Large scale structure in the HI Parkes All-Sky Survey: Filling the Voids with HI galaxies?

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dc.creatorBasilakos, S.
dc.creatorPlionis, M.
dc.creatorKovac, K.
dc.creatorVoglis, N.
dc.date2007-03-28
dc.date.accessioned2026-07-07T11:01:16Z
dc.date.available2026-07-07T11:01:16Z
dc.descriptionWe estimate the two-point correlation function in redshift space of the recently compiled HIPASS neutral hydrogen (HI) sources catalogue, which if modeled as a power law, $ξ(r)=(r_{0}/r)^γ$, the best-fitting parameters for the HI selected galaxies are found to be $r_{0}=3.3 \pm 0.3 h^{-1}$ Mpc with $γ=1.38 \pm 0.24$. Fixing the slope to its universal value $γ=1.8$, we obtain $r_{0}= 3.2\pm 0.2 h^{-1}$ Mpc. Comparing the measured two point correlation function with the predictions of the concordance cosmological model, we find that at the present epoch the HI selected galaxies are anti-biased with respect to the underlying matter fluctuation field with their bias value being $b_{0}\simeq 0.68$. Furthermore, dividing the HI galaxies into two richness subsamples we find that the low mass HI galaxies have a very low present bias factor ($b_{0}\simeq 0.48$), while the high mass HI galaxies trace the underlying matter distribution as the optical galaxies ($b_{0}\simeq 1$). Using our derived present-day HI galaxy bias we estimate their redshift space distortion parameter, and correct accordingly the correlation function for peculiar motions. The resulting real-space correlation length is $r^{\rm re}_{0}=1.8 \pm 0.2 h^{-1}$Mpc and $r^{\rm re}_{0}=3.9 \pm 0.6 h^{-1}$Mpc for the low and high mass HI galaxies, respectively. The low-mass HI galaxies appear to have the lowest correlation length among all extragalactic populations studied to-date. Also, we have correlated the IRAS-PSCz reconstructed density field, smoothed over scales of 5$h^{-1}$ Mpc, with the positions of the HI galaxies, to find that indeed the HI galaxies are typically found in negative overdensity regions ($δρ/ρ_{\rm PSCz} \mincir 0$).
dc.description9 pages, 8 figures, MNRAS in press
dc.identifierhttps://arxiv.org/abs/astro-ph/0703713
dc.identifierhttp://arxiv.org/abs/astro-ph/0703713
dc.identifierMon.Not.Roy.Astron.Soc.378:301-308,2007
dc.identifierdoi:10.1111/j.1365-2966.2007.11781.x
dc.identifier.urihttp://salesiana.dossiersoluciones.com/handle/123456789/187904
dc.subjectAstrophysics
dc.titleLarge scale structure in the HI Parkes All-Sky Survey: Filling the Voids with HI galaxies?
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