Dexter, Jason, Agol, Eric, Fragile, P. Chris
The recent VLBI observation of the Galactic center black hole candidate Sgr A* at 1.3mm shows source structure on event-horizon scales. This detection enables a direct comparison of the emission...
The 8 Micron Phase Variation of the Hot Saturn HD 149026b (2009)
Knutson, Heather A., Charbonneau, David, Cowan, Nicolas B., Fortney, Jonathan J., Showman, Adam P., Agol, Eric, ...
We monitor the star HD 149026 and its Saturn-mass planet at 8.0 micron over slightly more than half an orbit using the Infrared Array Camera (IRAC) on the Spitzer Space Telescope. We find an increase...
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...
Spitzer observations of a gravitationally lensed quasar, QSO 2237+0305 (2009)
Agol, Eric, Gogarten, Stephanie, Gorjian, Varoujan, Kimball, Amy
The four-image gravitationally lensed quasar QSO 2237+0305 is microlensed by stars in the lens galaxy. The amplitude of microlensing variability can be used to infer the relative size of the quasar...
MacLeod, Chelsea L., Kochanek, Christopher S., Agol, Eric
We present the first resolved mid-IR (11 micron) observations of the four-image quasar lens H1413+117 using the Michelle camera on Gemini North. All previous observations (optical, near-IR, and...
A Fast New Public Code for Computing Photon Orbits in a Kerr Spacetime (2009)
Relativistic radiative transfer problems require the calculation of photon trajectories in curved spacetime. We present a novel technique for rapid and accurate calculation of null geodesics in the...
Transit Timing Observations of the Extrasolar Hot-Neptune Planet GL 436b (2009)
Stringfellow, Guy S., Coughlin, Jeffrey L., López-Morales, Mercedes, Becker, Andrew C., Krajci, Tom, Mezzalira, Fabio, ...
Gliese 436 is an M dwarf with a mass of 0.45 Msun and hosts the extrasolar planet GL 436b [3, 6, 7, 2], which is currently the least massive transiting planet with a mass of ~23.17 Mearth [10], and...
Transits and secondary eclipses of HD 189733 with Spitzer (2008)
Agol, Eric, Cowan, Nicolas B., Bushong, James, Knutson, Heather, Charbonneau, David, Deming, Drake, ...
We present limits on transit timing variations and secondary eclipse depth variations at 8 microns with the Spitzer Space Telescope IRAC camera. Due to the weak limb darkening in the infrared and...
A Precise Estimate of the Radius of HD 149026b (2008)
Nutzman, Philip, Charbonneau, David, Winn, Joshua N., Knutson, Heather A., Fortney, Jonathan J., Holman, Matthew J., ...
We present Spitzer 8 micron transit observations of the extrasolar planet system HD 149026. At this wavelength, transit light curves are weakly affected by stellar limb-darkening, allowing for a...
Exoplanet Mapping Revealed (2008)
One of the most exciting results of the Spitzer era has been the ability to construct longitudinal brightness maps from the infrared phase variations of hot Jupiters. We presented the first such map...
A Precise Estimate of the Radius of the Exoplanet HD 149026b from Spitzer Photometry (2008)
Nutzman, Philip, Charbonneau, David, Winn, Joshua N., Knutson, Heather A., Fortney, Jonathan J., Holman, Matthew J., ...
We present Spitzer 8 micron transit observations of the extrasolar planet HD 149026b. At this wavelength, transit light curves are weakly affected by stellar limb-darkening, allowing for a simpler...
Inverting Phase Functions to Map Exoplanets (2008)
We describe how to generate a longitudinal brightness map for a tidally locked exoplanet from its phase function light curve. We operate under a number of simplifying assumptions, neglecting limb...
Multi-Wavelength Constraints on the Day-Night Circulation Patterns of HD 189733b (2008)
Knutson, Heather A., Charbonneau, David, Cowan, Nicolas B., Fortney, Jonathan J., Showman, Adam P., Agol, Eric, ...
We present new Spitzer observations of the phase variation of the hot Jupiter HD 189733b in the MIPS 24 micron bandpass, spanning the same part of the planet's orbit as our previous observations in...
