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<p><font size="2"><span style="font-size:10pt"><b><font style="font-family:Calibri,Helvetica,sans-serif,serif,"EmojiFont"" size="3" face="Calibri,Helvetica,sans-serif" color="black"><span id="divtagdefaultwrapper" style="font-size:12pt"><font color="black"><font size="3" face="Calibri,Helvetica,sans-serif,Helvetica,EmojiFont,Apple Color Emoji,Segoe UI Emoji,NotoColorEmoji,Segoe UI Symbol,Android Emoji,EmojiSymbols" color="black"><span id="divtagdefaultwrapper" style="font-size:12pt"></span></font></font></span></font></b></span></font></p>
<font size="2"><b><font style="font-family:Calibri,Helvetica,sans-serif,serif,"EmojiFont"" size="3" face="Calibri,Helvetica,sans-serif" color="black"><font color="black"><font size="3" face="Calibri,Helvetica,sans-serif,Helvetica,EmojiFont,Apple Color Emoji,Segoe UI Emoji,NotoColorEmoji,Segoe UI Symbol,Android Emoji,EmojiSymbols" color="black">
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</span></font></span></div>
<div style="margin-top:0; margin-bottom:0"><span style="font-weight:normal"><font style="font-family:Arial,Helvetica,sans-serif,serif,"EmojiFont"" size="3" face="Arial,Helvetica,sans-serif" color="black"><span style="font-size:12pt">On Friday the 18th we have
the next astronomy seminar with</span></font><font style="font-family:Arial,Helvetica,sans-serif,serif,"EmojiFont"" size="3" face="Arial,Helvetica,sans-serif" color="black"><span style="font-size:12pt">
</span></font><font style="font-family:Arial,Helvetica,sans-serif,serif,"EmojiFont"" size="3" face="Arial,Helvetica,sans-serif" color="black"><span style="font-size:12pt">Lorenzo Nativi (Stockholm University)
</span></font></span><font style="font-family:Arial,Helvetica,sans-serif,serif,"EmojiFont"" size="3" face="Arial,Helvetica,sans-serif"><span style="font-size:12pt"><span style="font-weight:normal">speaking at 10:30 via Zoom.</span></span></font></div>
<div style="margin-top:0; margin-bottom:0"><font style="font-family:Arial,Helvetica,sans-serif,serif,"EmojiFont"" size="3" face="Arial,Helvetica,sans-serif"><span style="font-size:12pt"><span style="font-weight:normal">(<span>Please, join the call before 10:30!</span>)<br>
</span></span></font></div>
</font></font></font><br>
</b></font>
<p></p>
<p><font size="2"><span style="font-size:10pt"><b>Investigating the jet-ejecta interaction in neutron star mergers</b><br>
<br>
GW170817 represented the first detection of a binary neutron star merger, and the coalescence of the two neutron stars was followed by both the ejection of neutron-rich material and the launch of a relativistic jet.<br>
These two dynamical components, mildly-relativistic ejecta, and ultra-relativistic outflow, were detected independently: the first one powered a "macronova" (or "kilonova"), a thermal transient powered by the radioactive decay of the freshly synthesized r-process
nuclei. The jet instead powered a short GRB consisting of an early gamma-ray signal followed by a multi-wavelength afterglow.<br>
The presence of a jet successfully breaking out from the ejecta was additionally confirmed by the detection of superluminal motion.<br>
These two components were detected and modelled independently, but they interact before becoming visible, and this might have left an imprint on the detected signals.<br>
I will discuss the results of the 3D special-relativistic simulations used to investigate the consequences of a jet propagating through a realistic environment, created by a neutrino-driven wind around the central remnant.<br>
I will show how a jet can "punch-away" a fraction of high-opacity material at early times, before the brightening of the macronova, and how this is going to impact the observed signal.<br>
Then I will show what happens in the other direction i.e., how the ejecta impact the jet. I will show that the emerging jets are mostly shaped by their interaction with the surrounding environment and their eventual initial structures only plays a minor role
in the final outcome. Moreover, turbulent motions arising during the interaction produce inhomogeneities in the jet profile when observed face-on.<br>
