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Cloverleaf quasar

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Cloverleaf, H1413+117, QSO 1415+1129
Observation data (Epoch J2000)
Right ascension  14 h  15 m  46.27 s
Declination+11°  29 ′  43.4 ″
Distance11 Gly
Apparent magnitude (V)17
Notable featuresFour-image lens, bright CO emission
Other designations
QSO J1415+1129 , QSO B1413+1143 , H 1413+117 , Clover Leaf Quasar
See also: Quasar, List of quasars

The Cloverleaf quasar (H1413+117, QSO J1415+1129) is a bright, gravitationally lensed quasar.


Molecular gas (notably CO) detected in the host galaxy associated with the quasar is the oldest molecular material known and provides evidence of large-scale star formation in the early universe. Thanks to the strong magnification provided by the foreground lens, the Cloverleaf is the brightest known source of CO emission at high redshift[1] and was also the first source at a redshift z = 2.56 to be detected with HCN[2] or HCO+ emission.[3] The 4 quasar images were originally discovered in 1984; in 1988, they were determined to be a single quasar split into four images, instead of 4 separate quasars. The X-rays from iron atoms were also enhanced relative to X-rays at lower energies. Since the amount of brightening due to gravitational lensing doesn't vary with the wavelength, this means that an additional object has magnified the X-rays. The increased magnification of the X-ray light can be explained by gravitational microlensing, an effect which has been used to search for compact stars and planets in our galaxy. Microlensing occurs when a star or a multiple star system passes in front of light from a background object. If a single star or a multiple star system in one of the foreground galaxies passed in front of the light path for the brightest image, then that image would be selectively magnified.

Black hole

The X-rays would be magnified much more than the visible light, if they came from a smaller region around the central supermassive black hole of the lensing galaxy than did the visible light. The enhancement of the X-rays from iron ions would be due to this same effect. The analysis indicates that the X-rays are coming from a very small region, about the size of the Solar System, around the central black hole. The visible light is coming from a region ten or more times larger. The angular size of these regions at a distance of 11 billion light years is tens of thousands times smaller than the smallest region that can be resolved by the Hubble Space Telescope. This provides a way to test models for the flow of gas around a supermassive black hole.

Lensing galaxy and partial Einstein ring

Data from NICMOS and a special algorithm resolved the lensing galaxy and a partial Einstein ring. The Einstein ring represents the host galaxy of the lensed quasar.[4]


The Cloverleaf quasar was discovered in 1988. Data on the Cloverleaf collected by the Chandra X-ray Observatory in 2004 was compared with that gathered by optical telescopes. One of the X-ray components (A) in the Cloverleaf is brighter than the others in both optical and X-ray light but was to be relatively brighter in X-ray than in optical light. The X-rays from iron atoms were also enhanced relative to X-rays at lower energies.

See also


  1. ^ S. Venturini; P. M. Solomon (2003). "The Molecular Disk in the Cloverleaf Quasar". Astrophysical Journal. 590: 740–745. arXiv:astro-ph/0210529. Bibcode:2003ApJ...590..740V. doi:10.1086/375050.
  2. ^ P. Solomon; P. Vanden Bout; C. Carilli; M. Guelin (2003). "The Essential Signature of a Massive Starburst in a Distant Quasar". Nature. 426 (6967): 636–638. arXiv:astro-ph/0312436. Bibcode:2003Natur.426..636S. doi:10.1038/nature02149. PMID 14668856.
  3. ^ D. A. Riechers; et al. (2006). "First Detection of HCO+ Emission at High Redshift". Astrophysical Journal Letters. 645: L13–L16. arXiv:astro-ph/0605437. Bibcode:2006ApJ...645L..13R. doi:10.1086/505908.
  4. ^ Chantry, Virginie; Magain, Pierre (August 2007). "Deconvolution of HST images of the Cloverleaf gravitational lens : detection of the lensing galaxy and a partial Einstein ring". Astronomy & Astrophysics. 470 (2): 467–473. doi:10.1051/0004-6361:20066839. ISSN 0004-6361.

Further reading

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Cloverleaf quasar
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