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HighMassClusterFormation_TracingTheFlow2018.html
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<!doctype html>
<html lang="en">
<head>
<meta charset="utf-8">
<title>High mass star cluster formation</title>
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<!-- Slides! -->
<div class="reveal">
<div class="slides">
<section data-id="9e1f37193271406fc72e974be0a8a3fe">
<div class="sl-block" data-block-type="text" style="width: auto; height: auto;" data-block-id="fa1e26dfdc2f3050895879d1fc1c4f1a">
<div class="sl-block-content" data-placeholder-tag="h1" data-placeholder-text="Title Text" style="z-index: 11;">
<h1 style="word-break: keep-all; hyphens: none;">High mass star cluster formation</h1>
<p>A mix of review & some recent results </p>
<br>
<p class="footer">Adam Ginsburg</p>
<p class="smaller footer">Jansky Fellow, NRAO Socorro</p>
<br>
<div style='font-size:30px'>This presentation can be found at <a href="https://tinyurl.com/HMCFormationTTF18">https://tinyurl.com/HMCFormationTTF18</a></div>
</div>
</div>
</section>
<section data-id="c1392fbd50110aefd563d28a68139a12">
<div class="sl-block" data-block-type="text" style="width: auto; height: auto;" data-block-id="151a50162be742f0390e9588549872f7">
<div class="sl-block-content" data-placeholder-tag="h2" data-placeholder-text="Title Text" style="z-index: 12;">
<h2>What is a high-mass cluster?</h2>
</div>
</div>
<div class="sl-block" data-block-type="text" style="width: auto; height: auto;" data-block-id="5dfe0d23dab8754dbcb054193314aee7">
<div class="sl-block-content" data-placeholder-tag="p" data-placeholder-text="Text" style="z-index: 11; background-color: rgba(0, 0, 0, 0);" data-has-custom-html="" dir="ui">
<ul>
<li>Gravitationally bound collection of stars that survives the loss of gas</li>
<li>Collection of coeval stars that 'fully samples' the IMF</li>
<li>Clusters where interactions are important </li>
<ul><div class="smaller">
<li><a href="http://adsabs.harvard.edu/abs/2016MNRAS.457..313P">Portegies-Zwart 2016</a>,
<a href="http://adsabs.harvard.edu/abs/2015A%26A...577A.115V">Vincke+ 2016</a>,
Gemma Busquet's talk earlier
</li></div></ul>
<li>Around \(10^4~\mathrm{M}_\odot \), \(v_{esc} \gtrsim10\) km
s\(^{-1}\), so ionization alone does not disrupt gas</li>
<div class="smaller"><ul><li>
<a href="http://adsabs.harvard.edu/abs/2012ApJ...758L..28B"> Bressert+ 2012</a>,
<a href="http://esoads.eso.org/abs/2015ApJ...815...68M"> Matzner & Jumper 2015</a>,
<a href="http://adsabs.harvard.edu/abs/2009ApJ...703.1352K">Krumholz & Matzner 2009 </a>,
<a href="http://adsabs.harvard.edu/abs/2018MNRAS.475.3511G">Grudić+ 2018</a>
</li></ul></div>
</ul>
</div>
</div>
From here on, these are Young Massive Clusters (YMCs)
</section>
<section>
<!--<span class="image" style="background-image: url(assets/cluster_mass_vs_n_ostars.png); width:100%; height=100%;"> -->
<div class='sl-block' style='display:block; height: 1024px; left:0 px; top: 0px;'>
<img src="assets/cluster_mass_vs_n_ostars.png" style=''>
</div>
</section>
<section>
<img src="assets/PortegiesZwartClusterMassFunction.png">
</section>
<section>
<!-- <div>
<div style="position:absolute; top:100px; left: 600px; width: 300px; font-size: 30px; z-index:10;">
Upper mass cutoff varies with Galactic radius in M83
<div><a style="font-size:80%" href="http://adsabs.harvard.edu/abs/2015MNRAS.452..246A">Adamo+ 2015</a>
</div>
</div>
<img src='assets/Adamo2015_Fig7_cutoffmassvsradius.png' style="z-index:1; width:80%">
</div>-->
<span class="image" style="background-image: url(assets/Adamo2015_Fig7_cutoffmassvsradius.png); width:85%; display: block;">
