Twin Quasar

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Twin Quasar
Observation data (Epoch J2000)
Constellation Ursa Major
Right ascension 10h 01m 20.99s
Declination +55° 53′ 56.5″
Redshift 1.413
Distance 7,800,000,000 ly (2,400,000,000 pc)
Type Rad
Apparent dimensions (V) 0.42´× 0.22´
Apparent magnitude (V) 16.7
Other designations
Double Quasar, QSO 0957+561, 8C 0958+561, PGC 2518326
See also: Quasar, List of quasars
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The Twin Quasar (Double Quasar) or Old Faithful is also known as Q0957+561, or QSO 0957+561. It was the first identified gravitationally lensed object.

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[edit] Quasar

Q0957+561 A (QSO 0957+561 A) and Q-0957+561 B (QSO 0957+561 B) is a double-imaged quasar, meaning that an intervening mass concentration between Earth and the quasar bends light so that two images of the quasar appear in the sky. This is known as gravitational lensing, and is a consequence of Einsteinian warped space-time. The 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 lies almost in line with the B image, lying 1" off. The quasar lies 10" north of NGC 3079, in the constellation Ursa Major.

The Twin Quasar's two images are separated by 6". 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.[1]

[edit] Lens

The lensing galaxy, YGKOW G1[2] (sometimes called G1 or Q0957+561 G1), is a giant elliptical (type cD) lying within a cluster of galaxies that also contribute to the lensing.

[edit] Suspected planet

A microlensing event in 1996 observed by R. E. Schild in the A lobe has led to a controversial, and unconfirmable theory that there is a planet approximately three Earth masses in size in the lensing galaxy. The speculation cannot be confirmed 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.

[edit] Magemtospheric Eternally Collapsing Objects MECO In Radio Loud and Radio Quiet Quasars

R. E. Schild, D. Leiter, and S. Robertson announced findings which suggest that the object at the heart of the radio loud quasar Q0957+561 is not a supermassive black hole, as is currently believed to be the case for all quasars. Schild and his team at the Harvard-Smithsonian Center for Astrophysics found that the jets originated 8000 AU from the poles of the centre, in a region 1000AU across. In addition they found that the accretion disc in this quasar appeared to be truncated at 2000AU from the centre, and the inner edge surrounding the apparently empty inner region of the disc contained a very thin annular region that was found to be intensely radiating. There also appeared to be a broad conic wind outflow from the accretion disc which created a luminous Broad Line Emission Region Elvis structure (cf. Martin Elvis). On the basis of these observations they came to the conclusion that "This quasar appears to be dynamically dominated by an intrinsic magnetic field which is internally anchored to its central, rotating supermassive compact object".

In "radio loud" quasars, which make up about 10% of the total quasar populations, some of that gas is forcefully ejected outward in two opposing jets at nearly the speed of light. On the other hand the remaining 90% of the quasars do not exhibit any jet structure and for that reason are "radio quiet". In order to better understand the difference between the two types of quasars, theorists struggle to understand the physics of the accretion disk and jets, while observers struggle to peer into the quasar's heart. However the manner in which the "central engine" is able to turn on radio emitting jet structures in radio loud quasars, while also being able to turn off the radio emitting jet structure in radio quiet quasars, is difficult problem for both theorists and observers because the central regions of quasars are so compact and the quasars so far away from Earth.

Using newly developed optical telescope techniques involving gravitational micro-lensing and reverberation analysis, Rudy Schild and his colleagues have also studied the internal structure of the radio quiet quasar Q2237 (known as the Einstein Cross), as well as the radio loud quasar Q0957 (known as the Twin) both of which are located more than 9 billion light-years from Earth. These two quasars, which are in distinctly different spectral states, have been observed to have central compact objects containing masses on the order of 3-4 billion Suns. For this reason most astrophysicists would consider the central objects in these two quasars to be "black holes," but Schild, Leiter, and Robertson's research has suggested otherwise. "We don't call the central objects in these quasars black holes because our observations indicate that these two quasars have central compact objects which contain internally anchored magnetic fields that are able to penetrate through the surface of their collapsed central objects and interact with the quasars accretion disk and its environment," they commented.

