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Simultaneous Multiwavelength Spectrum and Variability of 3C 279 from 10 9 to 10 24 Hz
Dermer, C. D.; Tornikoski, M.; Hermsen, W. +25 more
Data from a number of monitoring programs have been combined with data from the Compton Gamma Ray Observatory and the Ginga X-ray satellite to construct a spectrum covering nearly 15 decades in frequency during or near the time of the 3C 279 γ-ray flare observed by EGRET in 1991 June. A much less complete spectrum is presented for 1991 October. Li…
The Jet of M87 at Tenth-Arcsecond Resolution: Optical, Ultraviolet, and Radio Observations
Sparks, W. B.; Macchetto, F.; Biretta, J. A.
The European Space Agency's Faint Object Camera (FOC) on the Hubble Space Telescope (HST) was used to obtain optical and UV imaging of the jet of M87 prior to the HST refurbishment. We present a detailed comparison to new VLA radio observations at similar spatial resolution and flux information for the radio, optical, and UV bands. While the radio…
The Extragalactic Distance Scale Key Project. III. The Discovery of Cepheids and a New Distance to M101 Using the Hubble Space Telescope
Kelson, Daniel D.; Illingworth, Garth D.; Madore, Barry F. +15 more
We report on the discovery of 29 Cepheid variables in the galaxy M101 using the original Wide Field Camera (WFC) and the new Wide Field and Planetary Camera 2 (WFPC2) on the Hubble Space Telescope. We observed a field in M101 at 17 independent epochs in V (F555W), five epochs in I (F785LP/ F814W), and one epoch in B (F439W), with a time interval b…
Radio Outflows and the Origin of the Narrow-Line Region in Seyfert Galaxies
Boksenberg, A.; Capetti, A.; Sparks, W. B. +2 more
We present the results of Hubble Space Telescope medium-band imaging of four Seyfert 2 galaxies, Mrk 573, Mrk 348, Mrk 3, and Mrk 78, which show extended radio emission, and ground based Johnson A images of Mrk 3 and Mrk 78 obtained with the William Herschel Telescope. Together these two data sets allow us to investigate the relationship between t…
Reverberation Mapping and the Disk-Wind Model of the Broad-Line Region
Chiang, J.; Murray, N.
Using the disk-wind model of Murray et al., we calculate line profiles and frequency-resolved response functions for broad-line emission from the surface of an accretion disk in an active galactic nucleus in the presence of a radiatively driven wind. We find that the combined effects of the shears in the wind and in the dIsk itself produce anisotr…
The Subarcsecond Radio Structure in NGC 1068. II. Implications for the Central Engine and Unifying Schemes
O'Dea, C. P.; Baum, S. A.; Gallimore, J. F.
In this paper, we explore the nature of the subarcsecond radio components in the Seyfert nucleus of NGC 1068. The southernmost component (S) is the most likely candidate for the location of the central engine. The integrated Spectrum of this component is flat, and the radio brightness temperatures are T_b_ <~ 3 x 10^5^ K. The radio emission is …
Obscuration of LY alpha Photons in Star-forming Galaxies
Giavalisco, Mauro; Calzetti, Daniela; Koratkar, Anuradha
We present a new study of the correlations between the Lyα emission, the UV extinction, and the metal content in a sample of 21 local, low-metallicity starburst galaxies from archival IUE spectra. We have consistently reextracted all the spectra using the optimal extraction algorithm by Kinney and coworkers, and we have also included galaxies not …
The Variability of Quasars. II. Frequency Dependence
Giallongo, E.; Trevese, D.; Vagnetti, F. +2 more
The variability of 30 PG quasars has been observed in the red band during 3 years. A rest-frame structure function analysis shows an increase of variability with the time interval up to 0.2 mag rms after 2 years. A comparison with the IUE data available for PG quasars shows that the variability increases with the rest-frame frequency at each time …
A Solar Polar North-South Asymmetry for Cosmic-Ray Propagation in the Heliosphere: The ULYSSES Pole-to-Pole Rapid Transit
Simpson, J. A.; Bame, S.; Zhang, Ming
The pole-to-pole fast transit of the heliosphere at ~2 AU from the Sun by the international Ulysses spacecraft has made it possible for the first time to investigate in three dimensions the solar wind, interplanetary magnetic field, and---as reported herein---the global propagation of Galactic cosmic rays and anomalous helium. We use measurements …
Hubble Space Telescope Spectroscopic Evidence for a 1 X 10 9 Msun Black Hole in NGC 4594
Gebhardt, Karl; Richstone, Douglas; Kormendy, John +7 more
The discovery by Kormendy of a M• ~= 109 Msolar massive dark object (MDO) in NGC 4594 is confirmed with higher resolution spectroscopy from the Canada-France-Hawaii Telescope (CFHT) and the Hubble Space Telescope (HST). CFHT measurements with the Subarcsecond Imaging Spectrograph improve the resolution from sigma * = 0."40 to 0."27 Gaussian disper…