<div style="position:absolute; top:100px; right: 10%; width: 300px; font-size: 30px; z-index:10;">
Upper mass cutoff varies with Galactic radius in M83
<div><a style="font-size:80%" href="http://adsabs.harvard.edu/abs/2015MNRAS.452..246A">Adamo+ 2015</a>
</div>
</div>
</span>
</section>
<section>
<h6>YMCs are the best local analogs<br> of proto-Globular Clusters</h6>
<ul>
<li>
and they're pretty good analogs <div class=smaller>(Bastian+
<a href="http://adsabs.harvard.edu/abs/2013MNRAS.436.2852B">2013</a>,
<a href="http://adsabs.harvard.edu/abs/2014MNRAS.443.3594B">2014a</a>,
<a href="http://adsabs.harvard.edu/abs/2014MNRAS.445..378B">2014b</a>,
<a href="http://esoads.eso.org/abs/2016EAS....80....5B">2016</a>,
Cabrera-Ziri+
<a href="http://esoads.eso.org/abs/2014MNRAS.441.2754C">2014</a>,
<a href="http://esoads.eso.org/abs/2015MNRAS.448.2224C">2015</a>
) </div>
</li>
<li>GCs probe Galaxy formation histories
<div class=smaller style="display:inline">(e.g.,
<a href="http://adsabs.harvard.edu/abs/2006ARA%26A..44..193B">Brodie & Strader 2006</a>,
<a href='http://adsabs.harvard.edu/abs/2018MNRAS.475.4309P'>Pfeffer+ 2018</a>,
<a href="http://adsabs.harvard.edu/abs/2018arXiv180605680K">Kruijssen+ 2018</a>
)</div>
</li>
<li> Open questions in GC populations to address with YMCs:
<ul>
<li>How does the power-law cluster MF evolve to a peaked one?
<div class=smaller>Low-mass get destroyed, e.g. <a href="http://adsabs.harvard.edu/abs/2012MNRAS.426.3008K">Kruijssen 2012</a></div>
</li>
<li>How do GCs form? i.e., how should we form GCs in simulations?
<li>Why do GCs contain MSPs?
<div style='display: inline' class=smaller> (what are MSPs)</div>
</li>
</ul>
</li>
</ul>
</section>
<section>
<h6>MSPs in GCs</h6>
<ul>
<li><b>MSP</b>s = Multiple Stellar Populations,
as opposed to <div><b>SSP</b>s = Simple (or Single) Stellar Populations</div>
</li>
<ul><li> Distinct sub-populations exist within most or all globular clusters
that are younger and/or chemically different
</li></ul>
<li><a style="font-size:90%" href="https://www.annualreviews.org/doi/abs/10.1146/annurev-astro-081817-051839">Bastian & Lardo 2017 ARAA review</a>:
<div>"Many scenarios have been suggested to explain [MSPs], with most
invoking multiple epochs of star formation within the
cluster", but most of these fail</div>
</li>
<!--
<li> YMCs lack MSPs, but have other features that may be related </li>
<ul>
<li> Extended Main Sequence Turnoffs (EMSTOs) - stellar evolution or multiple SF events? </li>
<li> Split Main Sequence - cluster stars rotate more rapidly than field? </li>
</ul>
-->
</ul>
</section>
<section data-id="558348493b3fc8afd4de33237a452c98">
<div class="sl-block" data-block-type="text" style="width: 942px; height: auto;" data-block-id="fa12fcded28569f8d6b538f805cb869a">
<div class="sl-block-content" data-placeholder-tag="h2" data-placeholder-text="Title Text" style="z-index: 11;">
<h4>Observations:</h4>
<p class='subtitle' >Forming high-mass clusters in the Galaxy</p>
</div>
</div>
<center>
<div class="sl-block" data-block-type="text" style="width: 806px; height: auto;" data-block-id="abb85ba9b28630306509ba413c7de4e7">
<div class="sl-block-content" data-placeholder-tag="p" data-placeholder-text="Text" style="z-index: 12; font-size:24px">
<ul>
<li>Galactic plane surveys find few (~10s) of high-mass protoclusters
<ul>
<li style="font-size:18px">
<a href="http://adsabs.harvard.edu/abs/2012ApJ...758L..29G" target="_blank">Ginsburg+ 2012</a>,
Urquhart+ <a href="http://adsabs.harvard.edu/abs/2014MNRAS.437.1791U" target="_blank">2014a</a>,
