Search Publications
Theories of solar eruptions: a review
Lin, J.; Baliunas, S. L.; Soon, W.
This review highlights current theoretical research on eruptive phenomena in the solar atmosphere. We start by looking back upon the early theories and their development. Any theory and model of solar eruptions must explain two key aspects of eruption physics. The first aspect concerns the original cause of the eruption and the second pertains to …
Internal structure and dynamics of the kiloparsec-scale jet in M87
Lobanov, Andrei; Hardee, Philip; Eilek, Jean
Detailed analysis of HST and VLA observations enables quantitative modeling of the internal structure of the kiloparsec-scale jet in M87. The jet transverse profiles can be modeled by double-Gaussian profiles. The jet structure is dominated by two threads resembling closely a double helix visible until about 20″ distance. It is produced by a combi…
New detections of optical emission from kiloparsec-scale quasar jets
Cheung, C. C.; Wardle, J. F. C.; Chen, Tingdong +1 more
We report initial results from the detection of optical emission in the arcsecond-scale radio jets of two quasars utilizing images from the Hubble Space Telescope archive. The optical emission has a very knotty appearance and is consistent with synchrotron emission from highly relativistic electrons in the jet. Combining these observations with th…
Multiwavelength imaging of kpc-scale jets in AGN with Chandra and HST
Sambruna, Rita M.
I highlight recent developments from Chandra and HST observations of kpc-scale jets in AGN, with particular emphasis on our survey of 17 radio jets in a sample of FR II radio galaxies. These observations show that: (1) X-ray and optical emission is common from kpc-scale jets, (2) a large fraction of the bolometric luminosity is emitted at X-rays, …
The downward X-ray spectrum of PKS 2155-304 in the inner jet description
Ciprini, Stefano
The compact radio source PKS 2155-304 ( z=0.116) is a gamma-ray blazar and one of the brightest in UV and X-ray bands, repeatedly monitored at X-ray frequencies in the past years, and observed recently by Chandra and XMM-Newton. Various intensity states and a continuously downward-curved trend with the energy is displayed clearly, summarizing some…
XMM-Newton observations of absorption features towards PKS 2155-304
Maraschi, L.; Tavecchio, F.; Treves, A. +2 more
We present XMM-Newton grating spectra of the bright BL Lac object PKS 2155-304 taken in November 2000. Various absorption features are detected in the range 5-38 Å. The results are compared with those recently obtained with Chandra gratings [ApJ 573 (2002) 157; Nature, 421 (2003) 719]. We discuss whether the absorption occurs at the source (in the…
6C radio galaxies at z∼1: the influence of radio power on the alignment effect
Best, Philip N.; Inskip, Katherine J.; Longair, Malcolm S.
Powerful radio galaxies often display enhanced optical/UV continuum emission and extended emission line regions, elongated and aligned with the radio jet axis. The expansion of the radio source strongly affects the gas clouds in the surrounding IGM, and the kinematic and ionization properties of the extended emission line regions display considera…
Quasar hosts: differences between radio-loud and radio-quiet galaxies
Kukula, Marek J.
Strong evidence exists that radio-loud quasars and FR II radio galaxies differ only in the orientation of their central AGN, and HST studies of quasar hosts have confirmed that there are no significant differences between radio galaxies and the massive elliptical galaxies which host RLQs. Detailed studies of radio-quiet quasars show that these pow…
Radio galaxy host properties spanning three dex in radio luminosity
Willott, Chris J.; Rawlings, Steve; Jarvis, Matt J. +4 more
We describe a major study of radio source host galaxies being carried out with the HST and ground-based facilities. Our sample is selected from 4 complete samples with different radio flux-density limits, giving a range of three orders of magnitude in radio luminosity at a fixed epoch ( z=0.5). High-resolution HST WFPC2 imaging shows that all 44 r…
Temporal variability of Mrk 421 from XMM-Newton observations
Haberl, F.; Papadakis, I.; Brinkmann, W. +1 more
Mrk 421 has been observed several times as a calibration target for the instruments on board XMM-Newton. We have studied in some detail the temporal and spectral variability of the source during eight pointings, mainly from the PN camera, which provides the by far highest S/N data available for that source.