We present a broadband ( 0.4–70 keV ) X-ray spectral analysis of the luminous infrared galaxy ( LIRG ) system Mrk 463 observed with Nuclear Spectroscopic Telescope Array ( NuSTAR ) , Chandra , and XMM-Newton , which contains double active galactic nuclei ( AGNs ) ( Mrk 463E and Mrk 463W ) with a separation of \sim 3.8 kpc .
Detecting their transmitted hard X-ray > 10 keV continua with NuSTAR , we confirm that Mrk 463E and Mrk 463W have AGNs with intrinsic luminosities of ( 1.6–2.2 ) \times 10 ^ { 43 } and ( 0.5–0.6 ) \times 10 ^ { 43 } erg s ^ { -1 } ( 2–10 keV ) obscured by hydrogen column densities of 8 \times 10 ^ { 23 } and 3 \times 10 ^ { 23 } cm ^ { -2 } , respectively .
Both nuclei show strong reflection components from cold matter .
The luminosity ratio between X-ray ( 2–10 keV ) and [ O IV ] 25.89 \mu m of Mrk 463E is \sim 5 times smaller than those of normal Seyfert galaxies , suggesting that the intrinsic SED is X-ray weak relative to the UV luminosity .
In fact , the bolometric AGN luminosity of Mrk 463E estimated from L ^ { \prime } -band ( 3.8 \mu m ) , [ O IV ] 25.89 \mu m , and [ Ne V ] 14.32 \mu m lines indicate a large bolometric-to-X-ray luminosity ratio , \kappa _ { 2 - 10 keV } \approx 110–410 , and a high Eddington ratio , \lambda _ { Edd } \sim 0.4–0.8 .
We suggest that the merger triggered a rapid growth of the black hole in Mrk 463E , which is not yet deeply “ buried ” by circumnuclear dust .
By contrast , the L ^ { \prime } -band luminosity of Mrk 463W is unusually small relative to the X-ray luminosity , suggesting that the Eddington ratio is low ( < 10 ^ { -3 } ) and it might be still in an early phase of merger-driven AGN activity .