Aims: Our objectives are to determine the properties of the interstellar medium (ISM) and of star formation in typical star-forming galaxies at high redshift.
Methods: Following up on our previous multi-wavelength observations with HST, Spitzer, Herschel, and the Plateau de Bure Interferometer (PdBI), we have studied a strongly lensed z = 2.013 galaxy, the arc behind the galaxy cluster MACS J0451+0006, with ALMA to measure the [C ii] 158 μm emission line, one of the main coolants of the ISM.
Results: Emission of the [C ii] line from the southern part of this galaxy is detected at 10σ. Taking strong gravitational lensing into account, which provides a magnification of μ = 49, the intrinsic lensing-corrected [C ii] luminosity is L[CII] = 1.2 × 108L⊙. The observed ratio of [C ii]-to-IR emission, L[CII]/LFIR ≈ (1.2-2.4) × 10-3, is found to be similar to that in nearby galaxies. The same also holds for the observed ratio L[CII]/LCO= 2.3 × 103, which is comparable to that of star-forming galaxies and active galaxy nuclei (AGN) at low redshift.
Conclusions: We utilize strong gravitational lensing to extend diagnostic studies of the cold ISM to an order of magnitude lower luminosity (LIR ~ (1.1-1.3) × 1011L⊙) and SFR than previous work at high redshift. While larger samples are needed, our results provide evidence that the cold ISM of typical high-redshift galaxies has physical characteristics similar to normal star-forming galaxies in the local Universe.
Astronomy and Astrophysics
- Pub Date:
- April 2015
- galaxies: high-redshift;
- galaxies: ISM;
- galaxies: starburst;
- Astrophysics - Astrophysics of Galaxies
- 5 pages, 4 figures. Accepted for publication in Astronomy &