7 research outputs found
CO survey of high-z radio galaxies, revisited with ALMA: Jet-cloud Alignments and Synchrotron Brightening by Molecular Gas in the Circumgalactic Environment
Powerful radio sources associated with super-massive black holes are among
the most luminous objects in the Universe, and are frequently recognized both
as cosmological probes and active constituents in the evolution of galaxies. We
present alignments between radio jets and cold molecular gas in the environment
of distant radio galaxies, and show that the brightness of the radio
synchrotron source can be enhanced by its interplay with the molecular gas. Our
work is based on CO J>1 observations with the Atacama Large
Millimeter/submillimeter Array (ALMA) of three radio galaxies with redshifts in
the range 1.4 < z < 2.1, namely MRC 0114-211 (z = 1.41), MRC 0156-252 (z =
2.02), and MRC 2048-272 (z = 2.05). These ALMA observations support previous
work that found molecular gas out to 50 kpc in the circumgalactic environment,
based on a CO(1-0) survey performed with the Australia Telescope Compact Array
(ATCA). The CO emission is found along the radio axes but beyond the main radio
lobes. When compared to a large sample of high-z radio galaxies from the
literature, we find that the presence of this cold molecular medium correlates
with an increased flux-density ratio of the main vs. counter lobe. This suggest
that the radio lobe brightens when encountering cold molecular gas in the
environment. While part of the molecular gas is likely related to the
interstellar medium (ISM) from either the host or a companion galaxy, a
significant fraction of the molecular gas in these systems shows very low
excitation, with r and r values 0.2. This
could be part of the circumgalactic medium (CGM).Comment: Accepted for publication in ApJ (19 pages, 6 figures
The Dragonfly Galaxy. III. Jet-brightening of a High-redshift Radio Source Caught in a Violent Merger of Disk Galaxies
The Dragonfly Galaxy (MRC 0152-209), the most infrared-luminous radio galaxy
at redshift z~2, is a merger system containing a powerful radio source and
large displacements of gas. We present kpc-resolution data from ALMA and the
VLA of carbon monoxide (6-5), dust, and synchrotron continuum, combined with
Keck integral-field spectroscopy. We find that the Dragonfly consists of two
galaxies with rotating disks that are in the early phase of merging. The radio
jet originates from the northern galaxy and brightens when it hits the disk of
the southern galaxy. The Dragonfly Galaxy therefore likely appears as a
powerful radio galaxy because its flux is boosted into the regime of high-z
radio galaxies by the jet-disk interaction. We also find a molecular outflow of
(1100 550) M/yr associated with the radio host galaxy, but not
with the radio hot-spot or southern galaxy, which is the galaxy that hosts the
bulk of the star formation. Gravitational effects of the merger drive a slower
and longer lived mass displacement at a rate of (170 40) M/yr,
but this tidal debris contain at least as much molecular gas mass as the much
faster outflow, namely M(H2) = (3 1) x 10 (alpha(CO)/0.8)
M. This suggests that both the AGN-driven outflow and mass transfer
due to tidal effects are important in the evolution of the Dragonfly system.
The Keck data show Ly emission spread across 100 kpc, and CIV and HeII
emission across 35 kpc, confirming the presence of a metal-rich and extended
circumgalactic medium previously detected in CO(1-0).Comment: Accepted for publication in ApJ (15 pages, 9 figures
CO survey of high-z radio galaxies, revisited with ALMA: Jet-cloud Alignments and Synchrotron Brightening by Molecular Gas in the Circumgalactic Environment
International audiencePowerful radio sources associated with super-massive black holes are among the most luminous objects in the Universe, and are frequently recognized both as cosmological probes and active constituents in the evolution of galaxies. We present alignments between radio jets and cold molecular gas in the environment of distant radio galaxies, and show that the brightness of the radio synchrotron source can be enhanced by its interplay with the molecular gas. Our work is based on CO J>1 observations with the Atacama Large Millimeter/submillimeter Array (ALMA) of three radio galaxies with redshifts in the range 1.4 < z < 2.1, namely MRC 0114-211 (z = 1.41), MRC 0156-252 (z = 2.02), and MRC 2048-272 (z = 2.05). These ALMA observations support previous work that found molecular gas out to 50 kpc in the circumgalactic environment, based on a CO(1-0) survey performed with the Australia Telescope Compact Array (ATCA). The CO emission is found along the radio axes but beyond the main radio lobes. When compared to a large sample of high-z radio galaxies from the literature, we find that the presence of this cold molecular medium correlates with an increased flux-density ratio of the main vs. counter lobe. This suggest that the radio lobe brightens when encountering cold molecular gas in the environment. While part of the molecular gas is likely related to the interstellar medium (ISM) from either the host or a companion galaxy, a significant fraction of the molecular gas in these systems shows very low excitation, with r and r values 0.2. This could be part of the circumgalactic medium (CGM)
CO survey of high-z radio galaxies, revisited with ALMA: Jet-cloud Alignments and Synchrotron Brightening by Molecular Gas in the Circumgalactic Environment
International audiencePowerful radio sources associated with super-massive black holes are among the most luminous objects in the Universe, and are frequently recognized both as cosmological probes and active constituents in the evolution of galaxies. We present alignments between radio jets and cold molecular gas in the environment of distant radio galaxies, and show that the brightness of the radio synchrotron source can be enhanced by its interplay with the molecular gas. Our work is based on CO J>1 observations with the Atacama Large Millimeter/submillimeter Array (ALMA) of three radio galaxies with redshifts in the range 1.4 < z < 2.1, namely MRC 0114-211 (z = 1.41), MRC 0156-252 (z = 2.02), and MRC 2048-272 (z = 2.05). These ALMA observations support previous work that found molecular gas out to 50 kpc in the circumgalactic environment, based on a CO(1-0) survey performed with the Australia Telescope Compact Array (ATCA). The CO emission is found along the radio axes but beyond the main radio lobes. When compared to a large sample of high-z radio galaxies from the literature, we find that the presence of this cold molecular medium correlates with an increased flux-density ratio of the main vs. counter lobe. This suggest that the radio lobe brightens when encountering cold molecular gas in the environment. While part of the molecular gas is likely related to the interstellar medium (ISM) from either the host or a companion galaxy, a significant fraction of the molecular gas in these systems shows very low excitation, with r and r values 0.2. This could be part of the circumgalactic medium (CGM)