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14971. (Sub)millimeter RRL in high-mass star-forming clumps
ID:
ivo://CDS.VizieR/J/A+A/616/A107
Title:
(Sub)millimeter RRL in high-mass star-forming clumps
Short Name:
J/A+A/616/A107
Date:
21 Oct 2021
Publisher:
CDS
Description:
Previous radio recombination line (RRL) observations of dust clumps identified in the APEX Telescope Large Area Survey of the Galaxy (ATLASGAL) have led to the detection of a large number of RRLs in the 3mm range. Here, we aim to study their excitation with shorter wavelength (sub)millimeter radio recombination line (submm-RRL) observations. We made observations of submm-RRLs with low principal quantum numbers (n<=30) using the APEX 12m telescope, toward 104 HII regions associated with massive dust clumps from ATLASGAL. The observations covered the H25{alpha}, H28{alpha}, and H35{beta} transitions. Toward a small subsample the H26{alpha}, H27{alpha}, H29{alpha}, and H30{alpha} lines were observed to avoid contamination by molecular lines at adjacent frequencies. We have detected submm-RRLs (signal-to-noise >=3{sigma}) from compact HII regions embedded within 93 clumps. The submm-RRLs are approximately a factor of two brighter than the mm-RRLs and consistent with optically thin emission in local thermodynamic equilibrium (LTE). The average ratio (0.31) of the measured H35{beta}/H28{alpha} fluxes is close to the LTE value of 0.28. No indication of RRL maser emission has been found. The Lyman photon flux, bolometric, and submm-RRL luminosities toward the submm-RRL detected sources present significant correlations. The trends of dust temperature and the ratio of bolometric luminosity to clump mass, L_bol_/M_clump_, indicate that the HII regions are related to L_bol_/M_clump_, indicate that the HII regions are related to the most massive and luminous clumps. By estimating the production rate of ionizing photons, Q, from the submm-RRL flux, we find that the Q(H28{alpha}) measurements provide estimates of the Lyman continuum photon flux consistent with those determined from 5GHz radio continuum emission. Six RRL sources show line profiles that are a combination of a narrow and a broad Gaussian feature. The broad features are likely associated with high-velocity ionized flows. We have detected submm-RRLs toward 93 ATLASGAL clumps. Six RRL sources have high-velocity RRL components likely driven by high-velocity ionized flows. Their observed properties are consistent with thermal emission that correlates well with the Lyman continuum flux of the HII regions. The sample of HII regions with mm/submm-RRL detections probes, in our Galaxy, luminous clumps (L_bol_>10^4^L_{sun}_) with high L_bol_/M_clump_. We also provide suitable candidates for further studies of the morphology and kinematics of embedded, compact HII regions with the Atacama Large Millimeter/submillimeter Array (ALMA).
14972. Submillimetre obs. of 323 HRS nearby galaxies
ID:
ivo://CDS.VizieR/J/A+A/543/A161
Title:
Submillimetre obs. of 323 HRS nearby galaxies
Short Name:
J/A+A/543/A161
Date:
21 Oct 2021
Publisher:
CDS
Description:
The Herschel Reference Survey (HRS) is a guaranteed time Herschel key project aimed at studying the physical properties of the interstellar medium in galaxies of the nearby universe. This volume limited, K-band selected sample is composed of galaxies spanning the whole range of morphological types (from ellipticals to late-type spirals) and environments (from the field to the centre of the Virgo Cluster). We present flux density measurements of the whole sample of 323 galaxies of the HRS in the three bands of the Spectral and Photometric Imaging Receiver (SPIRE), at 250um, 350um and 500um. Aperture photometry is performed on extended galaxies and point spread function (PSF) fitting on timeline data for unresolved objects; we carefully estimate errors and upper limits. The flux densities are found to be in good agreement with those of the HeViCS and KINGFISH key projects in all SPIRE bands, and of the Planck consortium at 350um and 550um, for the galaxies in common. This submillimetre catalogue of nearby galaxies is a benchmark for the study of the dust properties in the local universe, giving the zero redshift reference for any cosmological survey.
