The Topology of HI in the SMC Jeremy Gordon University of Georgia August 2, 2007 Advisors: Dr. Chepurnov Dr. Lazarian

Overview:  Small Magellanic Cloud  Genus Statistics  HI Column Density Map  My Project  Results

The Small Magellanic Cloud  NGC 292  RA 00 h 52 m, Dec -72°50’  ~60 kpc distant, covers ~ 4.5° x 4.5° area  Knots, filaments, holes, oh my!

Genus Statistics  Initial Developments  2D Genus – ’89  G 2 = (isolated high-density regions) – (isolated low-density regions)  Mathematically Speaking:

Genus Statistics, Cont.  Random Distribution:  Genus Shift Δν  +Δν  ‘swiss- cheese’ topology  -Δν  ‘meatball’ topology Kim & Park, 2007

Applications: Turbulence  Studies of turbulence utilize the power spectrum, which contains information on velocity fluctuations  No topological information embedded in the power spectrum, however  Genus analysis is a complementary tool in the study of turbulence

Data and Analysis  Combination of Parkes & ATCA data  HI: 21 cm line (1420MHz)  Spatial resolution of 29.52”/8.59pc  Effective resolution of ~90”/30pc

HI Column Density Map

Methodology  SMC cropped into 9 overlapping 150x150 regions  ‘Entire’ SMC cropped in 400x300 pixel region  Smoothing scale λ ≤ 10% of image length

Results  30-75pc: clump topology, trending towards neutral shift

Results  30-75pc: clump topology, trending towards neutral shift  pc: neutral/slight positive shift, hole topology

Results  30-75pc: clump topology, trending towards neutral shift  pc: neutral/slight positive shift, hole topology  ≥ 125pc: shift becoming more negative, clump topology

Results, Cont.  150x150 Regions:  Small Scales: 30 pc ≤ λ ≤ 50 pc  Medium Scales 50 pc ≤ λ ≤ 75 pc  Large Scales λ ≥ 75 pc  Similarities & Differences

150x150 Results

Conclusion  SMC exhibits a clump topology at small scales  At medium scales, genus shift becomes less negative  neutral/slight positive shift  At large scales, genus shift levels out at a slight negative value  Genus Analysis is an effective, complementary tool in the study of turbulence

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