Welch, Jack, Backer, Don, Blitz, Leo, Bock, Douglas C.-J., Bower, Geoffrey C., Cheng, Calvin, ...
The first 42 elements of the Allen Telescope Array (ATA-42) are beginning to deliver data at the Hat Creek Radio Observatory in northern California. Scientists and engineers are actively exploiting...
Bower, Geoffrey C., Bolatto, Alberto, Ford, Eric, Kalas, Paul
Radio astrometry of nearby, low-mass stars has the potential to be a powerful tool for the discovery and characterization of planetary companions. We present a Very Large Array survey of 172 active M...
Imaging an Event Horizon: submm-VLBI of a Super Massive Black Hole (2009)
Doeleman, Sheperd, Agol, Eric, Backer, Don, Baganoff, Fred, Bower, Geoffrey C., Broderick, Avery, ...
A long standing goal in astrophysics is to directly observe the immediate environment of a black hole with angular resolution comparable to the event horizon. Realizing this goal would open a new...
Geoffrey C. Bower, Ilan M. Kroo
Historically, maximizing profits for corporate shareholders has been the primary goal for aircraft designers. Due to climate change concerns, environmental performance is quickly becoming a major...
Welch, Jack, Backer, Don, Blitz, Leo, Bock, Douglas, Bower, Geoffrey C., Cheng, Calvin, ...
The first 42 elements of the Allen Telescope Array (ATA-42) are beginning to deliver data at the Hat Creek Radio Observatory in Northern California. Scientists and engineers are actively exploiting...
Bloom, Joshua S., Holz, Daniel E., Hughes, Scott A., Menou, Kristen, Adams, Allan, Anderson, Scott F., ...
It is widely expected that the coming decade will witness the first direct detection of gravitational waves (GWs). The ground-based LIGO and Virgo GW observatories are being upgraded to advanced...
Falcke, Heino, Markoff, Sera, Bower, Geoffrey C.
The black hole at the Galactic Center, Sgr A*, is the prototype of a galactic nucleus at a very low level of activity. Its radio through submm-wave emission is known to come from a region close to...
Event-horizon-scale structure in the supermassive black hole candidate at the Galactic Centre (2008)
Doeleman, Sheperd, Weintroub, Jonathan, Rogers, Alan E. E., Plambeck, Richard, Freund, Robert, Tilanus, Remo P. J., ...
The cores of most galaxies are thought to harbour supermassive black holes, which power galactic nuclei by converting the gravitational energy of accreting matter into radiation (ref 1). Sagittarius...
VLBA Imaging at 7 mm and Linear Polarimetric Observations at 6 cm and 3 mm of Sgr A* (2008)
Geoffrey C. Bower, Heino Falcke, Don Backer, Melvyn Wright
. We summarize the results of 7 mm VLBA imaging of Sgr A* and discuss some of the difficulties of accurately constraining the size of Sgr A* with VLBI observations. Our imaging results are fully...
Heino Falcke, Geoffrey C. Bower, Andrew P. Lobanov, Thomas P. Krichbaum, Alok R. Patnaik, Margo F. Aller, ...
A major radio outburst in III Zw 2 with an extremely inverted, millimeter-peaked spectrum
The Linear Polarization of Sagittarius A* II. VLA and BIMA Polarimetry at 22, 43 and 86 GHz (2007)
Geoffrey Bower Melvyn, Geoffrey C. Bower, Donald C. Backer, Heino Falcke
We present a search for linear polarization at 22 GHz, 43 GHz and 86 GHz from the nearest super massive black hole candidate, Sagittarius A*. We find upper limits to the linear polarization of 0.2%,...
Detection of Circular Polarization in the Galactic Center Black Hole Candidate Sagittarius A* (2007)
Geoffrey Bower Heino, Geoffrey C. Bower, Heino Falcke, Donald C. Backer
We report here the detection of circular polarization in the Galactic Center black hole candidate, Sagittarius A*. The detection was made at 4.8 GHz and 8.4 GHz with the Very Large Array. We find...