14973. Submillimetric Class II sources of Taurus
ID:
ivo://CDS.VizieR/J/ApJ/771/129
Title:
Submillimetric Class II sources of Taurus
Short Name:
J/ApJ/771/129
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present a substantial extension of the millimeter (mm) wave continuum photometry catalog for circumstellar dust disks in the Taurus star-forming region, based on a new "snapshot" {lambda}=1.3mm survey with the Submillimeter Array. Combining these new data with measurements in the literature, we construct a mm-wave luminosity distribution, f(L_mm_), for Class II disks that is statistically complete for stellar hosts with spectral types earlier than M8.5 and has a 3{sigma} depth of roughly 3mJy. The resulting census eliminates a longstanding selection bias against disks with late-type hosts, and thereby demonstrates that there is a strong correlation between L_mm_ and the host spectral type. By translating the locations of individual stars in the Hertzsprung-Russell diagram into masses and ages, and adopting a simple conversion between L_mm_ and the disk mass, M_d_, we confirm that this correlation corresponds to a statistically robust relationship between the masses of dust disks and the stars that host them. A Bayesian regression technique is used to characterize these relationships in the presence of measurement errors, data censoring, and significant intrinsic scatter: the best-fit results indicate a typical 1.3mm flux density of ~25mJy for 1M_{sun}_ hosts and a power-law scaling L_mm_{propto}M_{star}_^1.5-2.0^. We suggest that a reasonable treatment of dust temperature in the conversion from L_mm_ to M_d_ favors an inherently linear M_d_{prop.to}M_*_ scaling, with a typical disk-to-star mass ratio of ~0.2%-0.6%. The measured rms dispersion around this regression curve is +/-0.7dex, suggesting that the combined effects of diverse evolutionary states, dust opacities, and temperatures in these disks imprint a full width at half-maximum range of a factor of ~40 on the inferred M_d_ (or L_mm_) at any given host mass.
14974. Sub-mJy radio sources complete sample
ID:
ivo://CDS.VizieR/J/PASP/113/10
Title:
Sub-mJy radio sources complete sample
Short Name:
J/PASP/113/10
Date:
21 Oct 2021
Publisher:
CDS
Description:
The Very Large Array has been used in C configuration to map an area ~=0.3deg^2^ at 1.4GHz with 5{sigma} sensitivities of 0.305, 0.325, 0.380, and 0.450mJy/beam over four equal subareas. Radio properties are presented for 62 detected sources. Deep optical imaging to Gunn r ~=25mag using the Hale 5m telescope covering ~=0.21deg^2^ is reported for a subset of 43 sources. This optical follow-up is much deeper than that of existing larger area radio surveys of similar radio sensitivity. Archival J-, H-, and K-band photometry from the Two-Micron All Sky Survey is also presented. Using a robust likelihood ratio technique, we optically identified 26 radio sources with probability >~80%, nine with uncertain/ambiguous detections, and eight with empty fields. Comparisons with a stellar synthesis model that includes radio emission and dust reddening suggest that the near-infrared-optical emission in a small, bright subsample is reddened by "optically thin" dust with absorption A_V_~=22.5mag, regardless of morphological type. This is consistent with other, more direct determinations of absorption. The radio-optical(-near-infrared) flux ratios of early-type galaxies require significant contamination in the radio by an active galactic nucleus, consistent with the current paradigm. Using our simple modeling approach, we also discuss a potential diagnostic for selecting ultraluminous infrared galaxies to z~=1.6 from microJansky radio surveys.
14975. Sub-mJy radio sources SF properties
ID:
ivo://CDS.VizieR/J/MNRAS/453/1079
Title:
Sub-mJy radio sources SF properties
Short Name:
J/MNRAS/453/1079
Date:
21 Oct 2021
Publisher:
CDS
Description:
We investigate the star formation properties of ~800 sources detected in one of the deepest radio surveys at 1.4GHz. Our sample spans a wide redshift range (~0.1-4) and about four orders of magnitude in star formation rate (SFR). It includes both star-forming galaxies (SFGs) and active galactic nuclei (AGNs), further divided into radio-quiet (RQ) and radio-loud objects. We compare the SFR derived from the far-infrared luminosity, as traced by Herschel, with the SFR computed from their radio emission. We find that the radio power is a good SFR tracer not only for pure SFGs but also in the host galaxies of RQ AGNs, with no significant deviation with redshift or specific SFR. Moreover, we quantify the contribution of the starburst activity in the SFG population and the occurrence of AGNs in sources with different level of star formation. Finally, we discuss the possibility of using deep radio survey as a tool to study the cosmic star formation history.
