The Canadian NIRISS Unbiased Cluster Survey (CANUCS) team discovered the most distant globular clusters ever found with the James Webb Space Telescope (JWST). These dense clusters of millions of stars may be relics containing the earliest, oldest stars in the universe.
This discovery in Webb’s first deep field already provides a detailed view of the earliest phase of star formation, confirming JWST’s incredible power.
Astronomers said the “Sparkler galaxy” nine billion light-years away was the focus of Webb’s first, exquisitely detailed deep-field image. The researchers called these compact objects around this galaxy “sparkles,” which appeared as small yellow dots.
According to the research team, these sparks could be new actively developing star clusters that formed three billion years after the Big Bang at the height of star formation or ancient globular clusters. Globular clusters are ancient collections of stars from the beginning of a galaxy, providing information about the early stages of its development and expansion.
From their initial analysis of 12 of these compact objects, the researchers determined that five of them are not only globular clusters but among the oldest known.
Kartheik G. Iyer, Dunlap Fellow at the University of Toronto’s Dunlap Institute for Astronomy and Astrophysics and co-senior author of the study, said: “Looking at the first JWST images and discovering ancient globular clusters around galaxies distance was incredible. moment, one that was not possible with previous images from the Hubble Space Telescope.”
“Because we could observe the sparks across a range of wavelengths, we could model them and better understand their physical properties, such as how old they are and how many stars they contain. We hope that the knowledge that the clusters globulars can be observed from such great distances with JWST will stimulate further science and searches for similar objects.”
Lamiya Mowla, Dunlap Fellow at the University of Toronto’s Dunlap Institute for Astronomy and Astrophysics and co-lead author of the study, said: “These newly identified clusters formed close to the first time it was even possible to create stars Since the Sparkler Galaxy is much further away than our own Milky Way, it is easier to determine the age of its globular clusters.
“We’re looking at the Sparkler as it was nine billion years ago, when the universe was only four and a half billion years old, looking at something that happened a long time ago. Think of it like guessing age of a person based on their appearance: it is easy to distinguish between a 5- and 10-year-old child, but difficult to distinguish between a 50-year-old and a 55-year-old”.
The Sparkler Galaxy is special because it’s magnified by a factor of 100 due to an effect called gravitational lensing, where the foreground galaxy cluster SMACS 0723 distorts what’s behind it like a giant magnifying glass. In addition, gravitational lensing produces three separate images of the Sparkler, allowing astronomers to study the galaxy in greater detail.
CANUCS team leader Chris Willott of the National Research Council’s Herzberg Center for Astronomy and Astrophysics said: “Our study of the Sparkler highlights the enormous power of combining JWST’s unique capabilities with the natural magnification provided by gravitational lensing. The team is excited for more discoveries when JWST turns its eyes on the CANUCS galaxy clusters next month.”
The researchers combined new data from JWST’s Near Infrared Camera (NIRCam) with archive HST data. NIRCam detects faint objects using longer, redder wavelengths to observe beyond what is visible to the human eye and even HST. Both the magnification due to the lensing of the galaxy cluster and the high resolution of JWST made the observation of compact objects possible.
JWST’s Near-Infrared Imager and Slitless Spectrograph (NIRISS) instrument confirmed that the objects are old globular clusters because the researchers did not observe oxygen emission lines—emissions with measurable spectra emitted by young clusters that are actively forming stars . . NIRISS also helped unravel the geometry of the Sparkler’s triple lens images.
Marcin Sawicki, Canada Research Chair in Astronomy, professor at Saint Mary’s University and co-author of the study, said: “JWST’s Canadian-made NIRISS instrument was vital in helping us understand how three images of the Sparkler and its globular clusters. connected Seeing several of the Sparkler globular clusters imaged three times made it clear that they are orbiting the Sparkler galaxy rather than just being in front of it by chance.
Journal reference:
- The Sparkler: High-Redshift Globular Cluster Candidates Captured by JWST. The Astrophysical Journal Letters (2022). DOI: 10.3847/2041-8213/ac90ca