We report on initial results from a Spitzer program to search for very low-mass brown dwarfs in Ophiuchus. This program is an extension of an earlier study by Allers et al. which had resulted in an extraordinary success rate, 18 confirmed out of 19 c
andidates. Their program combined near-infrared and Spitzer photom- etry to identify objects with very cool photospheres together with circumstellar disk emission to indicate youth. Our new program has obtained deep IRAC pho- tometry of a 0.5 deg2 field that was part of the original Allers et al. study. We report 18 new candidates whose luminosities extend down to 10-4 Lcdot which sug- gests masses down to ~ 2 MJ if confirmed. We describe our selection techniques, likely contamination issues, and follow-on photometry and spectroscopy that are in progress.
We present a publicly available code called Hammurabi for generating mock polarized observations of Galactic synchrotron emission for telescopes like LOFAR, SKA, Planck and WMAP, based on model inputs for the Galactic magnetic field (GMF), the cosmic
-ray density distribution and the thermal electron density. We also present mock UHECR deflection measure (UDM) maps based on model inputs for the GMF. In future, when UHECR sources are identified, this will allow us to define UDM as a GMF probe in a similar way as polarized radio sources permit us to define rotation measures. To demonstrate the codes abilities mock observations are compared to real data as a means to constrain the input parameters of our simulations with a focus on large-scale magnetic field properties. As expected, attempts at trying to model the synchrotron, UHECR deflection and RM input parameters, show that any additional observational data set greatly increases the constraints on the models. The hammurabi code addresses this by allowing to perform simulations of several different data sets simultaneously, providing the means for a more reliable constraint of the magnetized inter-stellar-medium.