<a href="http://esoads.eso.org/abs/2014MNRAS.443.1555U" target="_blank">b</a>,
<a href="http://adsabs.harvard.edu/abs/2018MNRAS.473.1059U" target="_blank">2018</a>,
<a href="http://esoads.eso.org/abs/2014prpl.conf..291L" target="_blank">Longmore+ 2014</a>,
<a href="http://adsabs.harvard.edu/abs/2017MNRAS.470.1462L">2017</a>
<a href="http://esoads.eso.org/abs/2017MNRAS.466..340C" target="_blank">Contreras+ 2017</a>
</li>
</ul>
</li>
<img src='assets/Urquhart2018_ATLASGAL.jpeg'>
</ul>
</div>
</div>
</center>
</section>
<section>
<h6>How many are there?</h6>
<ul>
<!-- \left(0.03^{+0.03}_{-0.015}\right) / -->
<li> SFR \(\times\) CFE:
<div align=center>\( \left(2~M_\odot~\mathrm{yr}^{-1}\right)
\left(0.07^{+0.07}_{-0.03}\right) f_{(>10^4\mathrm{M}_\odot)} /
\left(M_{cl,10^4 M_\odot}\right)\)</p>
<div align=center>\(= 3-12~\mathrm{clusters~Myr}^{-1}\) </p>
<div style="font-size:20px">(Galactic CFE from
<a href="http://adsabs.harvard.edu/abs/2003ARA%26A..41...57L">Lada & Lada 2003</a>,
<a href="http://esoads.eso.org/abs/2010MNRAS.405..857G">Goddard+ 2010</a>,
<a href="http://adsabs.harvard.edu/abs/2012MNRAS.426.3008K">Kruijssen 2012</a>; \(f_{(>10^4\mathrm{M}_\odot)} = 0.4\)</div>
</li>
<li>Observed: 12-18 currently forming YMCs <div style='font-size:16px; display:inline'>(excluding CMZ)</div></li>
<ul><li style="font-size:24px">Fewer (~2) if more conservative SFE ~10% is used</li>
<div style='font-size:20px'> (<a href="http://adsabs.harvard.edu/abs/2012ApJ...758L..29G" target="_blank">Ginsburg+ 2012</a>,
Urquhart+ <a href="http://adsabs.harvard.edu/abs/2014MNRAS.437.1791U" target="_blank">2014a</a>,
<a href="http://esoads.eso.org/abs/2014MNRAS.443.1555U" target="_blank">b</a>,
<a href="http://adsabs.harvard.edu/abs/2018MNRAS.473.1059U" target="_blank">2018</a>,
<a href="http://esoads.eso.org/abs/2014prpl.conf..291L" target="_blank">Longmore+ 2014</a>,
<a href="http://adsabs.harvard.edu/abs/2017MNRAS.470.1462L">2017</a>
<a href="http://esoads.eso.org/abs/2017MNRAS.466..340C" target="_blank">Contreras+ 2017</a>) </div>
</ul>
<li>Observable protocluster lifetime ~0.2-1 Myr
</li>
</ul>
</section>
<section>
<h6>YMCs form fast</h6>
<ul><li>Age spreads in YMCs are small, <1 Myr</li>
<ul><li><a href="http://adsabs.harvard.edu/abs/2012ApJ...750L..44K">Kudryavtseva+ 2012</a>,
<a href="http://adsabs.harvard.edu/abs/2015MNRAS.449.1106H">Hollyhead+ 2015</a>
</li></ul>
<li>There are no signs of starless proto-YMC clumps</li>
<ul><li>
<a href="http://adsabs.harvard.edu/abs/2012ApJ...758L..29G" target="_blank">Ginsburg+ 2012</a>,
<a href="http://adsabs.harvard.edu/abs/2018MNRAS.473.1059U" target="_blank">Urquhart+ 2018</a>
</li>
<li>Urquhart+ 2018 estimate the 'quiescent' phase is \(<2.4\times10^4 \mathrm{yr}\)
for \(M>10^4 \mathrm{M}_\odot\)
<!--<div style='font-size:70%'> however, there may be a bias against detecting massive, starless regions</div>-->
</li>
</ul>
<li style='max-width: 450px;'> YMCs are gas-free by ~a few Myr</li>
<ul><li style='max-width: 400px;'>
<a href="http://adsabs.harvard.edu/abs/2014MNRAS.443.3594B" target="_blank">Bastian+ 2014</a>,
<a href="http://adsabs.harvard.edu/abs/2015MNRAS.449.1106H" target="_blank">Hollyhead+ 2015</a>,
<a href="http://adsabs.harvard.edu/abs/2015MNRAS.448.2224C" target="_blank">Cabrera-Ziri+ 2015</a>,
<a href="http://adsabs.harvard.edu/abs/2013ApJ...764...73P">Pang+ 2013</a>
</li>
</ul>
</ul>
<span class=image style='height: 350px; background-position: center center; background-size: contain; background-image: url(assets/ngc3603.jpg);
position: absolute; left:250px; bottom: 100px'>
</section>
