SPT-CL J0546−5345

SPT-CL J0546−5345 is a massive galaxy cluster discovered at the South Pole Telescope in 2008 and was the first galaxy cluster discovered at ${\displaystyle z}$ > 1 using the Sunyaev–Zeldovich effect.^[2][5][6][7] It is thought to be 7 billion light years away and has a redshift of ${\displaystyle z}$ = 1.067.^[2]

The cluster hosts 49 galaxy members and has an estimated total mass of 4.85 × 10¹⁴${\displaystyle M_{\odot }}$ based on the Sunyaev–Zel'dovich effect.^[3][4] The cluster field has a galaxy density of approximately ${\displaystyle 13.1}$ galaxies per arcminute${\displaystyle ^{-2}}$, according to ACS data.^[3][4]

At the time of its discovery, SPT-CL J0546−5345 was the most massive galaxy cluster at ${\displaystyle z}$ > 1 until 2011 with the discovery of SPT-CL J2106−5844.^[2][8] Chandra observations measured the cluster's X-ray temperature as ${\displaystyle T_{X}={\displaystyle 6.7_{-0.9}^{+1.4}}(keV)}$.^[1] Follow-up observations using the Spitzer, Chandra, and other optical telescopes have allowed for identification and redshift measurements of cluster members within the galaxy.

SPT-CL J0546−5345 formed early through major galaxy mergers and later experienced adiabatic expansion driven by AGN winds causing mass loss.^[3]

Out of 49 cluster members, 21 were studied, with 18 of them exhibiting spectral features of Ca H & K lines while 3 displayed singly ionized oxygen (O${\displaystyle _{II}}$) lines. The cluster was also found to have a velocity dispersion of ${\displaystyle \sigma =1179_{-167}^{+232}}$ km s${\displaystyle ^{-1}}$. At the time of its discovery, SPT-CL J0546−5345 was the most dynamically active high-massive cluster identified at ${\displaystyle z}$ > 1.^[2]