407 research outputs found
The impact of the warm outflow in the young (GPS) radio source & ULIRG PKS 1345+12 (4C 12.50)
(Abridged) We present new deep VLT/FORS optical spectra with intermediate
resolution and large wavelength coverage of the GPS radio source and ULIRG
PKS1345+12 (4C12.50; z=0.122), taken with the aim of investigating the impact
of the nuclear activity on the circumnuclear ISM. PKS1345+12 is a powerful
quasar and is also the best studied case of an emission line outflow in a
ULIRG. Using the density sensitive transauroral emission lines [S II]4068,4076
and [O II]7318,7319,7330,7331, we pilot a new technique to accurately model the
electron density for cases in which it is not possible to use the traditional
diagnostic [S II]6716/6731, namely sources with highly broadened complex
emission line profiles and/or high (Ne > 10^4 cm^-3) electron densities. We
measure electron densities of Ne=2.94x10^3 cm^-3, Ne=1.47x10^4 cm^-3 and
Ne=3.16x10^5 cm^-3 for the regions emitting the narrow, broad and very broad
components respectively. We calculate a total mass outflow rate of 8 M_sun
yr^-1. We estimate the total mass in the warm gas outflow is 8x10^5 M_sun. The
total kinetic power in the warm outflow is 3.4x10^42 erg s^-1. We find that
only a small fraction (0.13% of Lbol) of the available accretion power is
driving the warm outflow, significantly less than currently required by the
majority of quasar feedback models (~5-10\% of Lbol), but similar to recent
findings by Hopkins et al. (2010) for a two-stage feedback model. The models
also predict that AGN outflows will eventually remove the gas from the bulge of
the host galaxy. The visible warm outflow in PKS1345+12 is not currently
capable of doing so. However, it is entirely possible that much of the outflow
is either obscured by a dense and dusty natal cocoon and/or in cooler or hotter
phases of the ISM. This result is important not just for studies of young
(GPS/CSS) radio sources, but for AGN in general.Comment: Accepted for publication in MNRAS. 11 pages, 4 figure
Fast Outflows of Neutral Hydrogen in Radio Galaxies
AGN activity is known to drive fast outflows of gas. We report the discovery
of fast outflows of neutral gas with velocities over 1000 km/s in a number of
radio galaxies. In the best studied object, 3C~293, the kinematical properties
of the neutral and ionised outflows are similar, indicating a common origin.
Moreover, the outflow appears to be located near the radio lobes and not near
the nucleus. This suggests that the interaction between the radio jet and the
ISM is driving the outflow.Comment: To appear in the proceedings of IAU Symposium 222,"The Interplay
among Black Holes, Stars and ISM in Galactic Nuclei", eds Storchi-Bergmann et
al; 2 pages, 1 figur
Gas outflows in radio galaxies
We present a summary of our recent results on gas outflows in radio galaxies.
Fast outflows (up to 2000 km/s) have been detected both in ionized and neutral
gas. The latter is particularly surprising as it shows that, despite the
extremely energetic phenomena occurring near an AGN, some of the outflowing gas
remains, or becomes again, neutral. These results are giving new and important
insights on the physical conditions of the gaseous medium around an AGN.Comment: To appear in the proceedings of the IAU Symposium #217, Recycling
Intergalactic and Interstellar Matter, eds. P.-A. Duc, J. Braine, and E.
