Showing papers by "Daniel Y. Gezari published in 2006"

A mid-infrared survey of the inner 2 ? 1.5 degrees of the Galaxy with Spitzer/IRAC

Abstract: We present a survey of Spitzer Space Telescope/IRAC observations of the central 2 × 1.5 degrees (265 × 200 pc) of the Galaxy at 3-8 μm. These data represent the highest spatial resolution and sensitivity large-scale map made to date of the Galactic Center (GC) at mid-infrared wavelengths. The IRAC data provide a census of the optically obscured stellar sources as well as a detailed map of the highly filamentary structure in the interstellar medium. The diffuse emission is dominated by PAH emission from small grains in star-forming regions. Dark clouds displaying a large variety of sizes and morphologies are imaged, many of which remain opaque at IRAC wavelengths. Using a multiwavelength comparison, we determine which objects are likely to be in the foreground and which are located at the GC. We find no counterparts at IRAC wavelengths to the unique system of linear, nonthermal radio filaments present at the GC.

The Stellar Population in the Galactic Center: Insights from the Spitzer Space Telescope

Abstract: The SpitzerIRAC observations (Stolovy et al., these proceedings) of the central 265 pc ? 210 pc provide an opportunity to study the relationships between massive stars, gas, and dust in the Galactic Center at unprecedented resolution. The observations are inclusive of the three known extremely dense clusters of massive hot young stars which ionize the unusual thermal filaments seen at both radio wavelengths and in PAH emission in the IRAC images. Here we explore the effects of the massive stars, particularly in regions including the Quintuplet and Arches clusters, on the nearby diffuse ISM emission (see also Simpson et al. these proceedings). We discuss the diagnostics available using the IRAC colors, and what these show us in regards to known massive stars. Finally, we discuss the 1-8 ?m SEDs which are currently under construction, and the preliminary results using a novel SED fitting program to determine the stellar type and extinction to all available point sources in the survey region.

Comparison of Spitzer/IRAC Galactic Center 3.6-8.0 μum survey results with X-ray emission in the central 40 × 40 parsecs

Abstract: We have studied the correlation between 2357 Chandra X-ray point sources identified by Muno et al. (2003) in a 40 × 40 parsec field and ~20,000 infrared sources we observed in the corresponding subset of our 2 × 1.5 degree Spitzer/IRAC Galactic Center Survey at 3.6-8.0 μm (see Stolovy et al.; this conference), using various spatial and brightness thresholds. The correlation was determined for source separations of less than 0.5, 1.0 or 2.0 arcsec. No significant correlation was found between the X-ray and infrared point sources on these scales. Only one compact infrared source, IRS 13, can be identiffed with any of the dozen prominent X-ray emission features in the 3 × 3 parsec region centered on Sgr A*, and the diffuse X-ray and infrared emission around Sgr A* seems to be anti-correlated on a few-arcsecond scale. We compare our results with previous identifications of near infrared companions to Chandra X-ray sources.