These inhomogeneities impact the peak afterglow flux, and the inferred kinetic energy of a single jet from different observers can cover a fraction about 1/3 of the observed short GRB population.</span></font>
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<div style="margin-top:14pt; margin-bottom:14pt"><font face="Calibri,Helvetica,sans-serif,serif,EmojiFont">If anyone is interested in chatting with the speaker, we can leave the zoom call opened after the seminar. </font></div>
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<p><font style="font-family:Calibri,Helvetica,sans-serif,serif,"EmojiFont"" size="3" face="Calibri,Helvetica,sans-serif" color="black"><span id="divtagdefaultwrapper" style="font-size:12pt"><font color="black"><font size="3" face="Calibri,Helvetica,sans-serif,Helvetica,EmojiFont,Apple Color Emoji,Segoe UI Emoji,NotoColorEmoji,Segoe UI Symbol,Android Emoji,EmojiSymbols" color="black"><span id="divtagdefaultwrapper" style="font-size:12pt"></span></font></font></span></font></p>
<font style="font-family:Calibri,Helvetica,sans-serif,serif,"EmojiFont"" size="3" face="Calibri,Helvetica,sans-serif" color="black"><font color="black"><font size="3" face="Calibri,Helvetica,sans-serif,Helvetica,EmojiFont,Apple Color Emoji,Segoe UI Emoji,NotoColorEmoji,Segoe UI Symbol,Android Emoji,EmojiSymbols" color="black">
<div style="margin-top:14pt; margin-bottom:14pt"><font face="Calibri,Helvetica,sans-serif,serif,EmojiFont">Cheers,</font></div>
<div style="margin-top:14pt; margin-bottom:14pt"><font face="Calibri,Helvetica,sans-serif,serif,EmojiFont">Chris and Carolina</font></div>
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<p>---------------------------------------------------------------------------------------------</p>
<p><br>
</p>
<p>Carolina Robustini is inviting you to a scheduled Zoom meeting.</p>
<p><br>
</p>
<p>Topic: Astronomy Department Seminar - Lorenzo Nativi</p>
<p>Time: Feb 18, 2022 10:30 AM Stockholm</p>
<p><br>
</p>
<p>Join Zoom Meeting</p>
<p>https://stockholmuniversity.zoom.us/j/66310610960?pwd=SitJZGI3ZUl5b3ZzWkNVZEZ1clpmdz09</p>
<p><br>
</p>
<p>Meeting ID: 663 1061 0960</p>
<p>Passcode: 621431</p>
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<p>Meeting ID: 663 1061 0960</p>
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<p><span style="margin:0px; padding:0px; border:0px none; outline:0px; font-size:12.15999984741211px; font-family:Verdana,Arial,Helvetica,sans-serif; vertical-align:baseline; display:block; color:rgb(38,44,42)"><br>
</span><span style="margin:0px; padding:0px; border:0px none; outline:0px; font-size:12.15999984741211px; font-family:Verdana,Arial,Helvetica,sans-serif; vertical-align:baseline; display:block; color:rgb(38,44,42)"></span><span style="margin:0px; padding:0px; border:0px none; outline:0px; vertical-align:baseline; display:block"><span style="color:rgb(33,33,33); font-family:wf_segoe-ui_normal,"Segoe UI","Segoe WP",Tahoma,Arial,sans-serif,serif,EmojiFont; font-size:13.333333015441895px">Carolina
Robustini </span></span><span style="margin:0px; padding:0px; border:0px none; outline:0px; vertical-align:baseline; display:block"><span style="color:rgb(33,33,33); font-family:wf_segoe-ui_normal,"Segoe UI","Segoe WP",Tahoma,Arial,sans-serif,serif,EmojiFont; font-size:13.333333015441895px">Inst.
f. Solar Physics, Dept. of Astronomy, Stockholm University</span><br style="color:rgb(33,33,33); font-family:wf_segoe-ui_normal,"Segoe UI","Segoe WP",Tahoma,Arial,sans-serif,serif,EmojiFont; font-size:13.333333015441895px">
<span style="color:rgb(33,33,33); font-family:wf_segoe-ui_normal,"Segoe UI","Segoe WP",Tahoma,Arial,sans-serif,serif,EmojiFont; font-size:13.333333015441895px">AlbaNova University Centre, SE-10691 Stockholm, Sweden</span><br style="color:rgb(33,33,33); font-family:wf_segoe-ui_normal,"Segoe UI","Segoe WP",Tahoma,Arial,sans-serif,serif,EmojiFont; font-size:13.333333015441895px">
<font size="2" face="wf_segoe-ui_normal, Segoe UI, Segoe WP, Tahoma, Arial, sans-serif, serif, EmojiFont" color="#212121"><span style="">Email: carolina.robustini@astro.su.se</span></font><br>
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