Starburst in our Backyard: Resolving the 5 Gyr Galaxy-wide Star-Formation Episode in the Milky Way

Rohan Naidu

Thursday December 3rd, 14:45

Recent work (e.g., Ruiz-Lara+20) has uncovered a starburst around the solar circle that occurred ~5 Gyrs ago. This starburst has been circumstantially associated with the timing of the 10:1 Sagittarius merger. In this talk I will show this starburst occurred not only at the solar circle, but across the disk, with its intensity peaking in the inner 5 kpc of the Galaxy, and falling off beyond ~15 kpc. I will demonstrate that this starburst is particularly prominent among metal-poor stars with strong vertical actions (Jz), lending strong support to a scenario where metal-poor gas from Sagittarius (which is on a high Jz orbit) was involved. While extragalactic starbursts have been studied for decades, and several mechanisms to trigger them have been proposed (e.g., disk disturbances funneling gas to central regions of the Galaxy), this starburst in our own backyard affords a unique, highly resolved opportunity to test models of star-formation. There is much work to be done on the theoretical side to understand the detailed dynamics of such a merger-induced starburst. Classical funneling models (e.g., Hernquist & Mihos 1995) for instance do not produce the kind of spatially extended star-burst, stretching all the way past the solar circle, seen in this case. The relationship between the metal-rich and metal-poor stars that formed around the time of this event (stars like our Sun!) is also a tantalizing open question. By laying out a complete observational picture of this Galaxy-shaping event clearly in this talk, I hope to spur discussion and collaboration at this workshop.