We analyze the 6.4 keV line and continuum emission from the molecular cloud Sgr B2 and the source HESS J1745-303, which is supposed to be a complex of molecular gas. From the HESS results it follows that Sgr A is a source of high energy protons, which penetrate into molecular clouds producing there a TeV gamma-ray flux. We present arguments that Sgr A may also produce a flux of subrelativistic ...

We measured the period and spin-down rate for SGR 1900+14 during the quiescient period two years before the recent interval of renewed burst activity. We have shown that the spin-down age of SGR 1900+14 is consistent with a braking index of ∼1 which is appropriate for wind torques and not magnetic dipole radiation. We have shown that a combination of dipole radiation, and wind luminosity, coupl...

We present the highest resolution VLBI imaging observations of Sgr A* made at both 7 and 3.5 mm. These data reveal wavelength-dependent intrinsic sizes with an intrinsic emitting region at 3.5 mm of about 1 AU (at a distance of 8 kpc to the Galactic Center). When combined with the lower limit on the mass of Sgr A*, these size measurements provide strong evidence that Sgr A* is a super-massive b...

Recent observations of the radio and NIR source Sgr A* reinforce the interpretation of the Galactic Center as a scaled down version of an AGN. The discovery of an elongated structure at 43 GHz and increasing evidence for the presence of an accretion disk surrounding a Black Hole lead us to assume that both, an accretion disk and a jet, are present in the Galactic Center and are physically linke...

We present measurements with the VLBA of the variability in the centroid position of Sgr A* relative to a background quasar at 7mm wavelength. We find an average centroid wander of 71±45μas for time scales between 50 and 100 min and 113± 50μas for timescales between 100 and 200 min, with no secular trend. These are sufficient to begin constraining the viability of the hot-spot model for the rad...

Sagittarius A*, the ∼ 4 × 106 M⊙ black hole candidate at the Galactic Center, can be studied on Schwarzschild radius scales with (sub)millimeter wavelength Very Long Baseline Interferometry (VLBI). We report on 1.3 mm wavelength observations of Sgr A* using a VLBI array consisting of the JCMT on Mauna Kea, the ARO/SMT on Mt. Graham in Arizona, and two telescopes of the CARMA array at Cedar Flat...

Doubling time (DT) is widely used for quantification of tumor growth rate. DT is usually determined from two volume estimations with measurement time intervals comparable with or shorter than DT. Clinical data show that the frequency distribution of DT in patients is positively skewed, with some very long DT values compared with the average DT. Growth rate can also be quantified using specific ...

We have used the Mopra Telescope to search for glycine and the simple chiral molecule propylene oxide in the Sgr B2 (LMH) and Orion KL, in the 3-mm band. We have not detected either species, but have been able to put sensitive upper limits on the abundances of both molecules. The 3–sigma upper limits derived for glycine conformer I are 3.7 ×10 cm in both Orion-KL and Sgr B2 (LMH), comparable to...

We report the discovery of complex high frequency variability during the August 27, 1998 giant flare from SGR 1900+14 using the Rossi X-ray Timing Explorer (RXTE). We detect an ≈ 84 Hz oscillation (QPO) during a 1 s interval beginning approximately 1 min after the initial hard spike. The modulation amplitude is energy dependent, reaching a maximum of 26% (rms) for photons above 30 keV, and is n...

Context. The source of emission from Sgr A*, the supermassive black hole at the Galactic Center, is still unknown. Flares and data from multiwavelength campaigns provide important clues about the nature of Sgr A* itself. Aims. Here we attempt to constrain the physical origin of the broadband emission and the radio flares from Sgr A*. Methods. We developed a time-dependent jet model, which for t...