A Mid-Infrared Census of Star Formation Activity in Bolocam Galactic Plane Survey Sources

TL;DR

This study investigates star formation activity in Bolocam Galactic Plane Survey sources by correlating millimeter and mid-infrared data, revealing that about 20% show signs of active star formation, with properties varying by activity level.

Contribution

It provides the first systematic correlation of BGPS sources with mid-IR catalogs to assess star formation activity and characterizes their properties based on activity probability.

Findings

20% of BGPS sources within survey overlap show active star formation signs.

Sources with higher star formation probability are more extended and have higher flux and mass.

Starless sources are more compact and less likely to be actively forming stars.

Abstract

We present the results of a search for mid-infrared signs of star formation activity in the 1.1 mm sources in the Bolocam Galactic Plane Survey (BGPS). We have correlated the BGPS catalog with available mid-IR Galactic plane catalogs based on the Spitzer Space Telescope GLIMPSE legacy survey and the Midcourse Space Experiment (MSX) Galactic plane survey. We find that 44% (3,712 of 8,358) of the BGPS sources contain at least one mid-IR source, including 2,457 of 5,067 (49%) within the area where all surveys overlap (10 deg < l < 65 deg). Accounting for chance alignments between the BGPS and mid-IR sources, we conservatively estimate that 20% of the BPGS sources within the area where all surveys overlap show signs of active star formation. We separate the BGPS sources into four groups based on their probability of star formation activity. Extended Green Objects (EGOs) and Red MSX Sources (RMS) make up the highest probability group, while the lowest probability group is comprised of "starless" BGPS sources which were not matched to any mid-IR sources. The mean 1.1 mm flux of each group increases with increasing probability of active star formation. We also find that the "starless" BGPS sources are the most compact, while the sources with the highest probability of star formation activity are on average more extended with large skirts of emission. A subsample of 280 BGPS sources with known distances demonstrates that mass and mean H_2 column density also increase with probability of star formation activity.