The nature of the relationship between low-level supermassive black hole ( SMBH ) activity and galactic cold gas , if any , is currently unclear .
Here , we test whether central black holes may feed at higher rates in gas-rich galaxies , probing SMBH activity well below the active regime down to Eddington ratios of \sim 10 ^ { -7 } .
We use a combination of radio data from the ALFALFA survey and from the literature , along with archival X-ray flux measurements from the Chandra X-ray observatory , to investigate this potential relationship .
We construct a sample of 129 late-type galaxies , with M _ { B } < -18 out to 50 Mpc , that have both HI masses and sensitive X-ray coverage .
Of these , 75 host a nuclear X-ray source , a 58 % detection fraction .
There is a highly significant correlation between nuclear X-ray luminosity L _ { X } and galaxy stellar mass M _ { star } with a slope of 1.7 \pm 0.3 , and a tentative correlation ( significant at the 2.8 \sigma level ) between L _ { X } and HI gas mass M _ { HI } .
However , a joint fit to L _ { X } as a function of both M _ { star } and M _ { HI } finds no significant dependence on M _ { HI } ( slope 0.1 \pm 0.3 ) , and similarly the residuals of L _ { X } - L _ { X } ( M _ { star } ) show no trend with M _ { HI } ; the apparent correlation between L _ { X } and M _ { HI } seems to be entirely driven by M _ { star } .
We demonstrate quantitatively that these results are robust against X-ray binary contamination .
We conclude that the galaxy-wide cold gas content in these spirals does not strongly correlate with their low-level supermassive black hole activity , and suggest fueling is a localized process .