Gergö Popping
ALMA reveals starburst-like interstellar medium conditions in a compact star-forming galaxy at z ~ 2 using [CI] and CO
Popping, Gergö; Decarli, Roberto; Man, Allison W.S.; Nelson, Erica J.; Béthermin, Matthieu; De Breuck, Carlos; Mainieri, Vincenzo; van Dokkum, Pieter G.; Gullberg, Bitten; van Kampen, Eelco; Spaans, Marco; Trager, Scott C.
Authors
Roberto Decarli
Allison W.S. Man
Erica J. Nelson
Matthieu Béthermin
Carlos De Breuck
Vincenzo Mainieri
Pieter G. van Dokkum
Bitten Gullberg
Eelco van Kampen
Marco Spaans
Scott C. Trager
Abstract
We present ALMA detections of the [CI] 1–0, CO J = 3–2, and CO J = 4–3 emission lines, as well as the ALMA band 4 continuum for a compact star-forming galaxy (cSFG) at z = 2.225, 3D-HST GS30274. As is typical for cSFGs, this galaxy has a stellar mass of 1.89 ± 0.47 × 1011M⊙, with a star formation rate (SFR) of 214 ± 44 M⊙ yr-1 putting it on the star-forming “main-sequence”, but with an H-band effective radius of 2.5 kpc, making it much smaller than the bulk of “main-sequence” star-forming galaxies. The intensity ratio of the line detections yield an ISM density (~ 6 × 104 cm-3) and a UV-radiation field (~ 2 × 104G0), similar to the values in local starburst and ultra-luminous infrared galaxy environments. A starburst phase is consistent with the short depletion times (tH2,dep ≤ 140 Myr) we find in 3D-HST GS30274 using three different proxies for the H2 mass ([CI], CO, dust mass). This depletion time is significantly shorter than in more extended SFGs with similar stellar masses and SFRs. Moreover, the gas fraction of 3D-HST GS30274 is smaller than typically found in extended galaxies. We measure the CO and [CI] kinematics and find a FWHM line width of ~ 750 ± 41 km s-1. The CO and [CI] FWHM are consistent with a previously measured Hα FWHM for this source. The line widths are consistent with gravitational motions, suggesting we are seeing a compact molecular gas reservoir. A previous merger event, as suggested by the asymmetric light profile, may be responsible for the compact distribution of gas and has triggered a central starburst event. This event gives rise to the starburst-like ISM properties and short depletion times in 3D-HST GS30274. The centrally located and efficient star formation is quickly building up a dense core of stars, responsible for the compact distribution of stellar light in 3D-HST GS30274.
Citation
Popping, G., Decarli, R., Man, A. W., Nelson, E. J., Béthermin, M., De Breuck, C., …Trager, S. C. (2017). ALMA reveals starburst-like interstellar medium conditions in a compact star-forming galaxy at z ~ 2 using [CI] and CO. Astronomy & Astrophysics, 602, Article A11. https://doi.org/10.1051/0004-6361/201730391
Journal Article Type | Article |
---|---|
Acceptance Date | Mar 9, 2017 |
Online Publication Date | May 24, 2017 |
Publication Date | May 24, 2017 |
Deposit Date | Jul 7, 2017 |
Publicly Available Date | Mar 29, 2024 |
Journal | Astronomy and astrophysics. |
Print ISSN | 0004-6361 |
Electronic ISSN | 1432-0746 |
Publisher | EDP Sciences |
Peer Reviewed | Peer Reviewed |
Volume | 602 |
Article Number | A11 |
DOI | https://doi.org/10.1051/0004-6361/201730391 |
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Copyright Statement
Reproduced with permission from Astronomy & Astrophysics, © ESO 2017
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