- ID:
- ivo://CDS.VizieR/J/MNRAS/473/1512
- Title:
- AMI 15.7GHz GRB catalogue
- Short Name:
- J/MNRAS/473/1512
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the Arcminute Microkelvin Imager (AMI) Large Array catalogue of 139 gamma-ray bursts (GRBs). AMI observes at a central frequency of 15.7GHz and is equipped with a fully automated rapid-response mode, which enables the telescope to respond to high-energy transients detected by Swift. On receiving a transient alert, AMI can be on-target within 2-min, scheduling later start times if the source is below the horizon. Further AMI observations are manually scheduled for several days following the trigger. The AMI GRB programme probes the early-time (<1d) radio properties of GRBs, and has obtained some of the earliest radio detections (GRB 130427A at 0.36 and GRB 130907A at 0.51d post-burst). As all Swift GRBs visible to AMI are observed, this catalogue provides the first representative sample of GRB radio properties, unbiased by multiwavelength selection criteria. We report the detection of six GRB radio afterglows that were not previously detected by other radio telescopes, increasing the rate of radio detections by 50 per cent over an 18-month period. The AMI catalogue implies a Swift GRB radio detection rate of >~15 per cent, down to ~0.2mJy/beam. However, scaling this by the fraction of GRBs AMI would have detected in the Chandra & Frail (2012, Cat. J/ApJ/746/156) sample (all radio-observed GRBs between 1997 and 2011), it is possible ~44-56 per cent of Swift GRBs are radio bright, down to ~0.1-0.15mJy/beam. This increase from the Chandra & Frail (2012, Cat. J/ApJ/746/156) rate (~30 per cent) is likely due to the AMI rapid-response mode, which allows observations to begin while the reverse-shock is contributing to the radio afterglow.
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Search Results
- ID:
- ivo://CDS.VizieR/J/MNRAS/415/893
- Title:
- AMI-LA 16 GHz sources in Perseus region
- Short Name:
- J/MNRAS/415/893
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present deep radio continuum observations of the cores identified as deeply embedded young stellar objects in the Perseus molecular cloud by the Spitzer c2d programme at a wavelength of 1.8cm with the Arcminute Microkelvin Imager Large Array (AMI-LA). We detect 72% of Class 0 objects from this sample and 31% of Class I objects. No starless cores are detected. We use the flux densities measured from these data to improve constraints on the correlations between radio luminosity and bolometric luminosity, infrared luminosity and, where measured, outflow force. We discuss the differing behaviour of these objects as a function of protostellar class and investigate the differences in radio emission as a function of core mass. Two of four possible very low luminosity objects (VeLLOs) are detected at 1.8cm.
- ID:
- ivo://CDS.VizieR/J/ApJS/209/23
- Title:
- Aminoacetonitrile transition frequencies
- Short Name:
- J/ApJS/209/23
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Aminoacetonitrile, NH_2-CH_2_-CN, has been considered one of the important precursors of glycine, the simplest amino acid, and was identified in Sgr B2(N) by Belloche et al. (2008, Cat. J/A+A/482/179) based on their reanalysis of previous laboratory measurements. However, these laboratory measurements were limited to the 1mm wavelength region even for the normal species, and recent new radio telescopes like ALMA require rest frequencies in a higher frequency range. Therefore, we have extended the pure rotational spectra of aminoacetonitrile and its amino-hydrogen-deuterated isotopologues (NHDCH_2_CN and ND_2_CH_2_CN) up to 1.2THz and 0.6THz, respectively. Belloche et al. indicated that the normal species may have been misassigned in a previous microwave study by Bogey et al. (1990JMoSp.143..180B). We found that two more b-type spectral transitions were misassigned, and all b-type transition frequencies above K_a_=2 had to be remeasured. For isotopologues, spectra above 40 GHz were observed for the first time and higher order centrifugal distortion constants have been determined. The extension of the measurements helped improve the molecular constants. The errors in the frequency catalog data of normal and deuterated isotopologues are on the order of 100kHz up to 1.2THz and 0.6THz, respectively, which are precise enough for the future astronomical observations.
- ID:
- ivo://CDS.VizieR/J/ApJ/756/60
- Title:
- A 3mm line survey in 37 IR dark clouds
- Short Name:
- J/ApJ/756/60
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have observed 37 Infrared Dark Clouds (IRDCs), containing a total of 159 clumps, in high-density molecular tracers at 3mm using the 22m ATNF Mopra Telescope located in Australia. After determining kinematic distances, we eliminated clumps that are not located in IRDCs and clumps with a separation between them of less than one Mopra beam. Our final sample consists of 92 IRDC clumps. The most commonly detected molecular lines are (detection rates higher than 8%) N_2_H^+^, HNC, HN^13^C, HCO^+^, H^13^CO^+^, HCN, C_2_H, HC_3_N, HNCO, and SiO. We investigate the behavior of the different molecular tracers and look for chemical variations as a function of an evolutionary sequence based on Spitzer IRAC and MIPS emission. Optical depth calculations show that in IRDC clumps the N_2_H^+^ line is optically thin, the C_2_ H line is moderately optically thick, and HNC and HCO^+^ are optically thick.
- ID:
- ivo://CDS.VizieR/J/A+A/549/A39
- Title:
- A 3mm molecular line survey of NGC1068
- Short Name:
- J/A+A/549/A39
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We study the molecular composition of the interstellar medium (ISM) surrounding an active galactic nucleus (AGN), by making an inventory of molecular species and their abundances, to establish a chemical differentiation between starburst galaxies and AGN. We used the IRAM-30m telescope to observe the central 1.5-2kpc region of NGC 1068, covering the frequencies between 86.2GHz and 115.6GHz. Using Boltzmann diagrams, we calculated the column densities of the detected molecules. We used a chemical model to reproduce the abundances found in the AGN, to determine the origin of each detected species, and to test the influence of UV fields, cosmic rays, and shocks on the ISM.
