1. 2MASS Tully-Fisher Survey
Mapping the Mass in the Universe
Tao Hong (NAOC, ICRAR, CAASTRO)
2MTF Team
Large Scale Structure and Galaxy Flow Conference
Quy Nhon, Vietnam,

2. Motivation Most of the matter is dark
Map all the matter in the local universe, by measuring the peculiar velocity field.

3. Peculiar velocity as a cosmological probe
Dark matter
Mass distribution, large-scale structure
Dark energy
Growth rate
Test cosmological models
ΛCDM
Constrain cosmological parameters
Ωm, σ8

4. Previous studies on PV field
Bulk flow measurement
Watkins et al., 2009
Depth ~ 50 h-1Mpc
Vpec = 407 ± 81 km/s
Inconsistent with ΛCDM at >98% confidence level
Weyant et al., 2011
Nusser & Davis., 2011
Depth ~ 40 h-1Mpc
Vpec = 333±38 km/s
Consistent with ΛCDM
Dai et al., 2011; Turnbull et al., 2012; Ma & Pan 2014…

5. Previous studies on PV field
Velocity power spectrum
Watkins & Feldman, 2007
Constrained shape parameter Γ
“lower than, but consistent with, CMB data”
Multipole components of PV field
Feldman, Watkins & Hudson, 2010
shear and octupole moments measured
“consistent with WMAP5 power spectrum”

6. Measure the Peculiar Velocity Using Tully-Fisher Relation
Tully-Fisher relation provides the redshift independent distances for spirals.
Unbiased matter tracer
Trace both visible matter
and dark matter

7. 2MASS Tully-Fisher Survey
Measure Tully-Fisher (TF) distances to nearby spirals
Galaxies are selected from the 2MASS Redshift Survey (2MRS)
Near Infrared magnitudes
Optical redshifts
High quality HI widths
New observation + ALFALFA + Archival

8. 2MTF bulk flow team Tao Hong (ICRAR/UWA, NAOC)
Thomas Jarrett (University of Cape Town)
Heath Jones (Monash University)
Baerbel Koribalski (ATNF)
David Lagattuta (Swinburne University)
Lucas Macri (Texas A&M University)
Karen Masters (University of Portsmouth)
Christopher Springob (ICRAR/UWA)
Lister Staveley-Smith (ICRAR/UWA)

9. Advantages of 2MTF Comparing with previous T-F surveys, we have:
Uniform source selection & sky-coverage
Better sample to measure the peculiar velocity field
Smaller zone of avoidance (ZoA)
2MTF goes down to b = ±5°
SFI++ covers to b = ±15°
Near Infrared magnitudes
Ks, H and J band magnitudes
SFI++ used optical magnitudes – I band

10. Scientific Goal of 2MTF Reconstruct the matter field
High quality Tully-Fisher distance catalog
Test cosmological models
Constrain cosmological parameters
Ωm, σ8
Reconstruct the matter field
compare with the field
from 2MRS, 6dF.
The 2MRS velocity field
Erdogdu et al., 2006

11. Source Selection Selection criteria Select from 2MASS Redshift Survey
Ks < mag
cz < 10,000 km/s
b/a < 0.5
Morphology
Selection limits on HI data
εw/w < 10%
S/N > 5

12. Observations & data collection
Green Bank Telescope (Masters et al., 2014)
Northern sky δ ≥ - 40◦
1194 galaxies observed, 479 well detected
Parkes Telescope (Hong et al., 2013)
Southern sky δ < - 40◦
305 galaxies observed, 151 well detected
ALFALFA
576 galaxies used (final ALFALFA has been included in 2016)
Archival data
1502 galaxies collected (mainly from Cornell archive)
Newly observed
by 2MTF team

13. Uniform Sky-coverage

14. Tully-Fisher calculation
TF plot of MTF galaxies
Distances & peculiar velocity calculated

15. Bulk Flow estimation Least χ2 fitting with Gaussian windows
Depth at 20, 30 and 40 h-1Mpc
Fitting in the log-normal space
Malmquist bias corrected
Error estimated by Jackknife method
Also adopted Maximum Likelihood Method (MLE; Kaiser 1998) & Minimum Variance method (MV; Watkins et al., 2009, Feldman et al., 2010)

16. Bulk Flow estimation
Direction of the bulk flow
Hong et al., 2014

17. Bulk Flow estimation Amplitude of the bulk flow
Disagreement between previous results

18. Bulk Flow estimation Amplitude of the bulk flow
Measured by 2MTF with χ2 method
Hong et al., 2014

19. Bulk Flow estimation
Compare with previous studies

20. Bulk Flow estimation Amplitude of the bulk flow
Measured by 2MTF with minimum variance method
Hong et al., 2014

21. Next steps Final ALFALFA data added
2062 2MTF galaxies after applying all criteria

22. Next steps Final ALFALFA data added
2062 2MTF galaxies after applying all criteria
Bulk flow estimation for the full sample

23. Next steps Final ALFALFA data added
2062 2MTF galaxies after applying all criteria
Bulk flow estimation for the full sample
Multipole fitting applied on the sample

24. Data availability 2MASS/2MRS data published
New GBT/Parkes data published
Masters+ 2014; Hong+ 2013
ALFALFA mostly published online
Peculiar velocities will be published later on:
ict.icrar.org/2MTF
to accompany final bulk flow paper in 2017

25. Conclusions 2MASS Tully-Fisher Survey
More uniform sky-coverage
Straightforward selection criteria
Smaller “Zone of Avoidance”
Distances for nearby spirals using T-F relation
Good sample for cosmological studies
Highly accurate bulk flow estimate
Measurements indicate consistency with ΛCDM
Full sample has been completed
Further analysis ongoing