Publication Date:
2016-07-31
Description:
As an alternate explanation for the cosmic acceleration, f ( R ) theories of gravity can predict an almost identical expansion history to standard cold dark matter (CDM), yet make very different predictions for the growth of cosmological structures. Measurements of the cosmic bulk flow provide a method for determining the strength of gravity over the history of structure formation. We use the modified gravity N -body code ecosmog to simulate dark matter particles and make predictions for the bulk flow magnitude in both CDM and f ( R ) gravity. With the peculiar velocities output by ecosmog , we determine the bulk flow at depths ranging from 20 to 50 h –1 Mpc, following the redshift and sky distribution of the 2MASS Tully–Fisher survey (2MTF). At each depth, we find that the CDM and f R 0 = 10 –5 simulations produce bulk flow measurements that are consistent with CDM predictions and the 2MTF survey at a 1 level. We also find that adopting an f ( R ) strength of f R 0 = 10 –3 predict a much larger value for the bulk flow, which disagree with CDM predictions at all depths considered. We conclude that f R 0 must be constrained to a level no greater than 10 –4 to agree with bulk flow measurements.
Print ISSN:
0035-8711
Electronic ISSN:
1365-2966
Topics:
Physics
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