The Baryonic and Dark Matter Distributions in Abell 401

We combine spatially resolved ASCA temperature data with ROSAT imaging data to constrain the total mass distribution in the cluster A401, assuming that the cluster is in hydrostatic equilibrium. We obtain a total mass within the X-ray core (290/h_50 kpc) of 1.2[+0.1,-0.5] 10^14 /h_50 Msun at the 90% confidence level, 1.3 times larger than the isothermal estimate. The total mass within r_500 (1.7/h_50 Mpc) is M_500 = 0.9[+0.3,-0.2] 10^15/ h_50 Msun at 90% confidence, in agreement with the optical virial mass estimate, and 1.2 times smaller than the isothermal estimate. Our M_500 value is 1.7 times smaller than that estimated using the mass-temperature scaling law predicted by simulations. The best fit dark matter density profile scales as r^{-3.1} at large radii, which is consistent with the Navarro, Frenk & White (NFW) ``universal profile'' as well as the King profile of the galaxy density in A401. From the imaging data, 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 = 0.21[+0.06,-0.05] h_50^{-3/2} (90% confidence errors). Assuming that f_gas (plus an estimate of the stellar mass) is the universal value of the baryon fraction, we estimate the 90% confidence upper limit of the cosmological matter density to be Omega_m < 0.31.Comment: 17 pages, 6 figures, accepted by Ap

The XMM-Newton EPIC Background and the production of Background Blank Sky Event Files

We describe in detail the nature of XMM-Newton EPIC background and its various complex components, summarising the new findings of the XMM-Newton EPIC background working group, and provide XMM-Newton background blank sky event files for use in the data analysis of diffuse and extended sources. Blank sky event file data sets are produced from the stacking of data, taken from 189 observations resulting from the Second XMM-Newton Serendipitous Source Catalogue (2XMMp) reprocessing. The data underwent several filtering steps, using a revised and improved method over previous work, which we describe in detail. We investigate several properties of the final blank sky data sets. The user is directed to the location of the final data sets. There is a final data set for each EPIC instrument-filter-mode combination.Comment: Paper accepted by A&A 22 December 2006. 14 pages, 8 figures. Paper can also be found at http://www.star.le.ac.uk/~jac48/publications

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

Androgen receptor-dependent and -independent mechanisms driving prostate cancer progression: Opportunities for therapeutic targeting from multiple angles.

Despite aggressive treatment for localized cancer, prostate cancer (PC) remains a leading cause of cancer-related death for American men due to a subset of patients progressing to lethal and incurable metastatic castrate-resistant prostate cancer (CRPC). Organ-confined PC is treated by surgery or radiation with or without androgen deprivation therapy (ADT), while options for locally advanced and disseminated PC include radiation combined with ADT, or systemic treatments including chemotherapy. Progression to CRPC results from failure of ADT, which targets the androgen receptor (AR) signaling axis and inhibits AR-driven proliferation and survival pathways. The exact mechanisms underlying the transition from androgen-dependent PC to CRPC remain incompletely understood. Reactivation of AR has been shown to occur in CRPC despite depletion of circulating androgens by ADT. At the same time, the presence of AR-negative cell populations in CRPC has also been identified. While AR signaling has been proposed as the primary driver of CRPC, AR-independent signaling pathways may represent additional mechanisms underlying CRPC progression. Identification of new therapeutic strategies to target both AR-positive and AR-negative PC cell populations and, thereby, AR-driven as well as non-AR-driven PC cell growth and survival mechanisms would provide a two-pronged approach to eliminate CRPC cells with potential for synthetic lethality. In this review, we provide an overview of AR-dependent and AR-independent molecular mechanisms which drive CRPC, with special emphasis on the role of the Jak2-Stat5a/b signaling pathway in promoting castrate-resistant growth of PC through both AR-dependent and AR-independent mechanisms

