Quasars, powered by supermassive black holes, are among the brightest objects in the universe, outshining the total starlight of their host galaxies.
Quasar host galaxies are hard or even impossible to see because the central quasar far outshines the galaxy. Therefore, it is difficult to estimate the mass of a host galaxy based on the collective brightness of its stars. However, gravitational lensing candidates are invaluable for estimating the mass of a quasar's host galaxy because the amount of distortion in the lens can be used to estimate a galaxy's mass.
Astronomers using NASA's Hubble Space Telescope have found several examples of galaxies containing quasars, which act as such gravitational lenses, amplifying and distorting images of galaxies aligned behind them.
To find these rare cases of galaxy-quasar combinations acting as lenses, a team of astronomers led by Frederic Courbin at the Ecole Polytechnique Federale de Lausanne (EPFL, Switzerland) selected 23,000 quasar spectra in the Sloan Digital Sky Survey (SDSS). They looked for the spectral imprint of galaxies at much greater distances that happened to align with foreground galaxies. Once candidates were identified, Hubble's sharp view was used to look for gravitational arcs and rings (which are indicated by the arrows in these three Hubble photos) that would be produced by gravitational lensing.
CLICK IMAGE FOR LARGER SIZE. Credit: NASA, ESA, and F. Courbin (EPFL, Switzerland)
The next step for the team is to build a catalog of "quasar-lenses" that will allow them to determine masses for a statistically significant number of quasar host galaxies and to compare them with galaxies without quasars. With the numerous wide-field surveys that will start in the near future or that are already started, hundreds of thousands of quasars will be accessible for looking for lensing effects.
The team involved in this research includes: F. Courbin, C. Faure, F. Rerat, M. Tewes, and G. Meylan (EPFL, Switzerland), S.G. Djorgovski, A. Mahabal (Caltech), D. Stern (JPL), T. Boroson (NOAO), D. Sluse (Bonn University, Germany), R. Dheeraj (University of Maryland). The full study is presented in the journal Astronomy and Astrophysics.
- PHYSICAL SCIENCES
- EARTH SCIENCES
- LIFE SCIENCES
- SOCIAL SCIENCES
Subscribe to the newsletter
Stay in touch with the scientific world!
Know Science And Want To Write?
- Suggestion: The EM Drive Is Getting The Appropriate Level Of Attention From The Science Community
- Will Aspartame Critics Now Be Less Bitter?
- (Well)-Paid PhD Position In Physics Offered In Padova, Italy
- GMOs Have Formaldehyde? Bizarre Claim Challenged By Experts
- Bees: Activists Remain Silent While This Pollinator Killer Decimates Millions
- New Ice Age Is Coming, By 2030, Says Analysis
- Epigenetics: Quackery Or Phenomenon?
- "Object recognition feature for the robots will be very helpful for us,now robots will be able to..."
- "You're correct John Baez,Lise Meitner didn't work on atom bombs directly. In fact she refused..."
- "Hello Alexander Parish, Probably hangover symptoms from dark wines and liquors, and especially..."
- "well, this is part of the problem of rush to publish, rather than proper peer review. ..."
- "this makes many things that I have been reading and experiencing make sense. thank you, Nina Tryggvas..."
- Paralyzed men move legs thanks to non-invasive spinal cord stimulation
- California 'rain debt' equal to average full year of precipitation
- Cancer patients lose faith in healthcare system if referred late by GP
- Prostate cancer is 5 different diseases
- When surgeons listen to their preferred music, their stitches are better and faster