Twin Quasar

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The Twin Quasar Q0957+561
QSO B0957+0561.jpg
The Twin Quasar QSO 0957+561, which lies 8.7 billion light-years from Earth, is seen right in the center of this picture. [1]
Observation data (Epoch J2000)
Constellation Ursa Major
Right ascension 10h 01m 20.99s
Declination +55° 53 56.5
Redshift 1.413
Distance 8,700,000,000 ly (2,400,000,000 pc)
Type Rad
Apparent dimensions (V)6" distance
Apparent magnitude  (V)16.7
Other designations
Twin Quasar, Double Quasar, Twin QSO, QSO  0957+561, Q0957+561, SBS 0957+561, TXS 0957+561, 8C  0958+561, PGC  2518326, A: USNO-A2 1425-7427021 B:USNO-A2 1425-7427023
See also: Quasar, List of quasars

The Twin Quasar (also known as Twin QSO, Double Quasar, SBS 0957+561, TXS 0957+561, Q0957+561 or QSO 0957+561 A/B), was discovered in 1979 and was the first identified gravitationally lensed object[ citation needed ], not to be confused with the first detection of light deflection in 1919. It is a quasar that appears as two images, a result from gravitational lensing caused by the galaxy YGKOW G1 that is located directly between Earth and the quasar.

Contents

Quasar

The Twin Quasar is a single quasar whose appearance is distorted by the gravity of another galaxy much closer to Earth along the same line of sight. This gravitational lensing effect is a result of the warping of space-time by the nearby galaxy, as described by general relativity. The single quasar thus appears as two separate images, separated by 6 arcseconds. Both images have an apparent magnitude of 17, with the A component having 16.7 and the B component having 16.5. There is a 417 ± 3-day time lag between the two images. [2]

The Twin Quasar lies at redshift z = 1.41 (8.7 billion ly), while the lensing galaxy lies at redshift z = 0.355 (3.7 billion ly). The lensing galaxy with apparent dimension of 0.42×0.22 arcminutes lies almost in line with the B image, lying 1 arcsecond off. The quasar lies 10 arcminutes north of NGC 3079, in the constellation Ursa Major. The astronomical data services SIMBAD and NASA/IPAC Extragalactic Database (NED) list several other names for this system.

Lens

The lensing galaxy, YGKOW G1 [3] (sometimes called G1 or Q0957+561 G1), is a giant elliptical (type cD) lying within a cluster of galaxies that also contributed to the lensing.

History

The quasars QSO 0957+561A/B were discovered in early 1979 by an Anglo-American team around Dennis Walsh, Robert Carswell and Ray Weyman, with the aid of the 2.1 m Telescope at Kitt Peak National Observatory in Arizona, United States. The team noticed that the two quasars were unusually close to each other, and that their redshift and visible light spectrum were very similar to each other. They published their suggestion of "the possibility that they are two images of the same object formed by a gravitational lens". [4]

The Twin Quasar was one of the first directly observable effects of gravitational lensing, which was described in 1936 by Albert Einstein as a consequence of his 1916 General Theory of Relativity, though in that 1936 paper he also predicted "Of course, there is no hope of observing this phenomenon directly." [5]

Critics identified a difference in appearance between the two quasars in radio frequency images. In mid-1979, a team led by David Roberts at the Very Large Array (VLA) near Socorro, New Mexico, discovered a relativistic jet emerging from quasar A with no corresponding equivalent in quasar B. [6] Furthermore, the distance between the two images, 6 arcseconds, was too great to have been produced by the gravitational effect of the galaxy G1, a galaxy identified near quasar B.

In 1980, Peter J. Young and collaborators discovered that galaxy G1 is part of a galaxy cluster which increases the gravitational deflection and can explain the observed distance between the images. [7] Finally, a team led by Marc V. Gorenstein observed essentially identical relativistic jets on very small scales from both A and B in 1983 using Very Long Baseline Interferometry (VLBI). [8] Subsequent, more detailed VLBI observations demonstrated the expected (parity reversed) magnification of the image B jet with respect to image A jet. [9] The difference between the large-scale radio images is attributed to the special geometry needed for gravitational lensing, which is satisfied by the quasar but not by all of the extended jet emission seen by the VLA near image A.