Richard Schilizzi, Stuart Vogel, Francesco Paresce, Martin Elvis, Heino Falcke, Peter L. Biermann, ...
Sgr A*: observations, models, and imaging of the event horizon with VLBI
THE PUZZLE OF THE LYMAN CONTINUUM POLARIZATION OF QSOS (2007)
Gregory A. Shields, Eric Agol, Omer Blaes
Mediante espectropolarimetra reciente de cuasares se ha encontrado un sorprendente incremento en la polarizacion del contnuo de Lyman en varios objetos. Discutimos algunos intentos recientes para...
THE PUZZLE OF THE LYMAN CONTINUUM POLARIZATION OF QSOS (2007)
Gregory A. Shields, Eric Agol, Omer Blaes
Mediante espectropolarimetría reciente de cuasares se ha encontrado un sorprendente incremento en la polarización del contínuo de Lyman en varios objetos. Discutimos algunos intentos recientes...
Observations of Extrasolar Planets During the non-Cryogenic Spitzer Space Telescope Mission (2007)
Deming, Drake, Agol, Eric, Charbonneau, David, Cowan, Nicolas, Knutson, Heather, Marengo, Massimo
Precision infrared photometry from Spitzer has enabled the first direct studies of light from extrasolar planets, via observations at secondary eclipse in transiting systems. Current Spitzer results...
New Worlds on the Horizon: Earth-Sized Planets Close to Other Stars (2007)
Gaidos, Eric, Haghighipour, Nader, Agol, Eric, Latham, David, Raymond, Sean, Rayner, John
The search for habitable planets like Earth around other stars fulfils an ancient imperative to understand our origins and place in the cosmos. The past decade has seen the discovery of hundreds of...
A map of the day-night contrast of the extrasolar planet HD 189733b (2007)
Knutson, Heather A., Charbonneau, David, Allen, Lori E., Fortney, Jonathan J., Agol, Eric, Cowan, Nicolas B., ...
"Hot Jupiter" extrasolar planets are expected to be tidally locked because they are close (
Detecting and Characterizing Planetary Systems with Transit Timing (2007)
Steffen, Jason H., Gaudi, B. Scott, Ford, Eric B., Agol, Eric, Holman, Mathew J.
In the coming decades, research in extrasolar planets aims to advance two goals: 1) detecting and characterizing low-mass planets increasingly similar to the Earth, and 2) improving our understanding...
Developments in Planet Detection using Transit Timing Variations (2006)
In a transiting planetary system, the presence of a second planet will cause the time interval between transits to vary. These transit timing variations (TTV) are particularly large near mean-motion...
Rounding up the wanderers: optimizing coronagraphic searches for extrasolar planets (2006)
I derive analytic scalings for coronagraphic imaging searches for extrasolar planets. I compute the efficiency of detecting planets about any given star, and from this compute dimensionless...
A limit on the presence of Earth-mass planets around a Sun-like star (2006)
We present a combined analysis of all publicly available, visible HST observations of transits of the planet HD 209458b. We derive the times of transit, planet radius, inclination, period, and...
The Puzzle of The Lyman Continuum Polarization of QSOs (2006)
Omer Blaes, Gregory A. Shields, Eric Agol
The Puzzle of The Lyman Continuum Polarization of QSOs
Hubble Imaging Excludes Cosmic String Lens (2006)
Agol, Eric, Hogan, Craig J., Plotkin, Richard M.
The galaxy image pair CSL-1 has been a leading candidate for a cosmic string lens. High quality imaging data from the Hubble Space Telescope presented here show that it is not a lens but a pair of...
Anderson, Scott, Haggard, Daryl, Homer, Lee, Joshi, Nikhil, Margon, Bruce, Silvestri, Nicole, ...
Also archived in: arXiv:astro-ph/0506730 v1 Jun 29 2005
An analysis of the transit times of TrES-1b (2005)
The presence of a second planet in a known, transiting-planet system will cause the time between transits to vary. These variations can be used to constrain the orbital elements and mass of the...
Anderson, Scott F., Haggard, Daryl, Homer, Lee, Joshi, Nikhil R., Margon, Bruce, Silvestri, Nicole M., ...
