Messung des Lebenszyklus von 30.000 Molekülwolken in Hauptreihen-Galaxien
Zusammenfassung der Projektergebnisse
The processes of star formation and stellar feedback within galaxies are fundamental in the Universe. They regulate how stars form, and how mass, energy and momentum are deposited by the stars back into the interstellar medium, and play a critical role in galaxy evolution. In turn, galaxy structure and properties influence these small scale processes by directly regulating the properties of the clouds in which stars form. To understand galaxy evolution across cosmic time, it is therefore critical to describe the physical processes of star formation and feedback from galactic scales down to the small scales of the individual clouds within which they take place. However, constraining these processes has remained a major observational challenge. Critical open questions are: what are the lifetimes of giant molecular clouds? What is the efficiency of star formation? What is the velocity at which stellar feedback evacuates the surrounding gas? How do these quantities vary with the environment, galactic structure and dynamics? This Sachbeihilfe project addresses the above questions by combining the latest observations from revolutionary telescopes, which for the first time allow us to see the star formation process in detail, with innovative analysis techniques relying on robust statistical methodology. Specifically, the PhD student funded by this Sachbeihilfe has applied the method of Kruijssen & Longmore (2014) and Kruijssen et al. (2018) to the large sample of 54 galaxies probed by the PHANGS-ALMA Large Programme. This constitutes a definitive measurement of the timescales of cloud evolution, star formation, and feedback in almost all massive star-forming galaxies within 17 Mpc. This survey has allowed for the first time to identify dependences between the measured parameters and the environment in a statistically robust way, revealing physical galaxy-to-galaxy variations of the cloud lifecycle. In particular, we showed that the measured cloud lifetimes become shorter with decreasing galaxy mass, mostly due to the increasing presence of CO-dark molecular gas in such environment. These results revealed the need for a more detailed analysis of the environmental dependency of the cloud lifecycle within galaxies. The PhD student also measured the total duration of the cloud destruction phase, including the earliest phases of star formation, which are only visible in the infrared, pioneering the way for more systematic studies with the new JWST. This constitutes a crucial step for direct comparison of the measured feedbackrelated quantities to the predictions of feedback models. This project allowed to make significant progress towards understanding which physical mechanisms are responsible for converting gas into stars within galaxies, and deriving empirical constraints that will be used in galaxy formation and evolution simulations. Over the course of this project, the student was actively involved (and still is) in the international PHANGS collaboration, and published a total of 21 peer-reviewed publications .
Projektbezogene Publikationen (Auswahl)
-
Environmental dependence of the molecular cloud lifecycle in 54 main-sequence galaxies. Monthly Notices of the Royal Astronomical Society, 516(2), 3006-3028.
Kim, Jaeyeon; Chevance, Mélanie; Kruijssen, J. M. Diederik; Leroy, Adam K.; Schruba, Andreas; Barnes, Ashley T.; Bigiel, Frank; Blanc, Guillermo A.; Cao, Yixian; Congiu, Enrico; Dale, Daniel A.; Faesi, Christopher M.; Glover, Simon C. O.; Grasha, Kathryn; Groves, Brent; Hughes, Annie; Klessen, Ralf S.; Kreckel, Kathryn; McElroy, Rebecca ... & Williams, Thomas G.
-
Towards a multitracer timeline of star formation in the LMC – II. The formation and destruction of molecular clouds. Monthly Notices of the Royal Astronomical Society, 516(3), 4025-4042.
Ward, Jacob L.; Kruijssen, J. M. Diederik; Chevance, Mélanie; Kim, Jaeyeon & Longmore, Steven N.
-
PHANGS–JWST First Results: Duration of the Early Phase of Massive Star Formation in NGC 628. The Astrophysical Journal Letters, 944(2), L20.
Kim, Jaeyeon; Chevance, Mélanie; Kruijssen, J. M. Diederik; Barnes, Ashley. T.; Bigiel, Frank; Blanc, Guillermo A.; Boquien, Médéric; Cao, Yixian; Congiu, Enrico; Dale, Daniel A.; Egorov, Oleg V.; Faesi, Christopher M.; Glover, Simon C. O.; Grasha, Kathryn; Groves, Brent; Hassani, Hamid; Hughes, Annie; Klessen, Ralf S.; Kreckel, Kathryn ... & Williams, Thomas G.
