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1751. Torun methanol source catalogue
ID:
ivo://CDS.VizieR/J/AN/333/634
Title:
Torun methanol source catalogue
Short Name:
J/AN/333/634
Date:
21 Oct 2021
Publisher:
CDS
Description:
We report the observations of 289 methanol maser sources at 6.7GHz obtained over a two month period with the Torun 32m telescope. The data form a catalogue of all objects north of {delta}=22{deg} brighter than 7.5Jy in the peak emission. The positions of sub-arcsecond accuracy are updated for 76% of the objects. We find that about one third of the sources show changes in the peak fluxes by a factor of two or more on time scales of 8.5-9.5 years.
1752. Transition frequencies of MN and DMN
ID:
ivo://CDS.VizieR/J/ApJ/805/141
Title:
Transition frequencies of MN and DMN
Short Name:
J/ApJ/805/141
Date:
21 Oct 2021
Publisher:
CDS
Description:
High-resolution pure rotational spectra of four alkylnaphthalenes were measured in the range of 6-15GHz using a molecular-beam Fourier-transform microwave spectrometer. Both a- and b-type transitions were observed for 1-methylnaphthalene (1-MN), 1,2-dimethylnaphthalene (1,2-DMN), and 1,3-dimethylnaphthalene (1,3-DMN); only a-type transitions were observed for 2-methylnaphthalene (2-MN). Geometry optimization and vibrational analysis calculations at the B3LYP/6-311++G(d,p) level of theory aided in the assignments of the spectra and the characterization of the structures. Differences between the experimental and predicted rotational constants are small, and they can be attributed in part to low-lying out-of-plane vibrations, which distort the alkylnaphthalenes out of their equilibrium geometries. Splittings of rotational lines due to methyl internal rotation were observed in the spectra of 2-MN, 1,2-DMN, and 1,3-DMN, and allowed for the determination of the barriers to methyl internal rotation, which are compared to values from density functional theory calculations. All four species are moderately polar, so they are candidate species for detection by radio astronomy, by targeting the transition frequencies reported here.
1753. Two distant massive clusters of galaxies
ID:
ivo://CDS.VizieR/J/MNRAS/339/913
Title:
Two distant massive clusters of galaxies
Short Name:
J/MNRAS/339/913
Date:
21 Oct 2021
Publisher:
CDS
Description:
We discuss the radio, optical, and X-ray properties of two newly discovered, very X-ray luminous, distant clusters of galaxies. Both systems were noted as cluster candidates in a cross-correlation of data from the WENSS (<VIII/162>) radio survey and the ROSAT All-Sky Survey (<IX/10>). Follow-up observations performed by us and the Massive Cluster Survey (MACS) team confirmed both sources as distant galaxy clusters. The first cluster, MACS J0717.5+3745 at a redshift of z=0.5548, contains a very extended, steep-spectrum radio source offset from the cluster core, making it the most distant radio relic known. The second cluster, MACS J1621.3+3810 at z=0.465, is a strong cooling flow with a relatively weak central radio source. We present results from ROSAT High-Resolution Imager (HRI, Cat. <IX/28>) observations of both clusters as well as from optical imaging and VLA radio interferometry observations. Our discoveries demonstrate that distant clusters can be efficiently identified in a relatively shallow X-ray survey, that radio/X-ray selection is efficient, and that both cooling flow and non-cooling flow clusters are selected.
