The MAssive Cluster Survey (MACS) compiled and characterized a sample of very X-ray luminous (and thus, by inference, massive), distant clusters of galaxies. The sample comprises 124 spectroscopically confirmed clusters at 0.3 < z < 0.7. Candidates were selected from the

ROSAT ROSAT (short for Röntgensatellit; in German X-rays are called Röntgenstrahlen, in honour of Wilhelm Röntgen) was a German Aerospace Center-led satellite X-ray telescope, with instruments built by West Germany, the United Kingdom and the Un ...

All-Sky Survey data. Cluster candidates that are south of

declination In astronomy, declination (abbreviated dec; symbol ''δ'') is one of the two angles that locate a point on the celestial sphere in the equatorial coordinate system, the other being hour angle. The declination angle is measured north (positive) or ...

-40° cannot be observed from Mauna Kea and fit into the Southern MACS (SMACS) extension. They are also being investigated when facilities are available.

History

One of the

galaxy cluster A galaxy cluster, or a cluster of galaxies, is a structure that consists of anywhere from hundreds to thousands of galaxies that are bound together by gravity, with typical masses ranging from 1014 to 1015 solar masses. Clusters consist of galax ...

s, MACS J0647+7015 was found to have gravitationally lensed the most distant

galaxy A galaxy is a Physical system, system of stars, stellar remnants, interstellar medium, interstellar gas, cosmic dust, dust, and dark matter bound together by gravity. The word is derived from the Ancient Greek, Greek ' (), literally 'milky', ...

( MACS0647-JD) then ever imaged, in 2012, by CLASH. The first statistical study of X-ray cavities in distant clusters of galaxies was performed by analyzing the

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 ...

X-ray observations of MACS. Out of 76 clusters representing a sample of the most luminous X-ray clusters, observers found 13 cut and clear cavities and 7 possible cavities. A new radio halo, as well as a relic applicant, were found in MACS, with the help of the Giant Meterwave Radio Telescope and the Karoo Array Telescope-7. The discovered radio halo has a largest linear scale of about 0.9Mpc. X-ray chosen clusters are almost free of projection effects because they are composed of intrinsically massive, gravitationally collapsed systems.

MACS team

The MACS team consists of: * Harald Ebeling,

University of Hawaii A university () is an educational institution, institution of tertiary education and research which awards academic degrees in several Discipline (academia), academic disciplines. ''University'' is derived from the Latin phrase , which roughly ...

, USA * Alastair Edge,

University of Durham Durham University (legally the University of Durham) is a collegiate public research university in Durham, England, founded by an Act of Parliament in 1832 and incorporated by royal charter in 1837. It was the first recognised university to ...

, UK * J. Patrick Henry,

, USA

Survey notation

Objects are labelled as JHHMM.m+DDMM where HHMM+DDMM are the coordinates in the J2000 system. Here H, D, and M refer to hours, degrees, and minutes, respectively, and m refers to tenths of minutes of time. * HH Hours of right ascension * MM.m Minutes of right ascension or declination * DD.d Degrees in declination

Southern MAssive Cluster Survey

The Southern MAssive Cluster Survey (SMACS) involved the

Hubble Space Telescope The Hubble Space Telescope (HST or Hubble) is a space telescope that was launched into low Earth orbit in 1990 and remains in operation. It was not the Orbiting Solar Observatory, first space telescope, but it is one of the largest and most ...

Notable surveyed objects

References

External links

* http://mnras.oxfordjournals.org/content/407/1/83.short * http://mnras.oxfordjournals.org/content/421/2/1360.short * http://mnras.oxfordjournals.org/content/458/2/1803.abstract {{Portal bar, Astronomy, Stars, Outer space Astronomical surveys