruct detailed PDFs. Comparisons with stellar parameter estimates from the literature show good agreement within uncertainties. We present UniDAM, the unified tool applicable to spectrophotometric data of different surveys, to obtain a homogenised set of stellar parameters.
- 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.
- 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.
