11 research outputs found
X-Ray Spectral Variability of PKS 2005-489 During the Spectacular November 1998 Flare
We report on monitoring of the BL Lac object PKS 2005-489 by the Rossi X-ray
Timing Explorer (RXTE) in October-December 1998. During these months, the
source underwent a spectacular flare; at its peak on November 10, its 2-10 keV
flux was , over 30 times
brighter than in quiescence. During the rising phase, the X-ray spectrum of PKS
2005-489 hardened considerably, reaching near maximum. During the declining phase, the X-ray spectrum
steepened rapidly, reaching , then became somewhat harder
towards the end of December (). While such behavior has been
seen before, the simplicity, magnitude and duration of this flare allowed us to
study it in great detail. We argue that this flare was caused by either the
injection of particles into the jet or {\it in situ} particle acceleration, and
that the spectral steepening which followed the flare maximum was the result of
synchrotron cooling. Contrary to other recently observed blazar flares (e.g.,
Mkn 501, 3C 279, PKS 2155-304), our results do not imply a major shift in the
location of the synchrotron peak during this flare.Comment: ApJ Letters in press, 6 pages, 2 figures Corrected reference
The Apparent Host Galaxy of PKS 1413+135: HST, ASCA and VLBA Observations
PKS 1413+135 (z=0.24671) is one of very few radio-loud AGN with an apparent
spiral host galaxy. Previous authors have attributed its nearly exponential
infrared cutoff to heavy absorption but have been unable to place tight limits
on the absorber or its location in the optical galaxy. In addition, doubts
remain about the relationship of the AGN to the optical galaxy given the
observed lack of re-emitted radiation. We present new HST, ASCA and VLBA
observations which throw significant new light on these issues. The HST
observations reveal an extrremely red color (V-H = 6.9 mag) for the active
nucleus of PKS 1413+135, requiring both a spectral turnover at a few microns
due to synchrotron aging and a GMC-sized absorber. We derive an intrinsic
column N_H = 4.6^{+2.1}_{-1.6} times 10^{22}cm^{-2} and covering fraction f =
0.12^{+0.07}_{-0.05}. As the GMC is likely in the disk of the optical galaxy,
our sightline is rather unlikely (P ~ 2 times 10^{-4}). The properties of the
GMC typical of GMCs in our own galaxy. The HI absorber appears centered 25
milliarcseconds away from the nucleus, while the X-ray and nearly all of the
molecular absorbers must cover the nucleus, implying a complicated geometry and
cloud structure, with a molecular core along our line of sight to the nucleus.
Interestingly, the HST/NICMOS data require the AGN to be decentered relative to
the optical galaxy by 13 +/- 4 milliarcseconds. This could be interpreted as
suggestive of an AGN location far in the background compared to the optical
galaxy, but it can also be explained by obscuration and/or nuclear structure,
which is more consistent with the observed lack of multiple images.Comment: 27 pages, 8 figures; accepted to A
The Grizzly, October 9, 1987
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The Grizzly, September 11, 1987
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The Grizzly, November 9, 1987
proTheatre Perfects Production • Balloon Bombings Banned • Norman Pearlstine Addresses Problems Associated with the U.S. Free Press • Letters: Beautifying Campus?; In One Ear, Out the Other • Rolling Stone Celebrates 20th Year • Iran Source of Conflict in Dialogue Discussion • Calix Relates Salvadorian Horrors • Notes: Room Policy Changed; Apartheid Subject of Forum; Discussion Includes Pretzels!; Myths to be Explained • Ursinus Not Affected by Stock Market Crash: Others Not as Lucky • Pray TV Damages Churches • UC Robs Team of Championship • Error Prone Bears Drop Another • Early Bowl Picture Thickens • Bears Battle Tough Season • Ursinus \u27Mers Open Season • Bear Pack Finishes Strong • Tri Lambda: Organization for Life Long Learners • Musser: The Year After • Get in The Real World Get the Grizzly Network • Busie Bodys Display Fancy Bodies • Welcome to the Greek Life: Congratulations 1987 Pledges • Phonathons Prove Successful: $30,000 Raised • Student Applauds Washington Semester • Seniors: Where Are You? • November Red and Gold Days • Eshbach Awards Winners • CAB Learns New Ideas • New Equipment Upgrades Dept.https://digitalcommons.ursinus.edu/grizzlynews/1198/thumbnail.jp
The Grizzly, September 25, 1987
Wild Weekend: Tippler Topples, Vandals Varnish, Class Cutters Cavort • Sororities to Begin Formal Rushing Season • Freshmen Find Fun on Campus • Letters: Unholy Parent\u27s Day Irks Jews; Old Men\u27s Life Bad News; Students Have Bills to Pay, Too • Freshman AIDS Orientation • Domestic Violence an Issue • Cameron a Pro Habla-ing • House Bill 749 • Victorious Volleyballers • Soccer\u27s Hoover Earns Athlete of the Week • Football Falls to F&M • Scabs to Score for NFL? • Cross Country Running to the Top • Hockey Lashes LaSalle • Busie Bodys Rehearse • Lantern Announces Deadline • All Greeks Not Geeks • Nautical Natives Sailing with Club Revival • Fat Fear: Freshman Fifteen Thickens Frosh • Ills a Problem Already • E-burg Offers Basic Grub • It\u27s Your Future • CAB Gets Some Public Relations • As Members Drop, the Show Must Go On • Entertainment: Ursinus Stylehttps://digitalcommons.ursinus.edu/grizzlynews/1193/thumbnail.jp
Preprint typeset using L ATEX style emulateapj v. 04/03/99 X–RAY SPECTRAL VARIABILITY OF PKS 2005-489 DURING THE SPECTACULAR
We report on monitoring of the BL Lac object PKS 2005−489 by the Rossi X–ray Timing Explorer (RXTE) in October-December 1998. During these months, the source underwent a spectacular flare; at its peak on November 10, its 2−10 keV flux was 3.33 × 10 −10 erg cm −2 s −1, over 30 times brighter than in quiescence. During the rising phase, the X–ray spectrum of PKS 2005−489 hardened considerably, reaching α = 1.32 (Fν ∝ ν −α) near maximum. During the declining phase, the X–ray spectrum steepened rapidly, reaching α = 1.82, then became somewhat harder towards the end of December (α ∼ 1.6). While such behavior has been seen before, the simplicity, magnitude and duration of this flare allowed us to study it in great detail. We argue that this flare was caused by either the injection of particles into the jet or in situ particle acceleration, and that the spectral steepening which followed the flare maximum was the result of synchrotron cooling. Contrary to other recently observed blazar flares (e.g., Mkn 501, 3C 279, PKS 2155-304), our results do not imply a major shift in the location of the synchrotron peak during this flare