%0 Generic %1 mukae2016cosmic %A Mukae, Shiro %A Ouchi, Masami %A Kakiichi, Koki %A Suzuki, Nao %A Ono, Yoshiaki %A Cai, Zheng %A Inoue, Akio K. %A Chiang, Yi-Kuan %A Shibuya, Takatoshi %A Matsuda, Yuichi %D 2016 %K correlation galaxy igm %T Cosmic Galaxy-IGM HI Relation at $z2-3$ Probed in the COSMOS/UltraVISTA $1.6$ deg$^2$ Field %U http://arxiv.org/abs/1605.00379 %X We present spatial correlations of galaxies and IGM neutral hydrogen HI in the COSMOS/UltraVISTA 1.62 deg$^2$ field. Our data consist of 13415 photo-$z$ galaxies at $z\sim2-3$ with $K_s<23.4$ and the Ly$\alpha$ forest absorptions in the background quasar spectra selected from SDSS data with no signature of damped Ly$\alpha$ system contamination. We estimate a galaxy overdensity $\delta_gal$ in an impact parameter of 2.5 pMpc, and calculate the Ly$\alpha$ forest fluctuations $\delta_F\rangle$ whose negative values correspond to the strong Ly$\alpha$ forest absorptions. We identify a weak anti-correlation between $\delta_gal$ and $\delta_F\rangle$ with a Spearman's rank correlation coefficient of $-0.39$ suggesting that the galaxy overdensities and the Ly$\alpha$ forest absorptions positively correlate in space at the $\sim90\%$ confidence level. This positive correlation indicates that high-$z$ galaxies exist around an excess of HI gas in the Ly$\alpha$ forest. We find four cosmic volumes, dubbed $A_obs$-$D_obs$, that have extremely large (small) values of $\delta_gal \simeq0.8$ ($-1$) and $\delta_F\rangle$ $\simeq0.1$ ($-0.4$), three out of which, $B_obs$-$D_obs$, significantly depart from the correlation, and weaken the correlation signal. We perform cosmological hydrodynamical simulations, and compare with our observational results. Our simulations reproduce the correlation, agreeing with the observational results. Moreover, our simulations have model counterparts of $A_obs$-$D_obs$, and suggest that the observations pinpoint, by chance, a galaxy overdensity like a proto-cluster, gas filaments lying on the sightline, a large void, and orthogonal low-density filaments. Our simulations indicate that the significant departures of $B_obs$-$D_obs$ are produced by the filamentary large-scale structures and the observation sightline effects.

@misc{mukae2016cosmic, abstract = {We present spatial correlations of galaxies and IGM neutral hydrogen HI in the COSMOS/UltraVISTA 1.62 deg$^2$ field. Our data consist of 13415 photo-$z$ galaxies at $z\sim2-3$ with $K_s<23.4$ and the Ly$\alpha$ forest absorptions in the background quasar spectra selected from SDSS data with no signature of damped Ly$\alpha$ system contamination. We estimate a galaxy overdensity $\delta_{gal}$ in an impact parameter of 2.5 pMpc, and calculate the Ly$\alpha$ forest fluctuations $\delta_{\langle F\rangle}$ whose negative values correspond to the strong Ly$\alpha$ forest absorptions. We identify a weak anti-correlation between $\delta_{gal}$ and $\delta_{\langle F\rangle}$ with a Spearman's rank correlation coefficient of $-0.39$ suggesting that the galaxy overdensities and the Ly$\alpha$ forest absorptions positively correlate in space at the $\sim90\%$ confidence level. This positive correlation indicates that high-$z$ galaxies exist around an excess of HI gas in the Ly$\alpha$ forest. We find four cosmic volumes, dubbed $A_{obs}$-$D_{obs}$, that have extremely large (small) values of $\delta_{gal} \simeq0.8$ ($-1$) and $\delta_{\langle F\rangle}$ $\simeq0.1$ ($-0.4$), three out of which, $B_{obs}$-$D_{obs}$, significantly depart from the correlation, and weaken the correlation signal. We perform cosmological hydrodynamical simulations, and compare with our observational results. Our simulations reproduce the correlation, agreeing with the observational results. Moreover, our simulations have model counterparts of $A_{obs}$-$D_{obs}$, and suggest that the observations pinpoint, by chance, a galaxy overdensity like a proto-cluster, gas filaments lying on the sightline, a large void, and orthogonal low-density filaments. Our simulations indicate that the significant departures of $B_{obs}$-$D_{obs}$ are produced by the filamentary large-scale structures and the observation sightline effects.}, added-at = {2016-05-03T10:04:09.000+0200}, author = {Mukae, Shiro and Ouchi, Masami and Kakiichi, Koki and Suzuki, Nao and Ono, Yoshiaki and Cai, Zheng and Inoue, Akio K. and Chiang, Yi-Kuan and Shibuya, Takatoshi and Matsuda, Yuichi}, biburl = {https://www.bibsonomy.org/bibtex/2aed9b5573365a5b153346e5801a9122e/miki}, description = {[1605.00379] Cosmic Galaxy-IGM HI Relation at ${\it{z}}\sim 2-3$ Probed in the COSMOS/UltraVISTA $1.6$ deg$^2$ Field}, interhash = {c30d07f541f8bdd6334599d92069c36d}, intrahash = {aed9b5573365a5b153346e5801a9122e}, keywords = {correlation galaxy igm}, note = {cite arxiv:1605.00379Comment: 9 pages, 8 figures, submitted to ApJ}, timestamp = {2016-05-03T10:04:09.000+0200}, title = {Cosmic Galaxy-IGM HI Relation at ${\it{z}}\sim 2-3$ Probed in the COSMOS/UltraVISTA $1.6$ deg$^2$ Field}, url = {http://arxiv.org/abs/1605.00379}, year = 2016 }