Oxygen-enhanced extremely metal-poor DLAs: A signpost of the first stars?. (arXiv:2201.08394v1 [astro-ph.GA])
<a href="http://arxiv.org/find/astro-ph/1/au:+Welsh_L/0/1/0/all/0/1">Louise Welsh</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Cooke_R/0/1/0/all/0/1">Ryan Cooke</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Fumagalli_M/0/1/0/all/0/1">Michele Fumagalli</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Pettini_M/0/1/0/all/0/1">Max Pettini</a>
We present precise abundance determinations of two near-pristine damped
Ly$alpha$ systems (DLAs) to assess the nature of the [O/Fe] ratio at [Fe/H] <
-3 (i.e. <1/1000 of the solar metallicity). Prior observations indicate that
the [O/Fe] ratio is consistent with a constant value, [O/Fe] ~ +0.4, when -3 <
[Fe/H] < -2, but this ratio may increase when [Fe/H] < -3. In this paper, we
test this picture by reporting new, high-precision [O/Fe] abundances in two of
the most metal-poor DLAs currently known. We derive values of [O/Fe] = +0.50
+/- 0.10 and [O/Fe] = +0.62 +/- 0.05 for these two z ~ 3 near-pristine gas
clouds. These results strengthen the idea that the [O/Fe] abundances of the
most metal-poor DLAs are elevated compared to DLAs with [Fe/H] > -3. We compare
the observed abundance pattern of the latter system to the nucleosynthetic
yields of Population III supernovae (SNe), and find that the enrichment can be
described by a (19-25) M$_{odot}$ Population III SN that underwent a
(0.9-2.4)$times 10^{51}$ erg explosion. These high-precision measurements
showcase the behaviour of [O/Fe] in the most metal-poor environments. Future
high-precision measurements in new systems will contribute to a firm detection
of the relationship between [O/Fe] and [Fe/H]. These data will reveal whether
we are witnessing a chemical signature of enrichment from Population III stars
and allow us to rule out contamination from Population II stars.
We present precise abundance determinations of two near-pristine damped
Ly$alpha$ systems (DLAs) to assess the nature of the [O/Fe] ratio at [Fe/H] <
-3 (i.e. <1/1000 of the solar metallicity). Prior observations indicate that
the [O/Fe] ratio is consistent with a constant value, [O/Fe] ~ +0.4, when -3 <
[Fe/H] < -2, but this ratio may increase when [Fe/H] < -3. In this paper, we
test this picture by reporting new, high-precision [O/Fe] abundances in two of
the most metal-poor DLAs currently known. We derive values of [O/Fe] = +0.50
+/- 0.10 and [O/Fe] = +0.62 +/- 0.05 for these two z ~ 3 near-pristine gas
clouds. These results strengthen the idea that the [O/Fe] abundances of the
most metal-poor DLAs are elevated compared to DLAs with [Fe/H] > -3. We compare
the observed abundance pattern of the latter system to the nucleosynthetic
yields of Population III supernovae (SNe), and find that the enrichment can be
described by a (19-25) M$_{odot}$ Population III SN that underwent a
(0.9-2.4)$times 10^{51}$ erg explosion. These high-precision measurements
showcase the behaviour of [O/Fe] in the most metal-poor environments. Future
high-precision measurements in new systems will contribute to a firm detection
of the relationship between [O/Fe] and [Fe/H]. These data will reveal whether
we are witnessing a chemical signature of enrichment from Population III stars
and allow us to rule out contamination from Population II stars.
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