A deep search for metals near redshift 7: the line-of-sight towards ULAS J1120+0641

A deep search for metals near redshift 7: the line-of-sight towards ULAS J1120+0641. Bosman, S. E. I., Becker, G. D., Haehnelt, M. G., Hewett, P. C., McMahon, R. G., Mortlock, D. J., Simpson, C., & Venemans, B. P. ArXiv e-prints, 1705:arXiv:1705.08925, May, 2017.

Paper abstract bibtex

We present a search for metal absorption line systems at the highest redshifts to date using a deep (30h) VLT/X-Shooter spectrum of the z = 7.084 quasi-stellar object (QSO) ULAS J1120+0641. We detect seven intervening systems at z \textgreater 5.5, with the highest-redshift system being a C IV absorber at z = 6.51. We find tentative evidence that the mass density of C IV remains flat or declines with redshift at z \textless 6, while the number density of C II systems remains relatively flat over 5 \textless z \textless 7. These trends are broadly consistent with models of chemical enrichment by star formation-driven winds that include a softening of the ultraviolet background towards higher redshifts. We find a larger number of weak ( W_rest \textless 0.3A ) Mg II systems over 5.9 \textless z \textless 7.0 than predicted by a power-law fit to the number density of stronger systems. This is consistent with trends in the number density of weak Mg II systems at z = 2.5, and suggests that the mechanisms that create these absorbers are already in place at z = 7. Finally, we investigate the associated narrow Si IV, C IV, and N V absorbers located near the QSO redshift, and find that at least one component shows evidence of partial covering of the continuum source.

@article{bosman_deep_2017,
	title = {A deep search for metals near redshift 7: the line-of-sight towards {ULAS} {J1120}+0641},
	volume = {1705},
	shorttitle = {A deep search for metals near redshift 7},
	url = {http://adsabs.harvard.edu/abs/2017arXiv170508925B},
	abstract = {We present a search for metal absorption line systems at the highest 
redshifts to date using a deep (30h) VLT/X-Shooter spectrum of the z =
7.084 quasi-stellar object (QSO) ULAS J1120+0641. We detect seven
intervening systems at z {\textgreater} 5.5, with the highest-redshift system
being a C IV absorber at z = 6.51. We find tentative evidence that the
mass density of C IV remains flat or declines with redshift at z {\textless} 6,
while the number density of C II systems remains relatively flat over 5
{\textless} z {\textless} 7. These trends are broadly consistent with models of
chemical enrichment by star formation-driven winds that include a
softening of the ultraviolet background towards higher redshifts. We
find a larger number of weak ( W\_rest {\textless} 0.3A ) Mg II systems over 5.9
{\textless} z {\textless} 7.0 than predicted by a power-law fit to the number density
of stronger systems. This is consistent with trends in the number
density of weak Mg II systems at z = 2.5, and suggests that the
mechanisms that create these absorbers are already in place at z = 7.
Finally, we investigate the associated narrow Si IV, C IV, and N V
absorbers located near the QSO redshift, and find that at least one
component shows evidence of partial covering of the continuum source.},
	urldate = {2017-05-30},
	journal = {ArXiv e-prints},
	author = {Bosman, Sarah E. I. and Becker, George D. and Haehnelt, Martin G. and Hewett, Paul C. and McMahon, Richard G. and Mortlock, Daniel J. and Simpson, Chris and Venemans, Bram P.},
	month = may,
	year = {2017},
	keywords = {Astrophysics - Astrophysics of Galaxies},
	pages = {arXiv:1705.08925},
}

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We detect seven\nintervening systems at z {\\textgreater} 5.5, with the highest-redshift system\nbeing a C IV absorber at z = 6.51. We find tentative evidence that the\nmass density of C IV remains flat or declines with redshift at z {\\textless} 6,\nwhile the number density of C II systems remains relatively flat over 5\n{\\textless} z {\\textless} 7. These trends are broadly consistent with models of\nchemical enrichment by star formation-driven winds that include a\nsoftening of the ultraviolet background towards higher redshifts. We\nfind a larger number of weak ( W\\_rest {\\textless} 0.3A ) Mg II systems over 5.9\n{\\textless} z {\\textless} 7.0 than predicted by a power-law fit to the number density\nof stronger systems. 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