<html><head><meta http-equiv="Content-Type" content="text/html; charset=us-ascii"></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; line-break: after-white-space;" class=""><span style="caret-color: rgb(0, 0, 0); color: rgb(0, 0, 0);" class="">Dear all,</span><br style="caret-color: rgb(0, 0, 0); color: rgb(0, 0, 0);" class=""><br style="caret-color: rgb(0, 0, 0); color: rgb(0, 0, 0);" class=""><span style="caret-color: rgb(0, 0, 0); color: rgb(0, 0, 0);" class="">On Friday 24th of January, we have the next Astronomy seminar in room FC61 at 10:30.</span><br style="caret-color: rgb(0, 0, 0); color: rgb(0, 0, 0);" class=""><br style="caret-color: rgb(0, 0, 0); color: rgb(0, 0, 0);" class=""><span style="caret-color: rgb(0, 0, 0); color: rgb(0, 0, 0);" class="">Our speaker is Emil Rivera-Thorsen (SU):</span><br style="caret-color: rgb(0, 0, 0); color: rgb(0, 0, 0);" class=""><br style="caret-color: rgb(0, 0, 0); color: rgb(0, 0, 0);" class=""><span style="caret-color: rgb(0, 0, 0); color: rgb(0, 0, 0);" class="">Title: A cosmic Sunburst in stunning GravLens-vision</span><br style="caret-color: rgb(0, 0, 0); color: rgb(0, 0, 0);" class=""><br style="caret-color: rgb(0, 0, 0); color: rgb(0, 0, 0);" class=""><span style="caret-color: rgb(0, 0, 0); color: rgb(0, 0, 0);" class="">Abstract:</span><br style="caret-color: rgb(0, 0, 0); color: rgb(0, 0, 0);" class=""><br style="caret-color: rgb(0, 0, 0); color: rgb(0, 0, 0);" class=""><span style="caret-color: rgb(0, 0, 0); color: rgb(0, 0, 0);" class="">Despite a growing consensus that young galaxies contributed the majority of the</span><br style="caret-color: rgb(0, 0, 0); color: rgb(0, 0, 0);" class=""><span style="caret-color: rgb(0, 0, 0); color: rgb(0, 0, 0);" class="">extreme-UV photons that reionized the early Universe, we still do not have a</span><br style="caret-color: rgb(0, 0, 0); color: rgb(0, 0, 0);" class=""><span style="caret-color: rgb(0, 0, 0); color: rgb(0, 0, 0);" class="">firm grasp on which mechanisms have allowed these photons to escape through the</span><br style="caret-color: rgb(0, 0, 0); color: rgb(0, 0, 0);" class=""><span style="caret-color: rgb(0, 0, 0); color: rgb(0, 0, 0);" class="">abundant galactic neutral medium and into intergalactic space.</span><br style="caret-color: rgb(0, 0, 0); color: rgb(0, 0, 0);" class=""><br style="caret-color: rgb(0, 0, 0); color: rgb(0, 0, 0);" class=""><span style="caret-color: rgb(0, 0, 0); color: rgb(0, 0, 0);" class="">Low neutral column densities can arise either where a hot, luminous stellar</span><br style="caret-color: rgb(0, 0, 0); color: rgb(0, 0, 0);" class=""><span style="caret-color: rgb(0, 0, 0); color: rgb(0, 0, 0);" class="">population has ionized a large fraction of the galactic gas, or where</span><br style="caret-color: rgb(0, 0, 0); color: rgb(0, 0, 0);" class=""><span style="caret-color: rgb(0, 0, 0); color: rgb(0, 0, 0);" class="">turbulence, feedback or similar effects have created pathways through the</span><br style="caret-color: rgb(0, 0, 0); color: rgb(0, 0, 0);" class=""><span style="caret-color: rgb(0, 0, 0); color: rgb(0, 0, 0);" class="">neutral medium along certain lines of sight in an otherwise neutral medium.