SPT-CL J0546-5345 is a massive galaxy cluster discovered at the

South Pole Telescope The South Pole Telescope (SPT) is a diameter telescope located at the Amundsen–Scott South Pole Station, Antarctica. The telescope is designed for observations in the microwave, millimeter-wave, and submillimeter-wave regions of the electrom ...

in 2008 and was the first galaxy cluster discovered at

z

> 1 using the

Sunyaev–Zeldovich effect The Sunyaev–Zeldovich effect (named after Rashid Sunyaev and Yakov B. Zeldovich and often abbreviated as the SZ effect) is the spectral distortion of the cosmic microwave background (CMB) through inverse Compton scattering by high-energy e ...

. It is thought to be 7 billion light years away and has a

redshift In physics, a redshift is an increase in the wavelength, and corresponding decrease in the frequency and photon energy, of electromagnetic radiation (such as light). The opposite change, a decrease in wavelength and increase in frequency and e ...

z

= 1.067. The cluster hosts 49 galaxy members and has an estimated total mass of 4.85 x 10¹⁴

M_\odot

based on the Sunyaev-Zel'dovich effect. The cluster field has a galaxy density of approximately

13.1

galaxies per arcminute

^

, according to ACS data. At the time of its discovery, SPT-CL J0546-5345 was the most massive galaxy cluster at

z

> 1 until 2011 with the discovery of SPT-CL J2106-5844.

Chandra Chandra (), also known as Soma (), is the Hindu god of the Moon, and is associated with the night, plants and vegetation. He is one of the Navagraha (nine planets of Hinduism) and Dikpala (guardians of the directions). Etymology and other ...

observations measured the cluster's X-ray temperature as

T_X = 

(
k
e
V
)

. Follow-up observations using the Spitzer,

, 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 merger Galaxy mergers can occur when two (or more) Galaxy, galaxies collide. They are the most violent type of Interacting galaxy, galaxy interaction. The Gravitation, gravitational interactions between galaxies and the friction between the gas and Cosmi ...

s and later experienced

adiabatic expansion An adiabatic process (''adiabatic'' ) is a type of thermodynamic process that occurs without transferring heat between the thermodynamic system and its environment. Unlike an isothermal process, an adiabatic process transfers energy to the surr ...

driven by AGN winds causing mass loss. 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

_

) lines. The cluster was also found to have a

velocity dispersion In astronomy, the velocity dispersion (''σ'') is the statistical dispersion of velocities about the mean velocity for a group of astronomical objects, such as an open cluster, globular cluster, galaxy, galaxy cluster, or supercluster. By measu ...

\sigma = 1179_^

km s

^

. At the time of its discovery, SPT-CL J0546-5345 was the most dynamically active high-massive cluster identified at

z

> 1.

References

Galaxy clusters Pictor {{galaxy-stub

See also

References