Slight spectral differences between quasar A and quasar B can be explained by different densities of the intergalactic medium in the light paths, resulting in differing extinction. [10]

30 years of observation made it clear that image A of the quasar reaches earth about 14 months earlier than the corresponding image B, resulting in a difference of path length of 1.1 ly.

Possible planet

In 1996, a team at Harvard-Smithsonian Center for Astrophysics led by Rudy E. Schild discovered an anomalous fluctuation in one image's light curve, which they speculated was caused by a planet approximately three Earth masses in size within the lensing galaxy. This conjecture cannot be proven because the chance alignment that led to its discovery will never happen again. If it could be confirmed, however, it would make it the most distant known planet, 4 billion ly away. [11]

Candidate magnetospheric eternally collapsing object

In 2006, R. E. Schild suggested that the accreting object at the heart of Q0957+561 is not a supermassive black hole, as is generally believed for all quasars, but a magnetospheric eternally collapsing object. Schild's team at the Harvard-Smithsonian Center for Astrophysics asserted that "this quasar appears to be dynamically dominated by a magnetic field internally anchored to its central, rotating supermassive compact object" (R. E. Schild). [12]

See also

Related Research Articles

<span class="mw-page-title-main">Quasar</span> Active galactic nucleus containing a supermassive black hole

A quasar is an extremely luminous active galactic nucleus (AGN). It is sometimes known as a quasi-stellar object, abbreviated QSO. The emission from an AGN is powered by a supermassive black hole with a mass ranging from millions to tens of billions of solar masses, surrounded by a gaseous accretion disc. Gas in the disc falling towards the black hole heats up and releases energy in the form of electromagnetic radiation. The radiant energy of quasars is enormous; the most powerful quasars have luminosities thousands of times greater than that of a galaxy such as the Milky Way. Quasars are usually categorized as a subclass of the more general category of AGN. The redshifts of quasars are of cosmological origin.

<span class="mw-page-title-main">Gravitational lens</span> Light bending by mass between source and observer

A gravitational lens is a distribution of matter or a point particle between a distant light source and an observer that is capable of bending the light from the source as the light travels toward the observer. This effect is known as gravitational lensing, and the amount of bending is one of the predictions of Albert Einstein's general theory of relativity. Treating light as corpuscles travelling at the speed of light, Newtonian physics also predicts the bending of light, but only half of that predicted by general relativity.

<span class="mw-page-title-main">3C 273</span> Brightest quasar from Earth located in the constellation Virgo

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<span class="mw-page-title-main">Radio galaxy</span> Type of active galaxy that is very luminous at radio wavelengths

A radio galaxy is a galaxy with giant regions of radio emission extending well beyond its visible structure. These energetic radio lobes are powered by jets from its active galactic nucleus. They have luminosities up to 1039 W at radio wavelengths between 10 MHz and 100 GHz. The radio emission is due to the synchrotron process. The observed structure in radio emission is determined by the interaction between twin jets and the external medium, modified by the effects of relativistic beaming. The host galaxies are almost exclusively large elliptical galaxies. Radio-loud active galaxies can be detected at large distances, making them valuable tools for observational cosmology. Recently, much work has been done on the effects of these objects on the intergalactic medium, particularly in galaxy groups and clusters.

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<span class="mw-page-title-main">Einstein ring</span> Feature seen when light is gravitationally lensed by an object

An Einstein ring, also known as an Einstein–Chwolson ring or Chwolson ring, is created when light from a galaxy or star passes by a massive object en route to the Earth. Due to gravitational lensing, the light is diverted, making it seem to come from different places. If source, lens, and observer are all in perfect alignment (syzygy), the light appears as a ring.

<span class="mw-page-title-main">Halton Arp</span> American astronomer

Halton Christian "Chip" Arp was an American astronomer. He was known for his 1966 Atlas of Peculiar Galaxies, which catalogues many examples of interacting and merging galaxies, though Arp disputed the idea, claiming apparent associations were prime examples of ejections. Arp published Seeing Red: Redshift, Cosmology and Academic Science in 1998. Arp was also known as a critic of the Big Bang theory and for advocating a non-standard cosmology incorporating intrinsic redshift.

