A Search for Warm/Hot Gas Filaments Between Pairs of SDSS Luminous Red Galaxies. (arXiv:1709.05024v4 [astro-ph.CO] UPDATED)
<a href="http://arxiv.org/find/astro-ph/1/au:+Tanimura_H/0/1/0/all/0/1">Hideki Tanimura</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Hinshaw_G/0/1/0/all/0/1">Gary Hinshaw</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+McCarthy_I/0/1/0/all/0/1">Ian G. McCarthy</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Waerbeke_L/0/1/0/all/0/1">Ludovic Van Waerbeke</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Aghanim_N/0/1/0/all/0/1">Nabila Aghanim</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Ma_Y/0/1/0/all/0/1">Yin-Zhe Ma</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Mead_A/0/1/0/all/0/1">Alexander Mead</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Hojjati_A/0/1/0/all/0/1">Alireza Hojjati</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Troster_T/0/1/0/all/0/1">Tilman Tr&#xf6;ster</a>

We search the Planck data for a thermal Sunyaev-Zel’dovich (tSZ) signal due
to gas filaments between pairs of Luminous Red Galaxies (LRG’s) taken from the
Sloan Digital Sky Survey Data Release 12 (SDSS/DR12). We identify $sim$260,000
LRG pairs in the DR12 catalog that lie within 6-10 $h^{-1} mathrm{Mpc}$ of
each other in tangential direction and within 6 $h^{-1} mathrm{Mpc}$ in radial
direction. We stack pairs by rotating and scaling the angular positions of each
LRG so they lie on a common reference frame, then we subtract a circularly
symmetric halo from each member of the pair to search for a residual signal
between the pair members. We find a statistically significant (5.3$sigma$)
signal between LRG pairs in the stacked data with a magnitude $Delta y = (1.31
pm 0.25) times 10^{-8}$. The uncertainty is estimated from two Monte Carlo
null tests which also establish the reliability of our analysis. Assuming a
simple, isothermal, cylindrical filament model of electron over-density with a
radial density profile proportional to $r_c/r$ (as determined from
simulations), where $r$ is the perpendicular distance from the cylinder axis
and $r_c$ is the core radius of the density profile, we constrain the product
of over-density and filament temperature to be $delta_c times (T_{rm e}/10^7
, {rm K}) times (r_c/0.5h^{-1} , {rm Mpc}) = 2.7 pm 0.5$. To our
knowledge, this is the first detection of filamentary gas at over-densities
typical of cosmological large-scale structure. We compare our result to the
BAHAMAS suite of cosmological hydrodynamic simulations (McCarthy et al. 2017)
and find a slightly lower, but marginally consistent Comptonization excess,
$Delta y = (0.84 pm 0.24) times 10^{-8}$.

We search the Planck data for a thermal Sunyaev-Zel’dovich (tSZ) signal due
to gas filaments between pairs of Luminous Red Galaxies (LRG’s) taken from the
Sloan Digital Sky Survey Data Release 12 (SDSS/DR12). We identify $sim$260,000
LRG pairs in the DR12 catalog that lie within 6-10 $h^{-1} mathrm{Mpc}$ of
each other in tangential direction and within 6 $h^{-1} mathrm{Mpc}$ in radial
direction. We stack pairs by rotating and scaling the angular positions of each
LRG so they lie on a common reference frame, then we subtract a circularly
symmetric halo from each member of the pair to search for a residual signal
between the pair members. We find a statistically significant (5.3$sigma$)
signal between LRG pairs in the stacked data with a magnitude $Delta y = (1.31
pm 0.25) times 10^{-8}$. The uncertainty is estimated from two Monte Carlo
null tests which also establish the reliability of our analysis. Assuming a
simple, isothermal, cylindrical filament model of electron over-density with a
radial density profile proportional to $r_c/r$ (as determined from
simulations), where $r$ is the perpendicular distance from the cylinder axis
and $r_c$ is the core radius of the density profile, we constrain the product
of over-density and filament temperature to be $delta_c times (T_{rm e}/10^7
, {rm K}) times (r_c/0.5h^{-1} , {rm Mpc}) = 2.7 pm 0.5$. To our
knowledge, this is the first detection of filamentary gas at over-densities
typical of cosmological large-scale structure. We compare our result to the
BAHAMAS suite of cosmological hydrodynamic simulations (McCarthy et al. 2017)
and find a slightly lower, but marginally consistent Comptonization excess,
$Delta y = (0.84 pm 0.24) times 10^{-8}$.

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