Metal-Enriched Gaseous Halos around Distant Radio Galaxies: Clues to Feedback in Galaxy Formation

We present the results of an optical and near-IR spectroscopic study of giant nebular emission-line halos associated with three z > 3 radio galaxies, 4C 41.17, 4C 60.07, and B2 0902+34. Previous deep narrowband Lyα imaging revealed complex morphologies with sizes up to 100 kpc, possibly connected to outflows and AGN feedback from the central regions. The outer regions of these halos show quiet kinematics with typical velocity dispersions of a few hundred km s^(-1) and velocity shears that can mostly be interpreted as being due to rotation. The inner regions show shocked cocoons of gas closely associated with the radio lobes. These display disturbed kinematics and have expansion velocities and/or velocity dispersions >1000 km s^(-1). The core region is chemically evolved, and we also find spectroscopic evidence for the ejection of enriched material in 4C 41.17 up to a distance of ≈60 kpc along the radio axis. The dynamical structures traced in the Lyα line are, in most cases, closely echoed in the carbon and oxygen lines. This shows that the Lyα line is produced in a highly clumped medium of small filling factor and can therefore be used as a tracer of the dynamics of high-redshift radio galaxies (HzRGs). We conclude that these HzRGs are undergoing a final jet-induced phase of star formation with ejection of most of their interstellar medium before becoming "red and dead" elliptical galaxies

Halo ejection in distant radio galaxies: jet feedback in massive galaxy formation

We present results from a Keck optical and near IR spectroscopic study of the giant emission line halos of the z>3 High Redshift Radio Galaxies (HiZRGs) 4C 41.17, 4C 60.07 and B2 0902+34. The outer regions of these halos show quiet kinematics with typical velocity dispersions of a few hundred km∈s-1 and velocity shears consistent with rotation. The inner regions contain shocked, clumpy cocoons of gas closely associated with the radio lobes with disturbed kinematics and expansion velocities and/or velocity dispersions >1000 km∈s-1. We also find evidence for the ejection of chemically enriched material in 4C 41.17 up to a distance of 60 kpc along the radio-axis. We infer that these HiZRGs are undergoing a final jet-induced phase of star formation with the ejection of most of their interstellar medium before evolving to become "red and dead" Elliptical galaxies

Metal-Enriched Gaseous Halos around Distant Radio Galaxies: Clues to Feedback in Galaxy Formation

We present the results of an optical and near-IR spectroscopic study of giant nebular emission-line halos associated with three z > 3 radio galaxies, 4C 41.17, 4C 60.07, and B2 0902+34. Previous deep narrowband Lyα imaging revealed complex morphologies

Halo ejection in distant radio galaxies: jet feedback in massive galaxy formation

We present results from a Keck optical and near IR spectroscopic study of the giant emission line halos of the z > 3 High Redshift Radio Galaxies (HiZRGs) 4C 41.17, 4C 60.07 and B2 0902+34. The outer regions of these halos show quiet kinematics with typical velocity dispersions of a few hundred km s^(−1) and velocity shears consistent with rotation. The inner regions contain shocked, clumpy cocoons of gas closely associated with the radio lobes with disturbed kinematics and expansion velocities and/or velocity dispersions > 1000 km s^(−1). We also find evidence for the ejection of chemically enriched material in 4C 41.17 up to a distance of ~60 kpc along the radio-axis. We infer that these HiZRGs are undergoing a final jet-induced phase of star formation with the ejection of most of their interstellar medium before evolving to become “red and dead” Elliptical galaxies

The intense starburst HDF 850.1 in a galaxy overdensity at z=5.2 in the Hubble Deep Field

The Hubble Deep Field provides one of the deepest multiwavelength views of the distant Universe and has led to the detection of thousands of galaxies seen throughout cosmic time1. An early map of the Hubble Deep Field at a wavelength of 850 micrometres, which is sensitive to dust emission powered by star formation, revealed the brightest source in the field, dubbed HDF 850.1 (ref. 2). For more than a decade, and despite significant efforts, no counterpart was found at shorter wavelengths, and it was not possible to determine its redshift, size or mass3, 4, 5, 6, 7. Here we report a redshift of z = 5.183 for HDF 850.1, from a millimetre-wave molecular line scan. This places HDF 850.1 in a galaxy overdensity at z ≈ 5.2, corresponding to a cosmic age of only 1.1 billion years after the Big Bang. This redshift is significantly higher than earlier estimates3, 4, 6, 8 and higher than those of most of the hundreds of submillimetre-bright galaxies identified so far. The source has a star-formation rate of 850 solar masses per year and is spatially resolved on scales of 5 kiloparsecs, with an implied dynamical mass of about 1.3 × 1011 solar masses, a significant fraction of which is present in the form of molecular gas. Despite our accurate determination of redshift and position, a counterpart emitting starlight remains elusive