526 research outputs found
Feeding and Feedback in nearby AGN from Integral Field Spectroscopy
I report results of recent integral field spectroscopy of the inner few
hundred parsecs (pc) around nearby Active Galactic Nuclei (AGN) at a sampling
of a few pc, obtained with the Gemini Telescopes. In the lowest activity AGNs,
it is possible to observe inflows in ionized gas along nuclear spirals and
filaments. In more luminous AGN inflows have been observed also in hot
molecular gas (H_2) emission in the near-IR. In most cases the H_2 kinematics
is dominated by circular rotation in the plane around the nucleus, tracing the
AGN feeding. The ionized gas, on the other hand, traces the AGN feedback. Its
kinematics shows two components: (1) one originating in the plane, and
dominated by circular rotation; (2) another outflowing along the Narrow-Line
Region (NLR) whose flux distribution and kinematics frequently correlate with
structures seen in radio maps. Mass outflow rates along the NLR range from
10^-2 to 1 M_sun yr^-1, corresponding to 10-100 times the accretion rate to the
AGN, indicating that most of the NLR gas mass has been entrained from the
galaxy plane. The average kinetic power of the NLR outflows is ~10^-4 times the
bolometric luminosity.Comment: 4 pages, 2 figures, to appear in the proceedings of the conference
"The Monster's Fiery Breath", eds. Sebastian Heinz and Eric Wilcot
Spectral Models for Low-luminosity Active Galactic Nuclei in LINERs: The Role of Advection-dominated Accretion and Jets
We perform an exploratory study of the physical properties of accretion flows
and jets in low-luminosity active galactic nuclei (LLAGNs) by modeling the
spectral energy distributions (SEDs) of 12 LLAGNs in low-ionization nuclear
emission-line regions (LINERs). These SEDs we constructed from high-resolution
radio, X-ray and optical/UV observations of the immediate vicinity of the black
hole. We adopt a coupled accretion-jet model comprising an inner
advection-dominated accretion flow (ADAF) and an outer standard thin disk. We
present best-fit models in which either the ADAF or the jet dominate the X-ray
emission. Six sources in our sample display an optical-UV excess with respect
to ADAF and jet models; this excess can be explained as emission from the
truncated disk with transition radii 30-225 Rs in four of them. In almost all
sources the optical emission can also be attributed to unresolved, old stellar
clusters with masses ~1E7-1E8 Msun. We find evidence for a correlation between
the accretion rate and jet power and an anti-correlation between the
radio-loudness and the accretion rate. We confirm previous findings that the
radio emission is severely underpredicted by ADAF models and explained by the
relativistic jet. We find evidence for a nonlinear relation between the X-ray
and bolometric luminosities and a slight IR excess in the average model SED
compared to that of quasars. We suggest that the hardness of the X-ray spectrum
can be used to identify the X-ray emission mechanism and discuss directions for
progress in understanding the origin of the X-rays.Comment: Accepted for publication in MNRAS. 27 pages, 22 figures. arXiv admin
note: substantial text overlap with arXiv:1112.464
Feeding Versus Feedback in AGNs from Near-Infrared IFU Observations: The Case of Mrk79
We have mapped the gaseous kinematics and the emission-line flux
distributions and ratios from the inner ~680pc radius of the Seyfert 1 galaxy
Mrk79, using two-dimensional (2D) near-IR J- and Kl-band spectra obtained with
the Gemini instrument NIFS at a spatial resolution of ~100pc and velocity
resolution of ~40km/s. The molecular hydrogen flux distribution presents two
spiral arms extending by ~700pc, one to the north and another to the south of
the nucleus, with an excitation indicating heating by X-rays from the central
source. The low velocity dispersion (sigma~50km/s) and rotation pattern
supports a location of the H2 gas in the disk of the galaxy. Blueshifts
observed along the spiral arm in the far side of the galaxy and redshifts in
the spiral arm in the near side, suggest that the spiral arms are feeding
channels of H2 to the inner 200pc. From channel maps along the H2 l2.1218um
emission-line profile we estimate a mass inflow rate of ~4E-3 M_Sun/year, which
is one order of magnitude smaller than the mass accretion rate necessary to
power the AGN of Mrk79. The emission from the ionized gas (traced by Pabeta and
[FeII]l1.2570um emission lines) is correlated with the radio jet and with the
narrow-band [OIII] flux distribution. Its kinematics shows both rotation and
outflows to the north and south of the nucleus. The ionized gas mass outflow
rate through a cross section with radius ~320pc located at a distance of ~455pc
from the nucleus is 3.5 MSun/year, which is much larger than the AGN mass
accretion rate, indicating that most of the outflowing gas originates in the
interstellar medium surrounding the galaxy nucleus, which is pushed away by a
nuclear jet.Comment: Accepted by MNRA
An outflow perpendicular to the radio jet in the Seyfert nucleus of NGC5929
We report the observation of an outflow perpendicular to the radio jet in
near-infrared integral field spectra of the inner 250 pc of the Seyfert 2
galaxy NGC 5929. The observations were obtained with the Gemini Near infrared
Integral Field Spectrograph at a spatial resolution of ~20 pc and spectral
resolution R~5300 and reveal a region 50 pc wide crossing the nucleus and
extending by 300 pc perpendicularly to the known radio jet in this galaxy.
Along this structure - which we call SE-NW strip - the emission-line profiles
show two velocity components, one blueshifted and the other redshifted by -150
km/s and 150 km/s, respectively, relative to the systemic velocity. We
interpret these two components as due to an outflow perpendicular to the radio
jet, what is supported by low frequency radio emission observed along the same
region. We attribute this feature to the interaction of ambient gas with an
"equatorial outflow" predicted in recent accretion disk and torus wind models.
Perpendicularly to the SE-NW strip, thus approximately along the radio jet,
single component profiles show blueshifts of ~-150 km/s to the north-east and
similar redshifts to the south-west, which can be attributed to gas
counter-rotating relative to the stellar kinematics. More double-peaked
profiles are observed in association with the two radio hot-spots, attributed
to interaction of the radio jet with surrounding gas.Comment: Accepted for publication in ApJL; 5 page
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