<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
</head>
<body>
<p>Reminder of David's seminar in half an hour</p>
<p>C<br>
</p>
<div class="moz-cite-prefix">On 14/03/2022 13:31, Chris Usher wrote:<br>
</div>
<blockquote type="cite"
cite="mid:54f25263-56d0-1507-4963-6951d70f0491@astro.su.se">
<meta http-equiv="content-type" content="text/html; charset=UTF-8">
<p>On Friday, March 18th at 10:30 we have our next seminar with
David Sobral (Lancaster) speaking via Zoom</p>
<div dir="auto" style="word-wrap: break-word; -webkit-nbsp-mode:
space; line-break: after-white-space;" class=""><b> Resolving
the formation and evolution of primeval galaxies: from
re-ionisation to cosmic noon</b></div>
<div dir="auto" style="word-wrap: break-word; -webkit-nbsp-mode:
space; line-break: after-white-space;" class=""><br>
</div>
<div dir="auto" style="word-wrap: break-word; -webkit-nbsp-mode:
space; line-break: after-white-space;" class="">
<div dir="auto" style="word-wrap: break-word; -webkit-nbsp-mode:
space; line-break: after-white-space;" class=""> I will
present new results that reveal the nature and evolution of
primeval galaxies, picked up in large and deep surveys due to
their Lyman-alpha emission. I will show how Lyman-alpha
emitters (LAEs) are an incredibly rare population of galaxies
in the local Universe, but become dominant into the epoch of
re-ionisation and that they have the properties and the number
density necessary to dominate and drive cosmic re-ionisation.<br
class="">
<br class="">
Lyman-α (Lyα) is intrinsically the brightest line emitted from
active galaxies, but its resonant nature and susceptibility to
dust as a rest-frame UV photon makes Lyα very hard to
interpret due to the uncertain Lyα escape fraction, until now.
By conducting large blind surveys at different cosmic times
and the necessary spectroscopic follow-up, we have obtained a
simple empirical relation that robustly retrieves the Lyα
escape fraction as a function of Lyα rest-frame EW. We show
that the relation constrains a well-defined anti-correlation
between ionisation efficiency and dust extinction in
Lyman-alpha emitters (LAEs) which is likely an evolutionary
sequence for very young metal poor sources going through a LAE
phase. We also reveal how those LAEs/primeval galaxies have
high escape fractions of not just Lyman-alpha photons, but
also LyC, and how the production and escape seem to be linked
together.</div>
<div dir="auto" style="word-wrap: break-word; -webkit-nbsp-mode:
space; line-break: after-white-space;" class=""><br>
</div>
<div dir="auto" style="word-wrap: break-word; -webkit-nbsp-mode:
space; line-break: after-white-space;" class="">We are trying
something new this year with leaving the Zoom call open after
the formal hour of the seminar is up to allow the speaker, if
they wish, to chat informally with anyone who is interested.</div>
<div dir="auto" style="word-wrap: break-word; -webkit-nbsp-mode:
space; line-break: after-white-space;" class=""><br>
</div>
<div dir="auto" style="word-wrap: break-word; -webkit-nbsp-mode:
space; line-break: after-white-space;" class="">Thanks<br>
Chris and Carolina</div>
<div dir="auto" style="word-wrap: break-word; -webkit-nbsp-mode:
space; line-break: after-white-space;" class=""><br>
</div>
<div dir="auto" style="word-wrap: break-word; -webkit-nbsp-mode:
space; line-break: after-white-space;" class="">Christopher
Usher is inviting you to a scheduled Zoom meeting. <br>
<br>
Topic: Astronomy Department Seminar - David Sobral <br>
Time: Mar 18, 2022 10:30 AM Stockholm <br>
<br>
Join Zoom Meeting <br>
<a class="moz-txt-link-freetext"
href="https://stockholmuniversity.zoom.us/j/64177331893?pwd=bzRRT3BjTFZtVDdnL08rdlg1VEpUQT09"
moz-do-not-send="true">https://stockholmuniversity.zoom.us/j/64177331893?pwd=bzRRT3BjTFZtVDdnL08rdlg1VEpUQT09</a>
<br>
<br>
Meeting ID: 641 7733 1893 <br>
Passcode: eSPORdIpAR </div>
</div>
</blockquote>
</body>
</html>