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Bryony Martin SKA Conference 2011
1. Peculiar Velocities in Supernova Cosmology
Kessler, et al. 2009
Bryony Martin
MSc, Department of Astronomy, University of Cape Town
Supervised by:
Dr Kurt van der Heyden & Prof Bruce Bassett
SKA SA Postgraduate Bursary Conference, November 2011
2. Peculiar velocities
Additional motions specific to individual galaxies
Recession velocity i al
r ad
Overdensity
Peculiar velocity
HT
SIG
tr a
F
EO
ns
LIN
ve
rs e
• Recession velocity due to Hubble flow
• Peculiar velocity due to matter distribution of local environment
– baryonic and dark matter
2 Peculiar Velocities in Supernova Cosmology Bryony Martin 2011
3. Type Ia supernovae
The standard candles of the universe
Kim, et al. 1997
3 Peculiar Velocities in Supernova Cosmology Bryony Martin 2011
4. Supernova cosmology
Calculating constraints on cosmological parameters
Kessler, et al. 2009
Kessler, et al. 2009
4 Peculiar Velocities in Supernova Cosmology Bryony Martin 2011
5. Supernova cosmology with peculiar velocities
Peculiar velocities induce Doppler effects in supernova observations
Kessler, et al. 2009
Doppler
shifting
5 Peculiar Velocities in Supernova Cosmology Bryony Martin 2011
6. Supernova cosmology with peculiar velocities
Peculiar velocities induce Doppler effects in supernova observations
Kessler, et al. 2009
Doppler
shifting
INACCURATE
PARAMETER
CONSTRAINTS
Inaccurate best-fit
cosmology
6 Peculiar Velocities in Supernova Cosmology Bryony Martin 2011
7. Simulation data
Simulated galaxies with explicit velocity information
www.mpa-garching.mpg.de
Kitzbichler & White, 2007
7 Peculiar Velocities in Supernova Cosmology Bryony Martin 2011
8. Simulated galaxies
Mock survey galaxy catalogues showing structure
8 Peculiar Velocities in Supernova Cosmology Bryony Martin 2011
9. Supernova rates
Using galaxy properties to predict the presence of type Ia supernovae
Mannucci et al, 2005
9 Peculiar Velocities in Supernova Cosmology Bryony Martin 2011
10. Simulated Type Ia Supernovae
Supernova dataset with known peculiar velocities
10 Peculiar Velocities in Supernova Cosmology Bryony Martin 2011
12. Shifts in Ωm for various maximum redshifts
Average shifts in Ωm are within 1σ
12 Peculiar Velocities in Supernova Cosmology Bryony Martin 2011
13. Shifts in H0 for various maximum redshifts
Average shifts in H0 are ~1σ
13 Peculiar Velocities in Supernova Cosmology Bryony Martin 2011
14. Calculated values of Ωm using true and observed redshifts
Calculated values are 1-2σ from the fiducial value of Ωm
14 Peculiar Velocities in Supernova Cosmology Bryony Martin 2011
15. Calculated values of H0 using true and observed redshifts
Calculated values using observed redshifts are 2σ less than the fiducial value of H0
15 Peculiar Velocities in Supernova Cosmology Bryony Martin 2011
16. Summary
RESULTS
Simulated type Ia supernova dataset with peculiar velocity information
• Parameter estimates from simulated Hubble diagrams using both cosmological
and observed redshifts
• Measured shifts in parameters which are roughly of the order of 1σ
16 Peculiar Velocities in Supernova Cosmology Bryony Martin 2011
