T. M. Tripp

Publications (4)0 Total impact

• Source

  Available from: ArXiv

  Article: The Dearth of Chemically Enriched Warm-Hot Circumgalactic Gas

  Y Yao, Q. D. Wang, S. V. Penton, T. M. Tripp, J. M. Shull, J. T. Stocke
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  ABSTRACT: The circumgalactic medium (CGM) around galaxies is believed to record various forms of galaxy feedback and contain a significant portion of the "missing baryons" of individual dark matter halos. However, clear observational evidence for the existence of the hot CGM is still absent. We use intervening galaxies along 12 background AGNs as tracers to search for X-ray absorption lines produced in the corresponding CGM. Stacking Chandra grating observations with respect to galaxy groups and different luminosities of these intervening galaxies, we obtain spectra with signal-to-noise ratios of 46-72 per 20-mA spectral bin at the expected OVII Kalpha line. We find no detectable absorption lines of CVI, NVII, OVII, OVIII, or NeIX. The high spectral quality allows us to tightly constrain upper limits to the corresponding ionic column densities (in particular log[N(OVII)(cm^{-2})]<=14.2--14.8). These nondetections are inconsistent with the Local Group hypothesis of the X-ray absorption lines at z~0 commonly observed in the spectra of AGNs. These results indicate that the putative CGM in the temperature range of 10^{5.5}-10^{6.3} K may not be able to account for the missing baryons unless the metallicity is less than 10% solar. Comment: 10 pages, 7 figures, and 5 tables. Accepted for publication in the ApJ, June 2010 - 20 v716 issue.
  05/2010;
• Source

  Available from: Claude R. Canizares

  Article: X-raying the Intergalactic OVI Absorbers

  Y Yao, T. M. Tripp, Q. D. Wang, C. W. Danforth, C. R. Canizares, J. M. Shull, H. L. Marshall, L. Song
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  ABSTRACT: The observed intergalactic OVI absorbers at z>0 have been regarded as a significant reservoir of the ``missing baryons''. However, to fully understand how these absorbers contribute to the baryon inventory, it is crucial to determine whether the systems are collisionally ionized or photoionized (or both). Using the identified intergalactic OVI absorbers as tracers, we search for the corresponding X-ray absorption lines, which are useful for finding the missing baryons and for revealing the nature of the OVI absorbers. Stacking the Chandra grating spectra along six AGN sight lines, we obtain three spectra with signal-to-noise ratios of 32, 28, and 10 per 12.5 mA spectral bin around the expected OVII Kalpha wavelength. These spectra correspond to OVI absorbers with various dynamic properties. We find no detectable NeIX, OVII, OVIII, NVII, or CVI absorption lines in the spectra, but the high counting statistics allows us to obtain firm upper limits on the corresponding ionic column densities (in particular N(OVII)<=10 N(OVI) on average at the 95% confidence level). Jointly analyzing these non-detected X-ray lines with the averaged OVI column density, we further limit the average temperature of the OVI-bearing gas to be log[T(K)]<=5.7 in collisional ionization equilibrium. We discuss the implications of these results for physical properties of the putative warm-hot intergalactic medium and its detection in future X-ray observations.
  12/2008;
• Source

  Available from: arxiv.org

  Article: Warm-Hot Gas in and around the Milky Way: Detection and Implications of OVII Absorption toward LMC X-3

  Q. D. Wang, Y Yao, T. M. Tripp, T. -T. Fang, W. Cui, F. Nicastro, S. Mathur, R. J. Williams, L. Song, R. Croft
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  ABSTRACT: X-ray absorption lines of highly-ionized species such as OVII at about zero redshift have been firmly detected in the spectra of several active galactic nuclei. However, the location of the absorbing gas remains a subject of debate. To separate the Galactic and extragalactic contributions to the absorption, we have obtained Chandra LETG-HRC and FUSE observations of the black hole X-ray binary LMC X--3. A joint analysis of the detected OVII and Ne IX Kalpha lines, together with the non-detection of the OVII Kbeta and OVIII Kalpha lines, gives the measurements of the temperature, velocity dispersion, and hot oxygen column density. The X-ray data also allow us to place a 95% confidence lower limit to the Ne/O ratio as 0.14. The OVII line centroid and its relative shift from the Galactic OI Kalpha absorption line, detected in the same observations, are inconsistent with the systemic velocity of LMC X--3 ($+310 {\rm km s^{-1}}$). The far-UV spectrum shows OVI absorption at Galactic velocities, but no OVI absorption is detected at the LMC velocity at $> 3\sigma$ significance. Both the nonthermal broadening and the decreasing scale height with the increasing ionization state further suggest an origin of the highly-ionized gas in a supernova-driven galactic fountain. In addition, we estimate the warm and hot electron column densities from our detected OVII Kalpha line in the LMC X--3 X-ray spectra and from the dispersion measure of a pulsar in the LMC vicinity. We then infer the O/H ratio of the gas to be $\gtrsim 8 \times 10^{-5}$, consistent with the chemically-enriched galactic fountain scenario. We conclude that the Galactic hot interstellar medium should in general substantially contribute to zero-redshift X-ray absorption lines in extragalactic sources. Comment: 11 pages, accepted for publication in ApJ
  08/2005;
• Article: X-RAYING THE INTERGALACTIC O VI ABSORBERS

  Y Yao, T. M. Tripp, Q. D. Wang, C. W. Danforth, Claude R. Canizares, J. M. Shull, Herman Lee Marshall, L. Song
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  ABSTRACT: The observed intergalactic O vi absorbers at z > 0 have been regarded as a significant reservoir of the “missing baryons.” However, to fully understand how these absorbers contribute to the baryon inventory, it is crucial to determine whether the systems are collisionally ionized or photoionized (or both). Using the identified intergalactic Ovi absorbers as tracers, we search for the corresponding X-ray absorption lines, which are useful for finding the missing baryons and for revealing the nature of the O vi absorbers. Stacking the Chandra grating spectra along six AGN sight lines, we obtain three spectra with signal-to-noise ratios of 32, 28, and 10 per 12.5 mÅ spectral bin around the expected O vii Kα wavelength. These spectra correspond to O vi absorbers with various dynamic properties. We find no detectable Ne ix, O vii, O viii, N vii, or C vi absorption lines in the spectra, but the high counting statistics allows us to obtain firm upper limits on the corresponding ionic column densities (in particular NO vii < 10N [subscript Ovi] on average at the 95% confidence level). Jointly analyzing these nondetected Xray lines with the averaged O vi column density, we further limit the average temperature of the Ovi-bearing gas to be T < 10 [superscript 5.7] K in collisional ionization equilibrium. We discuss the implications of these results for physical properties of the putative warm–hot intergalactic medium and its detection in future X-ray observations. Smithsonian Astrophysical Observatory NASA Chandra
  Claude Canizares via Gail Monahan.