1754. Two new catalogs of blazar candidates
ID:
ivo://CDS.VizieR/J/ApJS/242/4
Title:
Two new catalogs of blazar candidates
Short Name:
J/ApJS/242/4
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present two catalogs of radio-loud candidate blazars whose Wide-Field Infrared Survey Explorer (WISE) mid-infrared colors are selected to be consistent with the colors of confirmed {gamma}-ray-emitting blazars. The first catalog is the improved and expanded release of the WISE Blazar-like Radio-Loud Sources (WIBRaLS) catalog presented by D'Abrusco et al. It includes sources detected in all four WISE filters, spatially cross-matched with radio sources in one of three radio surveys and radio-loud based on their q_22_ spectral parameter. WIBRaLS2 includes 9541 sources classified as BL Lacs, flat-spectrum radio quasars, or mixed candidates based on their WISE colors. The second catalog, called KDEBLLACS, based on a new selection technique, contains 5579 candidate BL Lacs extracted from the population of WISE sources detected in the first three WISE passbands ([3.4], [4.6], and [12]) only, whose mid-infrared colors are similar to those of confirmed, {gamma}-ray BL Lacs. Members of KDBLLACS are also required to have a radio counterpart and be radio-loud based on the parameter q_12_, defined similarly to the q_22_ used for the WIBRaLS2. We describe the properties of these catalogs and compare them with the largest samples of confirmed and candidate blazars in the literature. We cross-match the two new catalogs with the most recent catalogs of {gamma}-ray sources detected by the Fermi Large Area Telescope. Since spectroscopic observations of candidate blazars from the first WIBRaLS catalog within the uncertainty regions of {gamma}-ray unassociated sources confirmed that ~90% of these candidates are blazars, we anticipate that these new catalogs will again play an important role in the identification of the {gamma}-ray sky.
1755. Type IIP supernova SN 2004dj radio observations
ID:
ivo://CDS.VizieR/J/ApJ/863/163
Title:
Type IIP supernova SN 2004dj radio observations
Short Name:
J/ApJ/863/163
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present radio observations and modeling of one of the nearest and brightest Type IIP supernova SN 2004dj exploded in the galaxy NGC2403 at a distance of ~3.5Mpc. Our observations span a wide frequency and temporal range of 0.24-43GHz and ~1d to 12yrs since the discovery. We model the radio light curves and spectra with the synchrotron emission. We estimate the mass-loss rate of the progenitor star to be dM/dt~1x10^-6^M_{sun}_/yr for a wind speed of 10km/s. We calculate the radio spectral indices using 1.06, 1.40, 5.00, and 8.46GHz flux density measurements at multiple epochs. We witness steepening in the spectral index values for an extended period predominantly at higher frequencies. We explain this as a signature of electron cooling happening at the supernova shock in the plateau phase of the supernova. We estimate the cooling timescales for inverse Compton cooling and synchrotron cooling and find that inverse Compton cooling is the dominant cooling process.
1756. Type 2 quasars from SDSS
ID:
ivo://CDS.VizieR/J/AJ/136/2373
Title:
Type 2 quasars from SDSS
Short Name:
J/AJ/136/2373
Date:
21 Oct 2021
Publisher:
CDS
Description:
Type 2 quasars are luminous active galactic nuclei whose central regions are obscured by large amounts of gas and dust. In this paper, we present a catalog of type 2 quasars from the Sloan Digital Sky Survey, selected based on their optical emission lines. The catalog contains 887 objects with redshifts z<0.83; this is 6 times larger than the previous version and is by far the largest sample of type 2 quasars in the literature.
1757. UBVRI photometry of EUV stellar sources
ID:
ivo://CDS.VizieR/J/A+AS/138/87
Title:
UBVRI photometry of EUV stellar sources
Short Name:
J/A+AS/138/87
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present the results of high-precision UBV(RI)_c_ photometric observations and of spectroscopic radial velocity measurements obtained at the European Southern Observatory for a sample of 51 cool stars detected in the EUV by the ROSAT Wide Field Camera (WFC). Using also recent results from HIPPARCOS, we infer spectral types and investigate the single or binary nature of the sample stars. Optical variability, with periods in the 0.4-13 day range, has been detected for the first time in 15 of these stars.