Constituents of the soft X-ray background

The X-ray background is generated by various classes of objects and variety of emission mechanisms. Relative contribution of individual components depends on energy. The goal is to assess the integral emission of the major components of the soft X-ray background (extragalactic discrete sources dominated by AGNs, galactic plasma, and the Warm/Hot Intergalactic Medium), investigating the angular structure of the background. Fluctuations of the background are measured using the auto-correlation function of the XRB determined in 5 energy bands between 0.3 and 4.5 keV. The investigation is based on the extensive observational data set selected from the XMM-Newton archives. Amplitudes of the auto-correlation functions calculated in three energy bands above ~1 keV are consistent with the conjecture that the background fluctuations result solely from clustering of sources which produce the background. At energies below 1 keV the relative fluctuation amplitude decreases indicating that a fraction of the soft XRB is associated with a smooth plasma emission in the Galaxy. It is shown, however, that the mean spectrum of extragalactic discrete sources steepens in the soft X-rays and is not well represented by a single power law in the energy range 0.3-4.5 keV. The WHIM contribution to the total background fluctuations is small and consistent with the WHIM properties derived from the cross-correlation of the XRB with galaxies.Comment: 7 pages, 2 figure

Constraints on the parameters of radiatively decaying dark matter from the dark matter halo of the Milky Way and Ursa Minor

We improve the earlier restrictions on parameters of the dark matter (DM) in the form of a sterile neutrino. The results were obtained from non-observing the DM decay line in the X-ray spectrum of the Milky Way (using the recent XMM-Newton PN blank sky data). We also present a similar constraint coming from the recent XMM-Newton observation of Ursa Minor -- dark, X-ray quiet dwarf spheroidal galaxy. The new Milky way data improve on (by as much as the order of magnitude at masses ~3.5 keV) existing constraints. Although the observation of Ursa Minor has relatively poor statistics, the constraints are comparable to those recently obtained using observations of the Large Magellanic Cloud or M31. This confirms a recent proposal that dwarf satellites of the MW are very interesting candidates for the DM search and dedicated studies should be made to this purpose.Comment: 8 pp. v.2 - Final version to appear in A&

The X-ray Power Spectral Density Function and Black Hole Mass Estimate for the Seyfert AGN IC 4329a

We present the X-ray broadband power spectral density function (PSD) of the X-ray-luminous Seyfert IC 4329a, constructed from light curves obtained via Rossi X-ray Timing Explorer monitoring and an XMM-Newton observation. Modeling the 3-10 keV PSD using a broken power-law PSD shape, a break in power-law slope is significantly detected at a temporal frequency of 2.5(+2.5,-1.7) * 10^-6 Hz, which corresponds to a PSD break time scale T_b of 4.6(+10.1,-2.3) days. Using the relation between T_b, black hole mass M_BH, and bolometric luminosity as quantified by McHardy and coworkers, we infer a black hole mass estimate of M_BH = 1.3(+1.0,-0.3) * 10^8 solar masses and an accretion rate relative to Eddington of 0.21(+0.06,-0.10) for this source. Our estimate of M_BH is consistent with other estimates, including that derived by the relation between M_BH and stellar velocity dispersion. We also present PSDs for the 10-20 and 20-40 keV bands; they lack sufficient temporal frequency coverage to reveal a significant break, but are consistent with the same PSD shape and break frequency as in the 3-10 keV band.Comment: Accepted for publication in ApJ. 11 pages, 6 figures (5 color

Transcription factor signal transducer and activator of transcription 5 promotes growth of human prostate cancer cells in vivo

