3,633 research outputs found
Volume 32, Number 2, June 2012 OLAC Newsletter
Digitized June 2012 issue of the OLAC Newsletter
Volume 32, Number 3, September 2012 OLAC Newsletter
Digitized September 2012 issue of the OLAC Newsletter
Volume 32, Number 1, March 2012 OLAC Newsletter
Digitized March 2012 issue of the OLAC Newsletter
Volume 32, Number 4, December 2012 OLAC Newsletter
Digitized December 2012 issue of the OLAC Newsletter
Molecular Gas in the Powerful Radio Nucleus of the Ultraluminous Infrared Galaxy PKS 1345+12
Millimeter CO(1-0) interferometry and high resolution, Hubble Space Telescope
(HST) 1.1, 1.6, and 2.2 micron imaging of the radio compact galaxy PKS 1345+12
are presented. With an infrared luminosity of 2x10^{12} L_sun, PKS 1345+12 is a
prime candidate for studying the link between the ultraluminous infrared galaxy
phenomenon and radio galaxies. These new observations probe the molecular gas
distribution and obscured nuclear regions of PKS 1345+12 and provide
morphological support for the idea that the radio activity in powerful radio
galaxies is triggered by the merger of gas rich galaxies. Two nuclei separated
by 2" (4.0 kpc) are observed in the near-infrared; the extended southeastern
nucleus has colors consistent with reddened starlight, and the compact
northwestern nucleus has extremely red colors indicative of an optical quasar
with a warm dust component. Further, the molecular gas, 3mm continuum, and
radio emission are coincident with the redder nucleus, confirming that the
northwestern nucleus is the site of the AGN and that the molecular gas is the
likely fuel source.Comment: LaTex, 5 pages with 1 postscript and 1 jpg figure, ApJ Letters, in
press (August 20, 1999
Volume 33, Number 2, June 2013 OLAC Newsletter
Digitized June 2013 issue of the OLAC Newsletter
Volume 33, Number 1, March 2013 OLAC Newsletter
Digitized March 2013 issue of the OLAC Newsletter
Molecular Gas and Nuclear Activity in Radio Galaxies Detected by IRAS
This paper reports the latest results from a millimeter-wave (CO)
spectroscopic survey of IRAS-detected radio galaxies with L_1.4GHz ~ 10^23-28
W/Hz in the redshift range z ~ 0.02-0.15. The IRAS flux-limited sample contains
33 radio galaxies with different radio morphologies and a broad range of
infrared luminosities L_IR = 10^9-12 L_sun), allowing for an investigation of
(a) whether low-z radio-selected AGN reside in molecular gas-rich host galaxes,
and (b) whether the CO properties are correlated with the properties of the
host galaxy or the AGN. All of the radio galaxies in Mazzarella et al. (1993)
and Mirabel et al. (1989) have been reobserved. Three new CO detections have
been made, raising the total number of CO detections to nine and setting the
survey detection rate at ~ 25%. Many of the CO lines have double-peaked
profiles, and the CO line widths are broad (average Delta v_FWHM ~ 500+/-130
km/s), exceeding the average CO widths of both ultraluminous infrared galaxies
(300+/-90 km/s) and Palomar-Green QSOs (260+/-160 km/s), and thus being
indicative of massive host galaxies. The CO luminosities translate into
molecular gas masses of ~ 0.4-7x10^9 M_sun, however, the 3-sigma CO upper
limits for nondetections do not rule out a molecular gas mass as high as that
of the Milky Way (~ 3x10^9 M_sun). Optical images of eight out of nine
molecular gas-rich radio galaxies show evidence of close companions and/or
tidal features. Finally, there is no obvious correlation between radio power
and molecular gas mass. However, it is notable that only one F-R II galaxy out
of 12 is detected in this CO survey; the remaining detections are of galaxies
hosting F-R I and compact radio jets.Comment: LaTex, 33 pages, including 1 jpg figure and 14 postscript figures,
ApJS, in press (August 2005
Molecular Gas in Infrared-Excess, Optically-Selected QSOs and the Connection with Infrared Luminous Galaxies
The initial results of a millimeter (CO) survey of infrared-excess,
optically-selected quasars from the Palomar-Green (PG) Bright Quasar Survey
(BQS) with redshifts in the range 0.04 < z < 0.17 are presented. These
observations represent the first step towards establishing with a complete
sample whether or not quasi-stellar objects (QSOs) reside in molecular gas-rich
galaxies, as well as towards determining how the infrared and molecular gas
properties of QSOs compare with those of ultraluminous infrared galaxies
(ULIGs), which are a possible evolutionary precursor of QSOs. The sample
consists of QSOs having absolute blue magnitudes, M_B <~ -22.0, and infrared
excesses, L_IR (8-1000 um) /L_bbb (0.1-1.0 um) >0.36, where the contribution to
the bolometric luminosity of infrared thermal dust emission for all PG QSOs is
typically 20--40%. Six out of 10 of the QSOs observed are detected in the
CO(1-0) emission line; two detections confirm previous, less sensitive
detections of CO(1-0) in PG 1613+658 and PG 0838+770, and four additional QSOs
are detected for the first time (PG 1119+120, PG 1351+640, PG 1415+451, and PG
1440+356). These six detections, plus two previous detections of CO in IZw1 and
Mrk 1014, bring the total number of 0.04 < z < 0.17 infrared-excess PG QSOs
detected in CO to date to eight, and provide possible evidence that, in
addition to fueling star formation, molecular gas may also serve as a primary
source of fuel for QSO activity...Comment: LaTex, 16 pages, including 7 postscript figures, AJ, in press (April,
2001
Molecular gas in nearby low-luminosity QSO host galaxies
This paper addresses the global molecular gas properties of a representative
sample of galaxies hosting low-luminosity quasistellar objects. An abundant
supply of gas is necessary to fuel both the active galactic nucleus and any
circum-nuclear starburst activity of QSOs.
We selected a sample of nearby low-luminosity QSO host galaxies that is free
of infrared excess biases. All objects are drawn from the Hamburg-ESO survey
for bright UV-excess QSOs, have DEC>-30 degrees and redshifts that do not
exceed z=0.06. The IRAM 30m telescope was used to measure the CO(1-0) and
CO(2-1) transition in parallel.
27 out of 39 galaxies in the sample have been detected. The molecular gas
masses of the detected sources range from 0.4E9 M_sun to 9.7E9 M_sun. We can
confirm that the majority of galaxies hosting low-luminosity QSOs are rich in
molecular gas. The properties of galaxies hosting brighter type I AGN and
circumnuclear starformation regions differ from the properties of galaxies with
fainter central regions. The overall supply of molecular gas and the spread of
the line width distribution is larger. When comparing the far-infrared with the
CO luminosities, the distribution can be separated into two different
power-laws: one describing the lower activity Seyfert I population and the
second describing the luminous QSO population. The separation in the
L_FIR/L'_CO behavior may be explainable with differing degrees of compactness
of the emission regions. We provide a simple model to describe the two
power-laws. The sample studied in this paper is located in a transition region
between the two populations
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