We present newly acquired images of the near-infrared counterpart of 3CR
radio sources. All the sources were selected to have a redshift of less than
0.3 to allow us to obtain the highest spatial ...resolution. The observations were
carried out as a snapshot program using the Near-Infrared Camera and
Multiobject Spectrograph (NICMOS) on-board the Hubble Space Telescope (HST). In
this paper we describe 69 radio galaxies observed for the first time with
NICMOS during HST cycle 13. All the objects presented here are elliptical
galaxies. However, each of them has unique characteristics such as close
companions, dust lanes, unresolved nuclei, arc-like features, globular clusters
and jets clearly visible from the images or with basic galaxy subtraction.
(abridged) We investigate the kinematics of the central gas disk of the
radio-loud elliptical galaxy NGC 4335, derived from HST/STIS long-slit
spectroscopic observations of Halpha+NII along 3 ...parallel slit positions. The
observed mean velocities are consistent with a rotating thin disk. We model the
gas disk in the customary way. This sets a 3 sigma upper limit of 10^8 Msun on
black hole mass, Mbh. The velocity dispersion at r <0.5'' is in excess of that
predicted by the thin rotating disk model. This does not invalidate the model,
if the excess dispersion is caused by localized turbulent motion in addition to
bulk circular rotation. However, if instead the dispersion is caused by the BH
potential then a mass Mbh ~ 6x10^8 Msun is inferred by modeling the central gas
dispersion as due to an isotropic spherical distribution of collisionless gas
cloudlets. The stellar kinematics for NGC 4335 are derived from a ground-based
(WHT/ISIS) long-slit observation along the galaxy major axis. A two-integral
model of the stellar dynamics yields Mbh >= 3x10^9 Msun. However, there is
reason to believe that this model overestimates Mbh. Reported correlations
between black hole mass and inner stellar velocity dispersion sigma predict Mbh
to be >= 5.4x10^8 Msun in NGC 4335. If our standard thin disk modeling of the
gas kinematics is valid, then NGC 4335 has an unusually low Mbh for its
velocity dispersion. If, on the other hand, this approach is flawed, and
provides an underestimate of Mbh, then black hole masses for other galaxies
derived from HST gas kinematics with the same assumptions should be treated
with caution.
In this paper we analyze the relation between radio, optical continuum and Halpha+NII emission from the cores of a sample of 21 nearby Fanaroff & Riley type I galaxies as observed with the VLBA and ...HST. The emission arises inside the inner tens of parsec of the galaxies. Core radio emission is observed in 19/20 galaxies, optical core continuum emission is detected in 12/21 galaxies and Halpha+NII core emission is detected in 20/21 galaxies. We confirm the recently detected linear correlation between radio and optical core emission in FR I galaxies and show that both core emissions also correlate with central Halpha+NII emission. The tight correlations between radio, optical and Halpha+NII core emission constrain the bulk Lorentz factor to gamma ~ 2-5 and gamma =< 2 for a continuous jet and a jet consisting of discrete blobs, respectively, assuming jet viewing angles in the range 30deg,90deg. Radio and optical core emissions are likely to be synchrotron radiation from the inner jet, possibly with a significant contribution from emission by an accretion disk and/or flow. Elliptical galaxies with LINER nuclei without large-scale radio jets seem to follow the core emission correlations found in FR I galaxies. This suggests that the central engines could be very similar for the two classes of AGNs.
An optical-IR jet in 3C133 Floyd, David J. E; Laing, Robert; Chiaberge, Marco ...
02/2006
Journal Article
Odprti dostop
Astrophys.J. 643 (2006) 660-666 We report the discovery of a new optical-IR synchrotron jet in the radio
galaxy 3C133 from our HST/NICMOS snapshot survey. The jet and eastern hotspot
are well ...resolved, and visible at both optical and IR wavelengths. The IR jet
follows the morphology of the inner part of the radio jet, with three distinct
knots identified with features in the radio. The radio-IR SED's of the knots
are examined, along with those of two more distant hotspots at the eastern
extreme of the radio feature. The detected emission appears to be synchrotron,
with peaks in the NIR for all except one case, which exhibits a power-law
spectrum throughout.
(abridged) We investigate the kinematics of the central gas disk of the radio-loud elliptical galaxy NGC 4335, derived from HST/STIS long-slit spectroscopic observations of Halpha+NII along 3 ...parallel slit positions. The observed mean velocities are consistent with a rotating thin disk. We model the gas disk in the customary way. This sets a 3 sigma upper limit of 10^8 Msun on black hole mass, Mbh. The velocity dispersion at r <0.5'' is in excess of that predicted by the thin rotating disk model. This does not invalidate the model, if the excess dispersion is caused by localized turbulent motion in addition to bulk circular rotation. However, if instead the dispersion is caused by the BH potential then a mass Mbh ~ 6x10^8 Msun is inferred by modeling the central gas dispersion as due to an isotropic spherical distribution of collisionless gas cloudlets. The stellar kinematics for NGC 4335 are derived from a ground-based (WHT/ISIS) long-slit observation along the galaxy major axis. A two-integral model of the stellar dynamics yields Mbh >= 3x10^9 Msun. However, there is reason to believe that this model overestimates Mbh. Reported correlations between black hole mass and inner stellar velocity dispersion sigma predict Mbh to be >= 5.4x10^8 Msun in NGC 4335. If our standard thin disk modeling of the gas kinematics is valid, then NGC 4335 has an unusually low Mbh for its velocity dispersion. If, on the other hand, this approach is flawed, and provides an underestimate of Mbh, then black hole masses for other galaxies derived from HST gas kinematics with the same assumptions should be treated with caution.
We present newly acquired images of the near-infrared counterpart of 3CR radio sources. All the sources were selected to have a redshift of less than 0.3 to allow us to obtain the highest spatial ...resolution. The observations were carried out as a snapshot program using the Near-Infrared Camera and Multiobject Spectrograph (NICMOS) on-board the Hubble Space Telescope (HST). In this paper we describe 69 radio galaxies observed for the first time with NICMOS during HST cycle 13. All the objects presented here are elliptical galaxies. However, each of them has unique characteristics such as close companions, dust lanes, unresolved nuclei, arc-like features, globular clusters and jets clearly visible from the images or with basic galaxy subtraction.
An optical-IR jet in 3C133 Floyd, David J E; Laing, Robert; Chiaberge, Marco ...
arXiv.org,
02/2006
Paper
Odprti dostop
We report the discovery of a new optical-IR synchrotron jet in the radio galaxy 3C133 from our HST/NICMOS snapshot survey. The jet and eastern hotspot are well resolved, and visible at both optical ...and IR wavelengths. The IR jet follows the morphology of the inner part of the radio jet, with three distinct knots identified with features in the radio. The radio-IR SED's of the knots are examined, along with those of two more distant hotspots at the eastern extreme of the radio feature. The detected emission appears to be synchrotron, with peaks in the NIR for all except one case, which exhibits a power-law spectrum throughout.
