We present the results from a Chandra pilot study of 12 massive galaxy mergers selected from Galaxy Zoo. The sample includes major mergers down to a host galaxy mass of 1011M⊙ that already have optical AGN signatures in at least one of the progenitors. We find that the coincidences of optically selected active nuclei with mildly obscured (NH≲1.1×1022 cm−2) X-ray nuclei are relatively common (8/12), but the detections are too faint (<40 counts per nucleus; f2−10keV≲1.2×10−13 erg s−1 cm−2) to reliably separate starburst and nuclear activity as the origin of the X-ray emission. Only one merger is found to have confirmed binary X-ray nuclei, though the X-ray emission from its southern nucleus could be due solely to star formation. Thus, the occurrences of binary AGN in these mergers are rare (0-8%), unless most merger-induced active nuclei are very heavily obscured or Compton thick.
@article{arxiv.1206.1266,
title = {Chandra Observations of Galaxy Zoo Mergers: Frequency of Binary Active Nuclei in Massive Mergers},
author = {Stacy H. Teng and Kevin Schawinski and C. Megan Urry and Dan W. Darg and Sugata Kaviraj and Kyuseok Oh and Erin W. Bonning and Carolin N. Cardamone and William C. Keel and Chris J. Lintott and Brooke D. Simmons and Ezequiel Treister},
journal= {arXiv preprint arXiv:1206.1266},
year = {2015}
}
Comments
8 pages, including 5 figures and 1 table. Accepted by ApJ