Galaxies, the vast collections of stars in the universe, owe much of their structure to spheroids, or galactic bulges. Recent research has provided new insights into how these spheroids contribute to the massive sizes of galaxies. Understanding the role of spheroids is essential, as they contain most of the stars in both spiral and elliptical galaxies. This study not only advances our knowledge of galaxy formation but also opens up new avenues for exploring the evolution of the universe.
What Role Do Spheroids Play in Galaxy Formation?
Spheroids are central to determining the structure and size of galaxies. By concentrating stars in their cores, spheroids influence the overall mass and gravitational dynamics of galaxies. The research utilized the Atacama Large Millimeter/submillimeter Array (ALMA) to analyze the light distribution in over 100 ancient, starburst galaxies, revealing that most possess tri-axial shapes. This finding suggests that galaxy mergers significantly impact the formation and shaping of spheroids.
How Did Researchers Utilize ALMA in Their Study?
ALMA’s advanced capabilities allowed astronomers to observe submillimeter wavelengths, providing a clearer view of distant, dust-obscured galaxies. The team employed a novel technique to measure the brightness profiles of these galaxies, which helped in identifying their tri-axial structures. These observations were crucial in linking spheroid formation to periods of intense star formation triggered by galaxy mergers.
What Are the Implications of This Research?
“Our findings take us closer to solving a long-standing mystery in astronomy that will redefine our understanding of how galaxies were created in the early universe,”
stated Dr. Annagrazia Puglisi from the University of Southampton. The study’s results indicate that spheroids form rapidly during galaxy collisions, where cold gas funnels into the galactic center, fuelling starbursts that build up the spheroid. This process not only explains the current distribution of stars in galaxies but also highlights the critical role of mergers in galaxy evolution.
Previous investigations into the connection between spheroids and submillimeter-bright galaxies faced challenges due to lower signal-to-noise ratios and limited observational techniques. This new research, leveraging ALMA’s superior capabilities, provides more definitive evidence supporting the hypothesis that spheroids are formed through intense star-forming episodes during galaxy mergers. The enhanced data quality allows for a more accurate characterization of galaxy structures and their evolutionary paths.
The study concludes that early-universe galaxy mergers were pivotal in shaping the massive spheroids observed today. The rapid consumption of gas during these mergers led to the formation of spheroids populated by older stars, with residual gas eventually forming flat disks. This comprehensive understanding of spheroid formation offers valuable insights into the broader mechanisms of galaxy growth and the dynamic history of the cosmos.
