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Data on the cosmic microwave background (CMB) radiation by the Wilkinson Microwave Anisotropy Probe (WMAP) had a profound impact on the understanding of a variety of physical processes in the early phases of the Universe and on the estimation of the cosmological parameters. Here, the 7-year WMAP data are used to trace the disk and the halo of the nearby giant spiral galaxy M31. We analyzed the temperature excess in three WMAP bands (W, V, and Q) by dividing the region of the sky around M31 into several concentric circular areas. We studied the robustness of the detected temperature excess by considering 500 random control fields in the real WMAP maps and simulating 500 sky maps from the best-fitted cosmological parameters. By comparing the obtained temperature contrast profiles with the real ones towards the M31 galaxy, we find that the temperature asymmetry in the M31 disk is fairly robust, while the effect in the halo is weaker. An asymmetry in the mean microwave temperature in the M31 disk along the direction of the M31 rotation is observed with a temperature contrast up to about 130 microK/pixel. We also find a temperature asymmetry in the M31 halo, which is much weaker than for the disk, up to a galactocentric distance of about 10 degrees (120 kpc) with a peak temperature contrast of about 40 microK/pixel. Although the confidence level of the signal is not high, if estimated purely statistically, which could be expected due to the weakness of the effect, the geometrical structure of the temperature asymmetry points towards a definite effect modulated by the rotation of the M31 halo. This result might open a new way to probe these relatively less studied galactic objects using high-accuracy CMB measurements, such as those with the Planck satellite or planned balloon-based experiments, which could prove or disprove our conclusions., Comment: 6 pages, 5 figures, in press on Astronomy and Astrophysics Letters, 2011

The Kolmogorov stochasticity parameter is shown to act as a tool to detect point sources in the cosmic microwave background (CMB) radiation temperature maps. Kolmogorov CMB map constructed for the WMAP's 7-year datasets reveals tiny structures which in part coincide with point radio and Fermi/LAT gamma-ray sources. In the first application of this method, we identified several sources not present in the then available 0FGL Fermi catalog. Subsequently they were confirmed in the more recent and more complete 1FGL catalog, thus strengthening the evidence for the power of this methodology., Comment: 4 pages, 3 figs, 1 Table; to match the published version

The plane-mirror symmetry previously noticed in the Cosmic Microwave Background (CMB) temperature anisotropy maps of Wilkinson Microwave Anisotropy Probe is shown to possess certain anomalous properties. The degree of the randomness determined by the Kolmogorov stochasticity parameter in the both symmetry regions appears to have identical values which, however, essentially differ from the corresponding values for other sky regions. If the mirroring were of cosmological origin, this would imply either additional randomizing properties in those directions of the Universe or their different line-of-sight depth. This analysis also provides a way to test the hypothesis of a link between the nature of dark energy and inhomogeneities., Comment: A & A (Lett.) in press; 3 pages, 2 figs

We continue investigation of the hidden plane-mirror symmetry in the distribution of excursion sets in cosmic microwave background (CMB) temperature anisotropy maps, previously noticed in the three-year data of the Wilkinson microwave anisotropy probe (WMAP), using the WMAP 5 years maps. The symmetry is shown to have higher significance, ��^2 < 1.7, for low multipoles \ell < 5, while disappearing at larger multipoles, ��^2 > 3.5 for \ell > 10. The study of the sum and difference maps of temperature inhomogeneity regions, along with simulated maps, confirms its existence.The properties of these mirroring symmetries are compatible with those produced by the Sachs-Wolfe effect in the presence of an anomalously large component of horizon-size density perturbations, independent of one of the spatial coordinates, and/or a slab-like spatial topology of the Universe., A&A accepted

Context. A cataclysmic variable contains a white dwarf that accretes material from a secondary star via the Roche lobe mechanism. Systems with high line-of-sight inclination angles offer the possibility to pinpoint the location of the X-ray emitting region by characterizing the observed eclipse by the secondary star. Aims: We present an XMM-Newton observation of the dwarf nova Z Chamaleontis that we analyzed to determine the properties of the X-ray and optical light curves, as well as the high-energy spectrum. Methods: We performed a spectral analysis of the data taken by the EPIC camera, and a timing analysis of the observed X-ray and optical OM light curves. Results: We find that a multi-temperature plasma component absorbed by ionized material is required to describe the data. In particular, we estimate that the total absorbed flux in the 0.2-9.0 keV band is FAbs0.2-9.0 = (4.1±0.1) × 10-12 erg s-1 cm-2, which, when accounted for absorption and bolometric correction, corresponds to a bolometric luminosity of LBolX = (6.9±0.1) × 1030 erg s-1 at a distance of 97 pc. The mass accretion rate onto the white dwarf turns out to be about 1.1 × 10-11Msun yr-1. Our analysis of the optical and X-ray eclipse light curves and the mid-eclipse times of Z-Chamaleontis, in addition to the eclipse (during which the observed EPIC count rate is 0.033 ± 0.003 count s-1), implies that the X-ray light curve contains dips (at the orbital phases 0.30 ± 0.02 and 0.73 ± 0.02) that can be naturally explained as absorption effects by intervening stable gas clouds close to the accretor.

We describe here the realization and tests of a two stage torsion pendulum facility (nicknamed PETER, from Italian PEndolo Traslazionale E Rotazionale, namely translational and Rotational Pendulum) for the measurement of the Gravitational Reference Sensor (GRS) actuation Cross Talks (CT) for LISA-Pathfinder and its possible evolution. This project started within the ground testing activities for the characterization, before flight, of the GRS of LISA-Pathfinder, where it showed results consistent with what observed on flight. The apparatus could easily evolve to a facility to test small forces/torques on free falling instrumented masses, for future next generation space missions. Here, we will discuss the principle of operation of the double torsion pendulum and the initial goal of the activity, the description of the PETER apparatus, cross -talk measurement technique and results and possible extension to more than 2 DoF