<!--
<section>
<h6>Are z=0 high-mass clusters analogs to Globular Cluster progenitors?</h6>
</section>
-->
<section data-id="688e275e4f4751d7bc0fc68ee3d68b82">
<div class="sl-block" data-block-type="text" style="width: auto; height: auto;" data-block-id="fd2e732f3eb46152cc9857131e878116">
<div class="sl-block-content" data-placeholder-tag="h2" data-placeholder-text="Title Text" style="z-index: 10;">
<h2 style="word-break: keep-all; hyphens: none;">Is star formation in high-mass clusters different?</h2>
</div>
</div>
<div class="sl-block" data-block-type="text" style="width: auto; height: auto;" data-block-id="7b24eb3dce885998fa19c253a9f15bbf">
<div class="sl-block-content" data-placeholder-tag="p" data-placeholder-text="Text" style="z-index: 11;">
<ul>
<li>The IMF should depend on density, feedback <div style='font-size:24px'>(e.g., <a href="http://adsabs.harvard.edu/abs/2018MNRAS.tmp.1196J"
target="_blank">Jones & Bate 2018</a>, \(M_c \propto \rho^{-1/5}\) )</div></li>
<li>Feedback from one star affects many in clustered regions
<div style='font-size:24px; display:inline'>(<a href="http://adsabs.harvard.edu/abs/2016MNRAS.463.2553R">Rosen+ 2016</a>,
<a href="http://adsabs.harvard.edu/abs/2017ApJ...842...92G">Ginsburg+ 2017</a>)</div></li>
<li>Total star formation efficiency is higher. SFE<sub>ff</sub> may be higher?
<div style='font-size:24px; '>
(obs: <a href="http://adsabs.harvard.edu/abs/2016A%26A...595A..27G">Ginsburg+ 2016</a>,
<a href="http://adsabs.harvard.edu/abs/2017IAUS..316..117G">Gouliermis & Hony 2015</a>,
sim:
<a href="http://adsabs.harvard.edu/abs/2018MNRAS.475.3511G">Grudić+ 2018</a>
)
</div>
</li>
<li> Collisions assemble the most massive stars?
<div style='font-size:24px; '>
(e.g., <a href="http://adsabs.harvard.edu/abs/2013MNRAS.430.1018F">Fujii+ & PZ 2013</a>,
but see <a href="http://adsabs.harvard.edu/abs/2011MNRAS.410.2799M">Moeckel & Clarke 2011</a>)
</div>
<ul><li>
<div class=smaller>Interactions certainly affect disks (e.g., <a href="http://adsabs.harvard.edu/abs/2017A%26A...604A..91W">Wijnen+ 2017</a>,
<a href="http://adsabs.harvard.edu/abs/2016ApJ...828...48V">Vincke+ 2016</a>)
</div>
</li>
</ul>
</li>
</ul>
</div>
</div>
</section>
<section>
<span class="image" style="background-image: url(assets/W51e2TemperatureProfileSlide.png); width:90%">
<div style="position: absolute; bottom: 100px; left:100px" class="smaller2"><a href="http://adsabs.harvard.edu/abs/2017ApJ...842...92G">Ginsburg+ 2017</a></div>
</span>
</section>
<!-- TODO
<section>
<h4> Observations:</h4><p class="subtitle"> Massive clusters in other galaxies </p>
<ul>
<li> Forming and very young: "Super Star Clusters" </li>
<ul><li>
e.g., <a href="http://adsabs.harvard.edu/abs/2018arXiv180402083L">Leroy+ 2018</a>,
<a href="http://adsabs.harvard.edu/abs/2018ApJ...853..125J">Johnson+ 2018</a>,
<a href="http://adsabs.harvard.edu/abs/2018arXiv180500950C">Cohen+ 2018</a>
</li>
</ul>
<li> Gas-free but O-star rich: "Young Massive Clusters" </li>
<ul><li>
M83 (<a href="http://adsabs.harvard.edu/abs/2015MNRAS.449.1106H">Hollyhead+ 2015</a>,
<a href="http://adsabs.harvard.edu/abs/2015MNRAS.452..246A">Adamo+ 2015</a>,
)
Antennae (<a href="http://adsabs.harvard.edu/abs/2015MNRAS.448.2224C">Cabrera-Ziri+ 2015</a>)
</li> </ul>
</ul>
</section>
<section>
<p class=subtitle> Super star clusters in NGC 253</p>
<img src='assets/Leroy2018_Forming0.png' height=90%>
<p style="position: relative; bottom:90px; left: -22%; font-size:25px">
<a href="http://adsabs.harvard.edu/abs/2018arXiv180402083L">Leroy+ 2018</a>
</p>
</section>
-->
<section style='font-size:85%'>
