Detalles de publicación

PP 010019

The evolutionary sequence of sub-mm galaxies: from diffuse discs to massive compact ellipticals?

E. Ricciardelli (1,2), I. Trujillo (1,2), F. Buitrago (3) and C. J. Conselice (3)
(1) IAC, (2) Departamento de Astrofisica, Universidad de La Laguna (3) School of Physics and Astronomy, University of Nottingham
The population of compact massive galaxies observed at z > 1 are hypothesised, both
observationally and in simulations, to
be merger remnants of gas-rich disc galaxies. To probe such a scenario
we analyse a sample of 12 gas-rich and active star forming sub-mm galaxies (SMGs) at 1.8 < z < 3. We
present a structural and size measurement analysis for all of these objects
using very deep ACS and NICMOS imaging in the GOODS-North field. Our analysis reveals a heterogeneous mix of
morphologies and sizes. We find that four galaxies (33% \pm 17%) show clear signs of mergers or
interactions, which we classify as early-stage mergers. The remaining galaxies are
divided into two categories: five of them (42% \pm 18%) are diffuse and regular disc-like
objects, while three (25% \pm 14%) are very compact, spheroidal systems. We argue that these
three categories can be accommodated into an evolutionary sequence, showing the
transformation from isolated, gas-rich discs with typical sizes of 2-3 kpc, into compact (< 1 kpc)
galaxies through violent major merger events, compatible with the scenario depicted by
theoretical models. Our findings that some SMGs are already dense and compact
provides strong support to the idea that SMGs are the precursors of the compact, massive galaxies found at slightly lower redshift.

Aceptado para publicación en MNRAS | Enviado el 2010-03-18 | Proyecto 3I2406