Jet induced star formation in centrally dominant galaxies?

Using U-I CCD color maps of two centrally dominant cluster galaxies, we find unusual color structures which may be due to star formation which has been induced by their radio sources. These objects, located in the clusters A1795 and A2597, have blue central colors to radii of 20 kpc, spatially extended emission-line structures, and powerful radio sources. They reside at the centers of cooling flows with mass-accretion rates which are estimated to be approximately greater than 300 solar mass/yr. The regions of bluest local color are superposed on or along their radio-source structures. Our observations suggest that the radio sources associated with these objects may be inducing massive star formation in their central 20 kpc. The star formation may be the result of the radio plasma interacting with the warm emission-line gas and dense, x-ray emitting filaments similar to those recently discovered in two other clusters with the ROSAT Observatory. Since radio jets are likely to be transient, this may help to explain the scatter in the correlations between color and mass-accretion rate, although other factors may also contribute. Alternatively, scattered radiation from a hidden active nucleus or recent mergers may be responsible for the color structure. The color and radio properties of these objects are qualitatively similar but smaller in luminosity and spatial extent to those found in high redshift radio galaxies. Our observations of galaxies at z approximately = 0.06-0.1 show that processes similar to 'the alignment effect' found in high redshift radio galaxies occur at more recent epochs

The Halo Mass-Temperature Relation for Clusters, Groups, and Galaxies

The halo mass-temperature relation for a sample of 216 galaxy clusters, groups, and individual galaxies observed by $Chandra$ X-ray Observatory is presented. Using accurate spectral measurements of their hot atmospheres, we derive the $M-T$ relation for systems with temperatures ranging between 0.4-15.0 keV. We measure the total mass of clusters, groups, and galaxies at radius $R_{2500}$, finding that the $M_{2500} \propto T^{\alpha}$ relation follows a power-law with $\alpha$ = 1.65$\pm$0.06. Our relation agrees with recent lensing studies of the $M-T$ relation at $R_{200}$ and is consistent with self-similar theoretical prediction and recent simulations. This agreement indicates that the $M-T$ relation is weakly affected by non-gravitational heating processes. Using lensing masses within $R_{200}$ we find $M_{200}-T$ follows a power-law with slope 1.61$\pm$0.19, consistent with the $M_{2500}-T$ relation. No evidence for a break or slope change is found in either relation. Potential biases associated with sample selection, evolution, and the assumption of hydrostatic equilibrium that may affect the scaling are examined. No significant impacts attributable to these biases are found. Non-cool-core clusters and early spirals produce higher scatter in the $M-T$ relation than cool-core clusters and elliptical galaxies.Comment: 12 pages, 4 figures, submitted to the Astrophysical Journa

Adventures In Cyberspace: The Status Of Cybersquatting And ADR

The University of Nowhere owns a trademark for the “University of Nowhere” and for the University of Nowhere “Winners,” the university’s sports teams.  It also owns the domain name “www.un.edu.”  The University uses its Internet site to inform the public about its academic programs as well as its accomplishments on the sports fields.  The University has been recognized as one of the top universities in the United States for many years.  The University has also competed successfully for numerous NCAA titles over the years.  The University discovers that Mr. First, owner of Fast Services of America, Inc., registered and is using the Internet domain name “university of nowhere.com” and “universityofnowherewinners.com” on a continuing basis.  The University contacts Mr. First, who informs the University that he has no intention of relinquishing the domain names unless the University pays him $10,000 and gives him two lifetime passes to all “Winner” games.  The University declines the offer and writes a letter to Mr. First informing him that he must stop using the University domain names immediately.  Mr. First responds by sending the University an invoice for$10,000 and two lifetime tickets to “Winner” events.  The cover letter to the invoice states that he will not stop using the domain names until the invoice is paid.  This is now a dispute.  It is going to cost money for both parties, regardless of the outcome.  Additionally, there is the new area of law to contend with that relates to alleged cybersquatting and the improper use of domain names.  This paper will explore and review approaches for resolving this dispute through negotiation, mediation, and arbitration

The mass-L_x relation for moderate luminosity X-ray clusters

We present measurements of the masses of a sample of 25 moderate X-ray luminosity clusters of galaxies from the 160 square degree ROSAT survey. The masses were obtained from a weak lensing analysis of deep F814W images obtained using the Advanced Camera for Surveys (ACS). We present an accurate empirical correction for the effect of charge transfer (in)efficiency on the shapes of faint galaxies. A significant lensing signal is detected around most of the clusters. The lensing mass correlates tightly with the cluster richness. We measured the intrinsic scatter in the scaling relation between M_2500 and L_X and find the best fit power law slope and normalisation to be alpha=0.68+-0.07 and M_X=(1.2+-0.12)10^14M_sun (for L_X=2x10^44 erg/s). These results agree well with a number of recent studies, but the normalisation is lower compared to the study of Rykoff et al. (2008b). One explanation for this difference may be the fact that (sub)structures projected along the line-of-sight boost both the galaxy counts and the lensing mass. Such superpositions lead to an increased mass at a given L_X when clusters are binned by richness.Comment: accepted for publication in the Astrophysical Journal; 15 pages, 11 figure

The Insignificance of Global Reheating in the Abell 1068 Cluster: X-Ray Analysis

We report on a Chandra observation of the massive, medium redshift (z=0.1386) cooling flow cluster Abell 1068. We detect a clear temperature gradient in the X-ray emitting gas from kT ~ 5 keV in the outer part of the cluster down to roughly 2 keV in the core, and a striking increase in the metallicity of the gas toward the cluster center. The total spectrum from the cluster can be fit by a cooling flow model with a total mass deposition rate of 150 solar masses/yr. Within the core (r < 30 kpc), the mass depositon rate of 40 solar masses/yr is comparable to estimates for the star formation rate from optical data. We find an apparent correlation between the cD galaxy's optical isophotes and enhanced metallicity isocontours in the central ~100 kpc of the cluster. We show that the approximate doubling of the metallicity associated with the cD can be plausibly explained by supernova explosions associated with the cD's ambient stellar population and the recent starburst. Finally, we calculate the amount of heating due to thermal conduction and show that this process is unlikely to offset cooling in Abell 1068.Comment: Accepted for publication in ApJ, 26 pages, 12 b+w figures, 3 color figure

Software project management - there is never enough time to do it right!

Efficiency in software development projects is examined. Project management tools— GANTT charts, program evaluation and review technique (PERT), and critical path method (CPM) are defined and discussed. Of these productivity tools GANTT charts and PERT are the most relevant. Based on an analysis by Shelmerdine (1989), six steps that pro\ide guidelines for software development are presented. These steps provide the project manager with an opportunity to produce efficiency and deliver a software development project on time. Selected project management software packages are presented