Detection of Circular Polarization in the Galactic Center Black Hole Candidate Sagittarius A* (2007)
Geoffrey C. Bower, Heino Falcke, Donald C. Backer
We report here the detection of circular polarization in the Galactic Center black hole candidate, Sagittarius A*. The detection was made at 4.8 GHz and 8.4 GHz with the Very Large Array. We find...
The Linear Polarization of Sagittarius A* I. VLA Spectro-polarimetry at 4.8 and 8.4 GHz (2007)
Geoffrey C. Bower, Donald C. Backer, Jun-hui Zhao, Miller Goss, Heino Falcke
Synchrotron radiation from active galactic nuclei (AGN) is often highly polarized. We present a search for linear polarization with the Very Large Array (VLA) at 4.8 GHz and 8.4 GHz from the nearest...
The millimeter VLBI Properties of EGRET Blazars (2007)
We give a progress report on a snapshot 86 GHz-VLBI survey of the EGRET blazars with the observatories of the CMVA. A high fraction (17/18) of the EGRET blazars were detected on the Pico...
The Linear Polarization of Sagittarius A* I. VLA Spectro-polarimetry at 4.8 and 8.4 GHz (2007)
Geoffrey C. Bower, Donald C. Backer, Jun-hui Zhao, Miller Goss, Heino Falcke
Synchrotron radiation from active galactic nuclei (AGN) is often highly polarized. We present a search for linear polarization with the Very Large Array (VLA) at 4.8 GHz and 8.4 GHz from the nearest...
The power of jets: New clues from radio circular polarization and X-rays (2007)
Heino Falcke, Thomas Beckert, Sera Markoff, Elmar Körding, Geoffrey C. Bower, Rob Fender
Jets are ubiquitous in accreting black holes. Often ignored, they may be a major contributor to the emitted spectral energy distribution for sub-Eddington black holes. For example, recent...
Interferometric Detection of Linear Polarization from Sagittarius A* at 230 GHz (2007)
A At Ghz, Geoffrey C. Bower, Heino Falcke, Donald C. Backer
We measured the linear polarization of Sagittarius A* to be 7:20:6% at 230 GHz using the BIMA array with a resolution of 3:60:9 arcsec. This con rms the previously reported detection with the JCMT...
Sandstrom, Karin M., Peek, J. E. G., Bower, Geoffrey C., Bolatto, Alberto D., Plambeck, Richard L.
We determine the parallax and proper motion of the flaring, non-thermal radio star GMR A, a member of the Orion Nebula Cluster, using Very Long Baseline Array observations. Based on the parallax, we...
SubmilliJansky Transients in Archival Radio Observations (2007)
Bower, Geoffrey C., Saul, Destry, Bloom, Joshua S., Bolatto, Alberto, Filippenko, Alexei V., Foley, Ryan J., ...
[ABRIDGED] We report the results of a 944-epoch survey for transient sources with archival data from the Very Large Array spanning 22 years with a typical epoch separation of 7 days. Observations...
Bower, Geoffrey C., Bolatto, Alberto, Ford, Eric, Kalas, Paul, Ulvestad, Jim
The extraordinary astrometric accuracy of radio interferometry creates an important and unique opportunity for the discovery and characterization of exo-planets. Currently, the Very Long Baseline...
How to hide large scale outflows: size constraints on the jets of Sgr A* (2007)
Markoff, Sera, Bower, Geoffrey C., Falcke, Heino
Despite significant strides made towards understanding accretion, outflow, and emission processes in the Galactic Center supermassive black hole Sagittarius A*, the presence of jets has neither been...
The Intrinsic Size of Sagittarius A* from 0.35 cm to 6 cm (2006)
Bower, Geoffrey C., Goss, W. M., Falcke, Heino, Backer, Donald C., Lithwick, Yoram
We present new high-resolution observations of Sagittarius A* at wavelengths of 17.4 to 23.8 cm with the Very Large Array in A configuration with the Pie Town Very Long Baseline Array antenna. We use...
