Cloverleaf quasar

Short description: Rare example of a quadruply-lensed quasar

Cloverleaf, H1413+117, QSO 1415+1129

Observation data (Epoch J2000)
Right ascension|  14 h 15 m 46.27 s
Declination| +11° 29 ′ 43.4 ″
Redshift| 2.56
Distance| 11 Gly
Apparent magnitude (V)| 17
Notable features| Four-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.

## Contents

* 1 Quasar
* 1.1 Black hole
* 1.2 Lensing galaxy and partial Einstein ring
* 2 History
* 3 See also
* 4 References
* 5 Further reading
* 6 External links

## 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.[citation needed]

### Black hole

The X-rays would be magnified much more than the visible light if they came from a region around the central supermassive black hole of the lensing galaxy that was smaller than the origin region of 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.[citation needed]

### 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]

## History

The Cloverleaf quasar was discovered in 1988. Data on the Cloverleaf collected by the Chandra X-ray Observatory in 2004 were 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 found 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.[citation needed]

## See also

* List of quasars

## References

1. ↑ S. Venturini; P. M. Solomon (2003). "The Molecular Disk in the Cloverleaf Quasar". Astrophysical Journal 590 (2): 740–745. doi:10.1086/375050. Bibcode: 2003ApJ...590..740V.
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. doi:10.1038/nature02149. PMID 14668856. Bibcode: 2003Natur.426..636S.
3. ↑ D. A. Riechers (2006). "First Detection of HCO+ Emission at High Redshift". Astrophysical Journal Letters 645 (1): L13–L16. doi:10.1086/505908. Bibcode: 2006ApJ...645L..13R.
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. Bibcode: 2007A&A...470..467C.

## Further reading

* R. Barvainis; L. Tacconi; R. Antonucci; D. Alloin; P. Coleman (2002). "Extremely strong carbon monoxide emission from the Cloverleaf quasar at a redshift of 2.5". Nature 371 (6498): 586–588. doi:10.1038/371586a0. Bibcode: 1994Natur.371..586B.
* C. M. Bradford (2009). "The Warm Molecular Gas Around the Cloverleaf Quasar". Astrophysical Journal 705 (1): 112. doi:10.1088/0004-637X/705/1/112. Bibcode: 2009ApJ...705..112B.

## External links

* Chandra at Havard CfA, "Cloverleaf Quasar: Chandra Looks Over a Cosmic Four-Leaf Clover", 20 February 2009

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