A quasar acting as a gravitational lens has now been observed for the first time. This discovery, made by the EPFL's Laboratory of Astrophysics in cooperation with Caltech, represents an advance in the field, since it will allow scientists to weigh and measure a galaxy that contains a quasar. The news is published today in the journal Astronomy & Astrophysics.
Gravitational lenses are common throughout the universe. They are caused by massive objects such as stars or galaxies that bend rays of light passing nearby. If these objects are between the earth and a more distant light source, the light will therefore be brighter and easier to observe, but also very distorted. If the alignment of the various stellar bodies is almost perfect, the image of the source will be multiplied.
The lens phenomenon is not only an interesting result of Einstein's theory of general relativity; it has also been a valuable astrophysical tool with important applications in the search for extrasolar planets and the study of stars, galaxies, clusters of galaxies and quasars. For example, the nature of the distortion, the number of images of the most distant objects and their position in the sky provide essential information about the distribution of matter in the lens galaxy and allow a measurement of its total matter, including dark matter, to be made.
A quasar is the heart of a galaxy, consisting of a supermassive black hole. The small fraction of the galaxy's mass that is close enough to be swallowed up by the black hole emits light before disappearing forever, giving rise to this extremely bright and transient phenomenon.
To date, about a hundred of these quasars emitting light that is concentrated by a lens galaxy located between them and the earth have been discovered. However, this is the first time that the opposite case has been observed, where the quasar is in the foreground and the galaxy behind it. The interest of this discovery lies in the fact that it provides an unprecedented opportunity to "weigh" a galaxy containing a quasar.
This advance was made thanks to the SLOAN Digital Sky survey database (www.sdss.org), which makes three-dimensional sky maps covering more than a quarter of the sky available to scientists and contains nearly a million galaxies and over 120,000 quasars. A sample of some 23,000 of these quasars in the northern hemisphere was selected by the Laboratory of Astrophysics team. In the end, only four of them seemed to act as a gravitational lens.
One of these was studied using the Keck telescope (Caltech) on Mauna Kea peak in Hawaii. These images will be supplemented in the coming months with very high-quality photographs from the Hubble Space Telescope, which will reveal more about the nature of this particular quasar.
- Professor Georges Meylan, Director of the EPFL's Laboratory of Astrophysics, firstname.lastname@example.org, tel. +41 22 379 24 25 or +41 21 693 06 44 or cell +41 79 856 34 85.
- Frederic Courbin, EPFL's Laboratory of Astrophysics, email@example.com or +41 22 379 24 18
- S. George Djorgovski, California Institute of Technology (Caltech), firstname.lastname@example.org or +1 (626) 395-4415
Links and documents:- Youtube video:
Sarah Perrin | EurekAlert!
Observing and controlling ultrafast processes with attosecond resolution
20.02.2018 | Technische Universität München
Unconventional superconductor may be used to create quantum computers of the future
19.02.2018 | Chalmers University of Technology
For the first time, a team of researchers at the Max-Planck Institute (MPI) for Polymer Research in Mainz, Germany, has succeeded in making an integrated circuit (IC) from just a monolayer of a semiconducting polymer via a bottom-up, self-assembly approach.
In the self-assembly process, the semiconducting polymer arranges itself into an ordered monolayer in a transistor. The transistors are binary switches used...
Breakthrough provides a new concept of the design of molecular motors, sensors and electricity generators at nanoscale
Researchers from the Institute of Organic Chemistry and Biochemistry of the CAS (IOCB Prague), Institute of Physics of the CAS (IP CAS) and Palacký University...
For photographers and scientists, lenses are lifesavers. They reflect and refract light, making possible the imaging systems that drive discovery through the microscope and preserve history through cameras.
But today's glass-based lenses are bulky and resist miniaturization. Next-generation technologies, such as ultrathin cameras or tiny microscopes, require...
Scientists from the University of Zurich have succeeded for the first time in tracking individual stem cells and their neuronal progeny over months within the intact adult brain. This study sheds light on how new neurons are produced throughout life.
The generation of new nerve cells was once thought to taper off at the end of embryonic development. However, recent research has shown that the adult brain...
Theoretical physicists propose to use negative interference to control heat flow in quantum devices. Study published in Physical Review Letters
Quantum computer parts are sensitive and need to be cooled to very low temperatures. Their tiny size makes them particularly susceptible to a temperature...
15.02.2018 | Event News
13.02.2018 | Event News
12.02.2018 | Event News
20.02.2018 | Power and Electrical Engineering
20.02.2018 | Materials Sciences
20.02.2018 | Life Sciences