Jeremy J. Drake

Publications (2)6.02 Total impact

• Article: Probing the Local Group Medium toward Markarian 421 with Chandra and the Far Ultraviolet Spectroscopic Explorer

  Rik J. Williams, Smita Mathur, Fabrizio Nicastro, Martin Elvis, Jeremy J. Drake, Taotao Fang, Fabrizio Fiore, Yair Krongold, Q. Daniel Wang, and Yangsen Yao
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  ABSTRACT: We report the detection of highly ionized gas at z ~ 0 seen in resonant UV and X-ray absorption lines toward the z = 0.03 blazar Mrk 421. A total of 13 X-ray and three UV lines were measured (or upper limits derived), including three lines in the O VII K series and Kα transitions from neon, carbon, and nitrogen. From the three O VII lines we derive a 2 σ Doppler parameter constraint of 24 km s-1 < b < 55 km s-1. The FUSE spectrum shows strong Galactic low-velocity O VI λ1032 absorption and a possible weak O VI high-velocity component (HVC). The Doppler parameter of the low-velocity O VI measured with FUSE is ~3 σ higher than that derived from the O VII line ratios, indicating that the O VII and Galactic O VI arise in different phases. This velocity dispersion along with limits on the gas temperature and density from the X-ray line ratios (assuming a single phase with collisional ionization equilibrium plus photoionization) are all consistent with an extragalactic absorber. However, the O VII Doppler parameter is inconsistent with the high temperature required to produce the observed O VIHVC/O VII ratio, implying that the HVC is probably not related to the O VII. In addition, the O VIKα line detected by Chandra implies a column density ~4 times higher than the λ1032 absorption. Although an extragalactic absorber is fully consistent with the measured column density ratios, a Galactic origin cannot be ruled out given the uncertainties in the available data.
  The Astrophysical Journal 12/2008; 631(2):856. · 6.02 Impact Factor
• Source

  Available from: arxiv.org

  Article: Probing the Local Group Medium Toward Mkn 421 with Chandra and FUSE

  Rik J. Williams, Smita Mathur, Fabrizio Nicastro, Martin Elvis, Jeremy J. Drake, Taotao Fang, Fabrizio Fiore, Yair Krongold, Q. Daniel Wang, Yangsen Yao
  [show abstract] [hide abstract]
  ABSTRACT: We report the detection of highly-ionized gas at z~0 seen in resonant UV and X-ray absorption lines toward the z=0.03 blazar Mkn 421. A total of 13 X-ray and 3 UV lines were measured (or upper limits derived), including three lines in the OVII K-series and K\alpha transitions from neon, carbon, and nitrogen. From the three OVII lines we derive a 2\sigma Doppler parameter constraint of 24<b<55 km/s. The FUSE spectrum shows strong Galactic low--velocity OVI 1032A absorption as well as a possible weak OVI high-velocity component (HVC). The Doppler parameter of the low-velocity OVI measured with FUSE is ~3\sigma higher than that derived from the OVII line ratios, indicating that the OVII and Galactic OVI arise in different phases. This velocity dispersion, along with limits on the gas temperature and density from the X-ray line ratios (assuming a single phase with collisional ionization equilibrium plus photoionization) are all consistent with an extragalactic absorber. However, the OVII Doppler parameter is inconsistent with the high temperature required to produce the observed OVI_HVC/OVII ratio, implying that the HVC is probably not related to the OVII. In addition, the OVI_K\alpha line detected by Chandra implies a column density ~4 times higher than the 1032A absorption. Although an extragalactic absorber is fully consistent with the measured column density ratios, a Galactic origin cannot be ruled out given the uncertainties in the available data. Comment: 31 pages including 8 figures, 1 table. Figures 6-8 corrected and pertinent discussions updated. Accepted to ApJ, 10 September 2005 issue
  04/2005;