15um ISO observations of a CFRS field: the cosmic SFR as derived from UV, optical, mid-IR and radio photometry

Flores, H., Hammer, F., Thuan, T., Césarsky, C., Désert, F. X., Omont, A., Lilly, S. J., Eales, Stephen Anthony ORCID: https://orcid.org/0000-0002-7394-426X, Crampton, D. and Le Fèvre, O. 1998. 15um ISO observations of a CFRS field: the cosmic SFR as derived from UV, optical, mid-IR and radio photometry. Astrophysical Journal

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Abstract

The CFRS 1452+52 field has been deeply imaged with the Infrared Space Observatory (ISO) using ISOCAM through the LW3 filter (12-18um). Careful data analysis and comparison to deep optical and radio data have allowed us to generate a catalog of 78 15um sources with both radio and optical identifications. They are redder and lie at higher redshift than I-band selected galaxies, with most of them being star-forming galaxies. We have considered the galaxies detected at radio and 15μ m wavelengths which potentially include all strong and heavily extincted starbursts, up to z=1. Spectral energy distributions (SED) for each of the sources have been derived using deep radio, mid-IR, near-IR, optical and UV photometry. The sources were then spectrally classified by comparing to SEDs of well known nearby galaxies. By deriving their FIR luminosities by interpolation, we can estimate their Star Formation Rate (SFR) in a way which does not depend sensitively on the extinction. 75% (-40%, +10%) of the star formation at z≤1 is related to IR emission and the global extinction is in the range Av=0.5 -- 0.85. While heavily extincted starbursts, with SFR in excess of 100 Mo/yr constitute less than a percent of all galaxies, they contribute about 18% of the SFR density out to z=1. Their morphologies range from S0 to Sab, and more than a third are interacting systems. The SFR derived by FIR fluxes is likely to be ~2.9 times higher than those previously estimated from UV fluxes. The derived stellar mass formed since the redshift of 1 could be too high when compared to the present day stellar mass density. This might be due to an IMF in distant star-forming galaxies different from the solar neighborhood one, or to an underestimate of the local stellar mass density.

Item Type:	Article
Date Type:	Published Online
Status:	Submitted
Schools:	Physics and Astronomy
Subjects:	Q Science > QB Astronomy
Publisher:	IOP Science
ISSN:	0004-637X
Date of Acceptance:	1998
Last Modified:	27 Oct 2022 09:27
URI:	https://orca.cardiff.ac.uk/id/eprint/65891

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