Thousands of galaxies flood this high-resolution near-infrared image of galaxy cluster SMACS 0723. Credit: NASA, ESA, CSA, STScI
A team of astronomers has used the James Webb Telescope (JWST) to identify the most distant globular clusters ever discovered. These dense clusters of millions of stars may be relics containing the first and oldest stars in the universe.
The first analysis of Webb’s first Deep Field image, which depicts some of the earliest galaxies in the universe, was published recently in Letters from the Astrophysical Journal. The work was led by a team of Canadian astronomers, including experts from the Dunlap Institute for Astronomy & Astrophysics at the University of Toronto’s Faculty of Arts and Sciences.
“JWST was designed to find the first stars and galaxies and to help us understand the origins of complexity in the universe, such as chemical elements and the building blocks of life,” says Lamiya Mowla, postdoctoral researcher at Dunlap Institute for Astronomy & Astrophysics and co-lead author of the study, which was carried out by the Canadian team NIRISS Unbiased Cluster Survey (CANUCS).
“This discovery in Webb’s first deep field already provides detailed insight into the early phase of star formation, confirming the incredible power of JWST.”
The researchers studied the Sparkler galaxy located in Webb’s first deep field and used JWST to determine that five of the twinkling objects surrounding it are globular clusters. Credit: Image via Canadian Space Agency with images from NASA, ESA, CSA, STScI; Mowla, Iyer et al. 2022
In Webb’s finely detailed first deep-field image, astronomers quickly zeroed in on what they dubbed “the Sparkler galaxy.” Located nine billion light-years away, this galaxy gets its name from the compact objects that appear as small yellow-red dots around it, which researchers call “sparks”. The research team determined that these sparks could either be young, actively forming star clusters – born three billion years after the
” data-gt-translate-attributes=”[{” attribute=””>Big Bang at the peak of star formation – or old globular clusters. Globular clusters are ancient collections of stars from a galaxy’s infancy and contain clues about its earliest phases of formation and growth.
From an initial analysis of 12 of these compact objects, the researcher team determined that five of them are not only globular clusters but among the oldest ones known.
“Looking at the first images from JWST and discovering old globular clusters around distant galaxies was an incredible moment – one that wasn’t possible with previous
Gravitational lensing is used by astronomers to study very distant and very faint galaxies. Credit: NASA, ESA & L. Calçada
The
From left: Kartheik Iyer, Vince Estrada-Carpenter, Guillaume Desperez, Lamiya Mowla, Marcin Sawicki, Victoria Strait, Gabe Brammer and Kate Gould (on laptop screen), Ghassan Sarrouh, Chris Willott, Bob Abraham, Gael Noirot, Yoshi Asada, Nick Martis, Credit: hoto courtesy of Lamiya Mowla and Kartheik Iyer
“Our study of the Sparkler highlights the tremendous power in combining the unique capabilities of JWST with the natural magnification afforded by gravitational lensing,” says CANUCS team lead Chris Willott from the National Research Council’s Herzberg Astronomy and Astrophysics Research Centre. “The team is excited about more discoveries to come when JWST turns its eye on the CANUCS galaxy clusters next month.”
The researchers combined new data from JWST’s Near-Infrared Camera (NIRCam) with Hubble Scape Telescope archival data. NIRCam detects faint objects using longer and redder wavelengths to observe past what is visible to the human eye and even the Hubble Space Telescope. Both magnifications due to the lensing by the galaxy cluster and the high resolution of JWST are what made observing compact objects possible.
The Canadian-made Near-Infrared Imager and Slitless Spectrograph (NIRISS) instrument on the JWST provided independent confirmation that the objects are old globular clusters because the researchers did not observe oxygen emission lines – emissions with measurable spectra given off by young clusters that are actively forming stars. NIRISS also helped unravel the geometry of the triply lensed images of the Sparkler.
“JWST’s made-in-Canada NIRISS instrument was vital in helping us understand how the three images of the Sparkler and its globular clusters are connected,” says Marcin Sawicki, a professor at Saint. Mary’s University who is Canada Research Chair in Astronomy and co-author of the study. “Seeing several of the Sparkler’s globular clusters imaged three times made it clear that they are orbiting around the Sparkler galaxy rather than being simply in front of it by chance.”
JWST will observe the CANUCS fields starting in October 2022, leveraging its data to examine five massive clusters of galaxies, around which the researchers expect to find more such systems. Future studies will also model the galaxy cluster to understand the lensing effect and execute more robust analyses to explain the star formation histories.
Reference: “The Sparkler: Evolved High-redshift Globular Cluster Candidates Captured by JWST” by Lamiya Mowla, Kartheik G. Iyer, Guillaume Desprez, Vicente Estrada-Carpenter, Nicholas S. Martis, Gaël Noirot, Ghassan T. Sarrouh, Victoria Strait, Yoshihisa Asada, Roberto G. Abraham, Gabriel Brammer, Marcin Sawicki, Chris J. Willott, Marusa Bradac, René Doyon, Adam Muzzin, Camilla Pacifici, Swara Ravindranath and Johannes Zabl, 29 September 2022, The Astrophysical Journal Letters.
DOI: 10.3847/2041-8213/ac90ca
Collaborating institutions include York University and institutions in the United States and Europe. The research was supported by the Canadian Space Agency and the Natural Sciences and Engineering Research Council of Canada.
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