%0 Generic %1 nicastro2012chandra %A Nicastro, F. %A Elvis, M. %A Krongold, Y. %A Mathur, S. %A Gupta, A. %A Danforth, C. %A Barcons, X. %A Borgani, S. %A Branchini, E. %A Cen, R. %A Davé, R. %A Kaastra, J. %A Paerels, F. %A Piro, L. %A Shull, J. M. %A Takei, Y. %A Zappacosta, L. %D 2012 %K absorption chandra hot igm warm %T Chandra View of the Warm-Hot IGM toward 1ES 1553+113: Absorption Line Detections and Identifications (Paper I) %U http://arxiv.org/abs/1210.7177 %X About 30-40 percent of the expected number of baryons is still missing in the local Universe (z 0.4). They are predicted to be hiding in a web of intergalactic gas at temperatures of about 10^5-10^7 K (the WHIM). Detecting this matter has had limited success so far, because of its low-density and high temperature, which makes it difficult to detect with current far-ultraviolet and X-ray instrumentation. Here we present the first results from our pilot 500 ks Chandra-LETG observation of the soft X-ray brightest source in the z > 0.4 sky, the blazar 1ES 1553+113. We identify a total of 11 possible absorption lines, with single-line statistical significances between 2.2-4.1 sigma. Six of these lines are detected at high significance (3.6 < < 4.1), while the remaining five are regarded as marginal detections in association with either other X-ray lines detected at higher significance and/or FUV signposts. Three of these lines are consistent with metal absorption at z~0. The remaining 8 lines may be imprinted by intervening absorbers and are all consistent with being high-ionization counterparts of FUV HI and/or OVI IGM signposts. In particular, four of these eight absorption lines (4.1\sigma, 4.1\sigma, 3.8and 2.7\sigma), are identified as CV and CVI absorbers belonging to two WHIM systems at z_X = 0.312 and z_X = 0.133, which also produce broad HI and OVI absorption in the FUV. The true statistical significances of these two X-ray absorption systems, after properly accounting for the number of redshift trials, are 5.8and 3.8\sigma.

@misc{nicastro2012chandra, abstract = {About 30-40 percent of the expected number of baryons is still missing in the local Universe (z \lesssim 0.4). They are predicted to be hiding in a web of intergalactic gas at temperatures of about 10^5-10^7 K (the WHIM). Detecting this matter has had limited success so far, because of its low-density and high temperature, which makes it difficult to detect with current far-ultraviolet and X-ray instrumentation. Here we present the first results from our pilot 500 ks Chandra-LETG observation of the soft X-ray brightest source in the z > 0.4 sky, the blazar 1ES 1553+113. We identify a total of 11 possible absorption lines, with single-line statistical significances between 2.2-4.1 sigma. Six of these lines are detected at high significance (3.6 < \sigma < 4.1), while the remaining five are regarded as marginal detections in association with either other X-ray lines detected at higher significance and/or FUV signposts. Three of these lines are consistent with metal absorption at z~0. The remaining 8 lines may be imprinted by intervening absorbers and are all consistent with being high-ionization counterparts of FUV HI and/or OVI IGM signposts. In particular, four of these eight absorption lines (4.1\sigma, 4.1\sigma, 3.8\sigma and 2.7\sigma), are identified as CV and CVI absorbers belonging to two WHIM systems at z_X = 0.312 and z_X = 0.133, which also produce broad HI and OVI absorption in the FUV. The true statistical significances of these two X-ray absorption systems, after properly accounting for the number of redshift trials, are 5.8\sigma and 3.8\sigma.}, added-at = {2012-10-29T15:23:34.000+0100}, author = {Nicastro, F. and Elvis, M. and Krongold, Y. and Mathur, S. and Gupta, A. and Danforth, C. and Barcons, X. and Borgani, S. and Branchini, E. and Cen, R. and Davé, R. and Kaastra, J. and Paerels, F. and Piro, L. and Shull, J. M. and Takei, Y. and Zappacosta, L.}, biburl = {https://www.bibsonomy.org/bibtex/210ef9b5ee8631e55ce0858ae3e1d07e3/miki}, description = {[1210.7177] Chandra View of the Warm-Hot IGM toward 1ES 1553+113: Absorption Line Detections and Identifications (Paper I)}, interhash = {fb5e75d9f64a0e5ad54148233fa5bb06}, intrahash = {10ef9b5ee8631e55ce0858ae3e1d07e3}, keywords = {absorption chandra hot igm warm}, note = {cite arxiv:1210.7177Comment: 26 pages, 3 figures, Submitted to the ApJ. Comments welcome}, timestamp = {2012-10-29T15:23:35.000+0100}, title = {Chandra View of the Warm-Hot IGM toward 1ES 1553+113: Absorption Line Detections and Identifications (Paper I)}, url = {http://arxiv.org/abs/1210.7177}, year = 2012 }