<h6 style='font-size:44px'> How do massive clusters get their mass? </h6>
<ol>
<li> The mass is <b>pre-assembled</b> in "starless" clumps, then collapses
<ul>
<li>Combined with gas expulsion, favored by Banerjee & Kroupa
(<a href="http://adsabs.harvard.edu/abs/2014ApJ...787..158B">2014</a>,
<a href="http://adsabs.harvard.edu/abs/2015MNRAS.447..728B">2015</a>,
<a href="http://adsabs.harvard.edu/abs/2017A%26A...597A..28B">2017</a>,
<a href="http://adsabs.harvard.edu/abs/2018ASSL..424..143B">2018</a>)
</li>
<li>
Requires protoclusters to start more compact, since they expand with expulsion
</li>
</ul>
</li>
<li> The mass is assembled as stars form: <div>there is <b>no starless phase</b>,
gas comes from larger scales </div>
<ul><li>Better supported by observational timescale arguments</li>
<li>"Conveyor Belt" of <a href="http://esoads.eso.org/abs/2014prpl.conf..291L">Longmore+ 2014</a>
</ul>
</li>
<li> Stars form in substructures, then <b>merge</b> into clusters
<div class=small>(e.g., Fujii+ <a href="http://adsabs.harvard.edu/abs/2012ApJ...753...85F">2012</a>)</div>
</li>
</ol>
<!--<div style='font-size: 22px'>
Minor quibble - Many papers on this topic have abstracts that say: <div>"We show
that clusters <i>can</i> assemble via this mechanism, therefore, they <i>do</i>."</div>
Don't do this.
</div>-->
</section>
<section>
<h6> YMCs start large, collapse to small </h6>
<div class="sl-block" style="width: auto; height: auto; font-size: 30px; font-weight: normal">
<ul>
<li><a href="http://adsabs.harvard.edu/abs/2017MNRAS.472.1760G">Gennaro+ 2017</a>: Westerlund 1 is collapsing</li>
<li> <a href="http://esoads.eso.org/abs/2015MNRAS.449..715W">Walker+ 2015</a>: gas is more extended than stellar cluster </li>
<div class=smaller> Caveat: Sgr B2 is optically thick, might be much denser </div>
</div>
<div class="sl-block" data-block-type="image"
style="margin-left:auto; margin-right: auto; max-width: 650px; max-height:500px;">
<div class="sl-block-content" style="z-index: 11;">
<p><center>
<img class="center-fit" src='assets/Walker2015_Tracing0_Fig7_annotated.png'>
</center> </p>
</div>
</div>
</section>
<section data-id="c6d0d12eb10e07a81dca15937cef8a52">
<h6>
Simulation: Accretion from large scales
</h6>
<div class="sl-block" data-block-type="image" style="margin-left:auto; margin-right: auto; width: 806px;" data-block-id="30338ab3762a7c761ad1e7f8d81fd3dc">
<div class="sl-block-content" style="z-index: 11;">
<p>
<center>
<img src="assets/Smilgys2017.png">
</center>
</p>
<p style="position: relative; bottom:90px; left: -30%; font-size:25px">
<a href="http://adsabs.harvard.edu/abs/2017MNRAS.472.4982S" target="_blank">Smilgys & Bonnell 2017</a>
</p>
<p style="position: relative; bottom:140px; right: -40%; font-size:25px">
No feedback
</p>
<div style='position: relative; bottom:850px; font-size:28px;'> Cloud collapse in the context of spiral arm potentials</div>
</div>
<!-- Can also show an exmaple from http://adsabs.harvard.edu/abs/2015PASJ..tmp..163F -->
</div>
</section>
<section>
<h6>Observations: Infall toward PMCs</h6>
<ul>
<li>Mass accretion rates \(\sim0.3-1.6\times10^{-2}~\mathrm{M}_\odot \mathrm{yr}^{-1}\) from THz NH<sub>3</sub> absorption
(Wyrowski+ <a href="http://adsabs.harvard.edu/abs/2012A%26A...542L..15W">2012<a>,
<a href="http://esoads.eso.org/abs/2016A%26A...585A.149W">2016</a>
), but only toward a limited subset of clumps
</li>
<li>See Roberto's talk next</li>
</ul>
</section>
<!-- I can't think of anything useful to say
<section>
<h6>Do cloud-cloud collisions assemble YMCs?</h6>
</section>
-->
<!-- Section on SFE and feedback - Ostriker, my work, ...? -->
