- ID:
- ivo://CDS.VizieR/J/A+A/643/A4
- Title:
- ALPINE-ALMA [CII] survey. IR luminosity
- Short Name:
- J/A+A/643/A4
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present dust attenuation properties of spectroscopically confirmed star forming galaxies on the main sequence at a redshift of ~4.4-5.8. Our analyses are based on the far infrared continuum observations of 118 galaxies at rest-frame 158 {mu}m obtained with the Atacama Large Millimeter Array (ALMA) Large Program to INvestigate [CII] at Early times (ALPINE). We study the connection between the ultraviolet (UV) spectral slope ({beta}), stellar mass (M*), and infrared excess (IRX=L_IR_/L_UV_). Twenty-three galaxies are individually detected in the continuum at > 3.5{sigma} significance. We perform a stacking analysis using both detections and nondetections to study the average dust attenuation properties at z~4.4-5.8. The individual detections and stacks show that the IRX-{beta} relation at z~5 is consistent with a steeper dust attenuation curve than typically found at lower redshifts (z<4). The attenuation curve is similar to or even steeper than that of the extinction curve of the Small Magellanic Cloud. This systematic change of the IRX-{beta} relation as a function of redshift suggests an evolution of dust attenuation properties at z>4. Similarly, we find that our galaxies have lower IRX values, up to 1dex on average, at a fixed mass compared to previously studied IRX-M* relations at z<=4, albeit with significant scatter. This implies a lower obscured fraction of star formation than at lower redshifts. Our results suggest that dust properties of UV-selected star forming galaxies at z>=4 are characterised by (i) a steeper attenuation curve than at z<=4, and (ii) a rapidly decreasing dust obscured fraction of star formation as a function of redshift. Nevertheless, even among this UV-selected sample, massive galaxies (logM*/M_{sun}_>10) at z~5-6 already exhibit an obscured fraction of star formation of ~45%, indicating a rapid build-up of dust during the epoch of reionization.
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Search Results
- ID:
- ivo://CDS.VizieR/J/A+A/643/A2
- Title:
- ALPINE DR1 merged catalog
- Short Name:
- J/A+A/643/A2
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The ALPINE-ALMA large program targets the [CII] 158um line and the far-infrared continuum in 118 spectroscopically confirmed star-forming galaxies between z=4.4 and z=5.9. It represents the first large [CII] statistical sample built in this redshift range. We present details of the data processing and the construction of the catalogs. We detected 23 of our targets in the continuum. To derive accurate infrared luminosities and obscured star formation rates, we measured the conversion factor from the ALMA 158um rest-frame dust continuum luminosity to the total infrared luminosity (LIR) after constraining the dust spectral energy distribution by stacking a photometric sample similar to ALPINE in ancillary single-dish far-infrared data. We found that our continuum detections have a median LIR of 4.4x10^11^L_{sun}_. We also detected 57 additional continuum sources in our ALMA pointings. They are at lower redshift than the ALPINE targets, with a mean photometric redshift of 2.5+/-0.2. We measured the 850um number counts between 0.35 and 3.5mJy, improving the current interferometric constraints in this flux density range. We found a slope break in the number counts around 3mJy with a shallower slope below this value. More than 40% of the cosmic infrared background is emitted by sources brighter than 0.35mJy. Finally, we detected the [CII] line in 75 of our targets. Their median [CII] luminosity is 4.8x108L_{sun}_ and their median full width at half maximum is 252km/s. After measuring the mean obscured SFR in various [CII] luminosity bins by stacking ALPINE continuum data, we find a good agreement between our data and the local and predicted SFR-L[CII] relations of De Looze et al. (2014A&A...568A..62D) and Lagache et al. (2018A&A...609A.130L).