AM CVn systems are a rare (about a dozen previously known) class of cataclysmic variables, arguably encompassing the shortest orbital periods (down to about 10 minutes) of any known binaries. Both...
Spectropolarimetry and Modeling of the Eclipsing T Tauri Star KH 15D (2003)
Agol, Eric, Barth, Aaron, Wolf, Sebastian, Charbonneau, David
KH 15D is a strongly variable T Tauri star in the young star cluster NGC 2264 that shows a decrease in flux of 3.5 magnitudes lasting for 18 days and repeating every 48 days. The eclipsing material...
Microlensing of Large Sources (2003)
We prove a gravitational lensing theorem: the magnification of a source of uniform brightness by a foreground spherical lens is mu =1+pi(2R_E^2-R_L^2)/A, where A is the area of the source and R_E and...
Finding White Dwarfs with Transit Searches (2003)
We make predictions for the rate of discovery of eclipsing white dwarf-main sequence (WD-MS) binaries in terrestrial-planet transit searches, taking the planned Kepler and Eddington missions as...
Analytic Lightcurves for Planetary Transit Searches (2002)
We present exact analytic formulae for the eclipse of a star described by quadratic or nonlinear limb darkening. In the limit that the planet radius is less than a tenth of the stellar radius, we...
Occultation and Microlensing (2002)
Occultation and microlensing are different limits of the same phenomena of one body passing in front of another body. We derive a general exact analytic expression which describes both microlensing...
Finding Black Holes with Microlensing (2002)
Agol, Eric, Kamionkowski, Marc, Koopmans, Leon, Blandford, Roger
The MACHO and OGLE collaborations have argued that the three longest duration bulge microlensing events are likely caused by nearby black holes, given the small velocities measured with microlensing...
Agol, Eric, Fluke, Christopher Jon, Wyithe, Stuart
Abstract not available.
Agol, Eric, Fluke, Christopher J., Wyithe, Stuart
Abstract not available.
Agol, Eric, Fluke, Christopher J., Wyithe, Stuart
Abstract not available.
Agol, Eric, Fluke, Christopher J., Wyithe, Stuart
Abstract not available.
Agol, Eric, Fluke, Christopher J., Wyithe, Stuart
Abstract not available.
X-Rays from Isolated Black Holes in the Milky Way (2001)
Agol, Eric, Kamionkowski, Marc
Galactic stellar-population-synthesis models, chemical-enrichment models, and long-duration Bulge microlensing events indicate about N_tot=(0.1-1) billion stellar-mass black holes reside in our...
Blaes, Omer, Hubeny, Ivan, Agol, Eric, Krolik, Julian H.
We fit general relativistic, geometrically thin accretion disk models with non-LTE atmospheres to near simultaneous multiwavelength data of 3C~273, extending from the optical to the far ultraviolet....
Compact Objects and Accretion Disks (2001)
Blandford, Roger, Agol, Eric, Broderick, Avery, Heyl, Jeremy, Koopmans, Leon, Lee, Hee-Won
Recent developments in the spectropolarimetric study of compact objects, specifically black holes (stellar and massive) and neutron stars are reviewed. The lectures are organized around five topics:...
Two-Dimensional Hydrodynamic Simulations of Convection in Radiation-Dominated Accretion Disks (2001)
Agol, Eric, Krolik, Julian, Turner, Neal, Stone, James
The standard equilibrium for radiation-dominated accretion disks has long been known to be viscously, thermally, and convectively unstable, but the nonlinear development of these...
Mid-infrared imaging of the Einstein Cross QSO (2001)
Agol, Eric, Fluke, Christopher J., Jones, Barbara, Wyithe, Stuart
Observations of the Einstein Cross QSO reveal that the mid-infrared region is unaffected by microlensing. Thus, the infrared emission region must be extended on a scale >1017 cm, ruling out...
The puzzle of the lyman continuum polarization of qsos (2001)
Agol , Eric, Blaes , Omer, Shields , Gregory A.
Recent spectropolarimetry of QSOs has revealed a surprising rise in polar- ization in the Lyman continuum of several objects. We discuss several recent at- tempts to interpret this feature, including...
