%0 Generic %1 battaia2016stacked %A Battaia, Fabrizio Arrigoni %A Hennawi, Joseph F. %A Cantalupo, Sebastiano %A Prochaska, J. Xavier %D 2016 %K cgm emission quasar %T The Stacked Lyman-Alpha Emission Profile from the Circum-Galactic Medium of z~2 Quasars %U http://arxiv.org/abs/1604.02942 %X In the context of the FLASHLIGHT survey, we obtained deep narrow band images of 15 $z\sim2$ quasars with GMOS on Gemini-South in an effort to measure Ly$\alpha$ emission from circum- and inter-galactic gas on scales of hundreds of kpc from the central quasar. We do not detect bright giant Ly$\alpha$ nebulae (SB~10$^-17$ erg s$^-1$ cm$^-2$ arcsec$^-2$ at distances >50 kpc) around any of our sources, although we routinely ($\simeq47$%) detect smaller scale <50 kpc Ly$\alpha$ emission at this SB level emerging from either the extended narrow emission line regions powered by the quasars or by star-formation in their host galaxies. We stack our 15 deep images to study the average extended Ly$\alpha$ surface brightness profile around $z\sim2$ quasars, carefully PSF-subtracting the unresolved emission component and paying close attention to sources of systematic error. Our analysis, which achieves an unprecedented depth, reveals a surface brightness of SB$_\rm Ly\alpha\sim10^-19$ erg s$^-1$ cm$^-2$ arcsec$^-2$ at $\sim200$ kpc, with a $2.3\sigma$ detection of Ly$\alpha$ emission at SB$_\rm Ly\alpha=(5.5\pm3.1)\times10^-20$ erg s$^-1$ cm$^-2$ arcsec$^-2$ within an annulus spanning 50 kpc <R< 500 kpc from the quasars. Assuming this Ly$\alpha$ emission is powered by fluorescence from highly ionized gas illuminated by the bright central quasar, we deduce an average volume density of $n_H=0.6\times10^-2$ cm$^-3$ on these large scales. Our results are in broad agreement with the densities suggested by cosmological hydrodynamical simulations of massive ($M\simeq10^12.5M_ødot$) quasar hosts, however they indicate that the typical quasars at these redshifts are surrounded by gas that is a factor of ~100 times less dense than the (~1 cm$^-3$) gas responsible for the giant bright Ly$\alpha$ nebulae around quasars recently discovered by our group.

@misc{battaia2016stacked, abstract = {In the context of the FLASHLIGHT survey, we obtained deep narrow band images of 15 $z\sim2$ quasars with GMOS on Gemini-South in an effort to measure Ly$\alpha$ emission from circum- and inter-galactic gas on scales of hundreds of kpc from the central quasar. We do not detect bright giant Ly$\alpha$ nebulae (SB~10$^{-17}$ erg s$^{-1}$ cm$^{-2}$ arcsec$^{-2}$ at distances >50 kpc) around any of our sources, although we routinely ($\simeq47$%) detect smaller scale <50 kpc Ly$\alpha$ emission at this SB level emerging from either the extended narrow emission line regions powered by the quasars or by star-formation in their host galaxies. We stack our 15 deep images to study the average extended Ly$\alpha$ surface brightness profile around $z\sim2$ quasars, carefully PSF-subtracting the unresolved emission component and paying close attention to sources of systematic error. Our analysis, which achieves an unprecedented depth, reveals a surface brightness of SB$_{\rm Ly\alpha}\sim10^{-19}$ erg s$^{-1}$ cm$^{-2}$ arcsec$^{-2}$ at $\sim200$ kpc, with a $2.3\sigma$ detection of Ly$\alpha$ emission at SB$_{\rm Ly\alpha}=(5.5\pm3.1)\times10^{-20}$ erg s$^{-1}$ cm$^{-2}$ arcsec$^{-2}$ within an annulus spanning 50 kpc <R< 500 kpc from the quasars. Assuming this Ly$\alpha$ emission is powered by fluorescence from highly ionized gas illuminated by the bright central quasar, we deduce an average volume density of $n_{\rm H}=0.6\times10^{-2}$ cm$^{-3}$ on these large scales. Our results are in broad agreement with the densities suggested by cosmological hydrodynamical simulations of massive ($M\simeq10^{12.5}M_\odot$) quasar hosts, however they indicate that the typical quasars at these redshifts are surrounded by gas that is a factor of ~100 times less dense than the (~1 cm$^{-3}$) gas responsible for the giant bright Ly$\alpha$ nebulae around quasars recently discovered by our group.}, added-at = {2016-04-12T12:11:17.000+0200}, author = {Battaia, Fabrizio Arrigoni and Hennawi, Joseph F. and Cantalupo, Sebastiano and Prochaska, J. Xavier}, biburl = {https://www.bibsonomy.org/bibtex/2e112ed03908e7e7acbe2b689a38d5ab2/miki}, description = {[1604.02942] The Stacked Lyman-Alpha Emission Profile from the Circum-Galactic Medium of z~2 Quasars}, interhash = {d69afde407c9a9dd3cdfffb0290c99d6}, intrahash = {e112ed03908e7e7acbe2b689a38d5ab2}, keywords = {cgm emission quasar}, note = {cite arxiv:1604.02942Comment: 22 pages, 13 figures, 1 table, submitted to ApJ}, timestamp = {2016-04-12T12:11:17.000+0200}, title = {The Stacked Lyman-Alpha Emission Profile from the Circum-Galactic Medium of z~2 Quasars}, url = {http://arxiv.org/abs/1604.02942}, year = 2016 }