- ID:
- ivo://CDS.VizieR/J/MNRAS/401/1240
- Title:
- Light curves of flat-spectrum radio sources
- Short Name:
- J/MNRAS/401/1240
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Calibrated data for 143 flat-spectrum extragalactic radio sources are presented at a wavelength of 850um covering a 5-yr period from 2000 April. The data, obtained at the James Clerk Maxwell Telescope using the Submillimetre Common-User Bolometer Array (SCUBA) camera in pointing mode, were analysed using an automated pipeline process based on the Observatory Reduction and Acquisition Control - Data Reduction (ORAC-DR) system. This paper describes the techniques used to analyse and calibrate the data, and presents the data base of results along with a representative sample of the better-sampled light curves. A re-analysis of previously published data from 1997 to 2000 is also presented. The combined catalogue, comprising 10493 flux density measurements, provides a unique and valuable resource for studies of extragalactic radio sources.
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- ID:
- ivo://CDS.VizieR/J/A+A/657/A70
- Title:
- Linking high- and low-mass star formation
- Short Name:
- J/A+A/657/A70
- Date:
- 21 Mar 2022 09:28:51
- Publisher:
- CDS
- Description:
- Astronomers have yet to establish whether high-mass protostars form from high-mass prestellar cores, similar to their lower-mass counterparts, or from lower-mass fragments at the heart of a pre-protostellar cluster undergoing large-scale collapse. Part of the uncertainty is due to a shortage of envelope structure data on protostars of a few tens of solar masses, where we expect to see a transition from intermediate-mass star formation to the high-mass process. We sought to derive the masses, luminosities, and envelope density profiles for eight sources in Cygnus-X, whose mass estimates in the literature placed them in the sampling gap. Combining these sources with similarly evolved sources in the literature enabled us to perform a meta-analysis of protostellar envelope parameters over six decades in source luminosity. We performed spectral energy distribution (SED) fitting on archival broadband photometric continuum data from 1.2 to 850 microns, to derive bolometric luminosities for our eight sources plus initial mass and radius estimates for modelling density and temperature profiles with the radiative transfer package Transphere. The envelope masses, densities at 1000AU, outer envelope radii, and density power law indices as functions of bolometric luminosity all follow established trends in the literature spanning six decades in luminosity. Most of our sources occupy an intermediate to moderately high range of masses and luminosities, which helps more firmly establish the continuity between low- and high-mass star formation mechanisms. Our density power law indices are consistent with observed values in literature, which show no discernible trends with luminosity. Finally, we show that the trends in all of the envelope parameters for high-mass protostars are statistically indistinguishable from trends in the same variables for low- and intermediate-mass protostars.
- ID:
- ivo://CDS.VizieR/J/A+A/475/915
- Title:
- L1489IRS observed by the submillimeter array
- Short Name:
- J/A+A/475/915
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Submillimeter Array observations of the Young Stellar Object L1489IRS (IRAS 04016+2610). These include images of the continuum at 267 GHz (1.12 mm) and line emission of the HCO+ J=3-2 transition at 267.55762 GHz. The HCO+ image is available in two different (u,v)-weighting schemes, natural and uniform, optimizing for S/N and resolution respectively. The continuum image is only available in uniform weighting. The synthesized beam size is 1".
- ID:
- ivo://CDS.VizieR/J/ApJ/811/145
- Title:
- LMC & SMC evolved stars detected with Herschel
- Short Name:
- J/ApJ/811/145
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Using observations from the Herschel Inventory of The Agents of Galaxy Evolution (HERITAGE) survey of the Magellanic Clouds (MC), we have found 35 evolved stars and stellar end products that are bright in the far-infrared. These 28 (LMC) and 7 (SMC) sources were selected from the 529 evolved star candidates in the HERITAGE far-infrared point source catalogs. Our source identification method is based on spectral confirmation, spectral energy distribution characteristics, careful examination of the multiwavelength images and includes constraints on the luminosity, resulting in a thoroughly vetted list of evolved stars. These sources span a wide range in luminosity and hence initial mass. We found 13 low- to intermediate-mass evolved stars, including asymptotic giant branch (AGB) stars, post-AGB stars, planetary nebulae, and a symbiotic star. We also identify 10 high mass stars, including 4 of the 15 known B[e] stars in the MC, 3 extreme red supergiants that are highly enshrouded by dust, a Luminous Blue Variable, a Wolf-Rayet star, and two supernova remnants. Further, we report the detection of 9 probable evolved objects which were previously undescribed in the literature. These sources are likely to be among the dustiest evolved objects in the MC. The Herschel emission may either be due to dust produced by the evolved star or it may arise from swept-up interstellar medium material.
