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0957 + 561 A, B: twin quasistellar objects or gravitational lens?
Nature
|May 31, 1979
Summary
Two quasars (QSOs), 0957 + 561 A and B, at redshift 1.405 show spectral similarities suggesting association. Their close proximity and spectral data raise questions about whether they are distinct objects or a gravitationally lensed single quasar.
Area of Science:
- Astronomy and Astrophysics
- Cosmology
- Gravitational Lensing
Background:
- Quasars (QSOs) are highly luminous active galactic nuclei.
- Gravitational lensing is the bending of light from a distant source by the gravity of an object between the source and the observer.
- The quasar pair 0957 + 561 A and B are observed with a separation of 5.7 arcseconds.
Purpose of the Study:
- To investigate the nature of the quasar pair 0957 + 561 A and B.
- To determine if the two objects are distinct quasars or gravitational images of a single object.
- To analyze spectral data for evidence of association.
Main Methods:
- Spectroscopic analysis of quasars 0957 + 561 A and B.
- Photometric measurements to determine apparent magnitude.
- Analysis of spatial separation and redshift.
Main Results:
- The spectra of 0957 + 561 A and B indicate they are associated.
- A redshift of 1.405 was determined for both objects.
- The close angular separation (5.7 arcseconds) and spectral similarity present challenges in classifying them as two separate objects.
Conclusions:
- The spectral evidence strongly suggests that 0957 + 561 A and B are associated.
- The possibility of 0957 + 561 A and B being two images of the same quasar, formed by gravitational lensing, is a significant consideration.
- Further investigation is warranted to definitively distinguish between two separate quasars and a gravitationally lensed system.
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