Brinks, 6 pages. The full paper with high resolution images can be downloaded
from http://www.astron.nl/~morganti/Papers/outflows.ps.g
Spatially resolved kinematics, galactic wind, and quenching of star formation in the luminous infrared galaxy IRAS F11506-3851
We present a multi-wavelength integral field spectroscopic study of the low-z
LIRG IRAS F11506-3851, on the basis of VIMOS and SINFONI (ESO-VLT)
observations. The morphology and the 2D kinematics of the gaseous (neutral and
ionized) and stellar components have been mapped using the NaD doublet, the
H line, and the near-IR CO(2-0) and CO(3-1) bands. The kinematics of
the ionized gas and the stars are dominated by rotation, with large observed
velocity amplitudes and centrally peaked velocity dispersion maps. The stars
lag behind the warm gas and represent a dynamically hotter system, as indicated
by the observed dynamical ratios. Thanks to these IFS data we have disentangled
the contribution of the stars and the ISM to the NaD feature, finding that it
is dominated by the absorption of neutral gas clouds in the ISM. The neutral
gas 2D kinematics shows a complex structure dominated by two components. On the
one hand, the thick slowly rotating disk lags significantly compared to the
ionized gas and the stars, with an irregular and off-center velocity dispersion
map. On the other hand, a kpc-scale neutral gas outflow is observed along the
semi-minor axis of the galaxy, as revealed by large blueshifted velocities
(30-154 km/s). We derive an outflowing mass rate in neutral gas of about 48
/yr. Although this implies a global mass loading factor of
1.4, the 2D distribution of the ongoing SF suggests a much larger value of mass
loading factor associated with the inner regions (R200 pc), where the
current SF represents only 3 percent of the total. All together these results
strongly suggest that we are witnessing (nuclear) quenching due to SF feedback
in IRAS F11506-3851. However, the relatively large mass of molecular gas
detected in the nuclear region via the H2 1-0 S(1) line suggests that further
episodes of SF may take place again
Large-scale HI in nearby radio galaxies: segregation in neutral gas content with radio source size
We present results of a study of neutral hydrogen (HI) in a complete sample
of nearby non-cluster radio galaxies. We find that radio galaxies with large
amounts of extended HI (M_HI >= 10^9 M_solar) all have a compact radio source.
The host galaxies of the more extended radio sources, all of Fanaroff & Riley
type-I, do not contain these amounts of HI. We discuss several possible
explanations for this segregation. The large-scale HI is mainly distributed in
disk- and ring-like structures with sizes up to 190 kpc and masses up to 2 x
10^10 M_solar. The formation of these structures could be related to past
merger events, although in some cases it may also be consistent with a
cold-accretion scenario.Comment: 4 pages, 2 figures. Accepted for publication in A&A Letters. A
version with full resolution figures can be found at
http://www.astro.rug.nl/~emonts/emonts_HIletter_jan07.pd
Outflows of hot molecular gas in ultra-luminous infra-red galaxies mapped with VLT-SINFONI
We present the detection and morphological characterization of hot molecular
gas outflows in nearby ultra-luminous infrared galaxies, using the near-IR
integral-field spectrograph SINFONI on the VLT. We detect outflows observed in
the 2.12 micron H 1-0 S(1) line for three out of four ULIRGs analyzed;
IRAS 12112+0305, 14348-1447, and 22491-1808. The outflows are mapped on scales
of 0.7-1.6 kpc, show typical outflow velocities of 300-500 km/s, and appear to
originate from the nuclear region. The outflows comprise hot molecular gas
masses of ~6-8x10 M(sun). Assuming a hot-to-cold molecular gas mass ratio
of 6x10, as found in nearby luminous IR galaxies, the total (hot+cold)
molecular gas mass in these outflows is expected to be ~1x10 M(sun). This
translates into molecular mass outflow rates of ~30-85 M(sun)/yr, which is a
factor of a few lower than the star formation rate in these ULIRGs. In
addition, most of the outflowing molecular gas does not reach the escape
velocity of these merger systems, which implies that the bulk of the outflowing
molecular gas is re-distributed within the system and thus remains available
for future star formation. The fastest H outflow is seen in the
Compton-thick AGN of IRAS 14348-1447, reaching a maximum outflow velocity of
~900 km/s. Another ULIRG, IRAS 17208-0014, shows asymmetric H line
profiles different from the outflows seen in the other three ULIRGs. We discuss
several alternative explanations for its line asymmetries, including a very
gentle galactic wind, internal gas dynamics, low-velocity gas outside the disk,
or two superposed gas disks. We do not detect the hot molecular counterpart to
the outflow previously detected in CO(2-1) in IRAS 17208-0014, but we note that
our SINFONI data are not sensitive enough to detect this outflow if it has a
small hot-to-cold molecular gas mass ratio of < 9x10.Comment: Accepted for publication in A&A (11 pages, 10 figures
- âŠ