- ID:
- ivo://CDS.VizieR/J/ApJ/663/218
- Title:
- Optical Spectroscopy of WIYN Hydra FLS sources
- Short Name:
- J/ApJ/663/218
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present an optical spectroscopic survey of 24um and 1.4GHz sources, detected in the Spitzer extragalactic First Look Survey (FLS), using the multifiber spectrograph, Hydra, on the WIYN telescope. We have obtained spectra for 772 sources, with flux densities above 0.15mJy in the infrared and 0.09mJy in the radio. The redshifts measured in this survey are mostly in the range 0<z<0.4, with a distribution peaking at z~0.2.
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Search Results
- ID:
- ivo://CDS.VizieR/J/AN/340/437
- Title:
- Optical variability of blazars
- Short Name:
- J/AN/340/437
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The analysis of blazars' parameters from BZCAT leads to a conclusion that they do not have the same properties. The preliminary criterion to include an object in the catalog was the strong radio emission; however, two type of radio sources were selected: BL Lacertae (BLL) objects and Flat Spectrum Radio Quasars (FSRQ). As a number of properties are typical of blazars (strong radio emission, optical variability, continuum optical spectra, polarization, high luminosity, etc.), using the optical data, we investigate them to clarify which property plays the most significant role in their classification as blazars. We found that 60% of blazars have optical variability. We use a technique developed based on POSS1 and POSS2 photometry and group the variability into extreme, strong, medium, and low classes. In the optical range, 51 blazars have powerful variability (extreme variables), and 126 are high variables. In addition, 63% of blazars have detected radiation in X-ray and 28% have detected radiation in gamma rays. We give the average statistical characteristics of blazars based on our analysis and calculations.
- ID:
- ivo://CDS.VizieR/J/A+A/455/971
- Title:
- Organic molecules in the Galactic center
- Short Name:
- J/A+A/455/971
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We carried out a systematic study of the complex organic molecules CH_3_OH, C_2_H_5_OH, (CH_3_)_2_O, HCOOCH_3_, HCOOH, CH_3_COOH, H_2_CO, and CS toward 40 GC molecular clouds. Using the LTE approximation, we derived the physical properties of GC molecular clouds and the abundances of the complex molecules.The abundances of complex organic molecules in the GC are compared with those measured in hot cores and hot corinos, in which these complex molecules are also abundant.
- ID:
- ivo://CDS.VizieR/J/A+A/658/A12
- Title:
- Origins of radio emission in NLS1s
- Short Name:
- J/A+A/658/A12
- Date:
- 02 Feb 2022 14:01:48
- Publisher:
- CDS
- Description:
- Narrow-line Seyfert 1 galaxies (NLS1s) are believed to be active galactic nuclei (AGN) in the early stages of their evolution. Several dozen of them have been found to host relativistic jets, whilst the majority of NLS1s have not even been detected in radio, emphasising the heterogeneity of the class in this band. In this paper, our aim is to determine the predominant source of radio emission in a sample of 44 NLS1s, selected based on their extended kiloparsec-scale radio morphologies at 5.2GHz. We accomplish this by analysing their spatially resolved radio spectral index maps, centred at 5.2 GHz, as the spectral index carries information about the production mechanisms of the emission. In addition, we utilise several diagnostics based on mid-infrared emission to estimate the star formation activity of their host galaxies. These data are complemented by archival data to draw a more complete picture of each source. We find an extraordinary diversity among our sample. Approximately equal fractions (~10-12 sources) of our sources can be identified as AGN-dominated, composite, and host-dominated. Among the AGN-dominated sources are a few NLS1s with very extended jets, reaching distances of tens of kiloparsecs from the nucleus. One of these, J0814+5609, hosts the most extended jets found in an NLS1 so far. We also identify five NLS1s that could be classified as compact steep-spectrum sources. In addition, one source shows a possible kiloparsec-scale relic that reaches well outside the host galaxy as well as restarted nuclear activity, and one could belong to the sub-class of NLS1s that host relativistic jets that seem to be absorbed at lower radio frequencies (<10GHz). We further conclude that, due to the variety seen in NLS1s, simple proxies, such as the star formation diagnostics also employed in this paper and the radio loudness parameter, are not ideal tools for characterising NLS1s. We emphasise the necessity of examining NLS1s as individuals instead of making assumptions based on their classification. When these issues are properly taken into account, NLS1s offer an exceptional environment for studying the interplay between the host galaxy and several AGN-related phenomena, such as jets and outflows.
