Point Sources from a Spitzer IRAC Survey of the Galactic Center

TL;DR

This paper presents a comprehensive catalog of over one million point sources in the Galactic Center region observed with Spitzer/IRAC, analyzing their distribution, brightness, and colors to identify stellar populations.

Contribution

The study provides the first large-scale, multi-wavelength point source catalog of the Galactic Center, including analysis of spatial distribution and stellar types based on IRAC colors.

Findings

Catalog contains 1,065,565 objects with IRAC and 2MASS photometry.

Point source density is spatially variable, influenced by stellar density and extinction.

Most sources are red giant and AGB stars based on color analysis.

Abstract

We have obtained Spitzer/IRAC observations of the central 2.0 x 1.4 degrees (~280 x 200 pc) of the Galaxy at 3.6-8.0 microns. A point source catalog of 1,065,565 objects is presented. The catalog includes magnitudes for the point sources at 3.6, 4.5, 5.8, and 8.0 microns, as well as JHK photometry from 2MASS. The point source catalog is confusion limited with average limits of 12.4, 12.1, 11.7, and 11.2 magnitudes for [3.6], [4.5], [5.8], and [8.0], respectively. We find that the confusion limits are spatially variable because of stellar surface density, background surface brightness level, and extinction variations across the survey region. The overall distribution of point source density with Galactic latitude and longitude is essentially constant, but structure does appear when sources of different magnitude ranges are selected. Bright stars show a steep decreasing gradient with Galactic latitude, and a slow decreasing gradient with Galactic longitude, with a peak at the position of the Galactic center. From IRAC color-magnitude and color-color diagrams, we conclude that most of the point sources in our catalog have IRAC magnitudes and colors characteristic of red giant and AGB stars.