- ID:
- ivo://CDS.VizieR/J/A+A/609/A9
- Title:
- Local Swift-BAT AGN observed with Herschel
- Short Name:
- J/A+A/609/A9
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We use Herschel data to analyze the size of the far-infrared 70micrometer emission for z<0.06 local samples of 277 hosts of Swift-BAT selected AGN, and 515 comparison galaxies that are not detected by BAT. For modest far-infrared luminosities 8.5<log(LFIR)<10.5, we find large scatter of half light radii for both populations, but a typical value ~1kpc for the BAT hosts that is only half that of comparison galaxies of same far-infrared luminosity. The result mostly reflects a more compact distribution of star formation (and hence gas) in the AGN hosts, but compact AGN heated dust may contribute in some extremely AGN-dominated systems. Our findings are in support of an AGN-host coevolution where accretion onto the central black hole and star formation are fed from the same gas reservoir, with more efficient black hole feeding if that reservoir is more concentrated. The significant scatter in the far-infrared sizes emphasizes that we are mostly probing spatial scales much larger than those of actual accretion, and that rapid accretion variations can smear the distinction between the AGN and comparison categories. Large samples are hence needed to detect structural differences that favour feeding of the black hole. No size difference AGN host vs. comparison galaxies is observed at higher far-infrared luminosities log(LFIR)>10.5 possibly because these are typically reached in more compact regions.
- ID:
- ivo://CDS.VizieR/J/A+A/515/A75
- Title:
- Low-mass population in {rho} Oph cloud
- Short Name:
- J/A+A/515/A75
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Star formation theories are currently divergent regarding the fundamental physical processes that dominate the substellar regime. Observations of nearby young open clusters allow the brown dwarf (BD) population to be characterised down to the planetary mass regime, which ultimately must be accommodated by a successful theory. We used near-IR deep images (reaching completeness limits of approximately 20.5mag in J, and 18.9mag in H and Ks taken with the Wide Field IR Camera (WIRCam) at the Canada France Hawaii Telescope (CFHT) to identify candidate members of {rho} Oph in the substellar regime. A spectroscopic follow-up of a small sample of the candidates allows us to assess their spectral type, and subsequently their temperature and membership. We select 110 candidate members of the {rho} Ophiuchi molecular cloud, from which 80 have not previously been associated with the cloud. We observed a small sample of these and spectroscopically confirm six new brown dwarfs with spectral types ranging from M6.5 to M8.25.
- ID:
- ivo://CDS.VizieR/J/AJ/152/36
- Title:
- Low-mass star-forming cores observed with SHARC-II
- Short Name:
- J/AJ/152/36
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a catalog of low-mass dense cores observed with the SHARC-II instrument at 350{mu}m. Our observations have an effective angular resolution of 10'', approximately 2.5 times higher than observations at the same wavelength obtained with the Herschel Space Observatory, albeit with lower sensitivity, especially to extended emission. The catalog includes 81 maps covering a total of 164 detected sources. For each detected source, we tabulate basic source properties including position, peak intensity, flux density in fixed apertures, and radius. We examine the uncertainties in the pointing model applied to all SHARC-II data and conservatively find that the model corrections are good to within ~3'', approximately 1/3 of the SHARC-II beam. We examine the differences between two array scan modes and find that the instrument calibration, beam size, and beam shape are similar between the two modes. We also show that the same flux densities are measured when sources are observed in the two different modes, indicating that there are no systematic effects introduced into our catalog by utilizing two different scan patterns during the course of taking observations. We find a detection rate of 95% for protostellar cores but only 45% for starless cores, and demonstrate the existence of a SHARC-II detection bias against all but the most massive and compact starless cores. Finally, we discuss the improvements in protostellar classification enabled by these 350{mu}m observations.
- ID:
- ivo://CDS.VizieR/J/AJ/145/94
- Title:
- Luminosities of protostars from two Spitzer surveys
- Short Name:
- J/AJ/145/94
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Motivated by the long-standing "luminosity problem" in low-mass star formation whereby protostars are underluminous compared to theoretical expectations, we identify 230 protostars in 18 molecular clouds observed by two Spitzer Space Telescope Legacy surveys of nearby star-forming regions. We compile complete spectral energy distributions, calculate L_bol_ for each source, and study the protostellar luminosity distribution. This distribution extends over three orders of magnitude, from 0.01L_{sun}_ to 69L_{sun}_, and has a mean and median of 4.3L_{sun}_ and 1.3L_{sun}_, respectively. The distributions are very similar for Class 0 and Class I sources except for an excess of low luminosity (L_bol_<~0.5L_{sun}_) Class I sources compared to Class 0. 100 out of the 230 protostars (43%) lack any available data in the far-infrared and submillimeter (70{mu}m<{lambda}<850{mu}m) and have L_bol_ underestimated by factors of 2.5 on average, and up to factors of 8-10 in extreme cases. Correcting these underestimates for each source individually once additional data becomes available will likely increase both the mean and median of the sample by 35%-40%. We discuss and compare our results to several recent theoretical studies of protostellar luminosities and show that our new results do not invalidate the conclusions of any of these studies. As these studies demonstrate that there is more than one plausible accretion scenario that can match observations, future attention is clearly needed. The better statistics provided by our increased data set should aid such future work.
