10655( 1) - 04/05/05 12:20 - [ 1] PROPOSAL FOR HUBBLE SPACE TELESCOPE OBSERVATIONS ST ScI Use Only ID: 10655 Version: 1 Check-in Date: 05-Apr-2005 16:20:26 1.Proposal Title: Flares from Tidal Disruption of Stars by Galactic Supermassive Black Holes ------------------------------------------------------------------------------------ 2. Proposal For 3. Cycle 4. Parallel Pointing Tolerance AR 14 ------------------------------------------------------------------------------------ 5. Investigators Contact? PI: Dr. Robert Geller University of California - Santa Barbara CoI: Dr. Robert Antonucci University of California - Santa Barbara N CoI: Dr. Makoto Kishimoto University of Edinburgh, Institute for N Astronomy CoI: Mr. Elijah Quetin University of California - Santa Barbara N CoI: Prof. David Merritt Rochester Institute of Technology N CoI: Mr. Gustavo Litvin University of California - Santa Barbara N CoI: Mr. Tom Fuller University of California - Santa Barbara N ------------------------------------------------------------------------------------ 6. Abstract We are searching for flares expected to occur when a supermassive black hole (SMBH) tidally disrupts a star from its host galaxy and accretes the captured gas. The expected event rate for complete stellar disruptions of main sequence stars is 2.2 x 10^-4 (L/10^10Lo)^-0.30 per galaxy per year, according to calculations recently published by one of us. The flares should be easy to detect, even for partial disruptions, if anywhere near the Eddington luminosity as expected theoretically. The HST archives are currently the best resource for finding flares. HST's resolution allows fitting of a host and nuclear component on galaxies that could barely be resolved from the ground. In the first of two methods, we will compare the same galaxies at two different HST imaging epochs: Approximately 30 flares are expected in about 16, 000 galaxies in WFPC2 archival images taken at two or more epochs. In a second method, we compare about 200, 000 galaxies in WFPC2 and ACS archival single-epoch images with subsequent Sloan images. This is expected to lead to the discovery of ~ 60 flares. ACS provides fewer two-epoch observations but a comparable database for the one-epoch method. Taken together, we estimate 90 detectable flares. ------------------------------------------------------------------------------------ 10655( 1) - 04/05/05 12:20 - [ 2] Summary Form for Proposal 10655 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Proposal Category AR ------------------------------------------------------------------------------------------------------------------------------------