- ID:
- ivo://CDS.VizieR/J/A+A/600/A141
- Title:
- Orion A integral shaped filament image
- Short Name:
- J/A+A/600/A141
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We study the fragmentation of the nearest high line-mass filament, the integral shaped filament (ISF, line-mass ~400M_{sun}_/pc) in the Orion A molecular cloud. We have observed a 1.6pc long section of the ISF with the Atacama Large Millimetre/submillimeter Array (ALMA) at 3mm continuum emission, at a resolution of ~3" (1200AU). We identify from the region 43 dense cores with masses about a solar mass. 60% of the ALMA cores are protostellar and 40% are starless. The nearest neighbour separations of the cores do not show a preferred fragmentation scale; the frequency of short separations increases down to 1200AU. We apply a two-point correlation analysis on the dense core separations and show that the ALMA cores are significantly grouped at separations below ~17000AU and strongly grouped below ~6000AU. The protostellar and starless cores are grouped differently: only the starless cores group strongly below ~6000AU. In addition, the spatial distribution of the cores indicates periodic grouping of the cores into groups of ~30000AU in size, separated by ~50000AU. The groups coincide with dust column density peaks detected by Herschel. These results show hierarchical, two-mode fragmentation in which the maternal filament periodically fragments into groups of dense cores. Critically, our results indicate that the fragmentation models for lower line-mass filaments (~16M_{sun}_/pc) fail to capture the observed properties of the ISF. We also find that the protostars identified with Spitzer and Herschel in the ISF are grouped at separations below ~17000AU. In contrast, young stars with disks do not show significant grouping. This suggests that the grouping of dense cores is partially retained over the protostar lifetime, but not over the lifetime of stars with disks. This is in agreement with a scenario where protostars are ejected from the maternal filament by the slingshot mechanism, a model recently proposed for the ISF. The separation distributions of the dense cores and protostars may also provide an evolutionary tracer of filament fragmentation.
- ID:
- ivo://CDS.VizieR/J/A+A/634/A115
- Title:
- Orion B9 dense cores H2D+ spectra
- Short Name:
- J/A+A/634/A115
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We aim to determine the ortho-H_2_D^+^ properties (e.g. column density and fractional abundance with respect to H_2_) in a sample of dense cores in the Orion B9 star-forming filament, and to compare those with the previously determined source characteristics, in particular with the gas kinetic temperature, [N_2_D^+^]/[N_2_H^+^] deuterium fractionation, and level of CO depletion. We used the Atacama Pathfinder EXperiment (APEX) telescope to observe the 372GHz o-H_2_D+(1_1,0_-1_1,1_) line towards three prestellar cores and three protostellar cores in Orion B9. We also employed our previous APEX observations of C^17^O, C^18^O, N_2_H^+^, and N_2_D^+^ line emission, and 870 micron dust continuum emission towards the target sources. The o-H_2_D^+^(1_1,0_-1_1,1_) line was detected in all three prestellar cores, but in _nly one of the protostellar cores. The corresponding o-H_2_D^+^ abundances were derived to be ~(12-30)x10^-11^ and ~6x10^-11^. Two additional spectral lines, DCO^+^(5-4) and N_2_H^+^(4-3), were detected in the observed frequency bands with high detection rates of 100% and 83%. We did not find any significant correlations among the explored parameters, although our results are mostly consistent with theoretical expectations. Also, the Orion B9 cores were found to be consistent with the relationship between the o-H_2_D^+^ abundance and gas temperature obeyed by other low-mass dense cores. The o-H_2_D^+^ abundance was found to decrease as the core evolves. The o-H_2_D^+^ abundances in the Orion B9 cores are in line with those found in other low-mass dense cores and larger than derived for high-mass star-forming regions. The higher o-H_2_D^+^ abundance in prestellar cores compared to that in cores hosting protostars is to be expected from chemical reactions where higher concentrations of gas-phase CO and elevated gas temperature accelerate the destruction of H_2_D^+^. The validity of using the [o-H_2_D^+^]/[N_2_D^+^] abundance ratio as an evolutionary indicator, which has been proposed for massive clumps, remains inconclusive when applied for the target cores. Similarly, the behaviour of the [o-H_2_D^+^]/[DCO^+^] ratio as the source evolves was found to be ambiguous. Still larger samples and observations of additional deuterated species are needed to explore these potential evolutionary indicators further. The low radial velocity of the line emission from one of the targeted prestellar cores, SMM 7 (~3.6km/s versus the systemic Orion B9 velocity of ~9km/s), suggests that it is a chance superposition seen towards Orion B9. Overall, as located in a dynamic environment of the Orion B molecular cloud, the Orion B9 filament provides an interesting target system to investigate the deuterium-based chemistry, and further observations of species like para-H_2_D^+^ and D_2_H^+^ would be of particular interest.
