Sign up for the Starts With a Bang newsletter
Travel the universe with Dr. Ethan Siegel as he answers the biggest questions of all.
The JWST era continues to show us the Universe as never before.
This highly unusual object was spotted with JWST: a background spiral galaxy heavily distorted by the gravitational lensing effects of a foreground elliptical galaxy. This data was part of the Strong Lensing and Cluster Evolution (SLICE) survey, which targets galaxy cluster evolution; an independent complement to the gravitational lenses found as part of the wider-field COSMOS-Web survey.
Its recently completed COSMOS-Web survey provides our deepest wide-field views ever.
This image composite shows the full-field of a large galaxy cluster within the COSMOS-Web survey, using a combination of JWST NIRCam and Hubble infrared data, with X-ray data from the Chandra X-ray telescope overlaid in violet. The X-rays are evidence from the heated gas that occurs when galaxy clusters merge or experience major disruptive events.
Revealing a whopping 780,000+ galaxies, some would inevitably be co-aligned with background objects.
This portion of the full COSMOS-Web field highlights several giant elliptical galaxies as well as many large, nearby massive spirals. Their large, massive, but low-surface-brightness extended halos are easily revealed by JWST, allowing astronomers to better determine how the stellar mass of galaxies evolves with time. Many candidate galaxy clusters and protoclusters, along with several gravitational lenses, can be seen in the background.
Massive objects, like foreground galaxies, gravitationally distort any light traveling along their line-of-sight.
An illustration of gravitational lensing showcases how background galaxies — or any light path — are distorted by the presence of an intervening mass, but it also shows how space itself is bent and distorted by the presence of the foreground mass itself. When multiple background objects are aligned with the same foreground lens, multiple sets of multiple images can be seen by a properly-aligned observer, or even an “Einstein ring” in the case of perfect alignment. If a transient event, like a supernova, occurs in the background galaxy, it will appear with time delays in the various images.
This leads to the phenomenon of strong gravitational lensing: magnifying, distorting, and creating multiple images of background sources.
Imaged here in 9 different wavelength filters (from 0.9 to 4.8 microns) for a total of 120 hours, this JWST view of Abell S1063 is one of the most massive clusters ever imaged with deep field techniques. Many gravitationally lensed features can be clearly seen even with the naked eye.
Many impressive gravitational lenses have been viewed with JWST before.
The triply lensed galaxy shown here is known as the Fishhook, after its unique appearance shaped by the foreground gravitational lens. While the entire foreground cluster, El Gordo, lenses the background galaxy, it’s the prominent double galaxy in the foreground cluster that provides the Fishhook with its remarkable appearance.
But the large, deep COSMOS-Web survey was predicted to yield 107 new gravitational lenses.
This view shows the (rotated) full field of the COSMOS-Web survey. Spanning 0.54 square degrees in the sky in NIRCam imaging, it represents the largest first-cycle general observer program of JWST observing programs awarded telescope time, at 255 hours: 209 with NIRCam and 46 with MIRI. Based on theoretical expectations, 107 galaxy-galaxy lenses were expected to be discovered, with lensed systems expected to stretch back to the first ~420 million years of cosmic history.
Credit: COSMOS-Web collaboration
Indeed, ~400 lensing candidates were identified, and the 17 most spectacular are already confirmed.
This image shows 17 of the most confidently identified strong gravitational lenses found in the COSMOS-Web data upon first-and-second visual inspections by members of the COSMOS-Web team. Although we had predictions for what types and abundances of lensed systems should appear, surprises in the data include foreground lenses being closer than anticipated and background, lensed objects appearing brighter than anticipated.
Among them are the incredible COSMOS-Web ring, dated at a cosmic age of just 1 billion years.
This object, known simply as the COSMOS-Web ring, is one of the most incredible gravitational lenses identified in the JWST era thus far. It not only features a distant foreground lens and a near-perfect alignment with a background object to create a ring, but the ring itself displays structure and has two bright spots in it: the same object split into multiple images.
It isn’t just giant elliptical galaxies that make lenses, but even edge-on spiral galaxies.
This highly unusual gravitational lens doesn’t have an elliptical galaxy, quasar, or galaxy cluster acting as the foreground lens, but rather an edge-on spiral galaxy. The properties of the candidate lensed object, seen making an arc around the spiral galaxy’s center, validate the interpretation of this lens as a spiral galaxy lensing a more distant background object: an extremely rare cosmic phenomenon.
Many lenses showcase multiply-imaged background galaxies,
This “upside down smiley face” isn’t a distant galaxy grinning at us, but rather is made of three objects: a foreground elliptical galaxy and two distant background galaxies, both lensed into arcs at the top of the lens and focused into more point-like structures below the elliptical galaxy’s center. The bright, blue galaxy at the upper-left is a foreground galaxy, unrelated to the lens system.
pearl-like lights within a lensed ring,
In this gravitational lens identified in JWST’s COSMOS-Web data, a giant elliptical galaxy lenses a background galaxy into a ring, with four bright points of light shining like pearls on that ring. Those points of light appear to all be the same object: a part of that background galaxy, lensed into multiple images by the foreground source.
arcing, tadpole-like shapes,
The long, red, arcing “tadpole-like” feature seen near the image center here is just a normal young galaxy from the early Universe, but it’s gravitationally lensed into the magnified, distended view seen here. The splotchy, bright lights seen within the central galaxy may not necessarily be features within the galaxy itself, but could be further instances of the lensing of background objects, distinct from the main, red tadpole.
plus other attention-grabbing features.
This gravitational lens is a part of JWST’s COSMOS-Web field, and showcases a giant elliptical galaxy that’s clearly lensing a single galaxy into multiple images seen arcing around the central lens source. The arcing shapes of some of the other galaxies seen, not just the two images to the right of the main lens, are further evidence of the gravitational influence of the foreground lens.
An eight-lens COSMOS-Web composite was named the European Space Agency’s picture of the month.
This image shows 8 of the most visually striking strong lensing candidates picked out of the JWST data by the COSMOS-Web team. Each image contains one prominent foreground galaxy with distorted, lensed images of galaxies in the background, including rings, arcs, and multiple images.
Over 100 of COSMOS-Web’s lens candidates are likely to be physically real gravitational lenses.
This composite image shows a selection of JWST galaxies that are lensing candidates from the COSMOS-Web survey, with a multiwavelength composite shown alongside a foreground-subtracted lens model of the background galaxies in one particular filter. The numerical rankings for each galaxy come from scientists who served as visual inspectors, with a maximum score of 12 and all galaxies shown here achieving a score of at least 9.
The observed brightnesses of these lensed systems are greater than expected: a scientific puzzle to be solved.
This COSMOS-Web view shows an extended elliptical galaxy, at center, with a blue, irregular ring around it: strong evidence for a gravitationally lensed background object behind it. The observed brightness of the lensed system in the background, as is the case for many such COSMOS-Web lensed galaxies, is brighter than theoretical predictions would have suggested.
Mostly Mute Monday tells an astronomical story in images, visuals, and no more than 200 words.
Sign up for the Starts With a Bang newsletter
Travel the universe with Dr. Ethan Siegel as he answers the biggest questions of all.
