STAR FORMATION IN LINER HOST GALAXIES AT z {approx} 0.3
- School of Physics and Astronomy, Tel Aviv University, Tel Aviv 69978 (Israel)
- MPE, Postfach 1312, 85741 Garching (Germany)
- INAF-Oservatorio Astronomico di Roma, via Frascati 33, 00040 Monte Porzio Catone (Roma) (Italy)
- Laboratoire AIM, CEA/DSM-CNRS-Universite Paris Diderot, IRFU/Service d'Astrophysique, Bat 709, CEA-Saclay, 91191 Gif-sur-Yvette Cedex (France)
- Dipartimento di Astronomia, Universita degli Studi di Bologna, via Ranzani 1, 40127 Bologna (Italy)
We present the results of a Herschel-PACS study of a sample of 97 low-ionization nuclear emission-line regions (LINERs) at redshift z {approx} 0.3 selected from the zCOSMOS survey. Of these sources, 34 are detected in at least one PACS band, enabling reliable estimates of the far-infrared L{sub FIR} luminosities, and a comparison to the FIR luminosities of local LINERs. Many of our PACS-detected LINERs are also UV sources detected by GALEX. Assuming that the FIR is produced in young dusty star-forming regions, the typical star formation rates (SFRs) for the host galaxies in our sample are {approx}10 M{sub Sun} yr{sup -1}, 1-2 orders of magnitude larger than in many local LINERs. Given stellar masses inferred from optical/NIR photometry of the (unobscured) evolved stellar populations, we find that the entire sample lies close to the star-forming 'main sequence' for galaxies at redshift 0.3. For young star-forming regions, the H{alpha}- and UV-based estimates of the SFRs are much smaller than the FIR-based estimates, by factors {approx}30, even assuming that all of the H{alpha} emission is produced by O-star ionization rather than by the active galactic nuclei (AGNs). These discrepancies may be due to large (and uncertain) extinctions toward the young stellar systems. Alternatively, the H{alpha} and UV emissions could be tracing residual star formation in an older, less obscured population with decaying star formation. We also compare L{sub SF} and L(AGN) in local LINERs and in our sample. Finally, we comment on the problematic use of several line diagnostic diagrams in cases with an estimated obscuration similar to that in the sample under study.
- OSTI ID:
- 22039372
- Journal Information:
- Astrophysical Journal, Vol. 753, Issue 2; Other Information: Country of input: International Atomic Energy Agency (IAEA); ISSN 0004-637X
- Country of Publication:
- United States
- Language:
- English
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