The galaxy cluster MACS-J0417.5-1154 is so massive that it warps the fabric of spacetime and distorts the appearance of galaxies behind it, an effect known as gravitational lensing. This natural phenomenon magnifies distant galaxies and can also cause them to appear multiple times in an image, as observed here by NASA’s James Webb Space Telescope. Two distant interacting galaxies—a spiral seen face-on and a dusty red galaxy seen edge-on—appear multiple times, tracing a familiar shape in the sky. The active star formation and remarkably intact spiral shape of the galaxy seen face-on indicate that the interaction of these galaxies is just beginning. Credit: NASA, ESA, CSA, STScI, V. Estrada-Carpenter (Saint Mary’s University).
Seven billion years ago, the peak of star formation in the universe began to slow down. What might our Milky Way galaxy have looked like at that time? Astronomers using NASA’s James Webb Space Telescope have found clues in the form of a cosmic question mark, the result of a rare alignment light-years away in space. The research paper is published in the journal Monthly Notices of the Royal Astronomical Society.
“We only know of three or four occurrences of similar gravitational lensing configurations in the observable universe, which makes this discovery exciting because it demonstrates the power of Webb and suggests that we may find more now,” said astronomer Guillaume Desprez of Saint Mary’s University in Halifax, Nova Scotia, a member of the team presenting Webb’s results.
Although this region has been observed before with NASA’s Hubble Space Telescope, the dusty red galaxy that forms the intriguing question mark has only been observed by Webb. This is because the wavelengths of light detected by Hubble are trapped in cosmic dust, while the longer wavelengths of infrared light can pass through and be detected by Webb’s instruments.
Astronomers used both telescopes to observe the galaxy cluster MACS-J0417.5–1154, which acts like a magnifying glass because the cluster is so massive that it distorts the fabric of space-time. This allows astronomers to see enhanced detail in much more distant galaxies behind the cluster. However, the same gravitational effects that magnify galaxies also cause distortions, making galaxies appear spread out across the sky in arcs and even appear multiple times. These optical illusions in space are called gravitational lenses.
The red galaxy revealed by Webb, as well as a spiral galaxy it interacts with that was previously detected by Hubble, are magnified and distorted in an unusual way that requires a special and rare alignment between the distant galaxies, the lens, and the observer, what astronomers call hyperbolic umbilical gravitational lensing.
This explains the five images of the pair of galaxies visible in Webb’s image, four of which trace the vertex of the question mark. The vertex of the question mark is an unrelated galaxy that is in the right place and in the right spacetime, from our perspective.
Wide-field view: The galaxy cluster MACS-J0417.5-1154 is so massive that it warps the fabric of spacetime and distorts the appearance of galaxies behind it, an effect known as gravitational lensing. This natural phenomenon magnifies distant galaxies and can also cause them to appear multiple times in an image, as observed here by NASA’s James Webb Space Telescope. Two distant interacting galaxies—a spiral seen face-on and a dusty red galaxy seen edge-on—appear multiple times, tracing a familiar pattern in the sky. The active star formation and remarkably intact spiral shape of the galaxy seen face-on indicate that the interaction of these galaxies is just beginning. Credit: NASA, ESA, CSA, STScI, V. Estrada-Carpenter (Saint Mary’s University).
In addition to producing a case study on the ability of Webb’s Near-Infrared Imager and Slitless Spectrograph (NIRISS) instrument to detect star formation locations in a galaxy billions of light-years away, the research team couldn’t resist pointing out the question mark shape.
“It’s really cool to look at. Amazing images like these are why I got interested in astronomy when I was young,” said astronomer Marcin Sawicki of Saint Mary’s University, one of the team’s lead researchers.
“Knowing when, where and how star formation occurs in galaxies is crucial to understanding how galaxies have evolved throughout the history of the universe,” said astronomer Vicente Estrada-Carpenter of Saint Mary’s University, who used ultraviolet data from Hubble and infrared data from Webb to show where new stars are forming in galaxies. The results show that star formation is widespread in both cases. The spectral data also confirmed that the new dusty galaxy is located at the same distance as the face-on spiral galaxy, and that they are likely beginning to interact.
“Both galaxies in the Question Mark pair show active star formation in several compact regions, likely the result of gas colliding between the two galaxies,” Estrada-Carpenter said. “However, neither galaxy’s shape appears to be too disrupted, so we are likely witnessing the beginning of their interaction.”
“These galaxies, observed billions of years ago when star formation was at its peak, have masses similar to what the Milky Way would have had at that time. Webb allows us to study what the teenage years of our own galaxy would have looked like,” Sawicki said.
The Webb images and spectra in this research come from the Canadian NIRISS Unbiased Cluster Survey (CANUCS).
More information:
Vicente Estrada-Carpenter et al., When, where and how star formation occurs in a galaxy pair at cosmic noon using CANUCS JWST/NIRISS grism spectroscopy, Monthly Notices of the Royal Astronomical Society (2024). DOI: 10.1093/mnras/stae1368
Quote: Webb Reveals Warped Cosmic Question Mark About Galaxy Formation (2024, September 4) Retrieved September 4, 2024 from
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