| Perseus cluster | |
|---|---|
 Chandra X-ray Observatory observations of the central regions of the Perseus galaxy cluster. Image is 284 arcsec across.RA 03h 19m 47.60sDec +41° 30' 37.00" inPerseus. Observation dates: 13 pointings between August 8, 2002 and October 20, 2004. Color code: Energy (Red 0.3–1.2 keV, Green 1.2-2 keV, Blue 2–7 keV). Instrument: ACIS. | |
| Observation data (EpochJ2000) | |
| Constellation(s) | Perseus |
| Right ascension | 03hh 18m[1] |
| Declination | +41° 30′[1] |
| Brightest member | NGC 1275 |
| Number of galaxies | >1000[1] |
| Richness class | 2[2] |
| Bautz–Morgan classification | II-III[2] |
| Redshift | 0.01790 (5 366 km/s)[1] |
| Distance | 73.6 Mpc (240.05 Mly)h−1 0.705[1] |
| X-rayflux | 9.1×10−11erg s−1 cm−2 (2–10keV)[1] |
| Other designations | |
| Abell 426,[1] NGC 1275 Cluster,[1]LGG 88 | |
ThePerseus cluster (Abell 426) is acluster of galaxies in the constellationPerseus. It has a recession speed of 5,366 km/s and a diameter of 863′.[1] It is one of the most massive objects in the knownuniverse, containing thousands of galaxies immersed in a vast cloud of multimillion-degree gas.
The Perseus galaxy cluster is the brightest cluster in the sky when observed in the X-ray band.[3]
The cluster contains the radio source3C 84 that is currently blowing bubbles ofrelativistic plasma into the core of the cluster. These are seen as holes in an X-ray image of the cluster, as they push away the X-ray emitting gas. They are known asradio bubbles, because they appear as emitters of radio waves due to the relativistic particles in the bubble. The galaxyNGC 1275 is located at the centre of the cluster, where the X-ray emission is brightest.
The first detection of X-ray emission from the Perseus cluster (astronomical designation Per XR-1) occurred during anAerobee rocket flight on March 1, 1970. The X-ray source may be associated with NGC 1275 (Per A, 3C 84), and was reported in 1971.[4] If the source is NGC 1275, then Lx is about 4 x 1045 ergs/s.[4] More detailed observations fromUhuru confirmed the earlier detection and its source within the Perseus cluster.[5]
In 2003, a team ofastronomers led byAndrew Fabian at Cambridge University discovered one of the deepestnotes ever detected, after 53 hours ofChandra observations.[6] No human will actually hear the note, because its time period between oscillations is 9.6 million years, which is 57octaves below the keys in the middle of a piano.[6] The sound waves appear to be generated by the inflation of bubbles of relativistic plasma by the centralactive galactic nucleus inNGC 1275. The bubbles are visible as ripples in theX-ray band since the X-ray brightness of theintracluster medium that fills the cluster is strongly dependent on the density of the plasma. In May 2022, NASA reported thesonification (converting astronomical data associated withpressure waves intosound) of the black hole at the center of the Perseus galaxy cluster.[7][8]
A similar case also happens in the nearbyVirgo Cluster, generated by an even larger supermassive black hole in the galaxyMessier 87, also detected by Chandra. Like the former, no human will hear the note. The tone is variable, and even lower than those generated by NGC 1275, from 56 octaves below middle C on minor eruptions, to as low as 59 octaves below middle C on major eruptions.[9]
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