Mid-infrared imaging of the Einstein Cross QSO (2001)
Agol, Eric, Fluke, Christopher J., Jones, Barbara, Wyithe, Stuart
Observations of the Einstein Cross QSO reveal that the mid-infrared region is unaffected by microlensing. Thus, the infrared emission region must be extended on a scale >1017 cm, ruling out...
Mid-infrared imaging of the Einstein Cross QSO (2001)
Agol, Eric, Fluke, Christopher J., Jones, Barbara, Wyithe, Stuart
Observations of the Einstein Cross QSO reveal that the mid-infrared region is unaffected by microlensing. Thus, the infrared emission region must be extended on a scale >1017 cm, ruling out...
Mid-infrared imaging of the Einstein Cross QSO (2001)
Agol, Eric, Fluke, Christopher J., Jones, Barbara, Wyithe, Stuart
Observations of the Einstein Cross QSO reveal that the mid-infrared region is unaffected by microlensing. Thus, the infrared emission region must be extended on a scale >1017 cm, ruling out...
Mid-infrared imaging of the Einstein Cross QSO (2001)
Agol, Eric, Fluke, Christopher J., Jones, Barbara, Wyithe, Stuart
Observations of the Einstein Cross QSO reveal that the mid-infrared region is unaffected by microlensing. Thus, the infrared emission region must be extended on a scale >1017 cm, ruling out...
Keck Mid-Infrared Imaging of the QSO 2237+0305 (2000)
Agol, Eric, Jones, Barbara, Blaes, Omer
Using the Long Wavelength Spectrometer on Keck I, we have imaged the gravitationally lensed radio quiet quasi-stellar object (QSO) 2237+0305 at 8.9 and 11.7 microns for the first time. The...
Sgr A* Polarization: No ADAF, Low Accretion Rate, and Non-Thermal Synchrotron Emission (2000)
The recent detection of polarized radiation from Sgr A* requires a non-thermal electron distribution for the emitting plasma. The Faraday rotation measure must be small, placing strong limits on the...
Viewing The Shadow Of The Black Hole At The Galactic Center (2000)
Heino Falcke, Fulvio Melia, Eric Agol
In recent years, the evidence for the existence of an ultra-compact concentration of dark mass associated with the radio source Sgr A* in the Galactic Center has become very strong. However, an...
Viewing the Shadow of the Black Hole at the Galactic Center (1999)
Falcke, Heino, Melia, Fulvio, Agol, Eric
In recent years, the evidence for the existence of an ultra-compact concentration of dark mass associated with the radio source Sgr A* in the Galactic Center has become very strong. However, an...
Hubeny, Ivan, Agol, Eric, Blaes, Omer, Krolik, Julian
We have constructed a grid of non-LTE disk models for a wide range of black hole mass and mass accretion rate, for several values of viscosity parameter alpha, and for two extreme values of the black...
Magnetic connections to the plunging region can exert stresses on the inner edge of an accretion disk around a black hole. We recompute the relativistic corrections to the thin-disk dynamics...
Imaging a Quasar Accretion Disk with Microlensing (1999)
We show how analysis of a quasar high-magnification microlensing event may be used to construct a map of the frequency-dependent surface brightness of the quasar accretion disk. The same procedure...
The Shadow of the Black Hole at the Galactic Center (1999)
Heino Falcke, Fulvio Melia, Eric Agol
. We show that perhaps already with the next generation of long-baseline interferometers at submm-wavelengths we will able to image the shadow of the black hole in the Galactic Center. To a distant...
Photon Damping of Waves in Accretion Disks (1998)
MHD turbulence is generally believed to have two important functions in accretion disks: it transports angular momentum outward, and the energy in its shortest wavelength modes is dissipated into the...
Continuum Spectra of Quasar Accretion Disk Models (1997)
Agol, Eric, Hubeny, Ivan, Blaes, Omer
We have calculated the spectrum and polarization of a standard thin accretion disk with parameters appropriate for a bright quasar. This model improves upon previous work by including ultraviolet...
Thesis (Ph. D.)--University of California, Santa Barbara, 1997.
Agol, Eric, Blaes, Omer, Ionescu-Zanetti, Cristian
Equipartition magnetic fields can dramatically affect the polarization of radiation emerging from accretion disk atmospheres in active galactic nuclei. We extend our previous work on this subject by...