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2MTF VI. Measuring the velocity power spectrum | | Cullan Howlett
; Lister Staveley-Smith
; Pascal J. Elahi
; Tao Hong
; Tom H. Jarrett
; D. Heath Jones
; Bärbel S. Koribalski
; Lucas M. Macri
; Karen L. Masters
; Christopher M. Springob
; | | Date: |
16 Jun 2017 | | Abstract: | We present measurements of the velocity power spectrum and constraints on the
growth rate of structure $fsigma_{8}$, at redshift zero, using the peculiar
motions of 2,062 galaxies in the completed 2MASS Tully-Fisher survey (2MTF). To
accomplish this we introduce a model for fitting the velocity power spectrum
including the effects of non-linear Redshift Space Distortions (RSD), allowing
us to recover unbiased fits down to scales $k=0.2,h,{
m Mpc}^{-1}$ without
the need to smooth or grid the data. Our fitting methods are validated using a
set of simulated 2MTF surveys. Using these simulations we also identify that
the Gaussian distributed estimator for peculiar velocities of
cite{Watkins2015} is suitable for measuring the velocity power spectrum, but
sub-optimal for the 2MTF data compared to using magnitude fluctuations $delta
m$, and that, whilst our fits are robust to a change in fiducial cosmology,
future peculiar velocity surveys with more constraining power may have to
marginalise over this. We obtain extit{scale-dependent} constraints on the
growth rate of structure in two bins, finding $fsigma_{8} =
[0.55^{+0.16}_{-0.13},0.40^{+0.16}_{-0.17}]$ in the ranges $k = [0.007-0.055,
0.55-0.150],h,{
m Mpc}^{-1}$. We also find consistent results using four
bins. Assuming scale- extit{independence} we find a value $fsigma_{8} =
0.51^{+0.09}_{-0.08}$, a $sim16\%$ measurement of the growth rate. Performing
a consistency check of General Relativity (GR) and combining our results with
CMB data only we find $gamma = 0.45^{+0.10}_{-0.11}$, a remarkable constraint
considering the small number of galaxies. All of our results are completely
independent of the effects of galaxy bias, and fully consistent with the
predictions of GR (scale-independent $fsigma_{8}$ and $gammaapprox0.55$). | | Source: | arXiv, 1706.5130 | | Services: | Forum | Review | PDF | Favorites | |
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