H1821+643 is the most X-ray luminous non-beamed AGN of L14β150keVβ=5.2Γ1045 erg sβ1 in the Swift/BAT ultra-hard X-ray survey
and it is also a hyper-luminous infrared (IR) galaxy LIRβ=1013.2Lββ residing in the center of a massive galaxy cluster, which is a unique
environment achieving the rapid mass assembly of black holes (BH) and host
galaxies in the local universe. We decompose the X-ray to IR spectral energy
distribution (SED) into the AGN and starburst component using the SED fitting
tool CIGALE-2022.0 and show that H1821+643 consumes a large amount of cold gas
(MΛconβ) with star-formation rate of log(SFR/MββΒ yrβ1)=3.01Β±0.04 and BH accretion rate
of log(MΛBHβ/MββΒ yrβ1)=1.20Β±0.05.
This high MΛconβ is larger than the cooling rate
(MΛcoolβ) of the intra-cluster medium (ICM),
MΛconβ/MΛcoolββ³1, which is one to two
order magnitude higher than the typical value of other systems, indicating that
H1821 provides the unique and extreme environment of rapid gas consumption. We
also show that H1821+643 has an efficient cooling path achieving from 107 K
to 102 K thanks to [OIII] 63 ΞΌm, which is a main coolant in
low temperature range (104 K to 102 K) with a cooling rate of
MΛcoolβ=3.2Γ105Β MββΒ yrβ1, and the
star-forming region extends over 40 kpc scale.Comment: 20 pages, 8 figures, accepted for publication in Ap