%0 Generic %1 Willott2011 %A Willott, Chris J. %D 2011 %K high-z xray %T No evidence of obscured, accreting black holes in most z=6 star-forming galaxies %U http://arxiv.org/abs/1110.4118 %X It has been claimed that there is a large population of obscured, accreting black holes at high-redshift and that the integrated black hole density at z=6 as inferred from X-ray observations is ~100 times greater than inferred from optical quasars. I have performed a stacking analysis of very deep Chandra X-ray data at the positions of photometrically-selected z=6 galaxy candidates. It is found that there is no evidence for a stacked X-ray signal in either the soft (0.5-2 keV) or hard (2-8 keV) X-ray bands. Previous work which reported a significant signal is affected by an incorrect method of background subtraction which underestimates the true background within the target aperture. The puzzle remains of why the z=6 black hole mass function has such a flat slope and a low normalization compared to the stellar mass function.

@misc{Willott2011, abstract = { It has been claimed that there is a large population of obscured, accreting black holes at high-redshift and that the integrated black hole density at z=6 as inferred from X-ray observations is ~100 times greater than inferred from optical quasars. I have performed a stacking analysis of very deep Chandra X-ray data at the positions of photometrically-selected z=6 galaxy candidates. It is found that there is no evidence for a stacked X-ray signal in either the soft (0.5-2 keV) or hard (2-8 keV) X-ray bands. Previous work which reported a significant signal is affected by an incorrect method of background subtraction which underestimates the true background within the target aperture. The puzzle remains of why the z=6 black hole mass function has such a flat slope and a low normalization compared to the stellar mass function. }, added-at = {2011-10-20T20:34:59.000+0200}, author = {Willott, Chris J.}, biburl = {https://www.bibsonomy.org/bibtex/232dd5ba508b3d792218fa7220e569f17/miki}, description = {[1110.4118] No evidence of obscured, accreting black holes in most z=6 star-forming galaxies}, interhash = {05388d7a558d9cf06317959f0ec30837}, intrahash = {32dd5ba508b3d792218fa7220e569f17}, keywords = {high-z xray}, note = {cite arxiv:1110.4118 Comment: 4 pages, 2 figures, ApJ Letters, in press}, timestamp = {2011-10-20T20:34:59.000+0200}, title = {No evidence of obscured, accreting black holes in most z=6 star-forming galaxies}, url = {http://arxiv.org/abs/1110.4118}, year = 2011 }