Dear all,
We invite you to please join us for CCAPP seminar this week! Our speakers this week will beRohan Naidu and Casey Lam. This will be a virtual seminar.
Our speakers’ titles and abstracts are listed below. Both Rohan and Casey will join us for valueadded at coffee on Tuesday. If you are interested in meeting with either of the speakers,please use the google docs provided here.
Meet with Rohan:
https://docs.google.com/spreadsheets/d/1FdKuWLecikTR5mSnKZVvr1-UFDYoWQMHIgQ7ZiUlSHw/edit?usp=sharing
Meet with Casey:
https://docs.google.com/spreadsheets/d/17UrmE1TAKroTTNRYkNIIT4b7cLzw-U4ILcfAsAflV0o/edit?usp=sharingLink for the
CCAPP Seminar on Tuesday:
https://osu.zoom.us/j/96209154804?pwd=d1lWZnRueGVVa2tabUZTak4xSkpaQT09password: CCAPP-2021
Speaker: Rohan Naidu
Title: Unraveling the Galactic Halo with the H3 Survey
Abstract: The Milky Way has assimilated smaller, immigrant galaxies throughout its history. Its outer reaches (the stellar halo) are a melting pot for stars that were born elsewhere but now call the Milky Way is their home. In this talk I will present results from the ongoing H3 Survey --the first dedicated halo survey in the Gaia era (150+ nights on the 6.5m MMT, 200k+ spectra of distant stars). I will present a comprehensive anatomy of our Galaxy out to 50 kpc, charting debris from various known and newly discovered mergers. I will focus on the last major merger at z~2 -- I will argue that it induced a ~30 degree tilt in the Milky Way’s dark matter halo with respect to the disk that remarkably persists to this day, requiring us to revisit a variety of conclusions drawn about the Galaxy assuming axisymmetry.
Speaker: Casey Lam
Title: Hunting for isolated black holes with gravitational microlensingAbstract: There are expected to be 100 million black holes (BHs) in the Milky Way, although mass measurements exist for only two dozen or so in binary systems. A substantial fraction of the Milky Way's BHs is expected to be isolated. This leaves large uncertainty in the number, masses, velocities, and formation channels of the Galactic BH population. Detection of isolatedBHs would enable the comparison of the single vs. binary/merger BH mass functions, which in turn would enable an improved understanding of BH formation channels. In this talk, I will present our analysis of 5 archival isolated BH hole candidates identified via microlensing. HST astrometry from 2009-2017 is jointly analyzed with photometry obtained from the MOA and OGLE microlensing surveys in order to measure the masses of the candidates, as well as identify their nature (substellar, stellar, or compact object). We find one of the five targets (OGLE-2011-BLG-0462/MOA-2011-BLG-191) is likely a neutron star or low-mass BH. In addition, we compare the full sample of 5 candidates to theoretical expectations of the number and masses of BHs in the Milky Way detectable via microlensing. Given the small sample size, the sample is consistent with the theoretical expectation of 100 million BHsin in the Milky Way.
