- ID:
- ivo://CDS.VizieR/J/A+A/562/A70
- Title:
- Imaging GRB 980425 in millimetic and submm
- Short Name:
- J/A+A/562/A70
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Gamma-ray bursts (GRBs) have been proposed as a tool to study star formation in the Universe, so it is crucial to investigate whether their host galaxies and immediate environments are in any way special compared with other star-forming galaxies. Here we present spatially resolved maps of dust emission of the host galaxy of the closest known GRB 980425 at z=0.0085 using our new high-resolution observations from Herschel, APEX, ALMA and ATCA. We modeled the spectral energy distributions of the host and of the star-forming region displaying the Wolf-Rayet signatures in the spectrum (WR region), located 800pc away from the GRB position. The host is characterised by low dust content and high fraction of UV-visible star-formation, similar to other dwarf galaxies. Such galaxies are abundant in the local universe, so it is not surprising to find a GRB in one of them, assuming the correspondence between the GRB rate and star-formation. The WR region contributes substantially to the host emission at the far-infrared, millimeter and radio wavelengths and we propose this to be a consequence of its high gas density. If dense environments are also found close to the positions of other GRBs, then the ISM density should also be considered as an important factor influencing whether a given stellar population can produce a GRB, in a similar way as metallicity.
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- ID:
- ivo://CDS.VizieR/J/MNRAS/439/545
- Title:
- Infrared-faint radio sources catalog
- Short Name:
- J/MNRAS/439/545
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a sample of 1317 Infrared-faint radio sources (IFRSs) that, for the first time, are reliably detected in the infrared, generated by cross-correlating the Wide-field Infrared Survey Explorer (WISE) all-sky survey with major radio surveys. Our IFRSs are brighter in both radio and infrared than the first-generation IFRSs that were undetected in the infrared by the Spitzer Space Telescope. We present the first spectroscopic redshifts of IFRSs, and find that all but one of the IFRSs with spectroscopy have z>2. We also report the first X-ray counterparts of IFRSs, and present an analysis of radio spectra and polarization, and show that they include gigahertz peaked-spectrum, compact steep-spectrum and ultra-steep-spectrum sources. These results, together with their WISE infrared colours and radio morphologies, imply that our sample of IFRSs represents a population of radio-loud active galactic nuclei at z>2. We conclude that our sample consists of lower redshift counterparts of the extreme first-generation IFRSs, suggesting that the fainter IFRSs are at even higher redshift.
- ID:
- ivo://CDS.VizieR/J/AZh/83/542
- Title:
- Integrated Radio Luminosities of Pulsars
- Short Name:
- J/AZh/83/542
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The integrated radio luminosities of 311 long-period (P>0.1s) and 27 short-period (P<0.1s) pulsars have been calculated using a new compilation of radio spectra. The luminosities are in the range 10^27^-10^30^erg/s for 88% of the long-period pulsars and 10^28^-10^31^erg/s for 88% of the short-period pulsars. We find a high correlation between the luminosity L and the estimate L1=S_(400)_*d^2^ from the catalog of Taylor et al. (1993, See Cat. <VII/189>. The factor 'eta' for transformation of the rotational energy of the neutron star into radio emission increases/decreases with increasing period for long-period/short-period pulsars. The mean value of 'eta'=-3.73 for the long-period and -4.85 for the short-period pulsars.
- ID:
- ivo://CDS.VizieR/J/ApJ/872/16
- Title:
- Integrated star formation law revisited. I.
