Space Warps ESA Euclid: 15,000 Strong Lenses found in Data Release 1!
We are so excited to share the strong lensing results of the first major data release from Euclid (called DR1-Foundation) that you have all contributed to with an incredible 5 million classifications after inspecting 240,000 images. Together we’ve found an astounding 15,000 strong lenses!
We are so humbled by your efforts which have been so significant to achieving this incredible sample of strong lenses. This is the largest sample of high grade strong lenses that have ever been discovered and you each played a part in achieving this goal. Thank you.
As you will see from the European Space Agency (ESA) and media outlets, today ESA and Euclid Consortium have released the first foundational release from the Euclid mission. This encompasses about thirteen months of observations with this innovative telescope optimised for mapping large areas of the celestial sky with very high quality imaging. This foundational Data Release 1 contains more than a billion astrophysical objects (including 900 million galaxies) over 1900 square degrees – which is about 5% of the sky or the area covered by 6 big dippers! With both imaging, that can tell us what kinds of objects are in the Universe, and spectroscopy, that tells us how far objects are away from us, what they are made up of and even how they move, Euclid data enables so much science. This data release is just the beginning of the largest ever 3D map of the sky.
The large area mapped, high quality space imaging and sensitive observations makes Euclid the perfect instrument to discover very rare objects such as strong lenses. Before Euclid, we were finding fewer than one good lens candidate per square degree of sky observed, on average. Euclid has increased that number to a whopping 8 per square degree! These 15,000 strong lenses are a stunning dataset. The team of international scientists thank you for your efforts. Once we had your classifications we were able to focus the team on looking at only the most promising candidates that you identified. As well as the 15,000 most reliable lens candidates, we also have many thousands of possible candidates. Even more excitingly we know we haven’t found everything yet with even more data to come!
Over the next weeks, we’ll be sharing some of the team’s favourite candidates, in the meantime, you can browse at the papers that came out today and under the ECLIPSE series:
- the lens discovery method and samples are described in papers by Natalie Lines and Phil Holloway (ECLIPSE A & B)
- the usually very time intensive lens modelling sped up at scale by James Nightingale (ECLIPSE C)
- estimating the redshifts (distances to the lenses) as a preview to galaxy evolution studies by Angelos Nersesian (ECLIPSE D)
- And a paper showing the potential of NISP spectroscopy for strong lenses by Pietro Bergamini
You can find these papers, and more, including the DR1 Foundation webinar, on the Euclid website https://euclid-ec.net/ from 12 noon CET today.
Congratulations to each and everyone of you who have taken part in the Space Warps ESA Euclid search, we can’t thank you enough!
Credit: ESA/Euclid/Euclid Consortium/NASA, image processing by N. Lines and T. Li
An overview of Euclid’s DR1, and information on how to access the data released in the DR1-Foundation, can be found here: cosmos.esa.int/web/euclid/data-release-dr1
Data can be explored, visualised and analysed on Euclid Data Space euclid.dataspace.esa.int
All of Euclid’s data and associated images can be explored in full colour on ESASky sky.esa.int
More in-depth stories about DR1-Foundation can be found on the Euclid Consortium website: euclid-ec.org
Rare strong lens gems emerging from the Space Warps ESA Euclid Data Release 1 search
A few months ago, we started the full-scale search for strong gravitational lenses in the ESA Euclid Data Release 1 (DR1) survey. While we are carefully analysing your classifications, in this blog post we highlight some of our favourite strong lens candidates that you’ve collectively found in this dataset.
Congratulations!! You’ve now passed the milestone of an incredible 5 million classifications since the first ESA Euclid Quick Data Release 1 (Q1) lens search began in 2024, including 2.7 million in the current ESA Euclid DR1 search. We have been completely blown away, and are excitedly analysing all your classifications! While the lens search and our analysis continue, we wanted to highlight some of the stunning strong lens candidates that you have found and let you know what’s happening next with the lens search.
Beyond the fascinating individual systems we highlight in this blog post, thousands of other lens candidates are emerging from your collective classifications – such a large population which will help to revolutionise the study of strong lenses. Prior to Euclid DR1 only a few hundred strong gravitational lenses had been identified in space-based imaging and so the thousands of lens systems which you have found will change how we can study these systems, enabling us to analyse the strong lens population as a whole.
Amongst this treasure trove of lens systems are some scientific gems:
First up is a lensed quasar (ID: 119727051); this has four lensed images forming a ‘quad’ configuration. The light from the quasar (a bright supermassive black-hole at the centre of a distant galaxy) is strong enough to outshine both the light of the deflector or lens galaxy and that of the host galaxy it resides in. Unlike galaxy-galaxy strong lenses, the light from the central deflector can’t be seen in the image. Quasars, in particular quadruply imaged quasars like this one, are particularly useful probes of cosmology. Light emitted from the background quasar will arrive at the Earth at different times depending on which of the four routes (corresponding to the 4 lensed images) that it takes. The arrival time of the emitted light is dependent on the degree of lensing (how much mass there is in the deflector galaxy), and the expansion rate of the universe. From the separation of the lensed images we can estimate the mass of the deflector or lens and therefore, by measuring the time delay of each of the four images, strongly lensed quasars can help to constrain the expansion of the universe!
Next up are two lens systems with bright dust lanes (119696543 and 119705025 ). In both of these systems, at least 3 lensed images are visible (in the left example the counter-image is likely hidden behind the smaller satellite galaxy to the right). These systems highlight the superb resolution of the Euclid telescope, as well as the benefits of colour imaging which helps distinguish the dust lanes from lensed arcs or tidal features.
This is an example of a candidate double-source-plane lens (ID: 119665581) – here the deflector galaxy is lensing two different background galaxies, creating two sets of lensed arcs. These are very rare systems even within strongly lensed systems since they require the close alignment of two source galaxies with the deflector galaxy rather than just one. They are also especially useful for a range of astrophysical and cosmological studies, for example the two Einstein rings allow us to tightly constrain how much mass is present in the deflector galaxy, and where it is most concentrated.
This final system (ID: 121188143) suggests that the lensed background galaxy has interesting structure. In this image you can see four images of the same bright, white blob but around these finer stellar filaments can be seen. This implies that the background galaxy has a central bright component and more extended fainter structure around it. By developing a model of such systems, we can remove the distortion caused by gravitational lensing and reconstruct what the source galaxy really looks like. The extra detail visible in the lensed arcs can help us produce a sharper, higher-resolution image of the background galaxy than would be possible if we were observing the same galaxy without the amplification and magnification by strong lensing.
These systems are just a small snapshot of the lensed systems you have already identified. Behind the scenes, we are analysing all of your classifications both in classify and refine in preparation for the public release of all the Euclid DR1 images in November this year. In the meantime, we are adding the second batch of approximately 50,000 Euclid DR1 images to Space Warps Classify. These systems were flagged as lens candidates by a new machine learning network, and we’re keen to see what you think! This network used multiple bands (colours) in order to classify the lensed images, so it will be really interesting to see if different types of strong lens systems appear in this second batch compared to the first.
Thank you again for your classifications and we look forward to discussing further exciting strong lens systems with you!
The Space Warps ESA Euclid Strong Lens team.