The Rotation Measure and 3.5mm Polarization of Sgr A* (2006)
Macquart, Jean-Pierre, Bower, Geoffrey C., Wright, Melvyn C. H., Backer, Donald C., Falcke, Heino
We report the detection of variable linear polarization from Sgr A* at a wavelength of 3.5mm, the longest wavelength yet at which a detection has been made. The mean polarization is 2.1 +/- 0.1% at a...
Radio Linear and Circular Polarization from M81* (2006)
Brunthaler, Andreas, Bower, Geoffrey C., Falcke, Heino
We present results from archival Very Large Array (VLA) data and new VLA observations to investigate the long term behavior of the circular polarization of M81*, the nuclear radio source in the...
Radio pulsars and transients in the Galactic center (2006)
Lazio, Joseph, Deneva, Julia S., Bower, Geoffrey C., Cordes, James M., Hyman, Scott D., Backer, Donald C., ...
Abstract not available.
Radio pulsars and transients in the Galactic center (2006)
Lazio, Joseph, Deneva, Julia S., Bower, Geoffrey C., Cordes, James M., Hyman, Scott D., Backer, Donald C., ...
Abstract not available.
Radio pulsars and transients in the Galactic center (2006)
Lazio, Joseph, Deneva, Julia S., Bower, Geoffrey C., Cordes, James M., Hyman, Scott D., Backer, Donald C., ...
Abstract not available.
Radio pulsars and transients in the Galactic center (2006)
Lazio, Joseph, Deneva, Julia S., Bower, Geoffrey C., Cordes, James M., Hyman, Scott D., Backer, Donald C., ...
Abstract not available.
Radio pulsars and transients in the Galactic center (2006)
Lazio, Joseph, Deneva, Julia S., Bower, Geoffrey C., Cordes, James M., Hyman, Scott D., Backer, Donald C., ...
Abstract not available.
Radio pulsars and transients in the Galactic center (2006)
Lazio, Joseph, Deneva, Julia S., Bower, Geoffrey C., Cordes, James M., Hyman, Scott D., Backer, Donald C., ...
Abstract not available.
A Radio Transient 0.1 pc from Sagittarius A* (2005)
Bower, Geoffrey C., Roberts, Doug A., Yusef-Zadeh, Farhad, Backer, Donald C., Cotton, W. D., Goss, W. M., ...
We report the discovery of a transient radio source 2.7 arcsec (0.1 pc projected distance) South of the Galactic Center massive black hole, Sagittarius A*. The source flared with a peak of at least...
Radio frequency interference (RFI) is a significant problem for current and future radio telescopes. We describe here a method for post-correlation cancellation of RFI for the special case of an...
Variable Linear Polarization from Sagittarius A*: Evidence for a Hot Turbulent Accretion Flow (2004)
Bower, Geoffrey C., Falcke, Heino, Wright, Melvyn C. H., Backer, Donald C.
We report the discovery of variability in the linear polarization from the Galactic Center black hole source, Sagittarius A*. New polarimetry obtained with the Berkeley-Illinois-Maryland Association...
Detection of 21 Centimeter HI Absorption at z = 0.78 in a Survey of Radio Continuum Sources (2004)
Darling, Jeremy, Giovanelli, Riccardo, Haynes, Martha P., Bolatto, Alberto D., Bower, Geoffrey C.
We report the detection of a deep broad HI 21 cm absorption system at z = 0.78 toward the radio source [HB89] 2351+456 (4C+45.51) at z = 1.992. The HI absorption was identified in a blind spectral...
Bower, Geoffrey C., Falcke, Heino, Herrnstein, Robeson M., Zhao, Jun-Hui, Goss, W. M., Backer, Donald C.
We have detected the intrinsic size of Sagittarius A*, the Galactic Center radio source associated with a supermassive black hole, showing that the short-wavelength radio emission arises from very...
Haiman, Zoltan, Quataert, Eliot, Bower, Geoffrey C.
We use a physically motivated semi-analytic model, based on the mass function of dark matter halos, to predict the number of radio-loud quasars as a function of redshift and luminosity. Simple models...
