Diego Muñoz

An x-ray, infrared, and submillimeter flare of Sagittarius A*

Energetic flares are observed in the Galactic supermassive black hole Sagittarius A* from radio to X-ray wavelengths. On a few occasions, simultaneous flares have been detected in IR and X-ray observations, but clear counterparts at longer wavelengths have not been seen. We present a flare observed over several hours on 2006 July 17 with the Chandra X-Ray Observatory, the Keck II telescope, the Caltech Submillimeter Observatory, and the Submillimeter Array. All telescopes observed strong flare events, but the submillimeter peak is found to occur nearly 100 minutes after the X-ray peak. Submillimeter polarization data show linear polarization in the excess flare emission, increasing from 9% to 17% as the flare passes through its peak, consistent with a transition from optically thick to thin synchrotron emission. The temporal and spectral behavior of the flare require that the energetic electrons responsible for the emission cool faster than expected from their radiative output. This is consistent with adiabatic cooling in an expanding emission region, with X-rays produced through self-Compton scattering, although not consistent with the simplest model of such expansion. We also present a submillimeter flare that followed a bright IR flare on 2005 July 31. Compared to 2006, this event had a larger peak IR flux and similar submillimeter flux, but it lacked measurable X-ray emission. It also showed a shorter delay between the IR and submillimeter peaks. Based on these events we propose a synchrotron and self-Compton model to relate the submillimeter lag and the variable IR/X-ray luminosity ratio.

Improving the convergence properties of the moving-mesh code AREPO

Accurate numerical solutions of the equations of hydrodynamics play an ever more important role in many fields of astrophysics. In this work, we reinvestigate the accuracy of the moving-mesh code \textsc{Arepo} and show how its convergence order can be improved for general problems. In particular, we clarify that for certain problems \textsc{Arepo} only reaches first-order convergence for its original formulation. This can be rectified by simple modifications we propose to the time integration scheme and the spatial gradient estimates of the code, both improving the accuracy of the code. We demonstrate that the new implementation is indeed second-order accurate under the

Massive Clumps in the NGC 6334 Star Forming Region

L^1

ALMA Observations of the T?Tauri Binary System AS?205: Evidence for Molecular Winds and/or Binary Interactions

norm, and in particular substantially improves conservation of angular momentum. Interestingly, whereas these improvements can significantly change the results of smooth test problems, we also find that cosmological simulations of galaxy formation are unaffected, demonstrating that the numerical errors eliminated by the new formulation do not impact these simulations. In contrast, simulations of binary stars followed over a large number of orbital times are strongly affected, as here it is particularly crucial to avoid a long-term build up of errors in angular momentum conservation.

Survival of planets around shrinking stellar binaries

We report observations of dust continuum emission at 1.2 mm toward the star forming region NGC 6334 made with the SEST SIMBA bolometer array. The observations cover an area of

Morphological and anatomical characterization of six jojoba clones at saline and non-saline sites

\sim 2

Planetary engulfment as a trigger for white dwarf pollution

square degrees with approximately uniform noise. We detected 181 clumps spanning almost three orders of magnitude in mass (3\Msun

A social cloud-based tool to deal with time and media mismatch of intergenerational family communication

-6\times10^3

THE CIRCULAR POLARIZATION OF SAGITTARIUS A* AT SUBMILLIMETER WAVELENGTHS

\Msun) and with sizes in the range 0.1--1.0 pc. We find that the clump mass function

Stellar orbit evolution in close circumstellar disc encounters

dN/d\log M