Amazing stuff!
"A serendipitous image taken by the European Space Agency’s Euclid telescope allowed astronomers to spot a stunning new example of an Einstein ring.
This extremely rare phenomenon occurs when a large space object acts like a lens and magnifies light from another object directly behind it. This was first predicted by Einstein’s general theory of relativity, which describes how the gravity of large objects, like galaxies, warp the spacetime fabric and alter the path of light. ...
The galaxy acting as a gravitational lens is called NCG 6505 and it lies 590 million light-years away from Earth, ‘a cosmic stone’s throw away,’ ... However, the light of the object it is magnifying lies more than 4.4 billion light-years away. This object has never been observed before and does not yet have a name. ..."
"... If the alignment is just right, the light from the distant source galaxy bends to form a spectacular ring around the foreground object. These Einstein rings are a rich laboratory for scientists. Studying their gravitational effects can help us learn about the expansion of the Universe, detect the effects of invisible dark matter and dark energy, and investigate the background source whose light is bent by dark matter in between us and the source. ...
By exploring how the Universe has expanded and formed over its cosmic history, Euclid will reveal more about the role of gravity and the nature of dark energy and dark matter. The space telescope will map more than a third of the sky, observing billions of galaxies out to 10 billion light-years. It is expected to find around 100 000 strong lenses, but to find one that’s so spectacular – and so close to home – is astonishing. Until now, less than 1000 strong lenses were known, and even fewer were imaged at high resolution. ..."
From the abstract:
"We report the discovery of a complete Einstein ring around the elliptical galaxy NGC 6505, at z = 0.042. This is the first strong gravitational lens discovered in Euclid and the first in an NGC object from any survey. The combination of the low redshift of the lens galaxy, the brightness of the source galaxy (IE = 18.1 lensed, IE = 21.3 unlensed), and the completeness of the ring make this an exceptionally rare strong lens, unidentified until its observation by Euclid.
We present deep imaging data of the lens from the Euclid Visible Camera (VIS) and Near-Infrared Spectrometer and Photometer (NISP) instruments, as well as resolved spectroscopy from the Keck Cosmic Web Imager (KCWI).
The Euclid imaging in particular presents one of the highest signal-to-noise ratio optical/near-infrared observations of a strong gravitational lens to date. From the KCWI data we measure a source redshift of z = 0.406.
Using data from the Dark Energy Spectroscopic Instrument (DESI) we measure a velocity dispersion for the lens galaxy of σ⋆ = 303 ± 15 km s−1. We model the lens galaxy light in detail, revealing angular structure that varies inside the Einstein ring. After subtracting this light model from the VIS observation, we model the strongly lensed images, finding an Einstein radius of 2.″5, corresponding to 2.1 kpc at the redshift of the lens. This is small compared to the effective radius of the galaxy, Reff ∼ 12.″3. Combining the strong lensing measurements with analysis of the spectroscopic data we estimate a dark matter fraction inside the Einstein radius of fDM = (11.1−3.5+5.4)% and a stellar initial mass-function (IMF) mismatch parameter of αIMF = 1.26−0.08+0.05, indicating a heavier-than-Chabrier IMF in the centre of the galaxy."
Euclid discovers a stunning Einstein ring (original news release)
Euclid: A complete Einstein ring in NGC 6505⋆ (open access)
Euclid image of a bright Einstein ring around galaxy NGC 6505
Close-up of the Einstein ring around galaxy NGC 6505
No comments:
Post a Comment