@article{kollmeier_photon_2014,
	title = {The {Photon} {Underproduction} {Crisis}},
	volume = {789},
	issn = {2041-8205},
	url = {http://stacks.iop.org/2041-8205/789/i=2/a=L32},
	doi = {10.1088/2041-8205/789/2/L32},
	abstract = {We examine the statistics of the low-redshift Lyα forest from smoothed particle hydrodynamic simulations in light of recent improvements in the estimated evolution of the cosmic ultraviolet background (UVB) and recent observations from the Cosmic Origins Spectrograph (COS). We find that the value of the metagalactic photoionization rate (Γ HI ) required by our simulations to match the observed properties of the low-redshift Lyα forest is a factor of five larger than the value predicted by state-of-the art models for the evolution of this quantity. This mismatch in Γ HI results in the mean flux decrement of the Lyα forest being overpredicted by at least a factor of two (a 10σ discrepancy with observations) and a column density distribution of Lyα forest absorbers systematically and significantly elevated compared to observations over nearly two decades in column density. We examine potential resolutions to this mismatch and find that either conventional sources of ionizing photons (galaxies and quasars) must contribute considerably more than current observational estimates or our theoretical understanding of the low-redshift universe is in need of substantial revision.},
	language = {en},
	number = {2},
	urldate = {2016-10-25},
	journal = {The Astrophysical Journal Letters},
	author = {Kollmeier, Juna A. and Weinberg, David H. and Oppenheimer, Benjamin D. and Haardt, Francesco and Katz, Neal and {Romeel Davé} and Fardal, Mark and Madau, Piero and Danforth, Charles and Ford, Amanda B. and Peeples, Molly S. and McEwen, Joseph},
	year = {2014},
	pages = {L32},
}

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We find that the value of the metagalactic photoionization rate (Γ HI ) required by our simulations to match the observed properties of the low-redshift Lyα forest is a factor of five larger than the value predicted by state-of-the art models for the evolution of this quantity. This mismatch in Γ HI results in the mean flux decrement of the Lyα forest being overpredicted by at least a factor of two (a 10σ discrepancy with observations) and a column density distribution of Lyα forest absorbers systematically and significantly elevated compared to observations over nearly two decades in column density. We examine potential resolutions to this mismatch and find that either conventional sources of ionizing photons (galaxies and quasars) must contribute considerably more than current observational estimates or our theoretical understanding of the low-redshift universe is in need of substantial revision.","language":"en","number":"2","urldate":"2016-10-25","journal":"The Astrophysical Journal Letters","author":[{"propositions":[],"lastnames":["Kollmeier"],"firstnames":["Juna","A."],"suffixes":[]},{"propositions":[],"lastnames":["Weinberg"],"firstnames":["David","H."],"suffixes":[]},{"propositions":[],"lastnames":["Oppenheimer"],"firstnames":["Benjamin","D."],"suffixes":[]},{"propositions":[],"lastnames":["Haardt"],"firstnames":["Francesco"],"suffixes":[]},{"propositions":[],"lastnames":["Katz"],"firstnames":["Neal"],"suffixes":[]},{"firstnames":[],"propositions":[],"lastnames":["Romeel Davé"],"suffixes":[]},{"propositions":[],"lastnames":["Fardal"],"firstnames":["Mark"],"suffixes":[]},{"propositions":[],"lastnames":["Madau"],"firstnames":["Piero"],"suffixes":[]},{"propositions":[],"lastnames":["Danforth"],"firstnames":["Charles"],"suffixes":[]},{"propositions":[],"lastnames":["Ford"],"firstnames":["Amanda","B."],"suffixes":[]},{"propositions":[],"lastnames":["Peeples"],"firstnames":["Molly","S."],"suffixes":[]},{"propositions":[],"lastnames":["McEwen"],"firstnames":["Joseph"],"suffixes":[]}],"year":"2014","pages":"L32","bibtex":"@article{kollmeier_photon_2014,\n\ttitle = {The {Photon} {Underproduction} {Crisis}},\n\tvolume = {789},\n\tissn = {2041-8205},\n\turl = {http://stacks.iop.org/2041-8205/789/i=2/a=L32},\n\tdoi = {10.1088/2041-8205/789/2/L32},\n\tabstract = {We examine the statistics of the low-redshift Lyα forest from smoothed particle hydrodynamic simulations in light of recent improvements in the estimated evolution of the cosmic ultraviolet background (UVB) and recent observations from the Cosmic Origins Spectrograph (COS). We find that the value of the metagalactic photoionization rate (Γ HI ) required by our simulations to match the observed properties of the low-redshift Lyα forest is a factor of five larger than the value predicted by state-of-the art models for the evolution of this quantity. This mismatch in Γ HI results in the mean flux decrement of the Lyα forest being overpredicted by at least a factor of two (a 10σ discrepancy with observations) and a column density distribution of Lyα forest absorbers systematically and significantly elevated compared to observations over nearly two decades in column density. We examine potential resolutions to this mismatch and find that either conventional sources of ionizing photons (galaxies and quasars) must contribute considerably more than current observational estimates or our theoretical understanding of the low-redshift universe is in need of substantial revision.},\n\tlanguage = {en},\n\tnumber = {2},\n\turldate = {2016-10-25},\n\tjournal = {The Astrophysical Journal Letters},\n\tauthor = {Kollmeier, Juna A. and Weinberg, David H. and Oppenheimer, Benjamin D. and Haardt, Francesco and Katz, Neal and {Romeel Davé} and Fardal, Mark and Madau, Piero and Danforth, Charles and Ford, Amanda B. and Peeples, Molly S. and McEwen, Joseph},\n\tyear = {2014},\n\tpages = {L32},\n}\n\n","author_short":["Kollmeier, J. A.","Weinberg, D. H.","Oppenheimer, B. D.","Haardt, F.","Katz, N.","Romeel Davé","Fardal, M.","Madau, P.","Danforth, C.","Ford, A. B.","Peeples, M. S.","McEwen, J."],"key":"kollmeier_photon_2014","id":"kollmeier_photon_2014","bibbaseid":"kollmeier-weinberg-oppenheimer-haardt-katz-romeeldav-fardal-madau-etal-thephotonunderproductioncrisis-2014","role":"author","urls":{"Paper":"http://stacks.iop.org/2041-8205/789/i=2/a=L32"},"metadata":{"authorlinks":{}}},"bibtype":"article","biburl":"https://bibbase.org/zotero/polyphant","dataSources":["7gvjSdWrEu7z5vjjj"],"keywords":[],"search_terms":["photon","underproduction","crisis","kollmeier","weinberg","oppenheimer","haardt","katz","romeel davé","fardal","madau","danforth","ford","peeples","mcewen"],"title":"The Photon Underproduction Crisis","year":2014}