- Short Name:
- J/ApJ/872/16
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We use new and updated gas- and dust-corrected star formation rate (SFR) surface densities to revisit the integrated star formation law for local "quiescent" spiral, dwarf, and low surface brightness galaxies. Using UV-based SFRs with individual IR-based dust corrections, we find that "normal" spiral galaxies alone define a tight Σ<SUB>(HI+H2)–Σ</SUB>SFR_ relation described by an n=1.41<SUB>–0.07</SUB><SUP>+0.07</SUP> power law with a dispersion of 0.28<SUB>–0.02</SUB><SUP>+0.02</SUP> (errors reflect fitting and statistical uncertainties). The SFR surface densities are only weakly correlated with HI surface densities alone, exhibiting a stronger and roughly linear correlation with H<SUB>2</SUB> surface densities, similar to what is seen in spatially resolved measurements of disks. However, many dwarf galaxies lie below the star formation law defined by spirals, suggesting a low-density threshold in the integrated star formation law. We consider alternative scaling laws that better describe both spirals and dwarfs. Our improved measurement precision also allows us to determine that much of the scatter in the star formation law is intrinsic, and we search for correlations between this intrinsic scatter and secondary physical parameters. We find that dwarf galaxies exhibit second-order correlations with the total gas fraction, stellar mass surface density, and dynamical time, which may explain much of the scatter in the star formation law. Finally, we discuss various systematic uncertainties that should be kept in mind when interpreting any study of the star formation law, particularly the X(CO) conversion factor and the diameter chosen to define the star-forming disk in a galaxy.
- ID:
- ivo://CDS.VizieR/J/AJ/77/405
- Title:
- Intense radio sources at 1400MHz (BDFL sample)
- Short Name:
- J/AJ/77/405
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Accurate flux densities, precise positions of unresolved sources, and structures of resolved sources have been derived from full-beam and interferometric observations of intense sources at 1400 MHz. Results are given for 424 sources in the area of sky -5{deg}<{delta}<+70{deg}, |b|>5 whose 1400-MHz integrated flux densities S_1400_ exceed 1.70Jy [1 Jy (flux unit) = 10^-26^w/m^2^/Hz]. The 234 sources with S_1400_>=2.00Jy, equivalent diameters <10arcmin, and |b|>20{deg} form a 98+/-2% complete sample comparable in number to the 178-MHz Revised Third Cambridge Catalogue in this 4.30-sr area of sky, but selected at 1400MHz. This sample is suitable for statistical studies of the properties of extragalactic radio sources. To facilitate its use, and that of other samples which may be drawn from these data, references to other studies of the positions, fine and extended structure, polarization, and variability of the sources have been assembled in the principal table of this paper (Table 2). A comparison is made with other 1400-MHz flux-density data (Sec. 3), and the spectral content of the complete sample is discussed (Sec. 4).
- ID:
- ivo://CDS.VizieR/VIII/60
- Title:
- Interferometer phase calibration sources
- Short Name:
- VIII/60
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The catalogue contains compact radio sources with accurate positions observed with the Very Large Array (VLA). These sources are primarily intended for use as phase calibration sources for the Multi-Element Radio Linked Interferometer Network (MERLIN); the sources are also suitable as phase calibrators for the VLA and can be considered as candidate phase calibrators for very long-baseline interferometry (VLBI) networks. The accuracy of the position is 12 mas for sources in Paper I, 14 mas for sources in Paper II, and 55 mas for sources in Paper III.
- ID:
- ivo://CDS.VizieR/J/MNRAS/473/2965
- Title:
- Interplanetary scintillation at 79 and 158MHz
- Short Name:
- J/MNRAS/473/2965
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the first dedicated observations of Interplanetary Scintillation (IPS) with the Murchison Widefield Array. We have developed a synthesis imaging technique, tailored to the properties of modern 'large-N' low-frequency radio telescopes. This allows us to image the variability on IPS time-scales across 900deg^2^ simultaneously. We show that for our observations, a sampling rate of just 2Hz is sufficient to resolve the IPS signature of most sources. We develop tests to ensure that IPS variability is separated from ionospheric or instrumental variability. We validate our results by comparison with existing catalogues of IPS sources, and near-contemporaneous observations by other IPS facilities. Using just 5 min of data, we produce catalogues at both 79 and 158MHz, each containing over 350 scintillating sources. At the field centre, we detect approximately one scintillating source per square degree, with a minimum scintillating flux density at 158MHz of 110mJy, corresponding to a compact flux density of approximately 400mJy. Each of these sources is a known radio source, however only a minority were previously known to contain sub-arcsecond components. We discuss our findings and the prospects they hold for future astrophysical and heliospheric studies.
