Search Publications
The Calm before the Storm: The Link between Quiescent Cavities and Coronal Mass Ejections
de Toma, G.; Gibson, S. E.; Burkepile, J. +2 more
Determining the state of the corona prior to CMEs is crucial to understanding and ultimately predicting solar eruptions. A common and compelling feature of CMEs is their three-part morphology, as seen in white-light observations of a bright expanding loop, followed by a relatively dark cavity, and finally a bright core associated with an erupting …
Dynamical Properties of Ultraluminous Infrared Galaxies. I. Mass Ratio Conditions for ULIRG Activity in Interacting Pairs
Lutz, D.; Genzel, R.; Tacconi, L. J. +6 more
We present first results from our Very Large Telescope large program to study the dynamical evolution of ultraluminous infrared galaxies (ULIRGs), which are the products of mergers of gas-rich galaxies. The full data set consists of high-resolution long-slit H- and K-band spectra of 38 ULIRGs and 12 QSOs (in the range 0.042<z<0.268). In this…
The Time Delays of Gravitational Lens HE 0435-1223: An Early-Type Galaxy with a Rising Rotation Curve
Kochanek, C. S.; Winn, J. N.; Falco, E. E. +4 more
We present Hubble Space Telescope images and 2 years of optical photometry of the quadruple quasar HE 0435-1223. The time delays between the intrinsic quasar variations are ΔtAD=-14.37+0.75-0.85, ΔtAB=-8.00+0.73-0.82, and ΔtAC=-2.10+0.78-0.71 days. W…
Models for the Type Ic Hypernova SN 2003lw associated with GRB 031203
Della Valle, Massimo; Tominaga, Nozomu; Nomoto, Ken'ichi +10 more
The gamma-ray burst GRB 031203 at a redshift z=0.1055 revealed a highly reddened Type Ic supernova, SN 2003lw, in its afterglow light. This is the third well-established case of a link between a long-duration GRB and a Type Ic SN. The SN light curve is obtained by subtracting the galaxy contribution and is modeled together with two spectra at near…
A Multiwavelength Study of Sgr A*: The Role of Near-IR Flares in Production of X-Ray, Soft γ-Ray, and Submillimeter Emission
Dowell, C. D.; Bélanger, G.; Goldwurm, A. +8 more
Although Sgr A* is known to be variable in radio, millimeter, near-IR, and X-rays, the correlation of the variability across its spectrum has not been fully studied. Here we describe highlights of the results of two observing campaigns in 2004 to investigate the correlation of flare activity in different wavelength regimes, using a total of nine g…
Probing the Coevolution of Supermassive Black Holes and Quasar Host Galaxies
Ho, Luis C.; Rix, Hans-Walter; Peng, Chien Y. +2 more
At low redshift, there are fundamental correlations between the mass of supermassive black holes (MBH) and the mass (Mbulge) and luminosity of the host galaxy bulge. We investigate the same relation at z>~1. Using virial mass estimates for 11 quasars at z>~2 to measure their black hole mass, we find that black holes at …
Nonthermal High-Energy Emission from Colliding Winds of Massive Stars
Reimer, A.; Reimer, O.; Pohl, M.
Colliding winds of massive star binary systems are considered as potential sites of nonthermal high-energy photon production. Motivated by the detection of synchrotron radio emission from the colliding wind location, we here investigate the properties of high-energy photon production in colliding winds of long-period WR+OB systems. Analytical form…
The Spiderweb Galaxy: A Forming Massive Cluster Galaxy at z ~ 2
Pentericci, Laura; Franx, Marijn; Illingworth, Garth D. +11 more
We present a deep image of the radio galaxy MRC 1138-262 taken with the Hubble Space Telescope (HST) at a redshift of z=2.2. The galaxy is known to have properties of a cD galaxy progenitor and be surrounded by a 3 Mpc-sized structure, identified with a protocluster. The morphology shown on the new deep HST ACS image is reminiscent of a spider's w…
Mid-Infrared Spectral Diagnostics of Nuclear and Extranuclear Regions in Nearby Galaxies
Helou, G.; Moustakas, J.; Roussel, H. +19 more
Mid-infrared diagnostics are presented for a large portion of the Spitzer Infrared Nearby Galaxies Survey (SINGS) sample plus archival data from ISO and Spitzer. The SINGS data set includes low- and high-resolution spectral maps and broadband imaging in the infrared for over 160 nuclear and extranuclear regions within 75 nearby galaxies spanning a…
The Outburst of HST-1 in the M87 Jet
Cheung, C. C.; Sparks, W. B.; Wilson, A. S. +4 more
The X-ray intensity of knot HST-1, 0.85" from the nucleus of the radio galaxy M87, has increased by more than a factor of 50 during the last 5 yr. The optical increase is similar, and our more limited radio data indicate a commensurate activity. We give the primary results of our Chandra X-Ray Observatory monitoring program and consider some of th…