Advanced search
1 file | 12.66 MB Add to list

The Herschel Dwarf Galaxy Survey II : physical conditions, origin of [CII] emission, and porosity of the multiphase low-metallicity ISM

Author
Organization
Abstract
The sensitive infrared telescopes, Spitzer and Herschel, have been used to target low-metallicity star-forming galaxies, allowing us to investigate the properties of their interstellar medium (ISM) in unprecedented detail. Interpretation of the observations in physical terms relies on careful modeling of those properties. We have employed a multiphase approach to model the ISM phases (HII region and photodissociation region) with the spectral synthesis code Cloudy. Our goal is to characterize the physical conditions (gas densities, radiation fields, etc.) in the ISM of the galaxies from the Herschel Dwarf Galaxy Survey. We are particularly interested in correlations between those physical conditions and metallicity or star-formation rate. Other key issues we have addressed are the contribution of different ISM phases to the total line emission, especially of the [CII]157um line, and the characterization of the porosity of the ISM. We find that the lower-metallicity galaxies of our sample 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 correlation - though 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. Such porosity may be typical of galaxies in the young Universe.
Keywords
radiative transfer, HII regions, photon-dominated region, galaxies: dwarf, galaxies: ISM, infrared: ISM, FINE-STRUCTURE LINES, FAR-INFRARED LINE, INTERSTELLAR-MEDIUM, STAR-FORMATION, MU-M, PHOTODISSOCIATION REGIONS, CHEMICAL-COMPOSITION, IONIZING-RADIATION, ELECTRON-DENSITY, MASSIVE STARS

Downloads

  • aa34457-18.pdf
    • full text (Published version)
    • |
    • open access
    • |
    • PDF
    • |
    • 12.66 MB

Citation

Please use this url to cite or link to this publication:

MLA
Cormier, D., et al. “The Herschel Dwarf Galaxy Survey II : Physical Conditions, Origin of  [CII] Emission, and Porosity of the Multiphase Low-Metallicity ISM.” ASTRONOMY & ASTROPHYSICS, vol. 626, 2019, doi:10.1051/0004-6361/201834457.
APA
Cormier, D., Abel, N. P., Hony, S., Lebouteiller, V., Madden, S. C., Polles, F. L., … Lambert-Huyghe, A. (2019). The Herschel Dwarf Galaxy Survey II : physical conditions, origin of  [CII] emission, and porosity of the multiphase low-metallicity ISM. ASTRONOMY & ASTROPHYSICS, 626. https://doi.org/10.1051/0004-6361/201834457
Chicago author-date
Cormier, D., N. P. Abel, S. Hony, V. Lebouteiller, S. C. Madden, F. L. Polles, F. Galliano, Ilse De Looze, M. Galametz, and A. Lambert-Huyghe. 2019. “The Herschel Dwarf Galaxy Survey II : Physical Conditions, Origin of  [CII] Emission, and Porosity of the Multiphase Low-Metallicity ISM.” ASTRONOMY & ASTROPHYSICS 626. https://doi.org/10.1051/0004-6361/201834457.
Chicago author-date (all authors)
Cormier, D., N. P. Abel, S. Hony, V. Lebouteiller, S. C. Madden, F. L. Polles, F. Galliano, Ilse De Looze, M. Galametz, and A. Lambert-Huyghe. 2019. “The Herschel Dwarf Galaxy Survey II : Physical Conditions, Origin of  [CII] Emission, and Porosity of the Multiphase Low-Metallicity ISM.” ASTRONOMY & ASTROPHYSICS 626. doi:10.1051/0004-6361/201834457.
Vancouver
1.
Cormier D, Abel NP, Hony S, Lebouteiller V, Madden SC, Polles FL, et al. The Herschel Dwarf Galaxy Survey II : physical conditions, origin of  [CII] emission, and porosity of the multiphase low-metallicity ISM. ASTRONOMY & ASTROPHYSICS. 2019;626.
IEEE
[1]
D. Cormier et al., “The Herschel Dwarf Galaxy Survey II : physical conditions, origin of  [CII] emission, and porosity of the multiphase low-metallicity ISM,” ASTRONOMY & ASTROPHYSICS, vol. 626, 2019.
@article{8694944,
  abstract     = {{The sensitive infrared telescopes, Spitzer and Herschel, have been used to
target low-metallicity star-forming galaxies, allowing us to investigate the
properties of their interstellar medium (ISM) in unprecedented detail.
Interpretation of the observations in physical terms relies on careful modeling
of those properties. We have employed a multiphase approach to model the ISM
phases (HII region and photodissociation region) with the spectral synthesis
code Cloudy. Our goal is to characterize the physical conditions (gas
densities, radiation fields, etc.) in the ISM of the galaxies from the Herschel
Dwarf Galaxy Survey. We are particularly interested in correlations between
those physical conditions and metallicity or star-formation rate. Other key
issues we have addressed are the contribution of different ISM phases to the
total line emission, especially of the [CII]157um line, and the
characterization of the porosity of the ISM. We find that the lower-metallicity
galaxies of our sample 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
correlation - though 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. Such porosity may be typical of
galaxies in the young Universe.}},
  articleno    = {{A23}},
  author       = {{Cormier, D. and Abel, N. P. and Hony, S. and Lebouteiller, V. and Madden, S. C. and Polles, F. L. and Galliano, F. and De Looze, Ilse and Galametz, M. and Lambert-Huyghe, A.}},
  issn         = {{0004-6361}},
  journal      = {{ASTRONOMY & ASTROPHYSICS}},
  keywords     = {{radiative transfer,HII regions,photon-dominated region,galaxies: dwarf,galaxies: ISM,infrared: ISM,FINE-STRUCTURE LINES,FAR-INFRARED LINE,INTERSTELLAR-MEDIUM,STAR-FORMATION,MU-M,PHOTODISSOCIATION REGIONS,CHEMICAL-COMPOSITION,IONIZING-RADIATION,ELECTRON-DENSITY,MASSIVE STARS}},
  language     = {{eng}},
  pages        = {{44}},
  title        = {{The Herschel Dwarf Galaxy Survey II : physical conditions, origin of  [CII] emission, and porosity of the multiphase low-metallicity ISM}},
  url          = {{http://doi.org/10.1051/0004-6361/201834457}},
  volume       = {{626}},
  year         = {{2019}},
}

Altmetric
View in Altmetric
Web of Science
Times cited: