# An X-Ray View of Star-Formation and Accretion in Normal Galaxies

## Contact

Daryl Haggard
Amherst College
dhaggard@amherst.edu

## Summary

Spectra for the optical counterparts of Chandra x-ray targets in the SDSS DR7 survey area

## Finding Targets

An object whose ANCILLARY_TARGET1 value includes one or more of the bitmasks in the following table was targeted for spectroscopy as part of this ancillary target program. See SDSS bitmasks to learn how to use these values to identify objects in this ancillary target program.

Program (bit name) Bit number Target Description Number of Fibers Number of Unique Primary Objects
CHANDRAV1 57 Positional match between SDSS DR7 photometric catalogs and the Chandra Source Catalog 1,367 1,272

## Description

The extended wavelength coverage and improved throughput of the BOSS spectrograph enables studies of the relationship between star formation and black hole accretion in galaxies, using the key diagnostic feature of Hα/N[II] to z ~0.49

## Target Selection

For this study, a target list was derived from the matched Chandra Source Catalog (CSC; version 1; Evans et al. 2010) and SDSS DR7 photometric catalogs. The following target selection steps were taken to identify targets from the list.

• High-quality matches underwent visual inspection in X-ray and optical imaging; positional matches between the SDSS DR7 catalog and the CSC used the matching method as defined by the Rots, Budavári, Szalay, & Hagler (2009), which incorporates positions, positional errors, and sky coverage.
• Matches with Bayesian probability < 0.5 suffered from a larger number of multiple matches and were therefore discarded
• Targets were required to have model magnitude 16.5 < r < 20.75
• Targets were also required to have Chandra off-axis angles < 10′
• Objects with existing SDSS spectroscopic proper motions from Munn et al. (2004, 2008) exceeding 11 mas/year, or poor-quality X-ray measurements, were removed from the sample.
• The full selection criteria are described further in Haggard et al. (2010).

Because only sources with Chandra coverage were included, targets naturally have a non-uniform distribution over the DR7 footprint. To avoid overlap between targets selected for this program and the program Remarkable X-ray Source Populations, the target lists were cross-correlated (using a 2″ match radius), and 754 duplicates were removed from this program designation and retained in the other.

## REFERENCES

Evans, I. N., et al., 2010, ApJS, 189, 37 doi:10.1088/0067-0049/189/1/37

Rots, A., Budavári, T., Szalay, A., & Hagler, J. 2009, in Chandra’s First Decade of Discovery, ed. S. Wolk, A. Fruscione, D. Swartz, Washington, DC:National Academy of Sciences