A multinational team of astronomers have found a new Einstein Ring, a rare image of a distant galaxy lensed by gravity. The scientists, from Spain, Italy and the USA, report their discovery in Monthly Notices of the Royal Astronomical Society.
In his seminal general theory of relativity
published a century ago, Albert Einstein predicted that gravity would
distort the fabric of spacetime, and that light would follow curved
paths as a result. Astronomers first observed this effect in 1919, by
measuring the position of stars near the Sun during the 1919 total solar eclipse,
and noting a slight shift resulting from the gravitational field of our
nearest star. On a larger scale, light from distant galaxies is bent by
black holes and massive galaxies that lie between them and the Earth.
The intervening objects act as lenses, creating arcs and ‘Einstein
rings’ of light.
These rings are still comparatively rare and usually appear as small
features in the sky. This makes them hard to see clearly, and most are
observed with radio telescopes, or with the Hubble Space Telescope.
Their rarity derives from the huge distances involved, and the low
probability of our Galaxy, the lens galaxy and the distant galaxy all
being almost exactly in line.
The newly discovered ring lies in the direction of the constellation of Sculptor in the southern sky. Margherita Bettinelli, a PhD student at the Instituto de Astrofisica de Canarias, found it while looking at archive images from the Dark Energy Camera (DECam) mounted on the Victor Blanco 4-m telescope at the Cerro Tololo Inter-American Observatory
in Chile. Margherita and her team named the ring 'Canarias', in homage
to the work carried out by astronomers on La Palma and Tenerife.
Light arriving at the Earth today left the Einstein ring 8 billion
years ago, so we see the ring as it was 5 billion years after the Big
Bang. Despite its relatively small apparent size (it stretches across an
angle on the sky of 4.5 arcseconds or about 1/800th of a degree), it is larger than most of the other rings found to date. Follow up work with the 10.4-m Gran Telescopio Canarias (GTC)
confirms its distance and shows that the intervening lens galaxy has a
mass equivalent to around a trillion (million million) Suns.
Dr Robert Massey
Royal Astronomical Society
Tel: +44 (0)20 7292 3979
Mob: +44 (0)7802 877 699
rm@ras.org.uk
Science contact
Margherita Bettinelli
Instituto de Astrofisica de Canarias
mbettine@iac.es
Further information
The new work appears in "The Canarias Einstein Ring: a Newly Discovered Optical Einstein Ring",
M. Bettinelli, M. Simioni, A. Aparicio, S. L. Hidalgo, S. Cassisi, A.
R. Walker, G. Piotto and F. Valdes, Monthly Notices of the Royal
Astronomical Society, in press.
Notes for editors
The scientific research following the discovery has been conducted
and coordinated by the Stellar Populations group at the Instituto de
Astrofisica de Canarias (IAC), led by Dr Antonio Aparicio Juan and Dr
Sebastian Hidalgo. The Einstein ring was found in plates of the Sculptor
dwarf galaxy, a companion to our own Milky Way, but is a far more
distant object.
Ms Bettinelli is supervised by Dr Santi Cassisi and Dr Hidalgo. Another PhD student, Matteo Simioni, carried out further analysis, under the supervision of Dr Aparicio and Giampaolo Piotto of the University of Padua.
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Ms Bettinelli is supervised by Dr Santi Cassisi and Dr Hidalgo. Another PhD student, Matteo Simioni, carried out further analysis, under the supervision of Dr Aparicio and Giampaolo Piotto of the University of Padua.
The Royal Astronomical Society (RAS), founded in 1820, encourages and promotes the study of astronomy, solar-system science, geophysics and closely related branches of science. The RAS organizes scientific meetings, publishes international research and review journals, recognizes outstanding achievements by the award of medals and prizes, maintains an extensive library, supports education through grants and outreach activities and represents UK astronomy nationally and internationally. Its more than 4000 members (Fellows), a third based overseas, include scientific researchers in universities, observatories and laboratories as well as historians of astronomy and others.
The RAS accepts papers for its journals based on the principle of peer review, in which fellow experts on the editorial boards accept the paper as worth considering. The Society issues press releases based on a similar principle, but the organisations and scientists concerned have overall responsibility for their content.
Follow the RAS on Twitter
Source: Royal Astronomical Society (RAS)