Molecular fraction limits in damped Lyman alpha absorption systems (2004)
Curran, Stephen J., Murphy, Michael T., Pihlstrom, Ylva M., Webb, J. K., Bolatto, A. D., Bower, Geoffrey C.
We have used the Green Bank Telescope (GBT) and Berkeley-Illinois-Maryland Association (BIMA) array to search for redshifted millimetre absorption in a sample of damped Lyman alpha absorption systems...
Molecular fraction limits in damped Lyman alpha absorption systems (2004)
Curran, Stephen J., Murphy, Michael T., Pihlstrom, Ylva M., Webb, J. K., Bolatto, A. D., Bower, Geoffrey C.
We have used the Green Bank Telescope (GBT) and Berkeley-Illinois-Maryland Association (BIMA) array to search for redshifted millimetre absorption in a sample of damped Lyman alpha absorption systems...
A Giant Outburst at Millimeter Wavelengths in the Orion Nebula (2003)
Bower, Geoffrey C., Plambeck, Richard L., Bolatto, Alberto, McCrady, Nate, Graham, James R., De Pater, Imke, ...
BIMA observations of the Orion nebula discovered a giant flare from a young star previously undetected at millimeter wavelengths. The star briefly became the brightest compact object in the nebula at...
Interferometric Detection of Linear Polarization from Sagittarius A* at 230 GHz (2003)
Bower, Geoffrey C., Wright, Melvyn C. H., Falcke, Heino, Backer, Donald C.
We measured the linear polarization of Sagittarius A* to be 7.2 +/- 0.6 % at 230 GHzusing the BIMA array with a resolution of 3.6 x 0.9 arcsec. This confirms the previously reported detection with...
Linear and Circular Polarization from Sagittarius A* and M81* (2003)
We describe recent results for Sgr A*, M81* and other low luminosity active galactic nuclei. We have conducted linear and circular polarimetry over a frequency range of 1.4 to 230 GHz and detected a...
A Radio Survey for Linear and Circular Polarization in Low Luminosity Active Galactic Nuclei (2002)
Bower, Geoffrey C., Falcke, Heino, Mellon, Richard R.
We conducted a Very Large Array survey of eleven low luminosity active galactic nuclei for linear and circular polarization at 8.4 GHz. We detected circular polarization in one source (M81*) and...
The Spectrum and Variability of Circular Polarization in Sagittarius A* from 1.4 to 15 GHz (2002)
Bower, Geoffrey C., Falcke, Heino, Sault, Robert J., Backer, Donald C.
We report here multi-epoch, multi-frequency observations of the circular polarization in Sagittarius A*, the compact radio source in the Galactic Center. Data taken from the VLA archive indicate that...
The Spectrum and Variability of Circular Polarization in Sagittarius A* from 1.4 to 15 GHz (2002)
Geoffrey C. Bower, Heino Falcke, Robert J. Sault, Donald C. Backer
We report here multi-epoch, multi-frequency observations of the circular polarization in Sagittarius A*, the compact radio source in the Galactic Center.
The Power of Jets: New Clues from Radio Circular Polarization and X-rays (2001)
Falcke, Heino, Beckert, Thomas, Markoff, Sera, Koerding, Elmar, Bower, Geoffrey C., Fender, Rob
Jets are ubiquitous in accreting black holes. Often ignored, they may be a major contributor to the emitted spectral energy distribution for sub-Eddington black holes. For example, recent...
BIMA Observations of Linear Polarization in Sagittarius A* at 112 GHz (2001)
Bower, Geoffrey C., Wright, Melvyn C. H., Falcke, Heino, Backer, Donald C.
We report here BIMA array observations of linear polarization in Sagittarius A*, the compact radio source in the Galactic Center. These observations had a resolution of 20 arcsec x 5 arcsec oriented...
VLBA Observations of Astrometric Reference Sources in the Galactic Center (2001)
Bower, Geoffrey C., Backer, Donald C., Sramek, Richard A.
