Near-infrared emission lines in starburst galaxies at 0.5 < z < 0.9 : Discovery of a merger sequence of extreme obscurations

A. Calabrò,Emanuele Daddi,P. Cassata,Masato Onodera,R. Gobat,A. Puglisi,S. Jin,D Liu,R. Amorin,Nobuo Arimoto,M. Boquien,Rosamaria Carraro,David Elbaz,E. Ibar,S. Juneau,Filippo Mannucci,Hugo Méndez Hernánez,E Oliva,G. Rodighiero,Francesco Valentino,Anita Zanella

Near-infrared emission lines in starburst galaxies at 0.5 < z < 0.9 : Discovery of a merger sequence of extreme obscurations

2018

We obtained optical/near-IR rest-frame Magellan FIRE spectra (including Pa$\beta$ and Pa$\gamma$) of 25 starburst galaxies at 0.5H$\alpha$ ratios to widespread shocks from accretion, turbulence and dynamic disturbances rather than to AGNs. The large range of optical depths demonstrates that substantial diversity is present within the starburst population, possibly connected to different merger phases or progenitor properties. The majority of our targets are, in fact, morphologically classified as mergers. We argue that the extreme obscuration provides in itself smoking gun evidence of their merger origin, and a powerful tool for identifying mergers at even higher redshifts.

Keywords:

Accretion (meteorology)
Population
Astronomy
Astrophysics
Stars
Galaxy
Emission spectrum
Physics
Star formation
Luminosity
Redshift

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