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Description
Utilizing ASCA archival data of about 300 objects - elliptical galaxies, groups, and clusters of galaxies - the authors performed systematic measurements of the X-ray properties of hot gas in their systems, and compiled them in this study. The steepness (power-law slope) of the luminosity-temperature (L-T) relation, L<sub>X</sub> ~ kT<sup>alpha</sup>, in the range of kT ~ 1.5 - 15 keV is alpha = 3.17 +/- 0.15, consistent with previous measurements. In the relation, the authors find two breaks at around intracluster medium (ICM) temperatures of 1 keV and 4 keV: alpha = 2.34 +/- 0.29 above 4 keV, 3.74 +/- 0.32 in the 1.5 to 5 keV range, and 4.03 +/- 1.07 below 1.5 keV. Two such breaks are also evident in the temperature and size relation. The steepness in the L-T relation at kT > 4 keV is consistent with the scale-relation derived from the CDM model, indicating that the gravitational effect is dominant in richer clusters, while poorer clusters suffer non-gravity effects. The steep L-T relation below 1 keV is mostly attributed to X-ray faint systems of elliptical galaxies and galaxy groups. The authors find that the ICM mass within the scaling radius R<sub>1500</sub> (the radius within which the averaged mass density is 1500 times higher than the critical density) follows the relation of M<sub>gas</sub> ~ T<sup>(2.33+/-0.07)</sup> from X-ray faint galaxies to rich clusters. Thus, the authors speculate that even such X-ray faint systems contain large-scale hot gas, which is too faint to detect. For this project, the authors utilized all of the ASCA data of elliptical galaxies and clusters of galaxies. Several clusters were observed more than once, and they chose the observation with the longest exposure. The total number of objects that the authors identified as elliptical galaxies and clusters was 313, and these are listed in this table. Some of the objects could not be utilized for deriving various correlations, due to either having an unknown redshift (17 objects), an insignificant detection (13 objects listed below), or contamination of the environmental X-ray emission, such as cluster emission around non-cD elliptical galaxies (10 objects: NGC 4472, NGC 4406, NGC 4374, NGC 1404, NGC 499, NGC 6034, NGC 2865, NGC 4291, CL 2236-04 and RX J1031.6-2607). Thus, the authors analyzed the ASCA data for 292 objects, among which were ~ 50 elliptical galaxies and galaxy groups. In this study, the authors assumed the Hubble constant to be 50 h<sub>50</sub> km s<sup>-1</sup> Mpc<sup>-1</sup> and q<sub>0</sub> to be 0. Table 1 of the reference paper (reproduced below) lists the 13 clusters for which only 90% confidence level upper limits to the flux in the observer's frame are available: <pre> Name Flux (0.5 - 2 keV) Upper Limit (erg/s/cm<sup>2</sup>) NGC 5018 9.8 x 10<sup>14</sup> GHO 1322+3114 1.3 x 10<sup>13</sup> J1888.16CL 5.9 x 10<sup>14</sup> CL 0317+1521 4.5 x 10<sup>14</sup> MS 1512.4+3647 1.0 x 10<sup>12</sup> PRG 38 6.9 x 10<sup>14</sup> SCGG 205 6.9 x 10<sup>14</sup> RGH 101 9.1 x 10<sup>14</sup> 3C 184 8.5 x 10<sup>14</sup> RX J1756.5+6512 1.6 x 10<sup>13</sup> 3C 324 5.4 x 10<sup>14</sup> PDCS 01 2.8 x 10<sup>14</sup> MS 0147.8-3941 5.0 x 10<sup>14</sup> </pre> This table was created by the HEASARC in December 2011 based on CDA Catalog J/PASJ/56/965 files table3.dat, table4.dat, table5.dat, table6.dat and table7.dat. This is a service provided by NASA HEASARC .
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