- ID:
- ivo://CDS.VizieR/J/MNRAS/474/4937
- Title:
- Interplanetary scintillation at 162 and 1400MHz
- Short Name:
- J/MNRAS/474/4937
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report the first astrophysical application of the technique of wide-field interplanetary scintillation (IPS) with the Murchison Widefield Array (MWA). This powerful technique allows us to identify and measure sub-arcsecond compact components in low-frequency radio sources across large areas of sky without the need for long-baseline interferometry or ionospheric calibration. We present the results of a 5-min observation of a 30x30deg^2^ MWA field at 162MHz with 0.5s time resolution. Of the 2550 continuum sources detected in this field, 302 (12 per cent) show rapid fluctuations caused by IPS. We find that at least 32 per cent of bright low-frequency radio sources contain a sub-arcsecond compact component that contributes over 40 per cent of the total flux density. Perhaps surprisingly, peaked-spectrum radio sources are the dominant population among the strongly scintillating, low-frequency sources in our sample. While gamma-ray active galactic nuclei are generally compact, flat-spectrum radio sources at higher frequencies (162MHz), the properties of many of the Fermi blazars in our field are consistent with a compact component embedded within more extended low-frequency emission. The detection of a known pulsar in our field shows that the wide-field IPS technique is at the threshold of sensitivity needed to detect new pulsars using image plane analysis, and scaling the current MWA sensitivity to that expected for SKA-low implies that large IPS-based pulsar searches will be feasible with SKA. Calibration strategies for the SKA require a better knowledge of the space density of compact sources at low radio frequencies, which IPS observations can now provide.
- ID:
- ivo://CDS.VizieR/J/A+A/403/555
- Title:
- Interplanetary Scintillation Pushchino Survey
- Short Name:
- J/A+A/403/555
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Interplanetary scintillating (IPS) radio sources from the Pushchino Survey (PS) in the area of 0.11sr have been cross-identified with objects from the 7C and FIRST catalogues. We have obtained improved positions of IPS radio sources, which are necessary for their optical identification. The data on sizes and morphology provided by the FIRST catalogue have shown that more than 50% of IPS radio sources are single and compact (<3") at {nu}=1400MHz. Most of them belong to the class of compact steep spectrum radio sources. About 15% of IPS radio sources are single partially resolved FIRST objects (sizes of 3"-9") and another 11% are double radio sources with compact components. The remaining 22% have larger sizes and, as a rule, a more complex structure too. Because IPS sources certainly contain an appreciable part of their radiation at low frequencies (100MHz) in very compact (~0.1") components and have steep spectra, we hope that a significant part of the Pushchino Survey objects are very probable candidates for steep spectrum quasars.
- ID:
- ivo://CDS.VizieR/J/A+A/421/455
- Title:
- Interplanetary Scintillation Pushchino Survey II
- Short Name:
- J/A+A/421/455
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the results of optical identification of 248 interplanetary scintillating (IPS) radio sources from the Pushchino Survey (PS) in the area of 0.11sr with the center at RA=10h28m, DE=+41{deg}. All 260 counterparts of IPS radio sources from the 7C and FIRST catalogues, which had been found in Paper I (Cat. <J/A+A/403/555>), were considered. We used USNO-B1.0 catalogue (limiting magnitude m_R_~21) for the optical identification and searched the literature to find optical data for fainter objects. Photometric and spectroscopic observations were conducted on the 1m and 6m telescopes of SAO RAS. Optical magnitudes or deep limits for 22 objects and redshifts for 26 ones have been obtained. In total, we collected optical data for 116 (68 with redshift) counterparts of the PS radio sources. For the subsample of the PS quasars (41 objects) the redshift distribution was compared to those of several other samples of quasars (BRL, 3CRR, MQS, B3-VLA, 7CRS I-III and PKS 0.25Jy) which have complete or nearly complete redshift information.
