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The XMM-Newton view of AGN with intermediate mass black holes
G. Miniutti, G. Ponti, J. E. Greene +3
We have observed with XMM-Newton four radiatively efficient active type 1 galaxies with black hole masses < 10^6 Msun, selected optically from the SDSS. We show here that their sof…
A Magnetohydrodynamic Model for the Formation of Episodic Jets
Feng Yuan, Jun Lin, Kinwah Wu +1
Episodic ejection of plasma blobs have been observed in many black hole systems. While steady, continuous jets are believed to be associated with large-scale open magnetic fields,…
Candidate AGNs in Late-Type Galaxies
Louis-Benoit Desroches, Luis Ho
We have assembled a sample of 64 late-type spiral galaxies (T types 6.0-9.0, corresponding to Hubble types Scd-Sm) with archival Chandra data. At a signal-to-noise (S/N) threshold…
Dynamical Constraints on The Masses of the Nuclear Star Cluster and Black Hole in the Late-Type Spiral Galaxy NGC 3621
A. J. Barth, L. E. Strigari, M. C. Bentz +2
NGC 3621 is a late-type (Sd) spiral galaxy with an active nucleus, previously detected through mid-infrared [Ne V] line emission. Archival Hubble Space Telescope (HST) images revea…
A Stellar Dynamical Measurement of the Black Hole Mass in the Maser Galaxy NGC 4258
Christos Siopis, Karl Gebhardt, Tod R. Lauer +13
We determine the mass of the black hole at the center of the spiral galaxy NGC 4258 by constructing axisymmetric dynamical models of the galaxy. These models are constrained by hig…
Caught in formation: the nuclear-cluster-to-be in NGC 2139
David R. Andersen, C. Jakob Walcher, Torsten Boeker +4
Close to its center, the bulgeless galaxy NGC 2139 hosts a star cluster that is younger and less massive than any actual nuclear star cluster (NC) studied so far. We have measured…
Hubble Space Telescope Spectroscopic Observations of the Narrow-Line Region in Nearby Low-Luminosity Active Galactic Nuclei
Jonelle L. Walsh, Aaron J. Barth, Luis C. Ho +5
(Abridged) We present STIS observations of 14 nearby low-luminosity active galactic nuclei, including 13 LINERs and 1 Seyfert, taken at multiple parallel slit positions centered on…
Low-Mass Seyfert 2 Galaxies in the Sloan Digital Sky Survey
A. J. Barth, J. E. Greene, L. C. Ho
(Abridged) We describe a sample of low-mass Seyfert 2 galaxies selected from the Sloan Digital Sky Survey, having a median absolute magnitude of M_g = -19.0 mag. These galaxies are…
An Offset Seyfert 2 Nucleus in the Minor Merger System NGC 3341
A. J. Barth, M. C. Bentz, J. E. Greene +1
We present the discovery of a triplet of emission-line nuclei in the disturbed disk galaxy NGC 3341, based on archival data from the Sloan Digital Sky Survey and new observations f…
Steep-Spectrum Radio Emission from the Low-Mass Active Galactic Nucleus GH 10
J. M. Wrobel, J. E. Greene, L. C. Ho +1
GH 10 is a broad-lined active galactic nucleus (AGN) energized by a black hole of mass 800,000 Solar masses. It was the only object detected by Greene et al. in their Very Large Ar…
A Systematic Analysis of Fe II Emission in Quasars: Evidence for Inflow to the Central Black Hole
Chen Hu, Jian-Min Wang, Luis C. Ho +4
Broad Fe II emission is a prominent feature of the optical and ultraviolet spectra of quasars. We report on a systematical investigation of optical Fe II emission in a large sample…
The Host Galaxy and Central Engine of the Dwarf AGN POX 52
C. E. Thornton, A. J. Barth, L. C. Ho +2
We present new multi-wavelength observations of the dwarf Seyfert 1 galaxy POX 52 in order to investigate the properties of the host galaxy and the active nucleus, and to examine t…
Decomposition of the Host Galaxies of Active Galactic Nuclei Using Hubble Space Telescope Images
Minjin Kim, Luis C. Ho, Chien Y. Peng +2
Investigating the link between supermassive black hole and galaxy evolution requires careful measurements of the properties of the host galaxies. We perform simulations to test the…
Nuclear Activity in Nearby Galaxies
Luis C. Ho
A significant fraction of nearby galaxies show evidence of weak nuclear activity unrelated to normal stellar processes. Recent high-resolution, multiwavelength observations indicat…
A New H I Survey of Active Galaxies
Luis C. Ho, Jeremy Darling, Jenny E. Greene
We have conducted a new Arecibo survey for H I emission for 113 galaxies with broad-line (type 1) active galactic nuclei (AGNs) out to recession velocities as high as 35,000 km/s.…
Outflow-Dominated Emission from the Quiescent Massive Black Holes in NGC 4621 and NGC 4697
J. M. Wrobel, Y. Terashima, L. C. Ho
The nearby elliptical galaxies NGC 4621 and NGC 4697 each host a supermassive black hole with a mass more than 1e8 Solar masses. Analysis of archival Chandra data and new NRAO Very…
The Black Hole Mass and Extreme Orbital Structure in NGC1399
Karl Gebhardt, Tod R. Lauer, Jason Pinkney +12
The largest galaxies, and in particular central galaxies in clusters, offer unique insight into understanding the mechanism for the growth of nuclear black holes. We present Hubble…
A supermassive binary black hole with triple disks
Kimitake Hayasaki, Shin Mineshige, Luis C. Ho
Hierarchical structure formation inevitably leads to the formation of supermassive binary black holes (BBHs) with a sub-parsec separation in galactic nuclei. However, to date there…
The radio properties of type II quasars
Dharam Vir Lal, Luis C. Ho
Quasars (of type I) are the luminous analogs of type I Seyfert galaxies. Within the framework of unified models of active galaxies, the population of quasars of type II recently di…
Radio Emission from the Intermediate-mass Black Hole in the Globular Cluster G1
James S. Ulvestad, Jenny E. Greene, Luis C. Ho
We have used the Very Large Array (VLA) to search for radio emission from the globular cluster G1 (Mayall-II) in M31. G1 has been reported by Gebhardt et al. to contain an intermed…
Nuclear Star Clusters (Nuclei) in Spiral Galaxies and Connection to Supermassive Black Holes
Roeland P. van der Marel, Joern Rossa, Carl Jakob Walcher +4
HST observations have revealed that compact sources exist at the centers of many, maybe even most, galaxies across the Hubble sequence. These sources are called "nuclei" or also "n…
The Centers of Early-Type Galaxies with HST. VI. Bimodal Central Surface Brightness Profiles
Tod R. Lauer, Karl Gebhardt, S. M. Faber +9
We combine the results from several HST investigations of the central structure of early-type galaxies to generate a large sample of parameterized surface photometry. The studies i…
Multiwavelength Monitoring of the Dwarf Seyfert 1 Galaxy NGC 4395. III. Optical Variability and X-ray/UV/Optical Correlations
Louis-Benoit Desroches, Alexei V. Filippenko, Shai Kaspi +11
We present optical observations of the low-luminosity Seyfert 1 nucleus of NGC 4395, as part of a multiwavelength reverberation-mapping program. Observations were carried out over…
The Masses of Nuclear Black Holes in Luminous Elliptical Galaxies and Implications for the Space Density of the Most Massive Black Holes
Tod R. Lauer, S. M. Faber, Douglas Richstone +11
Black hole masses predicted from the Mbh-sigma relationship conflict with those predicted from the Mbh-L relationship for the most luminous galaxies, such as brightest cluster gala…