- 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/ApJ/788/125
- Title:
- An ALMA survey of ECDFS submillimeter galaxies
- Short Name:
- J/ApJ/788/125
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the first photometric redshift distribution for a large sample of 870 {mu}m submillimeter galaxies (SMGs) with robust identifications based on observations with ALMA. In our analysis we consider 96 SMGs in the Extended Chandra Deep Field South, 77 of which have 4-19 band photometry. We model the SEDs for these 77 SMGs, deriving a median photometric redshift of z_phot_=2.3+/-0.1. The remaining 19 SMGs have insufficient photometry to derive photometric redshifts, but a stacking analysis of Herschel observations confirms they are not spurious. Assuming that these SMGs have an absolute H-band magnitude distribution comparable to that of a complete sample of z~1-2 SMGs, we demonstrate that they lie at slightly higher redshifts, raising the median redshift for SMGs to z_phot_=2.5+/-0.2. Critically we show that the proportion of galaxies undergoing an SMG-like phase at z>=3 is at most 35%+/-5% of the total population. We derive a median stellar mass of M_*_=(8+/-1)x10^10^ M_{sun}_, although there are systematic uncertainties of up to 5x for individual sources. Assuming that the star formation activity in SMGs has a timescale of ~100 Myr, we show that their descendants at z~0 would have a space density and M_H_ distribution that are in good agreement with those of local ellipticals. In addition, the inferred mass-weighted ages of the local ellipticals broadly agree with the look-back times of the SMG events. Taken together, these results are consistent with a simple model that identifies SMGs as events that form most of the stars seen in the majority of luminous elliptical galaxies at the present day.
- ID:
- ivo://CDS.VizieR/J/ApJS/248/18
- Title:
- 44 and 95GHz observations of class I methanol masers
- Short Name:
- J/ApJS/248/18
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report a simultaneous 44 and 95GHz class I methanol maser survey toward 144 sources from the 95GHz class I methanol maser catalog. The observations were made with the three telescopes of the Korean very long baseline interferometry network operating in single-dish mode. The detection rates are 89% at 44GHz and 77% at 95GHz. There are 106 new discoveries at 44GHz. Comparing the previous 95GHz detections with new observations of the same transitions made using the Purple Mountain Observatory 13.7m radio telescope shows no clear evidence of variability on a timescale of six years. Emission from the 44 and 95GHz transitions shows strong correlations in peak velocity, peak flux density, and integrated flux density, indicating that they are likely cospatial. We found that the peak flux density ratio S_pk,95_/S_pk,44_ decreases as the 44GHz peak flux density increases. We found that some class I methanol masers in our sample might be associated with infrared dark clouds, while others are associated with HII regions, indicating that some sources occur at an early stage of high-mass star formation, while others are located toward more evolved sources.
- ID:
- ivo://CDS.VizieR/J/MNRAS/440/942
- Title:
- 100 and 160um fluxes of nearby galaxies
- Short Name:
- J/MNRAS/440/942
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present Herschel/PACS 100 and 160{mu}m integrated photometry for the 323 galaxies in the Herschel Reference Survey (HRS), a K-band, volume-limited sample of galaxies in the local Universe. Once combined with the Herschel/SPIRE observations already available, these data make the HRS the largest representative sample of nearby galaxies with homogeneous coverage across the 100-500{mu}m wavelength range. In this paper, we take advantage of this unique data set to investigate the properties and shape of the far-infrared/submillimetre spectral energy distribution in nearby galaxies. We show that, in the stellar mass range covered by the HRS (8<~log(M*/M_{sun}_)<~12), the far-infrared/submillimetre colours are inconsistent with a single modified blackbody having the same dust emissivity index {beta} for all galaxies. In particular, either {beta} decreases or multiple temperature components are needed, when moving from metal-rich/gas-poor to metal-poor/gas-rich galaxies. We thus investigate how the dust temperature and mass obtained from a single modified blackbody depend on the assumptions made on {beta}. We show that, while the correlations between dust temperature, galaxy structure and star formation rate are strongly model dependent, the dust mass scaling relations are much more reliable, and variations of {beta} only change the strength of the observed trends.
- ID:
- ivo://CDS.VizieR/J/ApJS/231/20
- Title:
- A new 95GHz methanol maser catalog. I.
