Communications technology satellite output-tube design and development

The design and development of a 200-watt-output, traveling-wave tube (TWT) for the Communications Technology Satellite (CTS) is discussed, with emphasis on the design evolution during the manufacturing phase of the development program. Possible further improvements to the tube design are identified

Response to Crocetti et al.

No abstract available

Images, structural properties and metal abundances of galaxy clusters observed with Chandra ACIS-I at 0.1<z<1.3

We have assembled a sample of 115 galaxy clusters at 0.1<z<1.3 with archived Chandra ACIS-I observations. We present X-ray images of the clusters and make available region files containing contours of the smoothed X-ray emission. The structural properties of the clusters were investigated and we found a significant absence of relaxed clusters (as determined by centroid shift measurements) at z>0.5. The slope of the surface brightness profiles at large radii were steeper on average by 15% than the slope obtained by fitting a simple beta-model to the emission. This slope was also found to be correlated with cluster temperature, with some indication that the correlation is weaker for the clusters at z>0.5. We measured the mean metal abundance of the cluster gas as a function of redshift and found significant evolution, with the abundances dropping by 50% between z=0.1 and z~1. This evolution was still present (although less significant) when the cluster cores were excluded from the abundance measurements, indicating that the evolution is not solely due to the disappearance of relaxed, cool core clusters (which are known to have enhanced core metal abundances) from the population at z>0.5.Comment: 23 pages, 12 figures. Accepted for publication in ApJS. Updated to match published version. Redshifts of two clusters (RXJ1701 and CL0848) corrected and two observations of MACSJ0744.8 have been combined into one. Conclusions unchanged. A version with images of all of the clusters is available at http://hea-www.harvard.edu/~bmaughan/clusters.htm

The survival and destruction of X-ray coronae of early-type galaxies in the rich cluster environments: a case study of Abell 1367

A new Chandra observation of the northwest region of the galaxy cluster A1367 reveals four cool galaxy coronae (0.4 - 1.0 keV) embedded in the hot intracluster medium (ICM) (5 - 6 keV). While the large coronae of NGC 3842 and NGC 3837 appear symmetric and relaxed, the galaxy coronae of the \lsim L* galaxies (NGC 3841 and CGCG 97090) are disturbed and being stripped. Massive galaxies, with dense cooling cores, are better able to resist ram pressure stripping and survive in rich environments than \lsim L* galaxies whose galactic coronae are much less dense. The survival of these cool coronae implies that thermal conduction from the hot surrounding ICM has to be suppressed by a factor of at least 60, at the corona boundary. Within the galaxy coronae of NGC 3842 and NGC 3837, stellar mass loss or heat conduction with the Spitzer value may be sufficient to balance radiative cooling. Energy deposition at the ends of collimated jets may heat the outer coronae, but allow the survival of a small, dense gas core (e.g., NGC 3842 in A1367 and NGC 4874 in Coma). The survived X-ray coronae become significantly smaller and fainter with the increasing ambient pressure.Comment: 11 pages, 7 figures, emulateapj5, accepted by Ap

ROSAT PSPC Observations of the Richest (R≥2R \geq 2) ACO Clusters

We have compiled an X-ray catalog of optically selected rich clusters of galaxies observed by the PSPC during the pointed GO phase of the ROSAT mission. This paper contains a systematic X-ray analysis of 150 clusters with an optical richness classification of $R \geq 2$ from the ACO catalog (Abell, Corwin, and Olowin 1989). All clusters were observed within 45' of the optical axis of the telescope during pointed PSPC observations. For each cluster, we calculate: the net 0.5-2.0 keV PSPC count rate (or $4 \sigma$ upper limit) in a 1 Mpc radius aperture, 0.5-2.0 keV flux and luminosity, bolometric luminosity, and X-ray centroid. The cluster sample is then used to examine correlations between the X-ray and optical properties of clusters, derive the X-ray luminosity function of clusters with different optical classifications, and obtain a quantitative estimate of contamination (i.e, the fraction of clusters with an optical richness significantly overestimated due to interloping galaxies) in the ACO catalog

Study of diode-iris controlled waveguide slot radiators

Diode-iris controlled waveguide slot radiator

The ALMA Discovery of the Rotating Disk and Fast Outflow of Cold Molecular Gas in NGC 1275

We present ALMA Band 6 observations of the CO(2-1), HCN(3-2), and HCO$^{+}$(3-2) lines in the nearby radio galaxy / brightest cluster galaxy (BCG) of NGC 1275 with the spatial resolution of $\sim20$ pc. In the previous observations, CO(2-1) emission was detected as radial filaments lying in the east-west direction. We resolved the inner filament and found that the filament cannot be represented by a simple infalling stream both morphologically and kinematically. The observed complex nature of the filament resembles the cold gas structure predicted by recent numerical simulations of cold chaotic accretion. A crude estimate suggests that the accretion rate of the cold gas can be higher than that of hot gas. Within the central 100 pc, we detected a rotational disk of the molecular gas whose mass is \sim10^{8} M_{\sun}. This is the first evidence of the presence of massive cold gas disk on this spatial scale for BCGs. The disk rotation axis is approximately consistent with the axis of the radio jet on subpc scales. This probably suggests that the cold gas disk is physically connected to the innermost accretion disk which is responsible for jet launching. We also detected absorption features in the HCN(3-2) and HCO$^{+}$(3-2) spectra against the radio continuum emission mostly radiated by $\sim1.2$-pc size jet. The absorption features are blue-shifted from the systemic velocity by $\sim$300-600~km~s$^{-1}$, which suggests the presence of outflowing gas from the active galactic nucleus (AGN). We discuss the relation of the AGN feeding with cold accretion, the origin of blue-shifted absorption, and estimate of black hole mass using the molecular gas dynamics.Comment: Version 2 (accepted version). 18 pages, 16 figures. Accepted for publication in Ap

X-ray total mass estimate for the nearby relaxed cluster A3571

We constrain the total mass distribution in the cluster A3571, combining spatially resolved ASCA temperature data with ROSAT imaging data with the assumption that the cluster is in hydrostatic equilibrium. The total mass within r_500 (1.7/h_50 Mpc) is M_500 = 7.8[+1.4,-2.2] 10^14/ h_50 Msun at 90% confidence, 1.1 times smaller than the isothermal estimate. The Navarro, Frenk & White ``universal profile'' is a good description of the dark matter density distribution in A3571. The gas density profile is shallower than the dark matter profile, scaling as r^{-2.1} at large radii, leading to a monotonically increasing gas mass fraction with radius. Within r_500 the gas mass fraction reaches a value of f_gas = 0.19[+0.06,-0.03] h_50^{-3/2} (90% confidence errors). Assuming that this value of f_gas is a lower limit for the the universal value of the baryon fraction, we estimate the 90% confidence upper limit of the cosmological matter density to be Omega_m < 0.4.Comment: 10 pages, 4 figures, accepted by Ap