Search Publications
An HST emission-line imaging survey of 3CR radio galaxies
Sparks, W. B.; Macchetto, F.; McCarthy, P. J. +4 more
We present narrow-band images of sixty-four 3CR radio sources observed in lines of [OII] 3727 Å, [OIII] 5007 Å, and H α using the WFPC2 camera on-board HST. The images reveal a wide variety of emission lime morphologies, from compact nuclear regions to large-scale emission knots, filaments, and spiral-like structures. Many objects give evidence of…
Host galaxies and the unification of radio-loud AGN
Giavalisco, Mauro; Urry, C. Megan; O'Dowd, Matthew +4 more
Our HST WFPC2 survey of 110 BL Lac objects, from six complete X-ray-, radio-, and optically-selected catalogs, probes the host galaxies of low-luminosity radio sources in the redshift range 0< z<1.35. The host galaxies are luminous ellipticals, well matched in radio power and galaxy magnitude to FR I radio galaxies. Similarly, the host galax…
X-ray spectroscopy of supernova remnants
Ballet, Jean; Decourchelle, Anne
The new generation X-ray telescopes launched in 1999 ( Chandra and XMM-Newton) provide for the first time, good spatial and spectral resolution together, allowing to map emission lines of heavy elements in supernova remnants. In young supernova remnants this reflects nucleosynthesis in the progenitor, and gives access (in theory) to the absolute a…
HST imaging of nearby CSOs: obscuration and nuclear structures
Stocke, J. T.; Conway, J. E.; Reynolds, C. +2 more
We present 3-band HST imaging of three nearby ( z<0.1) compact symmetric objects: 4C31.04, 1946+708 and 1146+596 (NGC 3894). These objects were chosen for HST observation on the basis of detected HI and molecular line absorption. The images show large amounts of obscuration in each source, well distributed throughout the host galaxies, but some…
Interactions between the Abell 2597 central radio source and dense gas in its host galaxy
Koekemoer, Anton M.; Baum, Stefi A.; O'Dea, Christopher P. +5 more
We present a detailed HST/WFPC2 study of the complex network of emission-line filaments and blue continuum emission associated with the lobes of the radio source at the center of the nearby strong cooling-flow cluster Abell 2597. This object is a prototypical "blue-lobed" cluster radio galaxy. We discuss ways in which the radio source is interacti…
HST NICMOS and WFPC2 observations of molecular hydrogen and dust in the central galaxies in cluster cooling flows
Mack, Jennifer; Donahue, Megan
We present preliminary results of HST imaging observations of three central galaxies in X-ray luminous clusters of galaxies with putative major cooling flows in their cores: NGC 1275 in the Perseus cluster, Abell 2597, and PKS 0745-19. Narrow-band NICMOS imaging at 2 microns reveals extended, warm ( T∼2000-3000 K) molecular hydrogen structures in …
The synchrotron spectrum of the M87 jet
Leahy, J. P.; Macchetto, F. D.; Sparks, W. B. +2 more
We present 1998 HST observations which yield the first single-epoch spectrum of the M87 jet from 0.3 to 2.0 microns. The flattest optical spectra ( αo∼0.6, where F ν ∝ ν -α; comparable to αro) are found in two inner jet knots which contain the fastest superluminal components. Other knots have somewhat st…
Oxygen abundances derived in unevolved very metal-poor stars
Rebolo, R.; Bonifacio, P.; Molaro, P. +4 more
Oxygen abundances have been derived in a sample of very metal-poor stars from observations of the O I triplet at λλ 7771-5 Å and OH lines in the near UV. Iron abundances derived in LTE were corrected for NLTE effects following Thévenin and Idiart [ApJ 521 (1999) 753]. Furthermore, a detailed NLTE analysis of iron lines has been carried out for one…
Effects of massive star formation on the ISM of dwarf galaxies
Madden, Suzanne C.
We are studying star formation effects on the properties of the ISM in low metallicity environments using mid-infrared (MIR) and far-infrared (FIR) observations of starbursting dwarf galaxies taken with the Infrared Space Observatory (ISO) and the Kuiper Airborne Observatory (KAO). Effects of the hard pervasive radiation field on the gas and dust …
New insights into the narrow-line Seyfert 1 phenomenon
Mathur, Smita
I briefly review the X/UV absorber models and show that the observations of NLS1s are generally consistent with the models. The covering factor of absorbers in NLS1s is likely to be high and there is some evidence of super-solar metallicities. I argue that NLS1s may be active galaxies in the early stage of their evolution and as such, may be low l…