The researchers chose Q0957 and Q2237 because of their association with natural cosmic lenses. The gravity of nearby galaxies bends space, forming multiple images of the distant quasars and magnifying their light. Stars and planets within nearby galaxies can also affect the quasars light, causing small fluctuations in brightness (in a process called "micro-lensing") when they drift into the line of sight between Earth and the quasars.

Using this micro-lensing-reverberation technique on the radio loud quasar Q0957 Schild monitored the quasar's brightness for a period of 20 years, and led an international consortium of observers operating 14 telescopes to keep the object under steady around-the-clock watch at critical times. "With micro-lensing, we were able to discern more detail about the so-called 'black hole' in this quasar which is two- thirds of the way to the edge of the visible universe than we can from the black hole at the center of the Milky Way," said Schild. Through careful analysis, the team teased out details about the inner structure of this quasar For example, their calculations pinpointed the location where the jets form. "How when and where do these jets form? Even after 60 years of radio observations, we had no answer. Now the evidence is in, and we know," said Schild.

Schild, Leiter, and Robertson found that the jets in the radio loud quasar Q0957 appear to emerge from two regions 1,000 astronomical units in size (about 25 times larger than the Pluto-Sun distance) located 8,000 astronomical units directly above the poles of the central compact object. (An astronomical unit is defined as the average distance from the Earth to the Sun, or 93 million miles). However, that location would be expected only if the jets were powered by reconnecting magnetic field lines that were anchored to the rotating super massive compact object within the quasar. By interacting with a surrounding accretion disk, such spinning magnetic field lines spool up, winding tighter and tighter until they explosively unite, reconnect and break, releasing huge amounts of energy that power the jets. "This quasar appears to be dynamically dominated by an intrinsic magnetic field which is internally anchored to its central, rotating super massive compact object," they stated.

Since standard black hole models were found to be unable to explain the observed internal structure seen in the quasar Q0957, Schild and his colleagues, Darryl Leiter (Marwood Astrophysics Research Center and currenty a visitor at the National Radio Astronomy Observatory in Charlottesville Virginia) and Stanley Robertson (Southwestern Oklahoma State University), were led to propose a revolutionary new general relativistic theory for the quasar Q0957 in which the structure of the dominant magnetic field is intrinsic to the quasar's central, super massive compact object, rather than only being part of the accretion disk as thought by most researchers. "Our finding challenges the accepted view of black holes," said Leiter. "We've even proposed a new name for them Magnetospheric Eternally Collapsing Objects, or MECO," a magnetic generalization of the name coined in 1998 by Indian astrophysicist Abhas Mitra. This research suggests that, in addition to its mass and spin, the central compact object in Q0957 may have physical properties more like a highly red shifted, spinning magnetic dipole than like a black hole. According to this theory, a MECO does not have an event horizon, so any matter that is able to get by the magnetic propeller is gradually slowed down and stopped at the MECO's highly red shifted surface, with just a weak signal connecting the radiation from that matter to a distant observer. For this reason this signal has not been detected from Q0957 since it is very hard to observe.

On the basis of these observations and analysis Schild, Leiter, and Robertson were led to the conclusion that a simple and unified answer to the long-standing question: "Why are some quasars radio loud?" emerges naturally if the central objects of quasars are MECO, with radio-loud and radio-quiet states similar to the case of galactic black hole candidates.

This research was published in the March 2008 issue of Astronomical Journal, 135, 947 (2008). Also see the related publication Astronomical Journal, 132, 420,(2006) and http://arxiv.org/abs/astro-ph/0505518

.


[edit] See also

[edit] External links

[edit] References

[edit] Citations

  1. ^ Kundic, T., Turner, E.L., Colley, W.N., Gott, III, R., and Rhoads, J.E., ``A robust determination of the time delay in 0957+561A,B and a measurement of the global value of Hubble's constant, Astrophys. J., 482, 75-82, (1997).
  2. ^ Nomenclature of Celestial Objects (Result I)