Galaxy formation and evolution

Abstract:

The Herschel ATLAS is the largest open-time key project that will be carried out on the Herschel Space Observatory. It will survey 570 deg 2 of the extragalactic sky, 4 times larger than all the other Herschel extragalactic surveys combined, in five far-infrared and submillimeter bands. We describe the survey, the complementary multiwavelength data sets that will be combined with the Herschel data, and the six major science programs we are undertaking. Using new models based on a previous submillimeter survey of galaxies, we present predictions of the properties of the ATLAS sources in other wave bands. © 2010. The Astronomical Society of the Pacific. All rights reserved.

Abstract:

We present a range of new observations of the 'broad absorption-line radio galaxy' 4C +72.26 (z≈ 3.5), including sensitive rest-frame ultraviolet integral field spectroscopy using the Gemini/GMOS-N instrument and Subaru/CISCO K-band imaging and spectroscopy. We show that 4C +72.26 is a system of two vigorously star-forming galaxies superimposed along the line of sight separated by ∼1300 ± 200 km s-1 in velocity, with each demonstrating spectroscopically resolved absorption lines. The most active star-forming galaxy also hosts the accreting supermassive black hole which powers the extended radio source. We conclude that the star formation is unlikely to have been induced by a shock caused by the passage of the radio jet, and instead propose that a collision is a more probable trigger for the star formation. Despite the massive starburst, the ultraviolet-mid-infrared spectral energy distribution suggests that the pre-existing stellar population comprises ∼1012 M⊙ of stellar mass, with the current burst only contributing a further ∼2 per cent, suggesting that 4C +72.26 has already assembled most of its final stellar mass. © 2010 The Authors. Journal compilation © 2010 RAS.