</span><br style="caret-color: rgb(0, 0, 0); color: rgb(0, 0, 0);" class=""><span style="caret-color: rgb(0, 0, 0); color: rgb(0, 0, 0);" class="">Realistic systems are generally complicated combinations of these effects; but</span><br style="caret-color: rgb(0, 0, 0); color: rgb(0, 0, 0);" class=""><span style="caret-color: rgb(0, 0, 0); color: rgb(0, 0, 0);" class="">in their pure form, they define toy models which are very useful to understand</span><br style="caret-color: rgb(0, 0, 0); color: rgb(0, 0, 0);" class=""><span style="caret-color: rgb(0, 0, 0); color: rgb(0, 0, 0);" class="">the underlying physics.</span><br style="caret-color: rgb(0, 0, 0); color: rgb(0, 0, 0);" class=""><br style="caret-color: rgb(0, 0, 0); color: rgb(0, 0, 0);" class=""><span style="caret-color: rgb(0, 0, 0); color: rgb(0, 0, 0);" class="">Two years ago, our collaboration took spectra a gravtitationally lensed galaxy</span><br style="caret-color: rgb(0, 0, 0); color: rgb(0, 0, 0);" class=""><span style="caret-color: rgb(0, 0, 0); color: rgb(0, 0, 0);" class="">at z=2.4, which showed a theoretically predicted, but not previously observed,</span><br style="caret-color: rgb(0, 0, 0); color: rgb(0, 0, 0);" class=""><span style="caret-color: rgb(0, 0, 0); color: rgb(0, 0, 0);" class="">Lyman-alpha profile arising from light escaping through a narrow, channel with</span><br style="caret-color: rgb(0, 0, 0); color: rgb(0, 0, 0);" class=""><span style="caret-color: rgb(0, 0, 0); color: rgb(0, 0, 0);" class="">extremely low neutral column density in an otherwise opaque neutral medium, just</span><br style="caret-color: rgb(0, 0, 0); color: rgb(0, 0, 0);" class=""><span style="caret-color: rgb(0, 0, 0); color: rgb(0, 0, 0);" class="">like its namesake weather phenomenon gives a direct view of the sun through</span><br style="caret-color: rgb(0, 0, 0); color: rgb(0, 0, 0);" class=""><span style="caret-color: rgb(0, 0, 0); color: rgb(0, 0, 0);" class="">perforated clouds. Follow-up UV imaging with Hubble Space Telescope confirmed</span><br style="caret-color: rgb(0, 0, 0); color: rgb(0, 0, 0);" class=""><span style="caret-color: rgb(0, 0, 0); color: rgb(0, 0, 0);" class="">that ionizing Lyman-continuum photons in large amounts are pouring out from a</span><br style="caret-color: rgb(0, 0, 0); color: rgb(0, 0, 0);" class=""><span style="caret-color: rgb(0, 0, 0); color: rgb(0, 0, 0);" class="">very compact region, exactly where this channel was predicted to be, confirming</span><br style="caret-color: rgb(0, 0, 0); color: rgb(0, 0, 0);" class=""><span style="caret-color: rgb(0, 0, 0); color: rgb(0, 0, 0);" class="">that we are looking straight down the barrel of a narrow perforation of galactic</span><br style="caret-color: rgb(0, 0, 0); color: rgb(0, 0, 0);" class=""><span style="caret-color: rgb(0, 0, 0); color: rgb(0, 0, 0);" class="">ISM.