- ID:
- ivo://CDS.VizieR/J/A+A/626/A23
- Title:
- Herschel Dwarf Galaxy Survey PACS spectroscopy
- Short Name:
- J/A+A/626/A23
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We employ a multiphase approach to model the ISM phases of the galaxies from the Herschel Dwarf Galaxy Survey with the spectral synthesis code Cloudy. We characterize the physical conditions (gas densities, radiation fields, porosity) in those galaxies and investigate correlations with metallicity or star-formation activity. We find that the lower-metallicity galaxies tend to have higher ionization parameters and galaxies with higher specific star-formation rates have higher gas densities. The [CII] emission arises mainly from PDRs and the contribution from the ionized gas phases is small, typically less than 30% of the observed emission. We also find a correlation, with scatter, between metallicity and both the PDR covering factor and the fraction of [CII] from the ionized gas. Overall, the low metal abundances appear to be driving most of the changes in the ISM structure and conditions of these galaxies, and not the high specific star-formation rates. These results demonstrate in a quantitative way the increase of ISM porosity at low metallicity.
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- ID:
- ivo://CDS.VizieR/J/A+A/547/A49
- Title:
- Herschel EPoS: high-mass overview
- Short Name:
- J/A+A/547/A49
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Stars are born deeply embedded in molecular clouds. In the earliest embedded phases, protostars emit the bulk of their radiation in the far-infrared wavelength range, where Herschel is perfectly suited to probe at high angular resolution and dynamic range. In the high-mass regime, the birthplaces of protostars are thought to be in the high-density structures known as infrared-dark clouds (IRDCs). While massive IRDCs are believed to have the right conditions to give rise to massive stars and clusters, the evolutionary sequence of this process is not well-characterized. As part of the Earliest Phases of Star formation (EPoS) Herschel guaranteed time key program, we isolate the embedded structures within IRDCs and other cold, massive molecular clouds. We present the full sample of 45 high-mass regions which were mapped at PACS 70, 100, and 160um and SPIRE 250, 350, and 500um. In the present paper, we characterize a population of cores which appear in the PACS bands and place them into context with their host molecular cloud and investigate their evolutionary stage.
- ID:
- ivo://CDS.VizieR/J/MNRAS/441/2
- Title:
- Herschel far-IR counterparts of SDSS galaxies
- Short Name:
- J/MNRAS/441/2
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We study a hundred of galaxies from the spectroscopic Sloan Digital Sky Survey (SDSS) with individual detections in the far-infrared Herschel Photodetector Array Camera and Spectrometer bands (100 or 160um) and in the GALEX far-ultraviolet band up to z~0.4 in the COSMOS and Lockman Hole fields. The galaxies are divided into four spectral and four morphological types. For the star-forming and unclassifiable galaxies, we calculate dust extinctions from the ultraviolet (UV) slope, the H{alpha}/H{beta} ratio and the L_IR_/L_UV_ ratio. There is a tight correlation between the dust extinction and both L_IR_ and metallicity. We calculate SFRtotal and compare it with other star formation rate (SFR) estimates (H{alpha}, UV, SDSS) finding very good agreement between them with smaller dispersions than typical SFR uncertainties. We study the effect of mass and metallicity, finding that it is only significant at high masses for SFRH{alpha}. For the AGN and composite galaxies, we find a tight correlation between SFR and L_IR_({sigma}~0.29), while the dispersion in the SFR-L_UV_ relation is larger ({sigma}~0.57). The galaxies follow the prescriptions of the Fundamental Plane in the M-Z-SFR space.
- ID:
- ivo://CDS.VizieR/J/ApJ/846/32
- Title:
- Herschel FIR spectra of GOALS galaxies
- Short Name:
- J/ApJ/846/32
- Date:
- 13 Dec 2021 06:52:25
- Publisher:
- CDS
- Description:
- We present an analysis of [OI]_63_, [OIII]_88_, [NII]_122_, and [CII]_158_ far-infrared (FIR) fine-structure line observations obtained with Herschel/PACS, for ~240 local luminous infrared galaxies (LIRGs) in the Great Observatories All-sky LIRG Survey. We find pronounced declines ("deficits") of line-to-FIR continuum emission for [NII]_122_, [OI]_63_, and [CII]_158_ as a function of FIR color and infrared luminosity surface density, {Sigma}_IR_. The median electron density of the ionized gas in LIRGs, based on the [NII]_122_/[NII]_205_ ratio, is n_e_=41cm^-3^. We find that the dispersion in the [CII]_158_ deficit of LIRGs is attributed to a varying fractional contribution of photodissociation regions (PDRs) to the observed [CII]_158_ emission, f([CII]_158_^PDR^)=[CII]_158_^PDR^/[CII]_158_, which increases from ~60% to ~95% in the warmest LIRGs. The [OI]_63_/[CII]_158_^PDR^ ratio is tightly correlated with the PDR gas kinetic temperature in sources where [OI]_63_ is not optically thick or self-absorbed. For each galaxy, we derive the average PDR hydrogen density, n_H_, and intensity of the interstellar radiation field, G, in units of G_0_ and find G/n_H_ ratios of ~0.1-50G_0_.cm^3^, with ULIRGs populating the upper end of the distribution. There is a relation between G/n_H_ and {Sigma}_IR_, showing a critical break at {Sigma}_IR_^*^~5x10^10^L_{sun}_/kpc^2^. Below {Sigma}_IR_^*^, G/n_H_ remains constant, ~0.32G_0_.cm^3^, and variations in {Sigma}_IR_ are driven by the number density of star-forming regions within a galaxy, with no change in their PDR properties. Above {Sigma}_IR_^*^, G/n_H_ increases rapidly with {Sigma}_IR_, signaling a departure from the typical PDR conditions found in normal star-forming galaxies toward more intense/harder radiation fields and compact geometries typical of starbursting sources.
