Biological studies on some coprophilous sphaeroceridae (borboridae, diptera)

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A Large Mass of H2 in the Brightest Cluster Galaxy in Zwicky 3146

We present the Spitzer/IRS mid-infrared spectrum of the infrared-luminous (L_{IR}=4e11 L_sun) brightest cluster galaxy (BCG) in the X-ray-luminous cluster Z3146 (z=0.29). The spectrum shows strong aromatic emission features, indicating that the dominant source of the infrared luminosity is star formation. The most striking feature of the spectrum, however, is the exceptionally strong molecular hydrogen (H2) emission lines, which seem to be shock-excited. The line luminosities and inferred warm H2 gas mass (~1e10 M_sun) are 6 times larger than those of NGC 6240, the most H2-luminous galaxy at z <~ 0.1. Together with the large amount of cold H2 detected previously (~1e11 M_sun), this indicates that the Z3146 BCG contains disproportionately large amounts of both warm and cold H2 gas for its infrared luminosity, which may be related to the intracluster gas cooling process in the cluster core.Comment: 13 pages, 3 figures, 1 table; Accepted for publication in ApJ

The First Detailed X-ray Observations of High-Redshift, Optically-Selected Clusters: XMM-Newton Results for Cl 1324+3011 at z = 0.76 and Cl 1604+4304 at z = 0.90

We present the first detailed X-ray observations of optically-selected clusters at high redshift. Two clusters, Cl 1324+3011 at z = 0.76 and Cl 1604+4304 at z = 0.90, were observed with XMM-Newton. The optical center of each cluster is coincident with an extended X-ray source whose emission is detected out to a radius of 0.5 Mpc. The emission from each cluster appears reasonably circular, with some indication of asymmetries and more complex morphologies. Similarly to other optically-selected clusters at redshifts of z > 0.4, both clusters are modest X-ray emitters with bolometric luminosities of only Lx = 1.4 - 2.0 x 10^(44) erg/s. We measure gas temperatures of T = 2.88 (+0.71/-0.49) keV for Cl 1324+3011 and 2.51 (+1.05/-0.69) keV for Cl 1604+4304. The X-ray properties of both clusters are consistent with the high-redshift Lx-T relation measured from X-ray-selected samples at z > 0.5. However, based on the local relations, their X-ray luminosities and temperatures are low for their measured velocity dispersions (sigma). The clusters are cooler by a factor of 2 - 9 compared to the local sigma-T relation. We briefly discuss the possible explanations for these results.Comment: 14 pages, 4 figures; accepted for publication in Astrophysical Journal Letters; version with full resolution figures available at http://bubba.ucdavis.edu/~lubin/xmm.pd

X-ray Properties of the Abell 644 Cluster of Galaxies

We use new ASCA observations and archival ROSAT Position Sensitive Proportional Counter (PSPC) data to determine the X-ray spectral properties of the intracluster gas in Abell 644. From the overall spectrum, we determine the average gas temperature to be 8.64 (+0.67,-0.56) keV, and an abundance of 0.32 (+/-0.04) $Z_{\odot}$. The global ASCA and ROSAT spectra imply a cooling rate of 214 (+100,-91) $M_{\odot}$ yr$^{-1}$. The PSPC X-ray surface brightness profile and the ASCA data suggest a somewhat higher cooling rate. We determine the gravitational mass and gas mass as a function of radius. The total gravitating mass within 1.2 Mpc is $6.2\times10^{14}$ $M_{\odot}$, of which 20% is in the form of hot gas. There is a region of elevated temperature 1.5-5 arcmin to the west of the cluster center. The south-southwest region of the cluster also shows excess emission in the ROSAT PSPC X-ray image, aligned with the major axis of the optical cD galaxy in the center of the cluster. We argue that the cluster is undergoing or has recently undergone a minor merger. The combination of a fairly strong cooling flow and evidence for a merger make this cluster an interesting case to test the disruption of cooling flow in mergers.Comment: 26 pages LaTeX including 9 eps figures + 4 pages LaTeX tables (landscape); accepted to ApJ, uses aaspp

A Very Hot, High Redshift Cluster of Galaxies: More Trouble for Omega_0 = 1

We have observed the most distant (z=0.829) cluster of galaxies in the Einstein Extended Medium Sensitivity Survey, with the ASCA and ROSAT satellites. We find an X-ray temperature of 12.3 +3.1/-2.2 keV for this cluster, and the ROSAT map reveals significant substructure. The high temperature of MS1054-0321 is consistent with both its approximate velocity dispersion, based on the redshifts of 12 cluster members we have obtained at the Keck and the Canada-France-Hawaii telescopes, and with its weak lensing signature. The X-ray temperature of this cluster implies a virial mass ~ 7.4 x 10^14 h^-1 solar masses, if the mean matter density in the universe equals the critical value, or larger if Omega_0 < 1. Finding such a hot, massive cluster in the EMSS is extremely improbable if clusters grew from Gaussian perturbations in an Omega_0 = 1 universe. Combining the assumptions that Omega_0 = 1 and that the intial perturbations were Gaussian with the observed X-ray temperature function at low redshift, we show that the probability of this cluster occurring in the volume sampled by the EMSS is less than a few times 10^{-5}. Nor is MS1054-0321 the only hot cluster at high redshift; the only two other $z > 0.5$ EMSS clusters already observed with ASCA also have temperatures exceeding 8 keV. Assuming again that the initial perturbations were Gaussian and Omega_0 = 1, we find that each one is improbable at the < 10^{-2} level. These observations, along with the fact that these luminosities and temperatures of the high-$z$ clusters all agree with the low-z L_X-T_X relation, argue strongly that Omega_0 < 1. Otherwise, the initial perturbations must be non-Gaussian, if these clusters' temperatures do indeed reflect their gravitational potentials.Comment: 20 pages, 4 figures, To appear in 1 Aug 1998 ApJ (heavily revised version of original preprint

Particle acceleration in cooling flow clusters of galaxies: the case of Abell 2626

It has recently been proposed a theoretical model which accounts for the origin of radio mini-halos observed in some cooling flow clusters as related to electron re-acceleration by MHD turbulence (Gitti, Brunetti & Setti 2002). The MHD turbulence is assumed to be frozen into the flow of the thermal ICM and thus amplified in the cooling flow region. Here we present the application of this model to a new mini-halo candidate, the cluster A2626, and compare the results with those obtained for the mini-halo in the Perseus cluster. We present VLA data at 330 MHz and 1.5 GHz of the diffuse radio emission observed in A2626, and we show that its main properties can be explained by the model. We find that the power necessary for the re-acceleration of the relic electron population is only a factor ~ 0.7% of the maximum power that can be extracted by the cooling flow (as estimated on the basis of the standard model). We also discuss the observational properties of known mini-halos in connection with those of host clusters, showing that the radio power of mini--halos increases with the maximum power of cooling flows. This trend is expected in the framework of the model. Possible effects of new Chandra and XMM-Newton estimates of $\dot{M}$ on this trend are considered: we conclude that even if earlier derived cooling rates were overestimated, cooling flow powers are still well above the radio powers emitted by mini-halos.Comment: 12 pages, 11 figures, accepted for publication in Astronomy & Astrophysic