There are no scheduled talks today.
Converting non-relativistic dark matter to radiation
Dr. Felix Kahlhoefer
Mon, 23 Jul 2018, 16:30
Scattering amplitudes from first principles
Markos Maniatis
Tue, 24 Jul 2018, 10:00
Multi-scale searching machine to detect the cosmic strings network
Seyed Mohammad Sadegh Movahed
Tue, 24 Jul 2018, 11:00

Search for Star Cluster Age Gradients Across Spiral Arms of Three LEGUS Disk Galaxies

Fayezeh Shabani , ARI
Understanding how spiral arms form in disk galaxies is a long-standing issue in astrophysics. One of the main theories for explaining the formation of spiral patterns in disk galaxies is the stationary density wave theory. This theory predicts the existence of an age gradient across the arms. We use the stellar cluster catalogues of the galaxies NGC 1566, M51a, and NGC 628 from the Legacy Extragalactic UV Survey (LEGUS) program. In order to test the possible existence of an age sequence across the spiral arms, we quantified the azimuthal offset between star clusters at different ages in our target galaxies. We found that NGC 1566, a grand–design spiral galaxy with bisymmetric arms and a strong bar, shows a significant age gradient across the spiral arms that appears consistent with the prediction of the stationary density wave theory. In contrast, M51a with its two well–defined spiral arms and a weaker bar does not show an age gradient across the arms. We believe that the spiral structure of M51a is not the result of a stationary density wave with a fixed pattern speed. In this case, tidal interactions could be the dominant mechanism for the formation of spiral arms. We also found no offset in the azimuthal distribution of star clusters with different ages across the weak spiral arms of NGC 628.
ARI Institute Colloquium
8 Feb 2018, 11:15
ARI Moenchhofstrasse 12-14, Seminarraum 1

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