Q0957 + 561
| Q0957 + 561 | |
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Observation dates equinox : J2000.0 , epoch : J2000.0 |
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| Constellation | Ursa Major |
| Right ascension | 10 h 01 m 20.99 s |
| declination | + 55 ° 53 ′ 56.5 ″ |
| Gravitational lens | |
| Type | Galaxy clusters with cD galaxy |
| Brightness (V-band) | G1: 21.9 mag |
| Redshift | 0.36 |
| Time-of-flight distance | 4 billion ly |
| Moving distance | 1.4 billion pc |
| Pictured object | |
| Type | quasar |
| Brightness (V-band) | A: 16.7 mag B: 16.5 mag |
| Angular expansion | about 6" |
| Redshift | 1.41 |
| Time-of-flight distance | 9 billion ly |
| Moving distance | 4 billion pc |
| Catalog names | Q0957 + 561 • QSO 0957 + 561 |
| history | |
| Explorer | Dennis Walsh (UK) Robert Carswell (UK) Ray Weymann (USA) |
| discovery | March 1979 |
Q0957 + 561 , also known as QSO 0957 + 561 , Zwillingsquasar (engl. Twin Quasar ) or multiply imaged quasar (engl. Double Quasar ), is a by a gravitational lens twice mapped Quasar in the constellation Ursa Major , about 10 arc minutes north of the NGC 3079 . Q0957 + 561 was the first multi-image gravitational lens system to be discovered and is now one of the best-studied objects of its kind.
Recent publications express serious doubts as to whether there is an “ordinary”, very massive black hole in the center of this quasar . Rather, it is supposed to be a new phenomenon that the astronomers at the Harvard-Smithsonian Center for Astrophysics refer to as Magnetospheric Eternally Collapsing Object, or MECO for short .
Gravitational lens system
Due to the curvature of spacetime caused by the mass of the gravitational lens, the two images A and B of the quasar are created, which are 6 arc seconds apart. There is a time lag of 417.1 ± 0.1 days between the two images. The images have an apparent brightness of 16.7 mag for component A and 16.5 mag for component B. The quasar has a redshift of z = 1.41 (9 billion light years).
The main components of the gravitational lens are a galaxy cluster at z = 0.36 (4 billion ly) and its cD galaxy (G1) as well as a galaxy group at z = 0.5. The cD galaxy G1 of the galaxy cluster is only about one arc second away from image B of the quasar.
Historical classification
First gravitational lens with quasar
The quasars QSO 0957 + 561A / B, called Twin Quasars (twin quasars), were installed in the spring of 1979 by the Anglo-American team led by the British Dennis Walsh and Robert Carswell and the American Ray Weymann with the help of the 2.1 meter telescope on the putty -Peak National Observatory discovered in Arizona / USA. The team noticed that the quasars are not only unusually close together, but that the redshift and the light spectrum in the visible range are amazingly similar. They published the speculation that it is likely just a quasar that appears double due to a gravitational lensing effect .
The twin quasar quickly attracted the attention of specialist astronomers, as it is one of the first directly visible evidence of a gravitational lens, as described in 1915 by Albert Einstein in his general theory of relativity .
Scientific clarification
Critics, however, pointed out differences between the two quasars in the radio wave range. For example, a team led by David Roberts at the VLA (Very Large Array) in Socorro, New Mexico / USA, discovered a matter jet of quasar A in summer 1979 , to which there was apparently no equivalent in quasar B. In addition, the distance between the two images at 6 arc seconds was too great to be generated by the galaxy G1 found close to quasar B alone.
It was only on high-resolution images of the region that were recorded with VLBI (Very Long Baseline Interferometry) that a team led by Marc V. Gorenstein found clearly mirror-symmetrical matter jets of quasars A and B in 1983. It was also possible to determine that the galaxy G1 is part of a cluster of galaxies , which increases the deflection of light.
The slight spectral differences between Quasar A and B are explained by the fact that different conditions can prevail on the two light paths, such as different densities of the intergalactic medium and thus different extinctions .
Time delay of the images
Due to the observation period of over 30 years, it is now certain that the northern image A of the quasar reaches the earth around 14 months earlier than the southern image B, which obviously covers a path 1.1 light years longer. In 2003, Wesley N. Colley published a time delay of 417.09 ± 0.07 days as the result of two 10-day observation phases in January 2000 and March 2001. Twelve observatories distributed around the earth took a total of 3543 images around the clock recordings and then evaluated.
| Q0957 + 561 / MECO model | |
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Schematic illustration with the most important luminous structures, which were determined by reverberation microlens analysis:
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Discovery of possible exo-planets
In 1996, the twin quasar made a name for itself when a team from the Harvard-Smithsonian Center for Astrophysics led by Rudy E. Schild observed a temporary anomaly in image B that was not found in image A. A possible explanation is the transit of a planet of the galaxy G1 with three times the mass of the earth, through the beam path of picture B. That would be the most distant observed planet with 4 billion light years. Further highly significant observations of this kind reinforce the suspicion that dark matter in the form of very distant planets repeatedly crosses the beam path B of the quasar.