14976. Sub-mm clumps at 450 and 850{mu}m in M17
ID:
ivo://CDS.VizieR/J/ApJ/644/990
Title:
Sub-mm clumps at 450 and 850{mu}m in M17
Short Name:
J/ApJ/644/990
Date:
21 Oct 2021
Publisher:
CDS
Description:
We have mapped a 5.5x5.5pc portion of the M17 massive star-forming region in both 850 and 450{mu}m dust continuum emission using the Submillimeter Common-User Bolometer Array (SCUBA) on the James Clerk Maxwell Telescope (JCMT). The maps reveal more than 100 dusty clumps with deconvolved linear sizes of ~0.05-0.2pc and masses of ~0.8-120M_{sun}_, most of which are not associated with known mid-infrared point sources. Fitting the clump mass function with a double power law gives a mean power-law exponent of {alpha}high=-2.4+/-0.3 for the high-mass power law, consistent with the exponent of the Salpeter stellar mass function. We show that a lognormal clump mass distribution with a peak at 4M_{sun}_ produces as good a fit to the clump mass function as does a double power law. This 4M_{sun}_ peak mass is well above the peak masses of both the stellar initial mass function and the mass function of clumps in low-mass star-forming regions. Despite the difference in intrinsic mass scale, the shape of the M17 clump mass function appears to be consistent with the shape of the core mass function in low-mass star-forming regions. Thus, we suggest that the clump mass function in high-mass star-forming regions may be a scaled up version of that in low-mass regions, instead of its extension to higher masses.
14977. Sub-mm clumps in Orion B South molecular cloud
ID:
ivo://CDS.VizieR/J/ApJ/639/259
Title:
Sub-mm clumps in Orion B South molecular cloud
Short Name:
J/ApJ/639/259
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present results from a survey of a 1300arcmin^2^ region of the Orion B South molecular cloud, including NGC 2024, NGC 2023, and the Horsehead Nebula (B33), obtained using the Submillimetre Common-User Bolometer Array (SCUBA) on the James Clerk Maxwell Telescope (JCMT). Submillimeter continuum observations at 450 and 850{mu}m are discussed. Using an automated algorithm, 57 discrete emission features ("clumps") are identified in the 850{mu}m map.
14978. Submm fluxes of very low-mass stars and BDs
ID:
ivo://CDS.VizieR/J/ApJ/773/168
Title:
Submm fluxes of very low-mass stars and BDs
Short Name:
J/ApJ/773/168
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present SCUBA-2 850{mu}m observations of seven very low mass stars (VLMS) and brown dwarfs (BDs). Three are in Taurus and four in the TW Hydrae Association (TWA), and all are classical T Tauri (cTT) analogs. We detect two of the three Taurus disks (one only marginally), but none of the TWA ones. For standard grains in cTT disks, our 3{sigma} limits correspond to a dust mass of 1.2M_{Earth}_ in Taurus and a mere 0.2M_{Earth}_ in the TWA (3-10x deeper than previous work). We combine our data with other submillimeter/millimeter (sub-mm/mm) surveys of Taurus, {rho} Oph, and the TWA to investigate the trends in disk mass and grain growth during the cTT phase.
14979. Sub-mm images of SSTB213 J041757.75+274105.5
ID:
ivo://CDS.VizieR/J/A+A/564/A32
Title:
Sub-mm images of SSTB213 J041757.75+274105.5
Short Name:
J/A+A/564/A32
Date:
21 Oct 2021
Publisher:
CDS
Description:
We observed the proto brown dwarf candidate SSTB213 J041757 with the Submillimeter Array to search for CO molecular outflow emission from the source. Our CO maps do not show any outflow emission from the proto brown dwarf candidate. The non-detection implies that the molecular outflows from the source are weak; deeper observations are therefore needed to probe the outflows from the source.
14980. Sub-mm mapping in Orion B molecular cloud
ID:
ivo://CDS.VizieR/J/ApJ/559/307
Title:
Sub-mm mapping in Orion B molecular cloud
Short Name:
J/ApJ/559/307
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present results from a survey of a 900 arcmin^2^ region of the Orion B molecular cloud, including NGC 2068, NGC 2071, and HH 24/25/26, at 850{mu}m using the Submillimeter Common-User Bolometer Array (SCUBA) on the James Clerk Maxwell Telescope. Following the techniques developed by Johnstone et al. (2000ApJ...545..327J), we identify 75 independent objects and compute size, flux, and degree of central concentration. Comparison with isothermal, pressure-confined, self-gravitating Bonnor-Ebert spheres implies that the clumps have internal temperatures of 20-40K and surface pressures 5.5<log(P/k)[CGS]<6.5. The clump masses span 0.2-12.3M_{sun}_ assuming typical dust temperatures and a dust emissivity {kappa}_850_=0.01cm^2^/g.

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