1758. UGSs. V. kernel approach
ID:
ivo://CDS.VizieR/J/ApJS/209/10
Title:
UGSs. V. kernel approach
Short Name:
J/ApJS/209/10
Date:
21 Oct 2021
Publisher:
CDS
Description:
Nearly one-third of the {gamma}-ray sources detected by Fermi are still unidentified, despite significant recent progress in this area. However, all of the {gamma}-ray extragalactic sources associated in the second Fermi-LAT catalog have a radio counterpart. Motivated by this observational evidence, we investigate all the radio sources of the major radio surveys that lie within the positional uncertainty region of the unidentified {gamma}-ray sources (UGSs) at a 95% level of confidence. First, we search for their infrared counterparts in the all-sky survey performed by the Wide-field Infrared Survey Explorer (WISE) and then we analyze their IR colors in comparison with those of the known {gamma}-ray blazars. We propose a new approach, on the basis of a two-dimensional kernel density estimation technique in the single [3.4]-[4.6]-[12]{mu}m WISE color-color plot, replacing the constraint imposed in our previous investigations on the detection at 22{mu}m of each potential IR counterpart of the UGSs with associated radio emission. The main goal of this analysis is to find distant {gamma}-ray blazar candidates that, being too faint at 22{mu}m, are not detected by WISE and thus are not selected by our purely IR-based methods. We find 55 UGSs that likely correspond to radio sources with blazar-like IR signatures. An additional 11 UGSs that have blazar-like IR colors have been found within the sample of sources found with deep recent Australia Telescope Compact Array observations.
1759. u_j_br photometry and redshifts of QSOs
ID:
ivo://CDS.VizieR/J/MNRAS/341/993
Title:
u_j_br photometry and redshifts of QSOs
Short Name:
J/MNRAS/341/993
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present a detailed analysis of a sample of radio-detected quasars, obtained by matching together objects from the FIRST (<VIII/71>) survey and the 2dF Quasar Redshift Survey (2dF, <VII/223>). The data set consists of 113 sources, spanning a redshift range 0.35<~z<~2.2, with optical magnitudes 18.25<=bj<=20.85 and radio fluxes S_1.4GHz_>=1mJy. These objects exhibit properties such as redshift and colour distribution in full agreement with those derived for the whole quasar population, suggesting that the mechanism(s) controlling the birth and lifetime of quasars are independent of their level of radio emission. The long-debated question of the radio-loud/radio quiet (RL/RQ) dichotomy is then investigated for the combined FIRST-2dF and FIRST-LBQS (Large Bright Quasar Survey) samples, as they present similar selection criteria.
1760. UKIDSS+FIRST+SDSS red QSOs candidates
ID:
ivo://CDS.VizieR/J/ApJ/778/127
Title:
UKIDSS+FIRST+SDSS red QSOs candidates
Short Name:
J/ApJ/778/127
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present the results of a pilot survey to find dust-reddened quasars by matching the Faint Images of the Radio Sky at Twenty-Centimeters (FIRST) radio catalog to the UKIDSS near-infrared survey and using optical data from Sloan Digital Sky Survey to select objects with very red colors. The deep K-band limit provided by UKIDSS allows for finding more heavily reddened quasars at higher redshifts as compared with previous work using FIRST and Two Micron All Sky Survey (2MASS). We selected 87 candidates with K<=17.0 from the UKIDSS Large Area Survey (LAS) First Data Release (DR1), which covers 190deg^2^. These candidates reach up to ~1.5mag below the 2MASS limit and obey the color criteria developed to identify dust-reddened quasars. We have obtained 61 spectroscopic observations in the optical and/or near-infrared, as well as classifications in the literature, and have identified 14 reddened quasars with E(B-V)>0.1, including 3 at z>2. We study the infrared properties of the sample using photometry from the Wide-Field Infrared Survey Explorer and find that infrared colors improve the efficiency of red quasar selection, removing many contaminants in an infrared-to-optical color-selected sample alone. The highest-redshift quasars (z>~2) are only moderately reddened, with E(B-V)~0.2-0.3. We find that the surface density of red quasars rises sharply with faintness, comprising up to 17% of blue quasars at the same apparent K-band flux limit. We estimate that to reach more heavily reddened quasars (i.e., E(B-V)>~0.5) at z>2 and a depth of K=17, we would need to survey at least ~2.5 times more area.