Teich, YG;
McNichols, AT;
Nims, E;
Cannon, JM;
Adams, EAK;
Bernstein-Cooper, EZ;
Giovanelli, R;
... Sistine, AV; + view all
(2016)
SHIELD: Comparing Gas and Star Formation in Low Mass Galaxies.
The Astrophysical Journal
, 832
(1)
, Article 85. 10.3847/0004-637X/832/1/85.
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Abstract
We analyze the relationships between atomic, neutral hydrogen (HI) and star formation (SF) in the 12 low-mass SHIELD galaxies. We compare high spectral (~0.82 km/s/channel) and spatial resolution (physical resolutions of 170 pc - 700 pc) HI imaging from the VLA with H\alpha and far-ultraviolet imaging. We quantify the degree of co-spatiality between star forming regions and regions of high HI column densities. We calculate the global star formation efficiencies (SFE, $\Sigma_{\rm SFR}$ / $\Sigma_{\rm HI}$), and examine the relationships among the SFE and HI mass, HI column density, and star formation rate (SFR). The systems are consuming their cold neutral gas on timescales of order a few Gyr. While we derive an index for the Kennicutt-Schmidt relation of N ~ 0.68 $\pm$ 0.04 for the SHIELD sample as a whole, the values of N vary considerably from system to system. By supplementing SHIELD results with those from other surveys, we find that HI mass and UV-based SFR are strongly correlated over five orders of magnitude. Identification of patterns within the SHIELD sample allows us to bin the galaxies into three general categories: 1) mainly co-spatial HI and SF regions, found in systems with highest peak HI column densities and highest total HI masses, 2) moderately correlated HI and SF regions, found in systems with moderate HI column densities, and 3) obvious offsets between HI and SF peaks, found in systems with the lowest total HI masses. SF in these galaxies is dominated by stochasticity and random fluctuations in their ISM.
| Type: | Article |
|---|---|
| Title: | SHIELD: Comparing Gas and Star Formation in Low Mass Galaxies |
| Open access status: | An open access version is available from UCL Discovery |
| DOI: | 10.3847/0004-637X/832/1/85 |
| Publisher version: | http://dx.doi.org/10.3847/0004-637X/832/1/85 |
| Language: | English |
| Additional information: | © 2016. The American Astronomical Society. Accepted for publication by the Astrophysical Journal, high-resolution version and survey data available at https://www.macalester.edu/~jcannon/shield/ |
| Keywords: | astro-ph.GA, astro-ph.GA |
| UCL classification: | UCL UCL > Provost and Vice Provost Offices > UCL BEAMS UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences > Dept of Physics and Astronomy |
| URI: | https://discovery-pp.ucl.ac.uk/id/eprint/1526851 |
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