- ID:
- ivo://CDS.VizieR/J/AJ/146/62
- Title:
- HERschel HERITAGE in Magellanic Clouds
- Short Name:
- J/AJ/146/62
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present an overview of the HERschel Inventory of The Agents of Galaxy Evolution (HERITAGE) in the Magellanic Clouds project, which is a Herschel Space Observatory open time key program. We mapped the Large Magellanic Cloud (LMC) and Small Magellanic Cloud (SMC) at 100, 160, 250, 350, and 500{mu}m with the Spectral and Photometric Imaging Receiver (SPIRE) and Photodetector Array Camera and Spectrometer (PACS) instruments on board Herschel using the SPIRE/PACS parallel mode. The overriding science goal of HERITAGE is to study the life cycle of matter as traced by dust in the LMC and SMC. The far-infrared and submillimeter emission is an effective tracer of the interstellar medium (ISM) dust, the most deeply embedded young stellar objects (YSOs), and the dust ejected by the most massive stars. We describe in detail the data processing, particularly for the PACS data, which required some custom steps because of the large angular extent of a single observational unit and overall the large amount of data to be processed as an ensemble. We report total global fluxes for the LMC and SMC and demonstrate their agreement with measurements by prior missions. The HERITAGE maps of the LMC and SMC are dominated by the ISM dust emission and bear most resemblance to the tracers of ISM gas rather than the stellar content of the galaxies. We describe the point source extraction processing and the criteria used to establish a catalog for each waveband for the HERITAGE program. The 250{mu}m band is the most sensitive and the source catalogs for this band have ~25,000 objects for the LMC and ~5500 objects for the SMC. These data enable studies of ISM dust properties, submillimeter excess dust emission, dust-to-gas ratio, Class 0 YSO candidates, dusty massive evolved stars, supernova remnants (including SN1987A), HII regions, and dust evolution in the LMC and SMC. All images and catalogs are delivered to the Herschel Science Center as part of the community support aspects of the project. These HERITAGE images and catalogs provide an excellent basis for future research and follow up with other facilities.
- ID:
- ivo://CDS.VizieR/J/AJ/148/124
- Title:
- Herschel key program Heritage
- Short Name:
- J/AJ/148/124
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Observations from the HERschel Inventory of the Agents of Galaxy Evolution (HERITAGE) have been used to identify dusty populations of sources in the Large and Small Magellanic Clouds (LMC and SMC). We conducted the study using the HERITAGE catalogs of point sources available from the Herschel Science Center from both the Photodetector Array Camera and Spectrometer (PACS; 100 and 160{mu}m) and Spectral and Photometric Imaging Receiver (SPIRE; 250, 350, and 500{mu}m) cameras. These catalogs are matched to each other to create a Herschel band-merged catalog and then further matched to archival Spitzer IRAC and MIPS catalogs from the Spitzer Surveying the Agents of Galaxy Evolution (SAGE) and SAGE-SMC surveys to create single mid- to far-infrared (far-IR) point source catalogs that span the wavelength range from 3.6 to 500{mu}m. There are 35,322 unique sources in the LMC and 7503 in the SMC. To be bright in the FIR, a source must be very dusty, and so the sources in the HERITAGE catalogs represent the dustiest populations of sources. The brightest HERITAGE sources are dominated by young stellar objects (YSOs), and the dimmest by background galaxies. We identify the sources most likely to be background galaxies by first considering their morphology (distant galaxies are point-like at the resolution of Herschel) and then comparing the flux distribution to that of the Herschel Astrophysical Terahertz Large Area Survey (ATLAS) survey of galaxies. We find a total of 9745 background galaxy candidates in the LMC HERITAGE images and 5111 in the SMC images, in agreement with the number predicted by extrapolating from the ATLAS flux distribution. The majority of the Magellanic Cloud-residing sources are either very young, embedded forming stars or dusty clumps of the interstellar medium. Using the presence of 24{mu}m emission as a tracer of star formation, we identify 3518 YSO candidates in the LMC and 663 in the SMC. There are far fewer far-IR bright YSOs in the SMC than the LMC due to both the SMC's smaller size and its lower dust content. The YSO candidate lists may be contaminated at low flux levels by background galaxies, and so we differentiate between sources with a high ("probable") and moderate ("possible") likelihood of being a YSO. There are 2493/425 probable YSO candidates in the LMC/SMC. Approximately 73% of the Herschel YSO candidates are newly identified in the LMC, and 35% in the SMC. We further identify a small population of dusty objects in the late stages of stellar evolution including extreme and post-asymptotic giant branch, planetary nebulae, and supernova remnants. These populations are identified by matching the HERITAGE catalogs to lists of previously identified objects in the literature. Approximately half of the LMC sources and one quarter of the SMC sources are too faint to obtain accurate ample FIR photometry and are unclassified.
