Cosmic flows in the nearby Universe: new peculiar velocities from SNe and cosmological constraints. (arXiv:1912.09383v1 [astro-ph.CO])
<a href="http://arxiv.org/find/astro-ph/1/au:+Boruah_S/0/1/0/all/0/1">Supranta S. Boruah</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Hudson_M/0/1/0/all/0/1">Michael J. Hudson</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Lavaux_G/0/1/0/all/0/1">Guilhem Lavaux</a>
The peculiar velocity field offers a unique way to probe dark matter density
field on large scales at low redshifts. In this work, we have compiled a new
sample of 465 peculiar velocities from low redshift $(z < 0.067)$ Type Ia
supernovae. We compare the reconstructed velocity field derived from the 2M++
galaxy redshift compilation to the supernovae, the SFI++ and the 2MTF
Tully-Fisher distance catalogues. We used a forward method to jointly infer the
distances and the velocities of distance indicators by comparing the
observations to the reconstruction. Comparison of the reconstructed peculiar
velocity fields to observations allows us to infer the cosmological parameter
combination $fsigma_8$, and the bulk flow velocity arising from outside the
survey volume. The residual bulk flow arising from outside the 2M++ volume is
inferred to be $159^{+12}_{-11}$ km s$^{-1}$ in the direction $l=259^{circ}
pm 4^{circ}$ and $b= 5^{circ}pm 3^{circ}$. We obtain $fsigma_{8} = 0.401
pm 0.017$, equivalent to $sigma_8(Omega_m/0.3)^{0.55}=0.775 pm 0.033$, a
$lesssim 4%,$ statistical uncertainty on the value of $fsigma_8$. Our
inferred value is consistent with other low redshift results in the literature.
The peculiar velocity field offers a unique way to probe dark matter density
field on large scales at low redshifts. In this work, we have compiled a new
sample of 465 peculiar velocities from low redshift $(z < 0.067)$ Type Ia
supernovae. We compare the reconstructed velocity field derived from the 2M++
galaxy redshift compilation to the supernovae, the SFI++ and the 2MTF
Tully-Fisher distance catalogues. We used a forward method to jointly infer the
distances and the velocities of distance indicators by comparing the
observations to the reconstruction. Comparison of the reconstructed peculiar
velocity fields to observations allows us to infer the cosmological parameter
combination $fsigma_8$, and the bulk flow velocity arising from outside the
survey volume. The residual bulk flow arising from outside the 2M++ volume is
inferred to be $159^{+12}_{-11}$ km s$^{-1}$ in the direction $l=259^{circ}
pm 4^{circ}$ and $b= 5^{circ}pm 3^{circ}$. We obtain $fsigma_{8} = 0.401
pm 0.017$, equivalent to $sigma_8(Omega_m/0.3)^{0.55}=0.775 pm 0.033$, a
$lesssim 4%,$ statistical uncertainty on the value of $fsigma_8$. Our
inferred value is consistent with other low redshift results in the literature.
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