- 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.
Number of results to display per page
Search Results
- 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/799/100
- Title:
- Herschel FIR observations of NGC3603
- Short Name:
- J/ApJ/799/100
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We observed the giant H II region around the NGC 3603 young stellar cluster (YC) with the five broad bands (70, 160, 250, 350, 500{mu}m) of the SPIRE and PACS instruments, on board the Herschel Space Observatory. Together with what is currently known of the stellar, atomic, molecular, and warm dust components, this additional and crucial information should allow us to better understand the details of the star-formation history in this region. The main objective of the investigation is to study, at high spatial resolution, the distribution and main physical characteristics of the cold dust. By reconstructing the temperature and density maps, we found, respectively, a mean value of 36K and log_10_N_H_=22.0+/-0.1/cm2. We carried out a photometric analysis detecting 107 point-like sources, mostly confined to the north and south of the cluster. By comparing our data with spectral energy distribution models, we found that 35 sources are well represented by young stellar objects in early evolutionary phases, from Class 0 to Class I. The Herschel detections also provided far-IR counterparts for 4 H_2_O masers and 11 objects previously known from mid-IR observations. The existence of so many embedded sources confirms the hypothesis of intense and ongoing star-formation activity in the region around NGC 3603 YC.
- 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/ApJ/745/95
- Title:
- Herschel FIR & submm photometry of KINGFISH sample
- Short Name:
- J/ApJ/745/95
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- New far-infrared and submillimeter photometry from the Herschel Space Observatory is presented for 61 nearby galaxies from the Key Insights on Nearby Galaxies: A Far-Infrared Survey with Herschel (KINGFISH) sample. The spatially integrated fluxes are largely consistent with expectations based on Spitzer far-infrared photometry and extrapolations to longer wavelengths using popular dust emission models. Dwarf irregular galaxies are notable exceptions, as already noted by other authors, as their 500{mu}m emission shows evidence for a submillimeter excess. In addition, the fraction of dust heating attributed to intense radiation fields associated with photodissociation regions is found to be (21+/-4)% larger when Herschel data are included in the analysis. Dust masses obtained from the dust emission models of Draine & Li (2007ApJ...657..810D) are found to be on average nearly a factor of two higher than those based on single-temperature modified blackbodies, as single blackbody curves do not capture the full range of dust temperatures inherent to any galaxy. The discrepancy is largest for galaxies exhibiting the coolest far-infrared colors.
- ID:
- ivo://CDS.VizieR/J/MNRAS/440/1571
- Title:
- Herschel fluxes of Fornax galaxies
- Short Name:
- J/MNRAS/440/1571
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Herschel Fornax Cluster Survey is a deep, far-infrared (FIR) survey of the Fornax cluster. The survey is in five Herschel bands (100-500{mu}m) and covers an area of 16deg^2^ centred on NGC 1399. This paper presents photometry, detection rates, dust masses, and temperatures using an optically selected sample from the Fornax Cluster Catalogue. Our results are compared with those previously obtained using data from the Herschel Virgo Cluster Survey (HeViCS). In Fornax, we detect 30 of the 237 (13%) optically selected galaxies in at least one Herschel band. The global detection rates are significantly lower than Virgo, reflecting the morphological make up of each cluster - Fornax has a lower fraction of late-type galaxies. For galaxies detected in at least three bands, we fitted a modified blackbody with a {beta}=2 emissivity. Detected early-type galaxies (E/S0) have a mean dust mass, temperature, and dust-to-stars ratio of log10(<M_dust_>/M_{sun}_)=5.82+/-0.20, <T_dust_>=20.82+/-1.77K, and log_10_(M_dust_/M_stars_)=-3.87+/-0.28, respectively. Late-type galaxies (Sa to Sd) have a mean dust mass, temperature, and dust-to-stars ratio of log10(M_dust_>/M_{sun}_)=6.54+/-0.19, <T_dust_>=17.47+/-0.97K, and log_10_(M_dust_/M_stars_)=-2.93+/-0.09, respectively. The different cluster environments seem to have had little effect on the FIR properties of the galaxies and so we conclude that any environment-dependent evolution has taken place before the cluster was assembled.
- ID:
- ivo://CDS.VizieR/J/ApJ/814/133
- Title:
- Herschel Galactic plane survey of [NII]
- Short Name:
- J/ApJ/814/133
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the first large-scale high angular resolution survey of ionized nitrogen in the Galactic Plane through emission of its two fine structure transitions ([N II]) at 122 and 205 {mu}m. The observations were largely obtained with the PACS instrument onboard the Herschel Space Observatory. The lines of sight were in the Galactic plane, following those of the Herschel OTKP project GOT C+. Both lines are reliably detected at the 10^-8^-10^-7^ W/m^2^/sr level over the range -60{deg}<=l<=60{deg}. The rms of the intensity among the 25 PACS spaxels of a given pointing is typically less than one third of the mean intensity, showing that the emission is extended. [N II] is produced in gas in which hydrogen is ionized, and collisional excitation is by electrons. The ratio of the two fine structure transitions provides a direct measurement of the electron density, yielding n(e) largely in the range 10-50 cm^-3^ with an average value of 29 cm^-3^ and N^+^ column densities 10^16^-10^17^ cm^-2^. [N II] emission is highly correlated with that of [C II], and we calculate that between 1/3 and 1/2 of the [C II] emission is associated with the ionized gas. The relatively high electron densities indicate that the source of the [N II] emission is not the warm ionized medium (WIM), which has electron densities more than 100 times smaller. Possible origins of the observed [N II] include the ionized surfaces of dense atomic and molecular clouds, the extended low-density envelopes of H II regions, and low-filling factor high-density fluctuations of the WIM.
6089. Herschel GOODS-N Catalog
- ID:
- ivo://irsa.ipac/Herschel/Catalog/GOODS/HGOODS-N
- Title:
- Herschel GOODS-N Catalog
- Short Name:
- HGOODS-N Catalog
- Date:
- 01 Oct 2018 20:27:20
- Publisher:
- NASA/IPAC Infrared Science Archive
- Description:
- GOODS-Herschel (Elbaz et al, 2011) is in ESA open time key project consisting of the deepest Herschel observations of the two Great Observatories Origins Deep Survey (GOODS) fields in the Northern and Southern hemispheres. The GOODS catalogs include photometry from Spitzer IRAC & MIPS and Herschel PACS & SPIRE observations.
6090. Herschel GOODS-S Catalog
- ID:
- ivo://irsa.ipac/Herschel/Catalog/GOODS/HGOODS-S
- Title:
- Herschel GOODS-S Catalog
- Short Name:
- HGOODS-S Catalog
- Date:
- 01 Oct 2018 20:27:20
- Publisher:
- NASA/IPAC Infrared Science Archive
- Description:
- GOODS-Herschel (Elbaz et al, 2011) is in ESA open time key project consisting of the deepest Herschel observations of the two Great Observatories Origins Deep Survey (GOODS) fields in the Northern and Southern hemispheres. The GOODS catalogs include photometry from Spitzer IRAC & MIPS and Herschel PACS & SPIRE observations.