- ID:
- ivo://CDS.VizieR/J/ApJ/759/139
- Title:
- Herschel + MIPS photometry of GOODS sources
- Short Name:
- J/ApJ/759/139
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We explore the effects of active galactic nuclei (AGNs) and star formation activity on the infrared (0.3-1000{mu}m) spectral energy distributions (SEDs) of luminous infrared galaxies from z=0.5 to 4.0. We have compiled a large sample of 151 galaxies selected at 24{mu}m (S_24_>~100{mu}Jy) in the GOODS-N and ECDFS fields for which we have deep Spitzer IRS spectroscopy, allowing us to decompose the mid-IR spectrum into contributions from star formation and AGN activity. A significant portion (~25%) of our sample is dominated by an AGN (>50% of the mid-IR luminosity) in the mid-IR. Based on the mid-IR classification, we divide our full sample into four sub-samples: z~1 star-forming (SF) sources, z~2 SF sources, AGNs with clear 9.7{mu}m silicate absorption, and AGNs with featureless mid-IR spectra. From our large spectroscopic sample and wealth of multi-wavelength data, including deep Herschel imaging at 100, 160, 250, 350, and 500{mu}m, we use 95 galaxies with complete spectral coverage to create a composite SED for each sub-sample. We then fit a two-temperature component modified blackbody to the SEDs. We find that the IR SEDs have similar cold dust temperatures, regardless of the mid-IR power source, but display a marked difference in the warmer dust temperatures. We calculate the average effective temperature of the dust in each sub-sample and find a significant (~20K) difference between the SF and AGN systems. We compare our composite SEDs to local templates and find that local templates do not accurately reproduce the mid-IR features and dust temperatures of our high-redshift systems. High-redshift IR luminous galaxies contain significantly more cool dust than their local counterparts. We find that a full suite of photometry spanning the IR peak is necessary to accurately account for the dominant dust temperature components in high-redshift IR luminous galaxies.
- ID:
- ivo://CDS.VizieR/VIII/95
- Title:
- Herschel Multi-tiered Extragalactic Survey
- Short Name:
- VIII/95
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Herschel Multi-tiered Extragalactic Survey (HerMES) is a legacy programme designed to map a set of nested fields totalling ~380deg^2^. Fields range in size from 0.01 to ~20deg^2^, using the Herschel-Spectral and Photometric Imaging Receiver (SPIRE) (at 250, 350 and 500um) and the Herschel-Photodetector Array Camera and Spectrometer (PACS) (at 100 and 160um), with an additional wider component of 270deg^2^ with SPIRE alone. These bands cover the peak of the redshifted thermal spectral energy distribution from interstellar dust and thus capture the reprocessed optical and ultraviolet radiation from star formation that has been absorbed by dust, and are critical for forming a complete multiwavelength understanding of galaxy formation and evolution.
- ID:
- ivo://CDS.VizieR/VIII/103
- Title:
- Herschel Multi-tiered Extragalactic Survey
- Short Name:
- VIII/103
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- HerMES is the Herschel Multi-tiered Extragalactic Survey, an astronomical project to study the evolution of galaxies in the distant Universe.It is the largest project on ESA's Herschel Space Observatory (900 hours). You will find more information about it on the HerMES website (http://hedam.lam.fr/HerMES/). The project is carried out by a large team, made up primarily of people who built one of the instruments on Herschel called SPIRE.
- ID:
- ivo://CDS.VizieR/VI/139
- Title:
- Herschel Observation Log
- Short Name:
- VI/139
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Herschel Space Observatory (Herschel) is an ESA (European Space Agency) project with instruments funded by ESA member states. It was operated from May 2009 till April 2013, offering unprecedent observational capabilities in the far-infrared and submillimetre spectral range (55-671 microns). Herschel carried a 3.5m diameter passively cooled Cassegrain telescope. The science payload comprised three instruments: two direct detection cameras/medium resolution spectrometers, PACS and SPIRE, and a very high-resolution heterodyne spectrometer, HIFI. Herschel successfully made over 37,000 scientific observations. Herschel Science Archive: The HSA is available at the Herschel Science Centre at http://herschel.esac.esa.int/Science_Archive.shtml Herschel helpdesk: http://herschel.esac.esa.int/esupport/ Herschel User Provided Data Products: http://herschel.esac.esa.int/UserProvidedDataProducts.shtml Postcard Server: http://archives.esac.esa.int/hsa/aio/doc/postcardGallery.html Observation Log: http://herschel.esac.esa.int/logrepgen/observationlist.do
