SIMBAD references

2015ApJ...805...12L - Astrophys. J., 805, 12 (2015/May-3)

An X-ray selected sample of candidate black holes in dwarf galaxies.


Abstract (from CDS):

We present a sample of hard X-ray-selected candidate black holes (BHs) in 19 dwarf galaxies. BH candidates are identified by cross-matching a parent sample of ∼44,000 local dwarf galaxies (,) with the Chandra Source Catalog and subsequently analyzing the original X-ray data products for matched sources. Of the 19 dwarf galaxies in our sample, eight have X-ray detections reported here for the first time. We find a total of 43 point-like hard X-ray sources with individual luminosities erg/s. Hard X-ray luminosities in this range can be attained by stellar-mass X-ray binaries (XRBs) and by massive BHs accreting at low Eddington ratio. We place an upper limit of 53% (10/19) on the fraction of galaxies in our sample hosting a detectable hard X-ray source consistent with the optical nucleus, although the galaxy center is poorly defined in many of our objects. We also find that 42% (8/19) of the galaxies in our sample exhibit statistically significant enhanced hard X-ray emission relative to the expected galaxy-wide contribution from low-mass and high-mass XRBs, based on thestar formation rate relation defined by more massive and luminous systems. For the majority of these X-ray-enhanced dwarf galaxies, the excess emission is consistent with (but not necessarily due to) a nuclear X-ray source. Follow-up observations are necessary to distinguish between stellar-mass XRBs and active galactic nuclei powered by more massive BHs. In any case, our results support the notion that X-ray-emitting BHs in low-mass dwarf galaxies may have had an appreciable impact on reionization in the early universe.

Abstract Copyright:

Journal keyword(s): galaxies: active - galaxies: dwarf - galaxies: nuclei - X-rays: binaries - X-rays: galaxies

Simbad objects: 28

goto Full paper

goto View the reference in ADS

To bookmark this query, right click on this link: simbad:2015ApJ...805...12L and select 'bookmark this link' or equivalent in the popup menu


© Université de Strasbourg/CNRS

    • Contact