- ID:
- ivo://CDS.VizieR/J/AJ/151/154
- Title:
- Second epoch VLBA Calibrator Survey (VCS-II)
- Short Name:
- J/AJ/151/154
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Six very successful Very Long Baseline Array (VLBA) calibrator survey campaigns were run between 1994 and 2007 to build up a large list of compact radio sources with positions precise enough for use as very long baseline interferometry (VLBI) phase reference calibrators. We report on the results of a second epoch VLBA Calibrator Survey campaign (VCS-II) in which 2400 VCS sources were re-observed in the X and S bands in order to improve the upcoming third realization of the International Celestial Reference Frame (ICRF3) as well as to improve their usefulness as VLBI phase reference calibrators. In this survey, some 2062 previously detected sources and 324 previously undetected sources were detected and revised positions are presented. Average position uncertainties for the re-observed sources were reduced from 1.14 and 1.98mas to 0.24 and 0.41mas in R.A. and decl., respectively, or by nearly a factor of 5. Minimum detected flux values were approximately 15 and 28mJy in the X and S bands, respectively, and median total fluxes are approximately 230 and 280mJy. The vast majority of these sources are flat-spectrum sources, with ~82% having spectral indices greater than -0.5.
Number of results to display per page
Search Results
- ID:
- ivo://CDS.VizieR/J/A+AS/147/187
- Title:
- Second list of the Karachentsev catalog
- Short Name:
- J/A+AS/147/187
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Table2 presents the results of HI observations of 78 'nearby dwarf galaxies' from Karachentseva et al. (1999A&AS..135..221K) obtained with the 100-m radio telescope at Effelsberg. This survey covers an area limited by R.A.[14h,23h30] and Dec[-20d,+60d] including the nearest cosmic void : R.A.[18h38m], Dec[+18d], V_0_<1500km/s.
- ID:
- ivo://CDS.VizieR/J/AJ/126/2562
- Title:
- Second VLBA calibrator survey: VCS2
- Short Name:
- J/AJ/126/2562
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- This paper presents an extension of the Very Long Baseline Array Calibrator Survey, called VCS2, containing 276 sources. This survey fills in regions of the sky that were not completely covered by the previous VCS1 calibrator survey. The VCS2 survey includes calibrator sources near the Galactic plane, -30{deg}<DE<-45{deg}, and VLA calibrators. The positions have been derived from astrometric analysis of the group delays measured at 2.3 and 8.4 GHz using the Goddard Space Flight Center CALC/SOLVE package. From the VLBA snapshot observations, images of the calibrators are available, and each source is given a quality code for anticipated use. The VCS2 catalog is available from the NRAO Web site.
- ID:
- ivo://CDS.VizieR/J/A+A/658/A160
- Title:
- SEDIGISM survey, search for molecular outflows
- Short Name:
- J/A+A/658/A160
- Date:
- 22 Feb 2022
- Publisher:
- CDS
- Description:
- The formation processes of massive stars are still unclear but a picture is emerging involving accretion disks and molecular outflows in what appears to be a scaled-up version of lower-mass star formation. A census of outflow activity towards high-mass star-forming clumps in various evolutionary stages has the potential to shed light on high-mass star formation. We conduct an outflow survey toward ATLASGAL (APEX Telescope Large Area Survey of the Galaxy) clumps, using SEDIGISM (structure, Excitation, and Dynamics of the Inner Galactic InterStellar Medium) data and aim to obtain a large sample of clumps exhibiting outflow activity in different evolutionary stages. We identify the high-velocity wings of the ^13^CO lines, indicating outflow activity, toward ATLASGAL clumps by (1) extracting the simultaneously observed ^13^CO(2-1) and C^18^O(2-1) spectra from SEDIGISM, and (2) subtracting the scaled C^18^O (cores emission) from the ^13^CO, after considering opacity broadening. We have detected high-velocity gas towards 1192 clumps out of a total sample of 2052 corresponding to an overall detection rate of 58%. Outflow activity has been detected from the earliest (apparently) quiescent clumps (i.e., 70 microns weak), to the most evolved HII region stages (i.e., 8 micron bright with tracers of massive star formation). The detection rate increases as a function of evolution (quiescent = 51%, protostellar = 47%, YSO = 57%, UCHII regions = 76%). Our sample is the largest outflow sample identified so far. The high detection rate from this large sample is consistent with the results of similar studies reported in the literature and supports the scenario that outflows are a ubiquitous feature of high-mass star formation. The lower detection rate in early evolutionary stages could be due to the fact that outflows in the early stages are weak and difficult to detect. We obtain a statistically significant number of outflow clumps for every evolutionary stage, especially for outflow clumps in the earliest stages (i.e., 70 microns dark cloud or massive starless core).
