A Break in Spiral Galaxy Scaling Relations at the Upper Limit of Galaxy Mass

Understand

Super spirals are the most massive star-forming disk galaxies in the universe (Ogle et al.

• 2016, 2019).
• We measured rotation curves for 23 massive spirals and find a wide range of fast rotation speeds (240-570 km/s), indicating enclosed dynamical masses of 0.6 - 4E12 Msun.
• Super spirals with mass in stars log Mstars / Msun > 11.5 break from the baryonic Tully-Fisher relation (BTFR) established for lower mass galaxies.