Purpose: Stat5a/b is the key mediator of prolactin (Prl) effects in prostate cancer cells via activation of Jak2. Prl is locally produced growth factor in human prostate cancer. Prl protein expression and constitutive activation of Stat5a/b are associated with high histological grade of clinical prostate cancer. Moreover, activation of Stat5a/b in primary prostate cancer predicts early disease recurrence. Here, we inhibited Stat5a/b by several different methodological approaches. Our goal was to establish a proof-of-principle that Stat5a/b is critical for prostate cancer cell viability in vitro and for prostate tumor growth in vivo. Experimental Design: We inhibited Stat5a/b protein expression by antisense oligonucleotides or RNA interference and transcriptional activity of Stat5a/b by adenoviral expression of a dominant-negative mutant of Stat5a/b in prostate cancer cells in culture. Moreover, Stat5a/b activity was suppressed in human prostate cancer xenograft tumors in nude mice. Stat5a/b regulation of BclXL and Cyclin-D1 protein levels was demonstrated by antisense suppression of Stat5a/b protein expression followed by Western blotting. Results and Conclusions: We show here that inhibition of Stat5a/b by antisense oligonuleotides, RNA interference, or adenoviral expression of DNStat5a/b all effectively kill prostate cancer cells. Moreover, we demonstrate that Stat5a/b is critical for human prostate cancer xenograft growth in nude mice. Stat5a/b effects on the viability of on prostate cancer cells involve Stat5a/b-regulation of BclXL and Cyclin-D1 protein levels, but not the expression or activation of Stat3. This work establishes Stat5a/b as a therapeutic target protein for prostate cancer. Pharmacological inhibition of Stat5a/b in prostate cancer can be achieved by small-molecule inhibitors of transactivation, dimerization or DNA-binding of Stat5a/b

XMM−NewtonXMM-Newton Ω\Omega project: III. Gas mass fraction shape in high redshift clusters

We study the gas mass fraction, $f\_{\rm gas},$ behavior in $XMM-Newton$ $\Omega$ project. The typical $f\_{\rm gas}$ shape of high redshift galaxy clusters follows the global shape inferred at low redshift quite well. This result is consistent with the gravitational instability picture leading to self similar structures for both the dark and baryonic matter. However, the mean $f\_{\rm gas} in distant clusters shows some differences to local ones, indicating a departure from strict scaling. This result is consistent with the observed evolution in the luminosity-temperature relation. We quantitatively investigate this departure from scaling laws. Within the local sample we used, a moderate but clear variation of the amplitude of the gas mass fraction with temperature is found, a trend that weakens in the outer regions. These variations do not explain departure from scaling laws of our distant clusters. An important implication of our results is that the gas fraction evolution, a test of the cosmological parameters, can lead to biased values when applied at radii smaller than the virial radius. From our$XMM$ clusters, the apparent gas fraction at the virial radius is consistent with a non-evolving universal value in a high matter density model and not with a concordance.Comment: Accepted, A&A, in pres

A revised Cepheid distance to NGC 4258 and a test of the distance scale

In a previous paper (Maoz et al. 1999), we reported a Hubble Space Telescope (HST) Cepheid distance to the galaxy NGC 4258 obtained using the calibrations and methods then standard for the Key Project on the Extragalactic Distance Scale. Here, we reevaluate the Cepheid distance using the revised Key Project procedures described in Freedman et al. (2001). These revisions alter the zero points and slopes of the Cepheid Period-Luminosity (P-L) relations derived at the Large Magellanic Cloud (LMC), the calibration of the HST WFPC2 camera, and the treatment of metallicity differences. We also provide herein full information on the Cepheids described in Maoz et al. 1999. Using the refined Key Project techniques and calibrations, we determine the distance modulus of NGC 4258 to be 29.47 +/- 0.09 mag (unique to this determination) +/- 0.15 mag (systematic uncertainties in Key Project distances), corresponding to a metric distance of 7.8 +/- 0.3 +/- 0.5 Mpc and 1.2 sigma from the maser distance of 7.2 +/- 0.5 Mpc. We also test the alternative Cepheid P-L relations of Feast (1999), which yield more discrepant results. Additionally, we place weak limits upon the distance to the LMC and upon the effect of metallicity in Cepheid distance determinations.Comment: 26 pages in emulateapj5 format, including 6 figures and 5 tables. Accepted for publication in the Astrophysical Journa