- ID:
- ivo://CDS.VizieR/J/ApJS/202/1
- Title:
- 1mm spectral line survey toward GLIMPSE EGOs
- Short Name:
- J/ApJS/202/1
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- A northern subsample of 89 Spitzer GLIMPSE extended green objects (EGOs), the candidate massive young stellar objects, are surveyed for molecular lines in two 1GHz ranges: 251.5-252.5 and 260.188-261.188GHz. A comprehensive catalog of observed molecular line data and spectral plots are presented. Eight molecular species are undoubtedly detected: H^13^CO^+^, SiO, SO, CH_3_OH, CH_3_OCH_3_, CH_3_CH_2_CN, HCOOCH_3_, and HN^13^C. The H^13^CO^+^ 3-2 line is detected in 70 EGOs, among which 37 also show the SiO 6-5 line, demonstrating their association with dense gas and supporting the outflow interpretation of the extended 4.5um excess emission. Our major dense gas and outflow tracers (H^13^CO^+^, SiO, SO, and CH_3_OH) are combined with our previous survey of ^13^CO, ^12^CO, and C^18^O 1-0 toward the same sample of EGOs for a multi-line, multi-cloud analysis of linewidth and luminosity correlations.
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- ID:
- ivo://CDS.VizieR/J/ApJS/207/7
- Title:
- Modeling Galactic extinction with dust and PAH
- Short Name:
- J/ApJS/207/7
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We investigate the remarkable apparent variety of galactic extinction curves by modeling extinction profiles with core-mantle grains and a collection of single polycyclic aromatic hydrocarbons. Our aim is to translate a synthetic description of dust into physically well-grounded building blocks through the analysis of a statistically relevant sample of different extinction curves. All different flavors of observed extinction curves, ranging from the average galactic extinction curve to virtually "bumpless" profiles, can be described by the present model. We prove that a mixture of a relatively small number (54 species in 4 charge states each) of polycyclic aromatic hydrocarbons can reproduce the features of the extinction curve in the ultraviolet, dismissing an old objection to the contribution of polycyclic aromatic hydrocarbons to the interstellar extinction curve. Despite the large number of free parameters (at most the 54x4 column densities of each species in each ionization state included in the molecular ensemble plus the 9 parameters defining the physical properties of classical particles), we can strongly constrain some physically relevant properties such as the total number of C atoms in all species and the mean charge of the mixture. Such properties are found to be largely independent of the adopted dust model whose variation provides effects that are orthogonal to those brought about by the molecular component. Finally, the fitting procedure, together with some physical sense, suggests (but does not require) the presence of an additional component of chemically different very small carbonaceous grains.
- ID:
- ivo://CDS.VizieR/J/ApJ/619/755
- Title:
- Modeling starburst SEDs
- Short Name:
- J/ApJ/619/755
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- In this paper, we combine the stellar spectral synthesis code STARBURST99, the nebular modeling code MAPPINGS IIIq, a one-dimensional dynamical evolution model of H II regions around massive clusters of young stars, and a simplified model of synchrotron emissivity to produce purely theoretical self-consistent synthetic spectral energy distributions (SEDs) for (solar metallicity) starbursts lasting ~10^8^yr. These SEDs extend from the Lyman limit to beyond 21cm. We present detailed SED fits to Arp 220 and NGC 6240, and we give the predicted colors for starburst galaxies derived from our models for the IRAS and the Spitzer Space Telescope MIPS and IRAC instruments. Our models reproduce the spread in observed colors of starburst galaxies. Finally, we present absolute calibrations to convert observed fluxes into star formation rates in the UV (GALEX), at optical wavelengths (H), and in the IR (IRAS or Spitzer).
- ID:
- ivo://CDS.VizieR/J/MNRAS/421/2786
- Title:
- Modelling of shock waves molecular line emission
- Short Name:
- J/MNRAS/421/2786
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have developed further the technique of time-dependent modelling of magnetohydrodynamic shock waves, with a view to interpreting the molecular line emission from outflow sources. The extensively observed source L1157 B1 was chosen as an exemplar of the application of this technique.
- ID:
- ivo://CDS.VizieR/J/A+A/453/635
- Title:
- Modelling the Galactic Interstellar Extinction
- Short Name:
- J/A+A/453/635
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Two Micron All Sky Survey (Cat. <II/246>), along with the Stellar Population Synthesis Model of the Galaxy, developed in Besancon, is used to calculate the extinction distribution along different lines of sight. The Galaxy model is used to provide the intrinsic colour of stars and their probable distances, so that the near infrared colour excess, and hence the extinction, may be calculated and its distance evaluated.
- ID:
- ivo://CDS.VizieR/J/MNRAS/468/4992
- Title:
- MOJAVE XIV. AGN jet shapes & opening angles
- Short Name:
- J/MNRAS/468/4992
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present 15 GHz stacked VLBA images of 373 jets associated with active galactic nuclei (AGN) having at least 5 observing epochs within a 20yr time interval 1994-2015 from the MOJAVE programme and/or its precursor, the 2 cm VLBA Survey. These data are supplemented by 1.4 GHz single-epoch VLBA observations of 135 MOJAVE AGNs to probe larger scale jet structures. The typical jet geometry is found to be close to conical on scales from hundreds to thousands of parsecs, while a number of galaxies show quasi-parabolic streamlines on smaller scales. A true jet geometry in a considerable fraction of AGNs appears only after stacking epochs over several years. The jets with significant radial accelerated motion undergo more active collimation. We have analyzed total intensity jet profiles transverse to the local jet ridgeline and derived both apparent and intrinsic opening angles of the flows, with medians of 21.5{deg} and 1.3{deg}, respectively. The Fermi LAT-detected gamma-ray AGNs in our sample have, on average, wider apparent and narrower intrinsic opening angle, and smaller viewing angle than non LAT-detected AGNs. We have established a highly significant correlation between the apparent opening angle and gamma-ray luminosity, driven by Doppler beaming and projection effects.