- Short Name:
- J/ApJS/231/20
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Purple Mountain Observatory 13.7m radio telescope has been used to search for 95GHz (8_0_-7_1_A^+^) class I methanol masers toward 1020 Bolocam Galactic Plane Survey (BGPS) sources, leading to 213 detections. We have compared the line width of the methanol and HCO^+^ thermal emission in all of the methanol detections, and on that basis, we find that 205 of the 213 detections are very likely to be masers. This corresponds to an overall detection rate of 95 GHz methanol masers toward our BGPS sample of 20%. Of the 205 detected masers, 144 (70%) are new discoveries. Combining our results with those of previous 95GHz methanol maser searches, a total of 481 95GHz methanol masers are now known. We have compiled a catalog listing the locations and properties of all known 95GHz methanol masers.
- ID:
- ivo://CDS.VizieR/J/ApJ/727/83
- Title:
- A panchromatic study of BLAST counterparts
- Short Name:
- J/ApJ/727/83
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We carry out a multi-wavelength study of individual galaxies detected by the Balloon-borne Large Aperture Submillimeter Telescope (BLAST) and identified at other wavelengths, using data spanning the radio to the ultraviolet (UV). We develop a Monte Carlo method to account for flux boosting, source blending, and correlations among bands, which we use to derive deboosted far-infrared (FIR) luminosities for our sample. We estimate total star-formation rates (SFRs) for BLAST counterparts with z<=0.9 by combining their FIR and UV luminosities. We assess that about 20% of the galaxies in our sample show indication of a type 1 active galactic nucleus, but their submillimeter emission is mainly due to star formation in the host galaxy. We compute stellar masses for a subset of 92 BLAST counterparts; these are relatively massive objects, with a median mass of ~10^11^M_{sun}_, which seem to link the 24um and Submillimetre Common-User Bolometer Array (SCUBA) populations, in terms of both stellar mass and star formation activity.
- ID:
- ivo://CDS.VizieR/J/ApJ/767/36
- Title:
- APEX observations of HOPS protostars
- Short Name:
- J/ApJ/767/36
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We perform a census of the reddest, and potentially youngest, protostars in the Orion molecular clouds using data obtained with the PACS instrument on board the Herschel Space Observatory and the LABOCA and SABOCA instruments on APEX as part of the Herschel Orion Protostar Survey (HOPS). A total of 55 new protostar candidates are detected at 70{mu}m and 160{mu}m that are either too faint (m_24_>7mag) to be reliably classified as protostars or undetected in the Spitzer/MIPS 24{mu}m band. We find that the 11 reddest protostar candidates with log{lambda}F_{lambda}_70/{lambda}F_{lambda}_24>1.65 are free of contamination and can thus be reliably explained as protostars. The remaining 44 sources have less extreme 70/24 colors, fainter 70{mu}m fluxes, and higher levels of contamination. Taking the previously known sample of Spitzer protostars and the new sample together, we find 18 sources that have log{lambda}F_{lambda}_70/{lambda}F_{lambda}_24>1.65; we name these sources "PACS Bright Red sources," or PBRs. Our analysis reveals that the PBR sample is composed of Class 0 like sources characterized by very red spectral energy distributions (SEDs; T_bol_<45K) and large values of sub-millimeter fluxes (L_smm_/L_bol_>0.6%). Modified blackbody fits to the SEDs provide lower limits to the envelope masses of 0.2-2M_{sun}_ and luminosities of 0.7-10L_{sun}_. Based on these properties, and a comparison of the SEDs with radiative transfer models of protostars, we conclude that the PBRs are most likely extreme Class 0 objects distinguished by higher than typical envelope densities and hence, high mass infall rates.
- ID:
- ivo://CDS.VizieR/J/A+A/590/A25
- Title:
- Arp 220 HCN and HCO^+^ data cubes
- Short Name:
- J/A+A/590/A25
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The origin of the enormous luminosities of the two opaque nuclei of Arp 220, the prototypical ultra-luminous infrared galaxy, remains a mystery because we lack observational tools to explore the innermost regions around the nuclei. We explore the potential of imaging vibrationally excited molecular emission at high angular resolution to better understand the morphology and physical structure of the dense gas in Arp 220 and to gain insight into the nature of the nuclear powering sources. The Atacama Large Millimeter/submillimeter Array (ALMA) provided simultaneous observations of HCN, HCO^+^, and vibrationally excited HCN v_2_=1f emission. Their J=4-3 and 3-2 transitions were observed at a matching resolution of ~0.5", which allows us to isolate the emission from the two nuclei.
