the topology of hi in the smc
DESCRIPTION
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 - PowerPoint PPT PresentationTRANSCRIPT
The Topology of HI in the SMC
Jeremy GordonUniversity 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 00h52m, 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
G2 = (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 & ATCAdata
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
75-125pc: neutral/slight positive shift, hole topology
Results 30-75pc: clump
topology, trending towards neutral shift
75-125pc: 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 negativeneutral/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
References
Gott, J. R., III, Dickinson, M., & Melott, A. L. 1986, ApJ, 306, 341
Kim, S., & Park, C. 2007, ApJ, 663, 244 Melott, A. L., Cohen, A. P., Hamilton, A. J. S., Gott, J. R. I.,
& Weinberg, D. H. 1989, ApJ, 345, 618 Stanimirovic, S., Staveley-Smith, L., Dickey, J. M., Sault,
R. J., & Snowden, S. L. 1999, MNRAS, 302, 417 Staveley-Smith, L., Sault, R. J., Hatzidimitriou, D.,
Kesteven, M. J., & McConnell, D. 1997, MNRAS, 289, 225