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 $3.33 \times 10^{-10} {\rm ~erg ~cm^{-2} ~s^{-1}}$, over 30 times brighter than in quiescence. During the rising phase, the X-ray spectrum of PKS 2005-489 hardened considerably, reaching $\alpha = 1.32~ (F_\nu \propto \nu^{-\alpha})$ near maximum. During the declining phase, the X-ray spectrum steepened rapidly, reaching $\alpha = 1.82$, then became somewhat harder towards the end of December ($\alpha \sim 1.6$). 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 {\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

The Stage is Set: Final Act to Complete Village • Center to Broaden Ursinus Horizons • We Are Seniors • Student Orientation Series Addresses Alcohol • Crackdown on Fake I.D. Users • Letter: Maintenance Poo Poo\u27s Paisley Two • Bennett Joins Political Science Department • Hood Offers Enthusiasm • R.A.\u27s Welcome Robson to U.C. • College Seeks Diverse Students • Notes: Looking for STARs; Scholarships Offered • Odger\u27s Optimism Leads Bears Back on the Field • Bears Are Back • Cross Country Struts Their Stuff • Run for Heisman May be a Catch • VBall: Set Your Eyes on These Spikers • Comics Step Up to Sophistication • Young Fares a C+ with Life • Get the Jump on the Jobhttps://digitalcommons.ursinus.edu/grizzlynews/1191/thumbnail.jp

The Grizzly, November 9, 1987

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The Grizzly, September 25, 1987

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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