- ID:
- ivo://CDS.VizieR/J/AJ/152/92
- Title:
- Ammonia and CO outflow around 6.7GHz methanol masers
- Short Name:
- J/AJ/152/92
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Single point observations are presented in NH_3_ (1, 1) and (2, 2) inversion transitions using the Effelsberg 100m telescope for a sample of 100 6.7GHz methanol masers and mapping observations in the ^12^CO and ^13^CO (1-0) transitions using the Purple Mountain Observatory Delingha 13.7m telescope for 82 sample sources with detected ammonia. A further 62 sources were selected for either ^12^CO or ^13^CO line outflow identification, producing 45 outflow candidates, 29 using ^12^CO and 16 using ^13^CO data. Twenty-two of the outflow candidates were newly identified, and 23 had trigonometric parallax distances. Physical properties were derived from ammonia lines and CO outflow parameters were calculated. Histograms and statistical correlations for ammonia, CO outflow parameters, and 6.7GHz methanol maser luminosities are also presented. No significant correlation was found between ammonia and maser luminosity. However, weak correlations were found between outflow properties and maser luminosities, which may indicate that outflows are physically associated with 6.7GHz masers.
- ID:
- ivo://CDS.VizieR/J/ApJ/790/84
- Title:
- Ammonia in high-mass star formation regions
- Short Name:
- J/ApJ/790/84
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report systematic mapping observations of the NH_3_(1, 1) and (2, 2) inversion lines toward 62 high-mass star-forming regions using the Very Large Array (VLA) in its D and DnC array configurations. The VLA images cover a spatial dynamic range from 40'' to 3'', allowing us to trace gas kinematics from ~1 pc scales to <~ 0.1 pc scales. Based on the NH_3_ morphology and the infrared nebulosity on 1 pc scales, we categorize three subclasses in the sample: filaments, hot cores, and NH_3_-dispersed sources. The ubiquitous gas filaments found on 1 pc scales have a typical width of ~0.1 pc and often contain regularly spaced fragments along the major axis. The spacing of the fragments and the column densities is consistent with the turbulent supported fragmentation of cylinders. Several sources show multiple filaments that converge toward a center where the velocity field in the filaments is consistent with gas flows. We derive rotational temperature maps for the entire sample. For the three hot core sources, we find a projected radial temperature distribution that is best fit by power-law indices from -0.18 to -0.35. We identify 174 velocity-coherent ~0.1 pc scale dense cores from the entire sample. The mean physical properties for these cores are 1.1 km/s in intrinsic linewidth, 18 K in NH_3_ rotational temperature, 2.3x10^15^/cm2 in NH_3_gas column density, and 67 M_{sun}_in molecular mass. The dense cores identified from the filamentary sources are closer to being virialized. Dense cores in the other two categories of sources appear to be dynamically unstable.
- ID:
- ivo://CDS.VizieR/J/A+A/564/A21
- Title:
- Ammonia observations in G79.29+0.46
- Short Name:
- J/A+A/564/A21
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the results of observations of the ammonia (1,1) and (2,2) lines in a field of 7'x7' centered in the LBV ring nebula G79.29+0.46. The survey also includes a significant part of the IRDC G79.3+0.3. Data have been gathered with the 100m radio telescope at Effelsberg. Both lines have been observed simultaneously with excellent spectral resolution. A clump of the IRDC, referred in the paper as the SW region, is sampled every 20"; sampling is 40" elsewhere.
- ID:
- ivo://CDS.VizieR/J/A+A/308/573
- Title:
- Ammonia on YSOs IRAS sources
- Short Name:
- J/A+A/308/573
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present observations of NH_3_ (1,1) and (2,2) lines in two flux-limited samples of IRAS sources selected according to colour criteria which should result in a high fraction of Young Stellar Objects. The first sample contains sources (named 'LOW') whose evolutionary status is essentially unknown, while the second sample contains sources (named 'HIGH') possibly associated with ultracompact HII regions, the distinction being based on the IRAS [25-12] colour.
- ID:
- ivo://CDS.VizieR/J/ApJS/175/509
- Title:
- Ammonia spectral atlas in Perseus
- Short Name:
- J/ApJS/175/509
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present ammonia observations of 193 dense cores and core candidates in the Perseus molecular cloud made using the Robert F. Byrd Green Bank Telescope. We simultaneously observed the NH_3_(1,1), NH_3_(2,2), C_2_S (2_1_=>1_0_), and C^34^_2_S(2_1_=>1_0_) transitions near {nu}=23GHz for each of the targets with a spectral resolution of {delta}v~0.024km/s. We find ammonia emission associated with nearly all of the (sub)millimeter sources, as well as at several positions with no associated continuum emission. For each detection, we have measured physical properties by fitting a simple model to every spectral line simultaneously. Where appropriate, we have refined the model by accounting for low optical depths, multiple components along the line of sight, and imperfect coupling to the GBT beam. For the cores in Perseus, we find a typical kinetic temperature of T_k_=11K, a typical column density of N_NH3_~10^14.5^/cm2, and velocity dispersions ranging from {sigma}v=0.07 to 0.7km/s. However, many cores with {sigma}v>0.2km/s show evidence for multiple velocity components along the line of sight.
