The Bright and Dark Sides of High-redshift Starburst Galaxies from Herschel and Subaru Observations

Autor(en)

A. Puglisi, Emanuele Daddi, Alvio Renzini, Christian Maier

Abstrakt

We present rest-frame optical spectra from the FMOS-COSMOS survey of 12 z ~ 1.6 Herschel starburst galaxies, with star formation rate (SFR) elevated by ×8, on average, above the star-forming main sequence (MS). Comparing the Hα to IR luminosity ratio and the Balmer decrement, we find that the optically thin regions of the sources contain on average only ~10% of the total SFR, whereas ~90% come from an extremely obscured component that is revealed only by far-IR observations and is optically thick even in Hα. We measure the [N II]6583/Hα ratio, suggesting that the less obscured regions have a metal content similar to that of the MS population at the same stellar masses and redshifts. However, our objects appear to be metal-rich outliers from the metallicity-SFR anticorrelation observed at fixed stellar mass for the MS population. The [S II]6732/[S II]6717 ratio from the average spectrum indicates an electron density n_e ~ 1100 cm^-3 , larger than what was estimated for MS galaxies but only at the 1.5σ level. Our results provide supporting evidence that high-z MS outliers are analogous of local ULIRGs and are consistent with a major-merger origin for the starburst event.

Organisation(en)

Institut für Astrophysik

Externe Organisation(en)

Università degli Studi di Padova, European Southern Observatory (Germany), Université Paris VII - Paris-Diderot, INAF - Osservatorio Astronomico di Padova

Journal

The Astrophysical journal Letters

Band

838

Anzahl der Seiten

6

ISSN

2041-8205

DOI

https://doi.org/10.3847/2041-8213/aa66c9

Publikationsdatum

04-2017

Peer-reviewed

Ja

ÖFOS 2012

103003 Astronomie, 103004 Astrophysik

Schlagwörter

ASJC Scopus Sachgebiete

Astronomy and Astrophysics, Space and Planetary Science

Link zum Portal

https://ucrisportal.univie.ac.at/de/publications/55a7ac51-4e86-4231-a5a6-eaf5f3dfe796