- ID:
- ivo://CDS.VizieR/J/A+A/645/A27
- Title:
- Orion B in 18 molecular tracers maps
- Short Name:
- J/A+A/645/A27
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Molecular hydrogen being unobservable in cold molecular clouds, the column density measurements of molecular gas currently rely either on dust emission observation in the far-IR or on star counting. (Sub-)millimeter observations of numerous trace molecules are effective from ground based telescopes, but the relationships between the emission of one molecular line and the H_2_ column density (NH_2_) is non-linear and sensitive to excitation conditions, optical depths, abundance variations due to the underlying physico-chemistry. We aim to use multi-molecule line emission to infer NH_2_ from radio observations. We propose a data-driven approach to determine NH_2_ from radio molecular line observations. We use supervised machine learning methods (Random Forests) on wide-field hyperspectral IRAM-30m observations of the Orion B molecular cloud to train a predictor of NH_2_, using a limited set of molecular lines as input, and the Herschel-based dust-derived NH_2_ as ground truth output. For conditions similar to the Orion B molecular cloud, we obtain predictions of NH_2_ within a typical factor of 1.2 from the Herschel-based estimates. An analysis of the contributions of the different lines to the predictions show that the most important lines are ^13^CO(1-0), ^12^CO(1-0), C^18^O(1-0), and HCO+(1-0). A detailed analysis distinguishing between diffuse, translucent, filamentary, and dense core conditions show that the importance of these four lines depends on the regime, and that it is recommended to add the N_2_H+(1-0) and CH_3_OH(2_0_-1_0_) lines for the prediction of NH_2_ in dense core conditions. This article opens a promising avenue to directly infer important physical parameters from the molecular line emission in the millimeter domain. The next step will be to try to infer several parameters simultaneously (e.g., NH_2_ and far-UV illumination field) to further test the method.
- ID:
- ivo://CDS.VizieR/J/A+A/581/A71
- Title:
- Orion-KL substructure at 1.3mm
- Short Name:
- J/A+A/581/A71
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Kleinmann-Low nebula in Orion (Orion-KL) is the nearest example of a high-mass star-forming environment. For the first time, we complemented 1.3mm Submillimeter Array (SMA) interferometric line survey with IRAM 30m single-dish observations of the Orion-KL region. Covering a 4GHz bandwidth in total, this survey contains over 160 emission lines from 20 species (25 isotopologues), including 10 complex organic molecules (COMs). At a spatial resolution of 1200AU, the continuum substructures are resolved. Extracting the spectra from individual substructures and providing the intensity-integrated distribution map for each species, we studied the small-scale chemical variations in this region. Our main results are: (1) We identify lines from the low-abundance COMs CH3COCH3 and CH3CH2OH, as well as tentatively detect CH3CHO and long carbon-chains C6H and HC7N. (2) We find that while most COMs are segregated by type, peaking either towards the hot core (e.g., N-bearing species) or the compact ridge (e.g., O-bearing species like HCOOCH3, CH3OCH3, the distributions of others do not follow this segregated structure (e.g., CH3CH2OH, CH3OH, CH3COCH3). (3) We find a second velocity component of HNCO, 34SO2, and SO lines, which may be associated with a strong shock event in the low-velocity outflow. (4) Temperatures and molecular abundances show large gradients between central condensations and the outflow regions, illustrating a transition between hot molecular core and shock-chemistry dominated regimes. Our observations of spatially resolved chemical variations in Orion-KL provide the nearest reference source for hot molecular core and outflow chemistry, which will be an important example for interpreting the chemistry of more distant HMSFRs.
- ID:
- ivo://CDS.VizieR/J/A+A/606/A126
- Title:
- Orion Source I 3mm SiO maser emission
- Short Name:
- J/A+A/606/A126
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- High-mass star formation remains poorly understood due to observational difficulties (e.g. high dust extinction and large distances) hindering the resolution of disk-accretion and out ow-launching regions. Orion Source I is the closest known massive young stellar object (YSO) and exceptionally powers vibrationally excited SiO masers at radii within 100AU, providing a unique probe of gas dynamics and energetics. We seek to observe and image these masers with Very Long Baseline Interferometry (VLBI). We present the first images of the ^28^SiO v=1, J=2-1 maser emission around Orion Source I observed at ({lambda}2mm) with the Very Long Baseline Array (VLBA). These images have high spatial (~0.3mas) and spectral (~0.054km/s) resolutions.
- ID:
- ivo://CDS.VizieR/J/MNRAS/431/L107
- Title:
- Outbursts of GX339-4 at 5.5 and 9.0GHz fluxes
- Short Name:
- J/MNRAS/431/L107
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Galactic black hole binaries produce powerful outflows which emit over almost the entire electromagnetic spectrum. Here, we report the first detection with the Herschel observatory of a variable far-infrared source associated with the compact jets of the black hole transient GX 339-4 during the decay of its recent 2010-2011 outburst, after the transition to the hard state. We also outline the results of very sensitive radio observations conducted with the Australia Telescope Compact Array, along with a series of near-infrared, optical (OIR) and X-ray observations, allowing for the first time the re-ignition of the compact jets to be observed over a wide range of wavelengths. The compact jets first turn on at radio frequencies with an optically thin spectrum that later evolves to an optically thick synchrotron emission. An OIR reflare is observed about 10d after the onset of radio and hard X-ray emission, likely reflecting the necessary time to build up enough density, as well as to have acceleration (e.g. through shocks) along an extended region in the jets. The Herschel measurements are consistent with an extrapolation of the radio inverted power-law spectrum, but they highlight a more complex radio to OIR spectral energy distribution for the jets.
