Density Weighted Angular Redshift Fluctuations: a New Cosmological Observable. (arXiv:1911.12056v2 [astro-ph.CO] UPDATED)

Density Weighted Angular Redshift Fluctuations: a New Cosmological Observable. (arXiv:1911.12056v2 [astro-ph.CO] UPDATED)
<a href="http://arxiv.org/find/astro-ph/1/au:+Hernandez_Monteagudo_C/0/1/0/all/0/1">Carlos Hernandez-Monteagudo</a> (1), <a href="http://arxiv.org/find/astro-ph/1/au:+Chaves_Montero_J/0/1/0/all/0/1">Jonas Chaves-Montero</a> (2), <a href="http://arxiv.org/find/astro-ph/1/au:+Angulo_R/0/1/0/all/0/1">Raul E. Angulo</a> (3) ((1) CEFCA, (2) ANL, (3) DIPC)

We propose the use of angular fluctuations in the galaxy redshift field as a
new way to extract cosmological information in the Universe. This new probe
$delta z (hat{n})$ consists on the statistics of sky maps built by projecting
redshifts under a Gaussian window of width $sigma_z$ centred upon a redshift
$z_{rm obs}$, and weighted by the galaxy density field. We compute the angular
power spectrum of the $delta z (hat{n})$ field in both numerical simulations
and in linear perturbation theory. From these we find that the $delta z
(hat{n})$ field: {it (i)} is sensitive to the underlying density and peculiar
velocity fields; {it (ii)} is highly correlated, at the $gtrsim 60,%$
level, to the line-of-sight projected peculiar velocity field; {it (iii)} for
narrow windows $(sigma_z < 0.03$), it is almost completely uncorrelated to the
projected galaxy angular density field under the same redshift window; and {it
(iv)} it is largely unaffected by multiplicative and additive systematic errors
on the observed number of galaxies that are redshift-independent over
$simsigma_z$. We conclude that $delta z (hat{n})$ is a simple and robust
tomographic measure of the cosmic density and velocity fields, complementary to
angular clustering, that will contribute to more complete exploitations of
current and upcoming galaxy redshift surveys.

We propose the use of angular fluctuations in the galaxy redshift field as a
new way to extract cosmological information in the Universe. This new probe
$delta z (hat{n})$ consists on the statistics of sky maps built by projecting
redshifts under a Gaussian window of width $sigma_z$ centred upon a redshift
$z_{rm obs}$, and weighted by the galaxy density field. We compute the angular
power spectrum of the $delta z (hat{n})$ field in both numerical simulations
and in linear perturbation theory. From these we find that the $delta z
(hat{n})$ field: {it (i)} is sensitive to the underlying density and peculiar
velocity fields; {it (ii)} is highly correlated, at the $gtrsim 60,%$
level, to the line-of-sight projected peculiar velocity field; {it (iii)} for
narrow windows $(sigma_z < 0.03$), it is almost completely uncorrelated to the
projected galaxy angular density field under the same redshift window; and {it
(iv)} it is largely unaffected by multiplicative and additive systematic errors
on the observed number of galaxies that are redshift-independent over
$simsigma_z$. We conclude that $delta z (hat{n})$ is a simple and robust
tomographic measure of the cosmic density and velocity fields, complementary to
angular clustering, that will contribute to more complete exploitations of
current and upcoming galaxy redshift surveys.

http://arxiv.org/icons/sfx.gif