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?
- Is The X(5568) A True Resonance ?
- How We Predict Climate For Decades - Yet Can't Forecast Weather For Ten Days - Chaos Patterned With Order
- The Five Stages Of A Dying Theory
- Should Pregnant Women Be Concerned About BPA?
- Why Science is Worth Studying.
- Neanderthals: Not So Dumb
- Baby Boomers Unbound: Marijuana Surges In The Elderly
- "Dawn, no there is nothing to be worried about at all. No need to warn anyone. It's just made up..."
- "So do i need to be worried or not do i need to warn anybody or not like tell my family and friends..."
- "Dawn, sorry to hear that you are freaking out about this. I've written up my answer to you as Debunked..."
- "aargh! I forgot you mentioned this promotion....let's see! Thanks...."
- "Hi,I know, the price is steep - not my choice unfortunately, WS has this kind of policy... But..."
- CSPI Demands US Government Put Cancer Warning Label On...Bacon
- Opioid Malfeasance At The CDC- Guess Who Is Getting Hurt?
- Dreading a Colonoscopy? There is More Than One Way to Save Your Behind
- Junk Science, Voodoo Medicine, And A List We're Glad Not To Be On
- At High Altitude with Buzz Aldrin
- Hand Sanitizer Can Cause a False Positive Breathalyzer Test