<section>
<h6>Feedback and Efficiency</h6>
<ul style='font-size:88%'>
<li>
Feedback appears ineffective at halting SF on small, dense scales
</li>
<ul>
<li>
Ionization-bounded HII regions are smaller, less massive: HCHII regions ionize small amounts of gas that does not escape
</li>
<li>
For high \(v_{esc}\) regions, mass loss can only occur via stellar winds, jets, radiation pressure, and champagne flows
<div style='font-size:18px; display:inline;'>(e.g.,
<a href="http://adsabs.harvard.edu/abs/2012ApJ...758L..28B">Bressert+2012</a>,
<a href="http://esoads.eso.org/abs/2015ApJ...815...68M">Matzner & Jumper 2015</a>)</div>
</li>
<ul>
<li><div style="font-size: 80%">Winds are ineffective (<a href="http://adsabs.harvard.edu/abs/2014MNRAS.442.2701R">Rosen+ 2014</a>,
<a href="http://adsabs.harvard.edu/abs/2014ApJ...795..121L">Lopez+ 2014</a>)</div>
</li>
</ul>
</ul>
<!-- probably don't want to include this; seems like a minor aside -->
<!--<li> Less efficient feedback on small scales can result in less-bound
clusters because rocketed-away dense clouds drag the stars along (<a href="http://adsabs.harvard.edu/abs/2018arXiv180610575G">Geen+ 2018</a>)
</li>-->
<center>
<span style="background-image: url(assets/Geen2018_SFEvsPhotons.png);
background-repeat: no-repeat; background-size: contain; display: block;
height:350px; margin-left: auto; margin-right:auto; width: 70%">
</span>
<div style='font-size: 24px'>
In simulations of smaller clouds, <a href="http://adsabs.harvard.edu/abs/2018arXiv180610575G">Geen+ (2018)</a> found factor of ~3-5
variation in efficiency purely from IMF sampling stochasticity
</div>
</section>
<section>
<h6>W51 IRS 2: Ionization is eroding gas inefficiently</h6>
<div class='sl-block' style='display: block; width: 768px; height: 1024px; left:0 px; top: 0px;'>
<span class="image" style="background-image:
url(assets/rgb_irs2_aplpy_withlabels.png); ">
</span></div>
<div style="position: absolute; bottom: 70px; left:100px" class="smaller2">
<a href="http://adsabs.harvard.edu/abs/2016A%26A...595A..27G">Ginsburg+ 2016</a>,
<a href="http://adsabs.harvard.edu/abs/2017ApJ...842...92G">2017</a>
</div>
<div style="position:absolute; bottom: 250px; right: 0px; max-width:25%; text-align: left;" class=smaller2>
Photoevaporation rate \(\dot{M}_{pe}< 0.001 \mathrm{~M}_\odot \mathrm{yr}^{-1}\) <br>
Star Formation Rate \(\dot{M}_{sf}\sim \epsilon_{ff} M_{gas} / t_{ff} \)
\(= 2000 \mathrm{M}_\odot / 10^4 \mathrm{yr}\)
\(=0.2 \epsilon_{ff}\mathrm{M}_\odot \mathrm{yr}^{-1}\) <br>
Even for \(\epsilon_{ff} = 0.01\), \(\dot{M}_{sf} > \dot{M}_{pe}\)
<br><br>
<div class=smaller>
\(\dot{M}_{pe}\) consistent with <a href="">Kim, Kim, & Ostriker 2018</a>
for \(M_{cluster}\sim2-10\times10^3 M_\odot\)
</div>
</div>
</section>
<!--
<section>
<h6> Simulations of forming individual clusters </h6>
<ul>
<li> Limited mass resolution: no massive clusters with \(M_{max} > 10~\mathrm{M}_{\odot}\) resolve low-mass stars
<div class=smaller>(e.g., Jim Dale+, Kim, Kim, & Ostriker)</div>
<ul><li>focus on cloud-scale effects</li></ul>
</li>
<li> Lower mass, higher resolution simulations including massive stars <div
class=smaller>(e.g., Rosen, Krumholz, Peters, Geen)</div>
<ul><li>Feedback from massive stars affects SF outcomes</li></ul>
</li>
</ul>
</section>
-->
<section
style="background: url(assets/rgb_overview_brightness_1.5.png);
background-position:center;
background-size:1500px;
width:100vw;
left:-50vw;
position:absolute;
">
<div style="color: white; position: absolute; bottom: 60px; width:400px; right:360px;"> Feedback is effective on cloud scales (e.g., Haid talk earlier)</div>