<span class="mw-page-title-main">Einstein Cross</span> Gravitationally lensed image of a quasar

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<span class="mw-page-title-main">Gravitational microlensing</span> Astronomical phenomenon due to the gravitational lens effect

Gravitational microlensing is an astronomical phenomenon due to the gravitational lens effect. It can be used to detect objects that range from the mass of a planet to the mass of a star, regardless of the light they emit. Typically, astronomers can only detect bright objects that emit much light (stars) or large objects that block background light. These objects make up only a minor portion of the mass of a galaxy. Microlensing allows the study of objects that emit little or no light. Gravitational microlensing was first theorised by Refstal (1964) and first discovered by Irwin et al (1988). The first object in the sky where it was discovered was the Einstein cross or Huchra lens 2237 +0305. The initial lightcurve of the object was published by Corrigan et al (1991). In Corrigan et al (1991) they calculated that the object causing the microlensing was a Jupiter sized object. This was the first discovery of a planet in another galaxy.

<span class="mw-page-title-main">APM 08279+5255</span> Quasar

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<span class="mw-page-title-main">Strong gravitational lensing</span>

Strong gravitational lensing is a gravitational lensing effect that is strong enough to produce multiple images, arcs, or even Einstein rings. Generally, for strong lensing to occur, the projected lens mass density must be greater than the critical density, that is . For point-like background sources, there will be multiple images; for extended background emissions, there can be arcs or rings. Topologically, multiple image production is governed by the odd number theorem.

The Cloverleaf quasar is a bright, gravitationally lensed quasar.

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<span class="mw-page-title-main">TON 618</span> Quasar and Lyman-alpha blob in the constellation Canes Venatici

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<span class="mw-page-title-main">Georges Meylan</span> Swiss astronomer

Georges Meylan is a Swiss astronomer, born on July 31, 1950, in Lausanne, Switzerland. He was the director of the Laboratory of Astrophysics of the Swiss Federal Institute of Technology (EPFL) in Lausanne, Switzerland, and now a professor emeritus of astrophysics and cosmology at EPFL. He is still active in both research and teaching.

<span class="mw-page-title-main">Peter J. Young</span> British astrophysicist

Peter John Young was a British astrophysicist, who made major contributions in theory and observation to extragalactic astronomy and cosmology. During five years at the California Institute of Technology in 1976-1981 he carried out foundational research, including the discovery of the intergalactic medium; the detection of a supermassive black hole in the galaxy M87; detecting the optical counterpart to the first gravitational lens; developing the theory of gravitational microlensing.

References

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  3. Nomenclature of Celestial Objects (Result I)
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  5. Einstein, Albert (1936). "Lens-like action of a star by the deviation of light in the gravitational field". Science. 84 (2188): 506–507. Bibcode:1936Sci....84..506E. doi:10.1126/science.84.2188.506. PMID   17769014.
  6. TIME (1 October 1979). "Science: The Mysterious Celestial Twins". Time. Archived from the original on 7 November 2012.
  7. Young, P.; Gunn, J.E.; Oke, J.B.; Westphal, J.A. & Kristian, J. (1980). "The double quasar Q0957 + 561 A, B – A gravitational lens image formed by a galaxy at Z = 0.39". Astrophysical Journal. 241: 507–520. Bibcode:1980ApJ...241..507Y. doi: 10.1086/158365 .
  8. M.V. Gorenstein; et al. (1984). "The milli-arcsecond images of Q0957 + 561". Astrophysical Journal. 287: 538–548. Bibcode:1984ApJ...287..538G. doi:10.1086/162712.
  9. M.V. Gorenstein; et al. (1988). "VLBI Observations of the Gravitational Lens System 0957+561: Structure and Relative Magnification of the A and B Images". Astrophysical Journal. 334: 42–58. Bibcode:1988ApJ...334...42G. doi: 10.1086/166816 .
  10. Andreas Müller (August 2007). ""Quasare im Doppelpack" aus "Astro-Lexikon"" (in German).
  11. Govert Schilling (6 July 1996). "Do alien worlds throng faraway galaxy?". New Scientist . No. 2037.
  12. "Research Sheds New Light on Quasars". SpaceDaily.com. 26 July 2006.