Effectiveness of screening space interferometry mission grid star candidates via radial velocity observations -- a Monte Carlo approach
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binary stars variable stars↗
Engineering topics
Wehrle, A.
Publications and source records attributed to Wehrle, A..
SIM science and the SOS
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SIM Space Interferometry Mission↗
Tracking the moving optical photocenters of active galaxies: binary black holes, accretion disks and relativistic jets
We will use the astrometric capabilities of the Space Interferometry Mission to answer three key questions about active galactic nuclei: 1) Does the separation of the radio core and optical photocenter of quasars change on the same timescale as their photometric variability? 2) Does the most compact optical emission from an active galactic nucleus come from an accretion disk or from a relativistic jet? and 3) Do the cores of galaxies harbor binary supermassive black holes remaining from galaxy mergers?
astrometry↗
External review board source interferometry mission
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interferometry↗
The Sub-Parsec Structure of Accretion Disks as Revealed by VLBI Imaging of Free-Free Absorption
The physical conditions in the inner parsec of accretion disks believed to orbit the central black holes in active galactic nuclei can be probed by imaging the absorption of background radio emission by ionized gas in the disk.
Active Galaxies Accretion Disks Interferometry↗
VSOP Observations of a Sub-Parsec Accretion Disk
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VLBI VSOP Active Galaxies Interferometry Accretion↗
Radio and Millimeter Spectral Properties of Newly Identified High Energy Gamma-Ray Sources
We have conducted a variability study of several radio/millimeter sources which are possible counterparts of high energy gamma-ray sources detected by EGRET.
radio sources quasars gamma-ray↗
VSOP and Ground-Based VLBI Imaging of the TEV Blazar Markarian 421 at Multiple Epochs
We present thirty VLBI images of the Tev blazar Markarian 421 (1101+384) at fifteen epochs spanning the time range from 1994 to 1997, and at six different frequencies form 2.3 to 43 GHz.
VSOP VLBI Blazars↗
High Resolution VLBA Observations of NGC 4261
The VLBA's high angular resolution at 22 and 43 GHz allows the nuclei of nearby radio galaxies to be imaged with very high linear resolution. This is the scale on which absorption by the dense ionized inner regions of nuclear accretion disk should be detected.
Interferometry↗
The First Few Parsecs of the Jets in NGC 4261
We have imaged the nucleus of the nearby radio galaxy NGC 4261 (3C270) with the VLBA at 1.6, 8.4, 22, and 43 GHz. At 8.4 GHz our image reveals a narrow gap in emission just east of the core, which we interpret as absorption by an inner accretion disk seen nearly edge-on.
interferometry↗
The Radio Jets and Accretion Disk in NGC 4261
The structure of AGN accretion disks on sub-parsec scales can be probed through free-free absorption of synchrotron emission from the base of symmetric radio jets.
radio jets accretion disk NGC AGN↗
The first few parsecs of the jets in NGC 4261
The double-lobed radio galaxy NGC 4261 (3C270) contains a pair of highly symmetric kpc-scale jets, as well as a two-sided morphology on parsec scales.
radio↗
Pushing the Limits: New Results from the ISO/IRAS Faint Galaxy Survey
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Faint Source Survey↗
The Nature of the Optical Jets in the Spiral Galaxy NGC 1097
We present new observations of the jet features in the barred spiral galaxy NGC 1097, including optical spectroscopy of the brightest jet features, two-color optical imagery, new VLA mapping at 327 MHz, and archival 1.4 GHz VLA data reprocessed for improved sensitivity.
spiral↗