Spiral arms and their effects on secular evolution and star formation in disk galaxies [Elektronische Ressource] / put forward by Kelly Foyle

DISSERTATIONSUBMITTED TO THECOMBINED FACULTIES OF THE NATURAL SCIENCES AND MATHEMATICSOF THE RUPERTO-CAROLA-UNIVERSITY OF HEIDELBERG, GERMANYFOR THE DEGREE OFDOCTOR OF NATURAL SCIENCESPUT FORWARD BYKELLY FOYLEBORN IN: MONTREAL, CANADAthORAL EXAMINATION: OCTOBER13 , 2010SPIRAL ARMS AND THEIR EFFECTS ON SECULAREVOLUTION AND STAR FORMATION IN DISKGALAXIESREFEREES: PROF. DR. HANS-WALTER RIXPROF. DR. RALF S. KLESSEN“The most important reason for going from one place to another is to see what’s in between.”- Norton Juster (The Phantom Tollbooth)AbstractWe investigate how spiral structure affects the observational properties of disk galaxies bothin terms of dynamical secular evolution and of star formation. We derived the first observa-tional estimate of the torque-induced instantaneous angular momentum flow, resulting fromnon-axisymmetric features in the stellar distribution for a sample of 24 galaxies. The strongesttorques were found among barred galaxies. In the inner regions, the average torques are strongenough to redistribute angular momentum on a timescale of4 Gyr with an outward angularmomentum flow. In examining the role of spiral arms in star formation we found that they donot dominate, even in grand-design spiral galaxies as there is a comparable amount of interarmstar formation. Further, we found that the arms show no enhancement in the efficiency of starformation in terms of molecular gas.