MECO hypothesis
Astronomers at the Harvard-Smithsonian Center for Astrophysics under the direction of Rudy E. Schild have been investigating Q0957 + 561 with up to 14 telescopes in international cooperation since the 1990s . By synchronizing images A and B, the optical resolution of the measured values was increased due to the gravitational lensing effect , as in a system of two telescopes . Rudy Schild (CfA), Darryl Leiter (Marwood Astrophysics Research Center) and Stan Robertson (Southwestern Oklahoma State Univ.) Named the central object with 3-4 billion solar masses "Magnetospheric Eternally Collapsing Object" or MECO for short . "We don't call the object a black hole because we found evidence that the object contains a magnetic field anchored inside that penetrates the surface of the central collapsing object and interacts with the quasar's surroundings," said Schild.
Schild and his colleagues found out that the 1000 AU wide matter jets over the poles do not begin near the Schwarzschild radius (around 80 AU) , as expected for black holes , but 8000 AU away from the center. In addition, the brightly glowing, hot inner edge of the accretion disk has a radius of 2000 AU. Both indicate that the central object itself generates a strong, rapidly rotating magnetic field that uses a “magnetic propeller effect” to keep the area around the central object free of matter. This contradicts the previous view that the magnetic fields of quasars are generated by ions in the rapidly rotating accretion disk and that this accretion disk ends directly at the event horizon of the Schwarzschild radius.
Observability
| Q0957 + 561 star field | |
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Because of its low brightness of 16.5 mag, the Twin Quasar Q0957 + 561 cannot be observed with smaller telescopes. Only from a telescope opening (aperture) of 50 cm can the two components be separated with long-exposure CCD camera images with good seeing .
Even with large optical telescopes, as with ordinary stars, only small, round diffraction disks are found , hence the name “quasar” for “quasi-stellar”. All further findings result from the scientific analysis of the electromagnetic waves received by this object .
The galaxy field around the main galaxy G1 (21.9 mag), which is responsible for the gravitational lensing effect, also results in only small blurred spots when using optical instruments with a very large aperture and long exposure time.
The object is listed in various astronomical catalogs , including USNO-A2.0 (1998) and USNO-B1.0 (2003). With the help of the United States Naval Observatory (USNO) laypeople can also download photographic recordings of the star field by entering the astronomical coordinates and study the properties of the listed objects.
See also
Web links
- Observing the Twin Quasar, accessed April 18, 2011
- Signpost to the twin quasar (German) accessed April 18, 2011
- USNO Archive Search Results for Field… USNO accessed April 18, 2011
- Q0957 + 561: The historically first lens with Quasar University of Cologne (English) accessed April 21, 2011
- SKY-MAP.ORG map of the area around the twin quasar sky-map.org (English) accessed June 29, 2011
References and comments
- ↑ a b c d Science: The Mysterious Celestial Twins ( English ) In: TIME . October 1, 1979. Retrieved April 16, 2011.
- ↑ Magnetospheric eternally collapsing object in the English language Wikipedia
- ↑ a b c Rudolph E. Schild, Darryl J. Head: Black Hole or MECO? Decided by a thin luminous ring structure deep within quasar Q0957 + 561 (PDF; 1.1 MB) In: Journal of Cosmology, Vol 6 . 2010. Retrieved April 16, 2011.
- ↑ a b Tomislav Kundíc, u. a .: A robust determination of the time delay in 0957 + 561A, B and a measurement of the global value of Hubble's constant (PDF; 701 kB) 1997. Retrieved on April 16, 2011.
- ↑ a b Wesley N. Colley, et al .: Around-the-Clock Observations of the Q0957 + 561A, B Gravitationally Lensed Quasar. II. Results for the Second Observing Season . In: The Astrophysical Journal, Vol.587, No.1 . April 10, 2003. Retrieved April 20, 2011.
- ^ D. Walsh, RF Carswell, RJ Weymann: 0957 + 561A, B: twin quasistellar objects or gravitational lens? (PDF) In: Nature, 279 . Pp. 381-384. May 31, 1979. Retrieved April 16, 2011.
- ↑ Albert Einstein: Lens-like action of a star by the deviation of light in the gravitational field (PDF; 112 kB) In: Science, 84 . Pp. 506-507. 1936. Retrieved April 16, 2011.
- ↑ Peter Schneider: Introduction to Extragalactic Astronomy and Cosmology . Jumper. Pp. 125-127. 2008. Retrieved April 16, 2011.
- ↑ Andreas Müller: Quasars in a double pack . In: Lexicon of Astrophysics . 2007. Retrieved April 16, 2011.
- ↑ Govert Schilling: Science: Do alien worlds throng faraway galaxy? . New Scientist (issue 2037). June 6, 1996. Retrieved April 16, 2011.
- ↑ Wesley N. Colley, Rudolph E. Schild: A Rapid Microlensing Event in the Q0957 + 561 A, B Gravitational Lens System . March 7, 2003, arxiv : astro-ph / 0303170 .
- ↑ Magnetospheric eternally collapsing object in the English language Wikipedia
- ^ New Picture of Quasar Emerges . physorg.com. July 25, 2006. Retrieved April 16, 2011.
- ↑ Bernd Nies: Deep-Sky Corner / UMa / QSO0957 + 561A / B: Twin Quasar . June 8, 2009. Retrieved April 18, 2011.
- ↑ United States Naval Observatory USNO archives Search Results for Field ... ( English ) June 8, 2009. Archived from the original on April 10, 2011. Information: The archive link is automatically inserted and not yet tested. Please check the original and archive link according to the instructions and then remove this notice. Retrieved April 18, 2011.
