What are found at the centers of most galaxies
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Supermassive Black Holes at the Centers of Most Galaxies
Supermassive Black Holes: The Dominant Central Feature
At the centers of most galaxies, supermassive black holes (SMBHs) are commonly found. These black holes are remnants of quasars, which are among the most energetic objects in the universe. Recent evidence strongly supports the presence of SMBHs at the centers of most galaxies, indicating that they play a crucial role in the formation and evolution of galaxies2. The gravitational influence of these black holes is significant, affecting the dynamics and structure of their host galaxies.
Formation and Influence of Central Black Holes
The formation of SMBHs is closely linked to the early stages of galaxy formation. These black holes likely formed from the collapse of massive stars in the early universe and grew by accreting gas and merging with other black holes. Their presence at the centers of galaxies suggests that they have a profound impact on the development of galactic structures, influencing star formation and the distribution of matter within galaxies2 8.
Central Galaxies in Clusters: Luminous and Massive
In galaxy clusters, the most luminous and massive galaxies are typically found at the centers. These central galaxies, often giant ellipticals, are thought to have formed through a series of mergers and accretion of smaller galaxies. The process of hierarchical clustering, where smaller structures merge to form larger ones, is a key mechanism in the formation of these central galaxies1 5 6. The intense star formation activity observed in some central galaxies further supports the idea that they are the result of complex and dynamic evolutionary processes.
Compact Stellar Nuclei and Their Relation to SMBHs
In addition to SMBHs, many galaxies also contain compact stellar nuclei at their centers. These nuclei are dense clusters of stars that obey a tight correlation with the masses of their host galaxies. Interestingly, the formation of these compact stellar nuclei appears to be a generic by-product of galaxy formation, similar to the formation of SMBHs. In galaxies with masses greater than a few times 10^10 solar masses, SMBHs tend to dominate, while in less massive galaxies, compact stellar nuclei are more common8.
Neutral Atomic Carbon and Star Formation in Galaxy Centers
The centers of galaxies, particularly spiral galaxies, often exhibit significant emission from neutral atomic carbon. This emission is associated with regions of active star formation and is typically found in galaxies with starburst or active nuclei. The presence of neutral carbon, along with other molecular emissions, indicates that the central regions of galaxies are rich in dense, warm gas that fuels star formation7.
Conclusion
In summary, the centers of most galaxies are dominated by supermassive black holes, which play a critical role in their formation and evolution. These black holes, along with compact stellar nuclei in some cases, significantly influence the dynamics and structure of their host galaxies. The presence of luminous and massive central galaxies in clusters, along with active star formation in the centers of spiral galaxies, highlights the complex and dynamic nature of galactic centers. Understanding these central features is essential for comprehending the broader processes of galaxy formation and evolution.
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Most relevant research papers on this topic
The formation of cluster elliptical galaxies as revealed by extensive star formation
This study confirms the presence of massive star-formation activity in radio galaxies and their environments, suggesting the synchronous formation of the most luminous elliptical galaxies found today at the centers of rich clusters of galaxies.
Highly CitedSupermassive black holes and the evolution of galaxies
Supermassive black holes, which reside at the centers of most galaxies, may have played a crucial role in galaxy formation and strongly influenced their present-day structure.
Highly CitedDetection of a Star-forming Galaxy in the Center of a Low-mass Galaxy Cluster
A superluminous disk galaxy is the central brightest cluster galaxy in a low-mass galaxy cluster, indicating that these clusters host quiescent massive elliptical galaxies at their center.
Early Formation and Late Merging of the Giant Galaxies
The central regions of large galaxies end up dominated by stars formed in dense cores before mergers, suggesting baryon loading may be erased and mass distribution may return to a universal profile.
Highly CitedNeutral atomic carbon in centers of galaxies
Most galaxy centers emit more strongly in neutral carbon than carbon monoxide, suggesting warm and dense gas in the cores, unlike Galactic molecular cloud regions.
A Fundamental Relation between Compact Stellar Nuclei, Supermassive Black Holes, and Their Host Galaxies
Compact stellar nuclei and supermassive black holes in galaxies have a tight correlation with their host galaxies' masses, suggesting that a central massive object (CMO) is a generic by-product of galaxy formation.
Highly CitedThe centre of the Galaxy
The center of our galaxy poses unique challenges, including understanding the source of power and how galaxies formed after the big bang.
The Centers of Early- to Intermediate-Type Spiral Galaxies: A Structural Analysis
Exponential bulges in early- and intermediate-type spiral galaxies likely grow due to orbital disruption of progenitor bars caused by the growth of a central concentration of mass.
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