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<p>Hi all, </p>
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<p>We will have our next PASS talk on Monday with al talk by
Issac. Please join us on <b>November 25th (Monday)</b> at <b>noon</b>
(from 12:00 pm to 1:00 pm) in the <b>Nebula Room</b> (PHYS
3027).</p>
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<p><span><span class="gmail-Y8pC0"></span></span></p>
<div aria-describedby="tt-display-name-field" class="gmail-YysZRb"
align="center"><b>Issac Ye Lin</b><b>, PhD Student<br>
</b></div>
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<p align="center">Monday, 12:00 pm, Nebula Room (PHYS 3027)</p>
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<div><b>KBSS-Lyα: Metallicity of Lyman-α Emitters at z~2.5</b></div>
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<div align="center">We present a Keck/MOSFIRE composite
spectrum for a sample of faint KBSS-Lyα emitters (z~2.5) in
the Keck Baryonic Structure Survey. With the new stacked
measurement of [OII] λλ3727,3729Å doublet, we combine
rest-optical measurements of O, H, and N lines to infer for
12+log(O/H) oxygen abundance with photoionization modeling.
In our 4-parameter MCMC inference (Z_neb, Z_star, N/O, and
log(U)), the input emission line ratios produce a bimodal
metallicity posterior (Z_neb=0.2 Z_sun}, Z_neb=0.9Z_sun).
Characterized by high O32 ratio (log([OIII]/[OII] = 0.78),
high ionization (log(U) = -2.2), and low dust attenuation
(E(B-V) = 0.12), we reconcile the lower metallicity peak
with other common metrics such as z~2-3 MZR, log(U)-M_sun
relation, and electron temperature metallicity inference.
The elevated O32 hints at density-bounded star forming
regions in contrast to the more commonly assumed
ionization-bounded case in photoionization models.
Therefore, additional parameters are needed to break the
degeneracy observed in the extreme physical environment of
faint LAEs.</div>
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<div>If you’re interested in sharing your work as a speaker,
please feel free to add your name to the spreadsheet [<a
href="https://docs.google.com/spreadsheets/d/1N3ncf43jdB6aHYHhyWmyHMycxDg4_phHZXLkQvviO0o/edit?usp=sharing"
target="_blank">Google Sheet</a>].
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<div>Best,</div>
<div>Pooyan</div>
<span><span>
<div>Physics and Astronomy Student Seminar (PASS)</div>
</span></span></div>
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