In the early Universe, galaxies proliferated by absorbing gas and forming stars. Eventually, this growth stops in a process called “quenching.” While quiescent galaxies, known as “red and dead,” are typical today, finding them in the early Universe is puzzling.
Researchers have been captivated by the search for massive quiescent galaxies (MQGs), which halt star formation after building substantial stellar mass. These galaxies usually take a long time to form, so discovering them in the early Universe could offer valuable insights into the processes that cause their sudden transition to inactivity.
Astronomers have made a groundbreaking discovery about the early Universe, challenging existing theories of galaxy evolution. Led by the University of Geneva (UNIGE), researchers used the James Webb Space Telescope (JWST) to identify a galaxy that stopped forming stars far earlier than expected. This finding highlights a growing gap between theoretical models and observational evidence.
Thanks to advancements in near-infrared spectroscopy that enable the detection of massive quiescent galaxies (MQGs) at increasingly earlier cosmic stages, the JWST has set a new benchmark by revealing a galaxy with a remarkable redshift of 7.29, indicating it existed just 700 million years after the Big Bang. These observations redefine our understanding of galaxy formation in the early Universe.
Astronomers observed oldest ‘dead’ galaxy yet
UNIGE researchers, in partnership with the RUBIES program, used the NIRSpec instrument to analyze thousands of galaxies and made a groundbreaking discovery. They identified RUBIES-UDS-QG-z7, the most distant massive quiescent galaxy (MQG) observed to date.
This galaxy ceased star formation within 600 million years of the Big Bang. With a stellar mass exceeding 10 billion solar masses, this galaxy challenges existing models, which had not predicted such rapid quenching at this stage of cosmic evolution.
The study reveals that MQGs in the early Universe are 100 times more abundant than theoretical models anticipated, highlighting a need to rethink assumptions about how stellar winds, outflows from star formation, and black hole activity influence star formation.
Andrea Weibel notes that “Galaxies died much earlier than these models can predict,” reshaping our understanding of galaxy life cycles in the cosmos’s infancy.
RUBIES-UDS-QG-z7 offers a fascinating glimpse into the origins of giant elliptical galaxies seen in the present day. Its compact size of only 650 light-years and high stellar density are reminiscent of the dense cores of massive ellipticals.
As principal investigator Anna de Graaff explains, this discovery provides compelling evidence that the cores of some massive ellipticals may have been formed as early as the first few hundred million years of the Universe.
With the remarkable capabilities of the James Webb Space Telescope (JWST), astronomers continue to uncover revelations like RUBIES-UDS-QG-z7, reshaping our understanding of cosmic evolution. Published in the Astrophysical Journal, these findings push the boundaries of galaxy formation theories and invite deeper inquiry into the Universe’s earliest structures.
Journal Reference:
- Andrea Weibel, Anna de Graaff, David J. Setton, Tim B. Miller, Pascal A. Oesch, Gabriel Brammer, Claudia D. P. Lagos, Katherine E. Whitaker, Christina C. Williams, Josephine F.W. Baggen. RUBIES Reveals a Massive Quiescent Galaxy at z = 7.3. The Astrophysical Journal. DOI 10.3847/1538-4357/adab7a
Source: Tech Explorist