</section>
<section>
<h6>Structure of forming clusters</h6>
<ul>
<li>Stars form in subtructures in the gas (e.g., filaments)</li>
<!--<ul><li>[no cites here; this is every work by everyone in the room]</li></ul>-->
<li>Merging substructures smooth out, become more symmetric</li>
<ul><li>
<a href="http://adsabs.harvard.edu/abs/2015MNRAS.451.3664P">Parker & Dale 2015</a>,
<a href="http://esoads.eso.org/abs/2004A%26A...413..929G">Goodwin & Whitworth 2004</a>,
<a href="http://adsabs.harvard.edu/abs/2017arXiv170809065G">Grudić+ 2017</a>
</li>
<li>There is debate about how long this takes and how it is affected by the presence of gas</li>
</ul>
<li>A consequence is that it is not immediately obvious which forming stars will become cluster members</li>
</ul>
</section>
<section class="fullscreen reveal slides">
<span class="image" style="background-image: url(assets/moxc_points_on_cband.png);">
<center><h6 style='position:relative'>W51: X-ray stars</h6></center>
<div class="smaller2"><a href="http://esoads.eso.org/abs/2014ApJS..213....1T">MOXC, Townsley+ 2014</a></div>
</span>
</section>
<section class="fullscreen reveal slides">
<span class="image" style="background-image: url(assets/moxc_points_contours_on_cband.png);">
<center><h6 style='position:relative'>W51: X-ray stars</h6></center>
<div class="smaller2"><a href="http://esoads.eso.org/abs/2014ApJS..213....1T">MOXC, Townsley+ 2014</a></div>
</span></section>
<section class="fullscreen reveal slides">
<span class="image" style="background-image: url(assets/moxc_points_contours_on_cband_withcores.png);">
<center><h6 style='position:relative'>W51: X-ray stars + Cores and UCHII regions</h6></center>
<div class="smaller2">Ginsburg+
<a href="http://adsabs.harvard.edu/abs/2016A%26A...595A..27G">2016</a>,
<a href="http://adsabs.harvard.edu/abs/2017ApJ...842...92G">2017</a>
</div>
</span></section>
<section class="fullscreen reveal slides">
<span class="image" style="background-image: url(assets/moxc_contours_on_cband_withcores.png);">
<center><h6 style='position:relative'>W51: Cores and UCHII regions</h6></center>
<div class="smaller2">Ginsburg+
<a href="http://adsabs.harvard.edu/abs/2016A%26A...595A..27G">2016</a>,
<a href="http://adsabs.harvard.edu/abs/2017ApJ...842...92G">2017</a>
</div>
</span></section>
<section>
<h6>Cluster Formation Efficiency revisited</h6>
<ul><li>What fraction of all stars form in bound clusters?</li>
<ul><li>Not all do (e.g., <a href="http://adsabs.harvard.edu/abs/2010MNRAS.409L..54B">Bressert+ 2010</a>, <a href="http://adsabs.harvard.edu/abs/2018MNRAS.475.5659W">Ward & Kruijssen 2018</a>)</li>
<li>Varies with environment, increasing toward higher density</li>
<li>More stars formed in higher density regions in the early universe,
so more in clusters</li>
</ul>
<li>We can measure this locally, given an appropriate change in environment
<div class=smaller>Talks by Lu, Battersby, Walker, Zeng; posters by Butterfield, Callanan, Hatchfield, Henshaw
</li>
</ul>
<span class=image style='height: 300px; background-position: center center; background-size: contain; background-image: url(assets/gc_fullres_6_small.jpg)'>
<!--<img src="assets/gc_fullres_6_small.jpg" style='max-width: 100%'>-->
</span>
</section>
<!--
<section>
<h6>What is the end state of gas in forming clusters?</h6>
Expulsion vs Exhaustion:
<p>
Expulsion: <a href="http://adsabs.harvard.edu/abs/2017A%26A...597A..28B">Banerjee & Kroupa 2017 </a>
</p>
</section>
-->
<section>
<h6>Sgr B2: Most massive cloud + protoclusters</h6>
<div class="sl-block" data-block-type="image"
