High redshift radio galaxies (HzRGs) are the most dramatic examples of theformation of massive galaxies in the early Universe, as evidenced by theirextreme (>1000Msun/yr) star formation rates. At the same time they coincidewith a phase of rapid coeval black hole (BH) growth, as revealed by their powerfulactive galactic nuclei (AGN). This makes HzRGs unique laboratories in which tostudy the coevolution of massive galaxies and their central BHs. Ourteam has successfully carried out comprehensive imaging surveys of 62 powerfulHzRGs at z > 1 using Spitzer and Herschel. These surveys have demonstrated thatHzRGs have high stellar masses (>1e11Msun), and mid-IR AGN luminositiescomparable to the most powerful QSOs known. Also, they have allowed usto separate the AGN and starburst contributions to the total IR luminosity. Inparallel to this, we are undertaking a large CO(1-0) line survey towards asubset of 10 HzRGs using ATCA, which will provide us with excitation-unbiased mass estimates of the total molecular gasavailable for star formation. With this proposal we will constrain the bulkphysical conditions of the star forming gas in HzRGs using the far-infrared OIfine-structure line at 63micron, which is one of the brightest diagnostic linesof the interstellar medium (ISM) in galaxies. The OI line, which can containas much as >0.1% of the total IR luminosity of a galaxy, is one of the majorcoolants of the ISM, and is expected to be particular bright in the type ofdense, hot, star forming gas expected to dominate the ISM in HzRGs. Utilizingour accurate IR luminosity estimates and molecular gas masses in combinationwith OI we will employ photo-dissociation models to constrain the gas densityand the impinging FUV radiation field. We request a total of 13.1hrs of PACSspectroscopy (virgul2.2hrs per source, ensuring a S/N > 5) in order to detect theOI line towards six carefully chosen HzRG, representative of the luminous 1 <z < 2.3 radio galaxy population.
Publication
Instrument
PACS_PacsRangeSpec_point
Temporal Coverage
2013-04-28T03:45:48Z/2013-04-28T05:54:11Z
Version
SPG v14.2.0
Mission Description
Herschel was launched on 14 May 2009! It is the fourth cornerstone mission in the ESA science programme. With a 3.5 m Cassegrain telescope it is the largest space telescope ever launched. It is performing photometry and spectroscopy in approximately the 55-671 µm range, bridging the gap between earlier infrared space missions and groundbased facilities.
European Space Agency, greve et al., 2013, 'Probing the Physical Conditions of the Interstellar Medium in High Redshift Radio Galaxies', SPG v14.2.0, European Space Agency, https://doi.org/10.5270/esa-sgbg99b