- ID:
- ivo://CDS.VizieR/J/ApJ/694/992
- Title:
- SED of cluster radio galaxies
- Short Name:
- J/ApJ/694/992
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- To explore the high-frequency radio spectra of galaxies in clusters, we used NRAO's Very Large Array at four frequencies, 4.9-43GHz, to observe 139 galaxies in low redshift (z<0.25), X-ray detected, clusters. The clusters were selected from the survey conducted by Ledlow and Owen (1997ApJS..108...41O), who provided redshifts and 1.4GHz flux densities for all the radio sources. We find that more than half of the observed sources have steep microwave spectra as generally expected ({alpha}<-0.5, in the convention S{proto}{nu}^{alpha}^). However, 60%-70% of the unresolved or barely resolved sources have flat or inverted spectra. Most of these show an upward turn in flux at {nu}>22GHz, implying a higher flux than would be expected from an extrapolation of the lower-frequency flux measurements. Our results quantify the need for careful source subtraction in increasingly sensitive measurements of the Sunyaev-Zel'dovich effect in clusters of galaxies (as currently being conducted by, for instance, the Atacama Cosmology Telescope and South Pole Telescope groups).
- ID:
- ivo://CDS.VizieR/J/ApJ/716/30
- Title:
- SED of Fermi bright blazars
- Short Name:
- J/ApJ/716/30
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have conducted a detailed investigation of the broadband spectral properties of the {gamma}-ray selected blazars of the Fermi LAT Bright AGN Sample (LBAS, Cat. J/ApJ/700/597). By combining our accurately estimated Fermi {gamma}-ray spectra with Swift, radio, infra-red, optical, and other hard X-ray/{gamma}-ray data, collected within 3 months of the LBAS data taking period, we were able to assemble high-quality and quasi-simultaneous spectral energy distributions (SED) for 48 LBAS blazars. We have used these SED to characterize the peak intensity of both the low- and the high-energy components. The results have been used to derive empirical relationships that estimate the position of the two peaks from the broadband colors (i.e., the radio to optical, {alpha}_ro_, and optical to X-ray, {alpha}_ox_, spectral slopes) and from the {gamma}-ray spectral index. While more than 50% of known radio bright high energy peaked (HBL) BL Lacs are detected in the LBAS sample, only less than 13% of known bright broad-lined flat spectrum radio quasars (FSRQs) and LBL BL Lacs are included. This suggests that the latter sources, as a class, may be much fainter {gamma}-ray emitters than LBAS blazars, and could in fact radiate close to the expectations of simple synchrotron self-Compton (SSC) models. We categorized all our sources according to a new physical classification scheme based on the generally accepted paradigm for Active Galactic Nuclei and on the results of this SED study.
- ID:
- ivo://CDS.VizieR/J/MNRAS/392/768
- Title:
- SED of 180 SIMBA 1.2mm sources
- Short Name:
- J/MNRAS/392/768
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Concatenating data from the millimetre regime to the infrared, we have performed spectral energy distribution (SED) modelling for 227 of the 405 millimetre continuum sources of Hill et al. (2005, Cat. J/MNRAS/363/405) which are thought to contain young massive stars in the earliest stages of their formation. Three main parameters are extracted from the fits: temperature, mass and luminosity. The method employed was the Bayesian inference, which allows a statistically probable range of suitable values for each parameter to be drawn for each individual protostellar candidate. This is the first application of this method to massive star formation.