style="margin-left:auto; margin-right: auto; width: 900px;">
<div class="sl-block-content" style="z-index: 11;">
<p><center>
<img class="center-fit" src='assets/cores_on_continuum_peak_full_zoomin.png'>
</center> </p>
</div>
</div>
<div style='position: absolute; bottom: 130px; left: 70px; font-size: 22px; width:300px'>
Tightly bound cluster: \(\sigma_{1D} \sim 9-12~\mathrm{km~s}^{-1} \)
\(\sigma_{1D} < v_{esc} \sim 14~\mathrm{km~s}^{-1}\)
from RRL LOS velocities
</div>
<div class="sl-block" style="width: auto; height: auto; font-size: 30px; font-weight: normal">
Clustered and unclustered star formation occur together
(<a href="http://adsabs.harvard.edu/abs/2018ApJ...853..171G">Ginsburg+ 2018</a>)
</div>
</section>
<section>
<h6>High-mass cluster formation: Sgr B2</h6>
<div class="sl-block" data-block-type="text" style="width: auto; height: auto; font-size: 30px; font-weight: normal" >
The Cluster Formation Efficiency (CFE) is a function of density (<a style='font-size:80%'
href="http://adsabs.harvard.edu/abs/2012MNRAS.426.3008K">Kruijssen
2012</a>).</div>
<div class="sl-block" data-block-type="image"
style="margin-left:auto; margin-right: auto; width: 700px;">
<div class="sl-block-content" style="z-index: 11;">
<p><center>
<img class="center-fit" src='assets/GammaVsSigmaGas_withTheory.png'>
</center> </p>
</div>
</div>
<div style="width: auto; height: auto; font-size: 30px; font-weight: normal">
Sgr B2 fits the predictions <div style='font-size:70%; display:inline'>(Ginsburg & Kruijssen, in prep)</a>.
</div>
</section>
<section>
<h6>Sgr B2 N: Collapse</h6>
<div class="sl-block" style="width: auto; height: auto; font-size: 26px; font-weight: normal">
Collapse is morphologically obvious, but very difficult to measure (Peretto's talk):
continuum is optically thick on ~1000 AU scales
(Schwörer, Ginsburg, Schilke+ in prep)
</div>
<div class="sl-block" style="width: auto; height: auto; font-size: 26px; font-weight: normal">
Fragmentation appears suppressed
</div>
<div class="sl-block" data-block-type="image"
style="margin-left:auto; margin-right: auto; width: 800px;">
<div class="sl-block-content" style="z-index: 11;">
<p><center>
<img class="center-fit" src='assets/cores_on_continuum_peak_fullN_zoomin.png'>
</center> </p>
</div>
</div>
<div style='position: absolute; bottom: 180px; left: 50px; font-size: 22px; width:400px'>
</div>
</section>
<section>
<h6>Summary</h6>
<ul>
<li>YMCs are important tools to understand Globular Cluster formation </li>
<li>They are at least in part assembled from larger scales and merging subclusters</li>
<li>More stars form in bound clusters at higher density</li>
</ul>
<div></div>
<p></p>
<ul>
<li>Within forming clusters, feedback from the most massive stars affects neighbors,
suppressing fragmentation</li>
<!--<li>Dynamical interactions are important in clusters, which means disk properties
are different (they're smaller)</li>-->
</ul>
</section>
<section>
<h6>Future Directions</h6>
<ul>
<li>Complete census of spatial and mass distribution of protostars
from the ALMA-IMF program
</li>
<li>A direct connection between the protostellar and stellar
populations with JWST imaging and spectroscopy to pierce the
extinction layers
</li>
</ul>
</section>
<section>
<p>
<em>Credits</em>:
<a href="http://newton.cx/~peter/">Peter Williams</a>,
<a href="http://git-scm.com/">git</a>,
<a href="http://lab.hakim.se/reveal-js/">reveal.js</a>,
<a href="http://www.mathjax.org/">MathJax</a>,
<a href="http://mozilla.github.io/pdf.js/">pdf.js</a>
</p>
</div>
</section>
</div>
</div>
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