betsy-mills-hot-gas-masers-and-cloud-collisions-the-extreme-properties-of-molecular-gas-at-the-heart-of-the-milky-way-galaxy.html

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      <a href="https://keflavich.github.io/blog/betsy-mills-hot-gas-masers-and-cloud-collisions-the-extreme-properties-of-molecular-gas-at-the-heart-of-the-milky-way-galaxy.html" rel="bookmark"
         title="Permalink to Betsy Mills: Hot Gas, Masers, and Cloud Collisions: The extreme properties of molecular gas at the heart of the Milky Way Galaxy">Betsy Mills: Hot Gas, Masers, and Cloud Collisions: The extreme properties of molecular gas at the heart of the Milky Way Galaxy</a></h2>
 
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  <footer class="post-info">
    <abbr class="published" title="2013-10-01T09:50:00-06:00">
      2013/10/01
    </abbr>
    <address class="vcard author">
      By <a class="url fn" href="https://keflavich.github.io/blog/author/adam-ginsburg.html">Adam Ginsburg</a>
    </address>
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  <div class="entry-content">
    <img alt="" src="https://keflavich.github.io/blog/iau303/images/mills.jpg" style="width: 800px;" />
<dl class="docutils">
<dt>VLA Survey</dt>
<dd><ul class="first last">
<li><p class="first">DnC at 24-36 GHz</p>
</li>
<li><p class="first">Brick NH3
+ very high temperatures in brick: 100's of K
+ optically thin 4-4,5-5,7-7
+ brightest, densest clumps have lowest temperatures
+ 300K gas, but no SF</p>
<blockquote>
<ul class="simple">
<li>CR heating?</li>
<li>Shock heating?</li>
</ul>
</blockquote>
</li>
<li><p class="first">36 GHz methanol maser
+ shock excited
+ dozens of point sources
+ 75 candidates, 29 T_B &gt; 1000K (masing)</p>
</li>
<li><p class="first">why so many masers?
+ large-scale shocks?
+ 80 km/s velocity gradient across cloud
+ methanol &amp; ammonia emission dominated by convergence point of velocities</p>
</li>
<li><p class="first">class I methanol masers usually show SF</p>
</li>
</ul>
</dd>
<dt>SF in the Brick?</dt>
<dd><ul class="first last simple">
<li>7 VLA continuum sources
+ peaks in a more distributed set of continuum emission</li>
<li>25 GHz continuum
+ most continuum outside of the molecular gas
+ external ionization</li>
</ul>
</dd>
<dt>Rest of the CMZ</dt>
<dd><ul class="first last simple">
<li>Pistol &amp; Quintuplet continuum with streaks from the nonthermal filaments
+ second LBV seen in radio</li>
<li>NH3 near Sgr A*
+ NH3 traces edges of Sgr A East SNR
+ some SF in 50km/s cloud and 20km/s cloud</li>
<li>CND not in HC3N, weakly in ammonia</li>
<li>no NH3 or HC3N at brightest submm clump</li>
<li>nonthermal 3-3 line</li>
</ul>
</dd>
<dt>Sgr B2</dt>
<dd><ul class="first last simple">
<li>CH3OH only non-self-absorbed against hot core
+ shell structure</li>
<li>NH3 2-2 maser</li>
</ul>
</dd>
</dl>
<div class="section" id="questions">
<h2>Questions</h2>
<blockquote>
<ul class="simple">
<li>Q Walsh: NH3 3-3 maser.  Expected more of those.  Were there others?</li>
<li>A: yes, there are at least 2 others</li>
<li>Q: Temperatures of ammonia.  Is ammonia the only tracer that gives high
temperature towards the Brick?</li>
<li>A: Yes, only one towards brick.  400-600K from H2 from Rodriguez-Fernandez.
400K in Sgr A from NH3 too.</li>
<li>Q: Formation pumping?</li>
<li>A: yes, possible.  Need to form on short timescales.</li>
<li>Q: Need hefty CR for that heating.  Can you expand on what VLA is good for?</li>
<li>A: CRs 10^-14, 10^-15.  May happen.  Hard to explain 100's K</li>
<li>A: VLA gets NH3 transitions for temperatures.  ALMA gives density.  VLA
gives free-free. No overlap in frequency</li>
<li>Q: Is the brick a cloud?  Is this really a transient colliding flow?</li>
<li>A: I don't claim that it's bound.</li>
</ul>
</blockquote>
</div>

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