- ID:
- ivo://CDS.VizieR/J/A+AS/119/111
- Title:
- Molecular abundances in dense interstellar clouds
- Short Name:
- J/A+AS/119/111
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- In this paper we present calculated fractional abundances in dense interstellar clouds for selected atomic and molecular species using three different homogeneous, pseudo-time-dependent models discussed by Bettens, Lee, & Herbst (1995): the new standard model, the new neutral-neutral model, and model 4. We have run each model with 3 different hydrogen densities - 1,000; 10,000; and 100,000cm-3 - and two temperatures - 10K and 50K. "Low metal" elemental abundances have been used for all three models; the new standard model has also been run with "high metal" abundances.
- ID:
- ivo://CDS.VizieR/J/ApJ/705/144
- Title:
- Molecular and atomic gas in the LMC. II.
- Short Name:
- J/ApJ/705/144
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We compare the CO (J=1-0) and HI emission in the Large Magellanic Cloud in three dimensions, i.e., including a velocity axis in addition to the two spatial axes, with the aim of elucidating the physical connection between giant molecular clouds (GMCs) and their surrounding HI gas. The CO(J=1-0) data set is from the second NANTEN CO survey (Fukui et al. 2008, Cat. J/ApJS/178/56) and the HI data set is from the merged Australia Telescope Compact Array (ATCA) and Parkes Telescope surveys (Kim et al. 2003ApJS..148..473K).
- ID:
- ivo://CDS.VizieR/J/A+A/658/A54
- Title:
- Molecular cloud assoc. to Milky Way spiral arms
- Short Name:
- J/A+A/658/A54
- Date:
- 22 Feb 2022
- Publisher:
- CDS
- Description:
- The morphology of the Milky Way is still a matter of debate. In order to shed light on the uncertainty surrounding the Galactic structure, in this paper, we study the imprint of spiral arms on the molecular gas distribution and properties. To do so, we take full advantage of the SEDIGISM (Structure, Excitation and Dynamics of the Inner Galactic Interstellar Medium) survey that observed a large area of the inner Galaxy in the ^13^CO(2-1) line at an angular resolution of 28". We analyse the influences of spiral arms by considering the features of the molecular gas emission as a whole across the longitude- velocity map built from the full survey. Additionally, we examine the properties of the molecular clouds in the spiral arms compared to those in the inter-arm regions. Through flux and luminosity probability distribution functions, we find that the molecular gas emission associated with the spiral arms does not differ much from the emission between the arms. On average, spiral arms show masses per unit length of ~10^5^-10^6^M_{sun}_/kpc. This is similar to values inferred from data sets in which emission distributions were segmented into molecular clouds. By examining the cloud distribution across the Galactic plane, we infer that the molecular mass in the spiral arms is a factor of 1.5 higher than that of the inter-arm medium, similar to what is found for other spiral galaxies in the local Universe. We observe that only the distributions of cloud mass surface densities and aspect ratio in the spiral arms show significant differences compared to those of the inter-arm medium; other observed differences appear instead to be driven by a distance bias. By comparing our results with simulations and observations of nearby galaxies, we conclude that the measured quantities would classify the Milky Way as a flocculent spiral galaxy, rather than as a grand-design one.
- ID:
- ivo://CDS.VizieR/J/ApJ/872/121
- Title:
- Molecular cloud cores in the GC 50km/s cloud
- Short Name:
- J/ApJ/872/121
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Galactic center 50km/s molecular cloud (50MC) is the most remarkable molecular cloud in the Sagittarius A region. This cloud is a candidate for the massive star formation induced by cloud-cloud collision (CCC) with a collision velocity of ~30km/s that is estimated from the velocity dispersion. We observed the whole of the 50MC with a high angular resolution (~2.0"x1.4") in Atacama Large Millimeter/submillimeter Array cycle 1 in the H^13^CO^+^ J=1-0 and C^34^S J=2-1 emission lines. We identified 241 and 129 bound cores with a virial parameter of less than 2, which are thought to be gravitationally bound, in the H^13^CO^+^ and C^34^S maps using the clumpfind algorithm, respectively. In the CCC region, the bound H^13^CO^+^ and C^34^S cores are 119 and 82, whose masses are 68% and 76% of those in the whole 50MC, respectively. The distribution of the core number and column densities in the CCC are biased to larger densities than those in the non-CCC region. The distributions indicate that the CCC compresses the molecular gas and increases the number of the dense bound cores. Additionally, the massive bound cores with masses of >3000M_{sun}_ exist only in the CCC region, although the slope of the core mass function (CMF) in the CCC region is not different from that in the non-CCC region. We conclude that the compression by the CCC efficiently formed massive bound cores even if the slope of the CMF is not changed so much by the CCC.