- ID:
- ivo://CDS.VizieR/J/MNRAS/444/117
- Title:
- Luminous (sub-)millimetre galaxies
- Short Name:
- J/MNRAS/444/117
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Motivated by the current controversy over the redshift distribution and physical properties of luminous (sub-)mm sources, we have undertaken a new study of the brightest sample of unlensed (sub-)mm sources with pre-Atacama Large Millimeter/submillimeter Array (ALMA) interferometric follow-up in the Cosmological Evolution Survey field. Exploiting the very latest multifrequency supporting data, we find that this sample displays a redshift distribution indistinguishable from that of the lensed sources uncovered with the South Pole Telescope, with z_median_=~3.5. We also find that, over the redshift range z=~2-6, the median stellar mass of the most luminous (sub-) mm sources is M_*_=~ 3x10^11^M_{sun}_, yielding a typical specific star formation rate sSFR=~3Gyr^-1^. Consistent with recent ALMA and the Submillimeter Array studies, we confirm that source blending is not a serious issue in the study of luminous (sub-)mm sources uncovered by ground-based, single-dish surveys; only =~10^-15^% of bright (S_850_=~5-10mJy) (sub-) mm sources arise from significant (i.e. >20%) blends, and so our conclusions are largely unaffected by whether we adopt the original single-dish mm/sub-mm flux densities/positions or the interferometric data. Our results suggest that apparent disagreements over the redshift distribution of (sub-)mm sources are a result of 'down-sizing' in dust-enshrouded star formation, consistent with existing knowledge of the star formation histories of massive galaxies. They also indicate that extreme star-forming galaxies at high redshift are, on average, subject to the same star formation rate-limiting processes as less luminous objects, and lie on the 'main sequence' of star-forming galaxies at z>3.
- ID:
- ivo://CDS.VizieR/J/A+A/643/A6
- Title:
- Ly{alpha}-[CII] velocity offsets in MS galaxies
- Short Name:
- J/A+A/643/A6
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Lyman-{alpha} line in the ultraviolet (UV) and the [CII] line in the far-infrared (FIR) are widely used tools to identify galaxies in the early Universe and to obtain insights into interstellar medium (ISM) properties in high-redshift galaxies. By combining data obtained with ALMA in band 7 at ~320GHz as part of the ALMA Large Program to INvestigate [CII] at Early Times (ALPINE) with spectroscopic data from DEIMOS at the Keck Observatory, VIMOS and FORS2 at the Very Large Telescope, we assembled a unique sample of 53 main-sequence star-forming galaxies at 4.4<z<6 in which we detect both the Lyman-{alpha} line in the UV and the [CII] line in the FIR. The goal of this paper is to constrain the properties of the Ly{alpha} emission in these galaxies in relation to other properties of the ISM. We used [CII], observed with ALMA, as a tracer of the systemic velocity of the galaxies, and we exploited the available optical spectroscopy to obtain the Ly{alpha}-[CII] and ISM-[CII] velocity offsets. We find that 90% of the selected objects have Ly{alpha}-[CII] velocity offsets in the range 0<{Delta}v_Ly{alpha}-[CII]_<400km/s, in line with the few measurements available so far in the early Universe, and significantly smaller than those observed at lower redshifts. At the same time, we observe ISM-[CII] offsets in the range -500<{Delta}v_ISM-[CII]_<0km/s, in line with values at all redshifts, which we interpret as evidence for outflows in these galaxies. We find significant anticorrelations between {Delta}v_Ly{alpha}-[CII]_ and the Ly{alpha} rest-frame equivalent width EW_0_(Ly{alpha}) (or equivalently, the Ly{alpha} escape fraction f_esc_(Ly{alpha})): galaxies that show smaller {Delta}v_Ly{alpha}-[CII]_ have larger EW_0_(Ly{alpha}) and f_esc_(Ly{alpha}). We interpret these results in the framework of available models for the radiative transfer of Ly{alpha} photons. According to the models, the escape of Ly{alpha} photons would be favored in galaxies with high outflow velocities, producing large EW_0_(Ly{alpha}) and small {Delta}v_Ly{alpha}-[CII]_, in agreement with our observations. The uniform shell model would also predict that the Ly{alpha} escape in galaxies with slow outflows (0<v_out_<300km/s) is mainly determined by the neutral hydrogen column density (NHI) along the line of sight, while the alternative model by Steidel et al. (2010ApJ...717..289S) would more highly favor a combination of NHI at the systemic velocity and covering fraction as driver of the Ly{alpha} escape. We suggest that the increase in Ly{alpha} escape that is observed in the literature between z~2 and z~6 is not due to a higher incidence of fast outflows at high redshift, but rather to a decrease in average NHI along the line of sight, or alternatively, a decrease in HI covering fraction.