We report here on multi-frequency VLBA observations of three extragalactic sources within 1 degree of the Galactic Center. These sources have been used as astrometric reference sources for VLA and...
Polarization in Sagittarius A* (2000)
We summarize the current state of polarization observations of Sagittarius A*, the compact radio source and supermassive black hole candidate in the Galactic Center. These observations are providing...
III Zw 2, the first superluminal jet in a Seyfert galaxy (2000)
Brunthaler, Andreas, Falcke, Heino, Bower, Geoffrey C., Aller, M. F., Aller, H. D., Teraesranta, H., ...
So far all relativistically boosted jets with superluminal motion have only been detected in typical radio galaxies with early type host galaxies. We have now discovered superluminal motion in the...
The millimeter VLBI Properties of EGRET Blazars (1999)
We give a progress report on a snapshot 86 GHz-VLBI survey of the EGRET blazars with the observatories of the CMVA. A high fraction (17/18) of the EGRET blazars were detected on the Pico...
The Linear Polarization of Sagittarius A* II. VLA and BIMA Polarimetry at 22, 43 and 86 GHz (1999)
Bower, Geoffrey C., Wright, Melvyn C. H., Backer, Donald C., Falcke, Heino
We present a search for linear polarization at 22 GHz, 43 GHz and 86 GHz from the nearest super massive black hole candidate, Sagittarius A*. We find upper limits to the linear polarization of 0.2%,...
Detection of Circular Polarization in the Galactic Center Black Hole Candidate Sagittarius A* (1999)
Bower, Geoffrey C., Falcke, Heino, Backer, Donald C.
We report here the detection of circular polarization in the Galactic Center black hole candidate, Sagittarius A*. The detection was made at 4.8 GHz and 8.4 GHz with the Very Large Array. We find...
The Linear Polarization of Sagittarius A* I. VLA Spectro-polarimetry at 4.8 and 8.4 GHz (1999)
Bower, Geoffrey C., Backer, Donald C., Zhao, Jun-Hui, Goss, Miller, Falcke, Heino
Synchrotron radiation from active galactic nuclei (AGN) is often highly polarized. We present a search for linear polarization with the Very Large Array (VLA) at 4.8 GHz and 8.4 GHz from the nearest...
A major radio outburst in III Zw 2 with an extremely inverted, millimeter-peaked spectrum (1999)
Falcke, Heino, Bower, Geoffrey C., Lobanov, Andrew P., Krichbaum, Thomas P., Patnaik, Alok R., Aller, Margo F., ...
III Zw 2 is a spiral galaxy with an optical spectrum and faint extended radio structure typical of a Seyfert galaxy, but also with an extremely variable, blazar-like radio core. We have now...
VLBA Imaging at 7 mm and Linear Polarimetric Observations at 6 cm and 3 mm of Sagittarius A* (1998)
Bower, Geoffrey C., Falcke, Heino, Backer, Don, Wright, Melvyn
We summarize the results of 7 mm VLBA imaging of Sgr A* and discuss some of the difficulties of accurately constraining the size of Sgr A* with VLBI observations. Our imaging results are fully...
Space VLBI Observations Show $T_b > 10^{12} K$ in the Quasar NRAO 530 (1998)
Bower, Geoffrey C., Backer, Donald C.
We present here space-based VLBI observations with VSOP and a southern hemisphere ground array of the gamma-ray blazar NRAO 530 at 1.6 GHz and 5 GHz. The brightness temperature of the core at 1.6 GHz...
7 mm lambda VLBA Observations of Sagittarius A* (1998)
Bower, Geoffrey C., Backer, Donald C.
We present 7 mm lambda VLBA observations of the compact nonthermal radio source in the Galactic Center, Sgr A*. These observations confirm the hypothesis that the image of Sgr A* is a resolved...
BIMA Observations of Linear Polarization in Sagittarius A* at 112 GHz
Geoffrey C. Bower, Heino Falcke, Donald C. Backer
We report here BIMA array observations of linear polarization in Sagittarius A*, the compact radio source in the Galactic Center. These observations had a resolution of 20 00 5 00 oriented...