</span><br style="caret-color: rgb(0, 0, 0); color: rgb(0, 0, 0);" class=""><br style="caret-color: rgb(0, 0, 0); color: rgb(0, 0, 0);" class=""><span style="caret-color: rgb(0, 0, 0); color: rgb(0, 0, 0);" class="">The galaxy is strongly gravitationally lensed by a massive foreground cluster,</span><br style="caret-color: rgb(0, 0, 0); color: rgb(0, 0, 0);" class=""><span style="caret-color: rgb(0, 0, 0); color: rgb(0, 0, 0);" class="">which leads to the galaxy being seen in 12 distorted copies, each magnified</span><br style="caret-color: rgb(0, 0, 0); color: rgb(0, 0, 0);" class=""><span style="caret-color: rgb(0, 0, 0); color: rgb(0, 0, 0);" class="">10-30 times; adding both extra scientific opportunity and visual spectacle to</span><br style="caret-color: rgb(0, 0, 0); color: rgb(0, 0, 0);" class=""><span style="caret-color: rgb(0, 0, 0); color: rgb(0, 0, 0);" class="">the mix.</span><br style="caret-color: rgb(0, 0, 0); color: rgb(0, 0, 0);" class=""><br style="caret-color: rgb(0, 0, 0); color: rgb(0, 0, 0);" class=""><a href="https://www.albanova.se/event/astronomy-seminar-emil-rivera-thorsen/" class="">https://www.albanova.se/event/astronomy-seminar-emil-rivera-thorsen/</a><br style="caret-color: rgb(0, 0, 0); color: rgb(0, 0, 0);" class=""><br style="caret-color: rgb(0, 0, 0); color: rgb(0, 0, 0);" class=""><span style="caret-color: rgb(0, 0, 0); color: rgb(0, 0, 0);" class="">Upcoming events:</span><br style="caret-color: rgb(0, 0, 0); color: rgb(0, 0, 0);" class=""><span style="caret-color: rgb(0, 0, 0); color: rgb(0, 0, 0);" class="">31/01 (Fri) @ 10:30: Jes Jorgensen (NBI)</span><br style="caret-color: rgb(0, 0, 0); color: rgb(0, 0, 0);" class=""><span style="caret-color: rgb(0, 0, 0); color: rgb(0, 0, 0);" class="">07/02 (Fri) @ 10:30: John Airy (SU Science Education)</span><br style="caret-color: rgb(0, 0, 0); color: rgb(0, 0, 0);" class=""><span style="caret-color: rgb(0, 0, 0); color: rgb(0, 0, 0);" class="">14/02 (Fri) @ 10:30: Per Calissendorff (PhD seminar)</span><br style="caret-color: rgb(0, 0, 0); color: rgb(0, 0, 0);" class=""><span style="caret-color: rgb(0, 0, 0); color: rgb(0, 0, 0);" class="">21/02 (Fri) @ 10:30: Beibei Liu (Lund)</span><br style="caret-color: rgb(0, 0, 0); color: rgb(0, 0, 0);" class=""><br style="caret-color: rgb(0, 0, 0); color: rgb(0, 0, 0);" class=""><span style="caret-color: rgb(0, 0, 0); color: rgb(0, 0, 0);" class="">Kind regards,</span><br style="caret-color: rgb(0, 0, 0); color: rgb(0, 0, 0);" class=""><span style="caret-color: rgb(0, 0, 0); color: rgb(0, 0, 0);" class="">Cristina & Arjan</span><br class=""><div class="">
<div dir="auto" style="caret-color: rgb(0, 0, 0); color: rgb(0, 0, 0); letter-spacing: normal; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px; -webkit-text-stroke-width: 0px; text-decoration: none; word-wrap: break-word; -webkit-nbsp-mode: space; line-break: after-white-space;" class=""><div style="text-align: start; text-indent: 0px; word-wrap: break-word; -webkit-nbsp-mode: space; line-break: after-white-space;" class="">-------------------------------------------<br class="">Dr. Arjan Bik<br class="">Stockholm University<br class="">AlbaNova University Center<br class="">Department of Astronomy<br class="">SE-106 91 Stockholm - Sweden<br class="">Tel: +46 (0) 85537 8549<br class=""><a href="https://www.su.se/english/profiles/abik" class="">https://www.su.se/english/profiles/abik</a></div><div style="text-align: start; text-indent: 0px; word-wrap: break-word; -webkit-nbsp-mode: space; line-break: after-white-space;" class="">-------------------------------------------<br class=""></div></div>
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