The fraction of cluster galaxies that host luminous AGN is an important probe of AGN fueling processes , the cold ISM at the centers of galaxies , and how tightly black holes and galaxies co-evolve .
We present a new measurement of the AGN fraction in a sample of 13 clusters of galaxies ( M \geq 10 ^ { 14 } M _ { \odot } ) at 1 < z < 1.5 selected from the Spitzer /IRAC Shallow Cluster Survey , as well as the field fraction in the immediate vicinity of these clusters , and combine these data with measurements from the literature to quantify the relative evolution of cluster and field AGN from the present to z \sim 3 .
We estimate that the cluster AGN fraction at 1 < z < 1.5 is f _ { A } = 3.0 ^ { +2.4 } _ { -1.4 } % for AGN with a rest-frame , hard X-ray luminosity greater than L _ { X,H } \geq 10 ^ { 44 } erg/s .
This fraction is measured relative to all cluster galaxies more luminous than M ^ { * } _ { 3.6 } ( z ) +1 , where M ^ { * } _ { 3.6 } ( z ) is the absolute magnitude of the break in the galaxy luminosity function at the cluster redshift in the IRAC 3.6 \mu m bandpass .
The cluster AGN fraction is 30 times greater than the 3 \sigma upper limit on the value for AGN of similar luminosity at z \sim 0.25 , as well as more than an order of magnitude greater than the AGN fraction at z \sim 0.75 .
AGN with L _ { X,H } \geq 10 ^ { 43 } erg/s exhibit similarly pronounced evolution with redshift .
In contrast with the local universe , where the luminous AGN fraction is higher in the field than in clusters , the X-ray and MIR-selected AGN fractions in the field and clusters are consistent at 1 < z < 1.5 .
This is evidence that the cluster AGN population has evolved more rapidly than the field population from z \sim 1.5 to the present .
This environment-dependent AGN evolution mimics the more rapid evolution of star-forming galaxies in clusters relative to the field .