A Catalog Sample of Low-mass Galaxies Observed in X-Rays with Central Candidate Black Holes

A. A. Nucita, L. Manni, F. De Paolis, M. Giordano, G. Ingrosso
2017 Astrophysical Journal  
We present a sample of X-ray selected candidate black holes in 51 low mass galaxies with z< 0.055 and mass up to 10^10 M_ obtained by cross-correlating the NASA-SLOAN Atlas with the 3XMM catalogue. We have also searched in the available catalogues for radio counterparts of the black hole candidates and find that 19 of the previously selected sources have also a radio counterpart. Our results show that about 37% of the galaxies of our sample host an X-ray source (associated to a radio
more » ... ) spatially coincident with the galaxy center, in agreement with other recent works. For these nuclear sources, the X-ray/radio fundamental plane relation allows one to estimate the mass of the (central) candidate black holes which results to be in the range 10^4-2×10^8 M_ (with median value of ≃ 3× 10^7 M_ and eight candidates having mass below 10^7 M_). This result, while suggesting that X-ray emitting black holes in low-mass galaxies may have had a key role in the evolution of such systems, makes even more urgent to explain how such massive objects formed in galaxies. Of course, dedicated follow-up observations both in the X-ray and radio bands, as well as in the optical, are necessary in order to confirm our results
doi:10.3847/1538-4357/aa5f4f fatcat:yux752sr65cljku6kcdubnsdbm