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<p>Happening in ~3 hours from now in the <b>Conference</b> room. </p>
<div class="moz-cite-prefix">On 2/27/26 3:03 PM, Pooyan Goodarzi
wrote:<br>
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cite="mid:CAN7Yd1KQWY6Lv+gmTJM_BVGDU0aS1KawE0wR5knPdoHiqh7=nA@mail.gmail.com">
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<p>Hi all,</p>
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<p>We will have a <span class="gmail-il">PASS</span> talk by
Morgan on <b>Monday, March 2nd</b>. Please join us at noon (<b>from
12:00 to 1:00 pm</b>) in the <b>Conference Room</b> (PHYS
3051).</p>
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<p align="center"><b>Morgan Ohana, PhD Student</b><br>
Monday, 12:00 pm, Conference Room (PHYS 3051)</p>
<p align="center"><b>Simulations of Eccentricity Growth in
Compact Binary Accretion Disks with Magnetohydrodynamic
Turbulence</b></p>
<div style="text-align:center">We present the results of four
magnetohydrodynamic simulations and one alpha-disk simulation
of accretion disks in a compact binary system, neglecting
vertical stratification and assuming a locally isothermal
equation of state. We demonstrate that in the presence of a
net vertical field, disks that extend out to the 3:1
mean-motion resonance grow eccentricity in full MHD in much
the same way as in hydrodynamical disks. Hence, turbulence due
to the magnetorotational instability (MRI) does not impede the
tidally driven growth of eccentricity in any meaningful way.
However, we find two important differences with alpha-disk
theory. First, in MHD, eccentricity builds up in the inner
disk with a series of episodes of radial disk-breaking into
two misaligned eccentric disks, separated by a region of
circular orbits. Standing eccentric waves are often present in
the inner eccentric disk. Second, the successful spreading of
an accretion disk with MRI turbulence out to the resonant
radius is nontrivial—and much harder than spreading an alpha
disk. This is due to the tendency to develop overdense rings
in which tidal torques overwhelm MRI transport and truncate
the disk too early. We believe that the inability to spread
the disk sufficiently was the reason why our previous attempt
to excite eccentricity via the 3:1 mean-motion resonance with
MHD failed. Exactly how MHD disks successfully spread outward
in compact binary systems is an important problem that has not
yet been understood.</div>
<div
id="m_6191282534260419912m_6597901899100687007m_-7314571423100097885m_-3414541767872711075m_9215603032040371864m_-1672972118947443868gmail-:1f4">
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<div dir="ltr"><b>If you’re interested in sharing your work
as a speaker, please feel free to add your name to this
spreadsheet [<a
href="https://docs.google.com/spreadsheets/d/1N3ncf43jdB6aHYHhyWmyHMycxDg4_phHZXLkQvviO0o/edit?usp=sharing"
target="_blank" moz-do-not-send="true">Google Sheet</a>].
Recordings of all the previous talks are available on
our website: <a href="https://ucrpass.arxiv.social/"
target="_blank" moz-do-not-send="true"
class="moz-txt-link-freetext">https://ucrpass.arxiv.social</a></b>
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Best,<br>
Pooyan<br>
Physics and Astronomy Student Seminar (<span><span><span
class="gmail-il">PASS</span></span></span>) <br>
<a href="https://ucrpass.arxiv.social/" target="_blank"
moz-do-not-send="true" class="moz-txt-link-freetext">https://ucrpass.arxiv.social</a></div>
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