HERSCHEL EXTREME LENSING LINE OBSERVATIONS: [C ii] VARIATIONS IN GALAXIES AT REDSHIFTS z = 1–3

Journal Article · Fri Jan 20 04:00:00 EST 2017 · Astrophysical Journal

DOI:https://doi.org/10.3847/1538-4357/835/1/110· OSTI ID:22664037

Malhotra, Sangeeta; Rhoads, James E.; Yang, Huan ^[1]; Finkelstein, K.; Finkelstein, Steven ^[2]; Carilli, Chris ^[3]; Combes, Françoise ^[4]; Dassas, Karine; Guillard, Pierre; Nesvadba, Nicole ^[5]; Frye, Brenda ^[6]; Gerin, Maryvonne ^[7]; Rigby, Jane ^[8]; Shin, Min-Su ^[9]; Spaans, Marco ^[10]; Strauss, Michael A. ^[11]; Papovich, Casey ^[12]

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1. School of Earth and Space Exploration, Arizona State University, Tempe, AZ 85287 (United States)
2. University of Texas, Austin, TX 78712 (United States)
3. National Radio Astronomy Observatory, Socorro, NM (United States)
4. Observatoire de Paris, LERMA, CNRS, 61 Avenue de l’Observatoire, F-75014 Paris (France)
5. Institut d’Astrophysique Spatiale, Centre Universitaire d’Orsay (France)
6. Steward Observatory, University of Arizona, Tucson, AZ (United States)
7. LERMA,24 rue Lhomond, F-75231 Paris Cedex 05 (France)
8. NASA Goddard Space Flight Center, Greenbelt, MD (United States)
9. Oxford University, Oxford, OX1 3PA (United Kingdom)
10. Kapteyn Astronomical Institute, University of Groningen, Groningen (Netherlands)
11. Department of Astrophysical Sciences, Princeton University, Peyton Hall, Princeton, NJ 08544 (United States)
12. George P. and Cynthia W. Mitchell Institute for Fundamental Physics and Astronomy, Department of Physics, Texas A and M University, College Station, TX 77843 (United States)

We observed the [C ii] line in 15 lensed galaxies at redshifts 1 < z < 3 using HIFI on the Herschel Space Observatory and detected 14/15 galaxies at 3 σ or better. High magnifications enable even modestly luminous galaxies to be detected in [C ii] with Herschel . The [C ii] luminosity in this sample ranges from 8 × 10{sup 7} L {sub ⊙} to 3.7 × 10{sup 9} L {sub ⊙} (after correcting for magnification), confirming that [C ii] is a strong tracer of the ISM at high redshifts. The ratio of the [C ii] line to the total far-infrared (FIR) luminosity serves as a measure of the ratio of gas to dust cooling and thus the efficiency of the grain photoelectric heating process. It varies between 3.3% and 0.09%. We compare the [C ii]/FIR ratio to that of galaxies at z = 0 and at high redshifts and find that they follow similar trends. The [C ii]/FIR ratio is lower for galaxies with higher dust temperatures. This is best explained if increased UV intensity leads to higher FIR luminosity and dust temperatures, but gas heating does not rise due to lower photoelectric heating efficiency. The [C ii]/FIR ratio shows weaker correlation with FIR luminosity. At low redshifts highly luminous galaxies tend to have warm dust, so the effects of dust temperature and luminosity are degenerate. Luminous galaxies at high redshifts show a range of dust temperatures, showing that [C ii]/FIR correlates most strongly with dust temperature. The [C ii] to mid-IR ratio for the HELLO sample is similar to the values seen for low-redshift galaxies, indicating that small grains and PAHs dominate the heating in the neutral ISM, although some of the high [CII]/FIR ratios may be due to turbulent heating.

• OSTI ID: 22664037
• Journal Information: Astrophysical Journal, Journal Name: Astrophysical Journal Journal Issue: 1 Vol. 835; ISSN ASJOAB; ISSN 0004-637X
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTRONOMY AND ASTROPHYSICS
ATOMS
COMPARATIVE EVALUATIONS
COOLING
CORRELATIONS
DUSTS
EFFICIENCY
GALAXIES
LENSES
LUMINOSITY
POLYCYCLIC AROMATIC HYDROCARBONS
RED SHIFT
SPACE
TURBULENT HEATING
VARIATIONS