- ID:
- ivo://CDS.VizieR/J/ApJ/836/185
- Title:
- SEDs of the radio continuum from KINGFISHER
- Short Name:
- J/ApJ/836/185
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We study the spectral energy distribution (SED) of the radio continuum (RC) emission from the Key Insight in Nearby Galaxies Emitting in Radio (KINGFISHER) sample of nearby galaxies to understand the energetics and origin of this emission. Effelsberg multi-wavelength observations at 1.4, 4.8, 8.4, and 10.5GHz combined with archive data allow us, for the first time, to determine the mid-RC (1-10GHz, MRC) bolometric luminosities and further present calibration relations versus the monochromatic radio luminosities. The 1-10GHz radio SED is fitted using a Bayesian Markov Chain Monte Carlo technique leading to measurements for the nonthermal spectral index (S_{nu}_~{nu}^-{alpha}_nt_^) and the thermal fraction (f_th_) with mean values of {alpha}_nt_=0.97+/-0.16 (0.79+/-0.15 for the total spectral index) and f_th_=(10+/-9)% at 1.4GHz. The MRC luminosity changes over ~3 orders of magnitude in the sample, 4.3x10^2^L_{sun}_<MRC<3.9x10^5^L_{sun}_. The thermal emission is responsible for ~23% of the MRC on average. We also compare the extinction-corrected diagnostics of the star-formation rate (SFR) with the thermal and nonthermal radio tracers and derive the first star-formation calibration relations using the MRC radio luminosity. The nonthermal spectral index flattens with increasing SFR surface density, indicating the effect of the star-formation feedback on the cosmic-ray electron population in galaxies. Comparing the radio and IR SEDs, we find that the FIR-to-MRC ratio could decrease with SFR, due to the amplification of the magnetic fields in star-forming regions. This particularly implies a decrease in the ratio at high redshifts, where mostly luminous/star-forming galaxies are detected.
- ID:
- ivo://CDS.VizieR/J/ApJ/759/6
- Title:
- SEDs of type I AGN in COSMOS. I. XMM-COSMOS
- Short Name:
- J/ApJ/759/6
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The "Cosmic Evolution Survey" (COSMOS) enables the study of the spectral energy distributions (SEDs) of active galactic nuclei (AGNs) because of the deep coverage and rich sampling of frequencies from X-ray to radio. Here we present an SED catalog of 413 X-ray (XMM-Newton)-selected type 1 (emission line FWHM>2000km/s) AGNs with Magellan, SDSS, or VLT spectrum. The SEDs are corrected for Galactic extinction, broad emission line contributions, constrained variability, and host galaxy contribution. We present the mean SED and the dispersion SEDs after the above corrections in the rest-frame 1.4GHz to 40keV, and show examples of the variety of SEDs encountered. In the near-infrared to optical (rest frame ~8{mu}m-4000{AA}), the photometry is complete for the whole sample and the mean SED is derived from detections only. Reddening and host galaxy contamination could account for a large fraction of the observed SED variety.
- ID:
- ivo://CDS.VizieR/J/MNRAS/442/577
- Title:
- Selected ALESS submm galaxies radio properties
- Short Name:
- J/MNRAS/442/577
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a study of the radio properties of 870 {mu}m-selected submillimetre galaxies (SMGs), observed at high resolution with Atacama Large Millimeter Array (ALMA) in the Extended Chandra Deep Field South. From our initial sample of 76 ALMA SMGs, we detect 52 SMGs at >3{sigma} significance in Karl G. Jansky Very Large Array 1400MHz imaging, of which 35 are also detected at >3{sigma} in new 610MHz Giant Metre-Wave Radio Telescope imaging. Within this sample of radio-detected SMGs, we measure a median radio spectral index {alpha}_{610}_^{1400}^=-0.79+/-0.06, (with inter-quartile range {alpha}=[-1.16,-0.56]) and investigate the far-infrared/radio correlation via the parameter q_IR_, the logarithmic ratio of the rest-frame 8-1000{mu}m flux and monochromatic radio flux. Our median q_IR_=2.56+/-0.05 (inter-quartile range q_IR_=[2.42,2.78]) is higher than that typically seen in single-dish 870{mu}m-selected sources (q_IR_~2.4), which may reflect the fact that our ALMA-based study is not biased to radio-bright counterparts, as previous samples were. Finally, we search for evidence that q_IR_ and {alpha} evolve with age in a codependent manner, as predicted by starburst models: the data populate the predicted region of parameter space, with the stellar mass tending to increase along tracks of q_IR_ versus {alpha} in the direction expected, providing the first observational evidence in support of these models.
