(Proposal ID) S15B-073

(PI) Okamoto, Sakurako

(Proposal Title)
M81; Near field cosmology beyond the Local Group 3

(Abstract)
We wish to take g and i-band images of the M81 halo by Hyper Suprime-Cam (HSC).
 Recent photometric surveys, such as SDSS and PAndAS, led to discover many 
substructures, satellites, and to refine characterization of halo properties 
of the Milky Way and M31, which make a progress on solving the missing 
satellite problem, together with subsequent improvements of simulations.  
Following the Milky Way and M31, nearby M81 is the best target to investigate 
the hierarchal structural formation on galactic scales, and the HSC is the 
only instrument which enable us to do this.  We ask for 2 nights to complete 
the mapping of M81 out to a projected radius of 120 kpc, together with the 
previous observation.  Our primary goals will be to [1] Establish the stellar 
population content of large-scale structures, [2] Understand the true nature 
of the extended envelope, [3] Search for new  satellites and tidal streams in 
the central regions of the M81 Group, that can be use to place constraints on 
the interaction history of M81 group, and [4] Search for globular clusters in 
entire region of M81 and around. This is an extremely important endeavour 
since a statistically significant sample of systems must be studied in order 
to place meaningful constraints on theory.