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<b><span style="font-size: 16pt;"><font color="#ff0000">To know more about this, please come to the colloquium tomorrow</font></span></b></p>
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<b><span style="font-size: 16pt; color: rgb(0, 176, 80);">Oct. 8, Thursdays, 4-5pm in Science 127 (coffee and cookies served at 3:50pm)<br>
</span></b><b><i><span style="font-size: 16pt;">All students currently enrolled in Physics 401 and 501 are required to atte<span style="color: rgb(31, 73, 125);">n</span>d all colloquia<span style="color: rgb(31, 73, 125);"></span></span></i></b></p>
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<b><span style="font-size: 36pt; font-family: Calibri, sans-serif;">Galactic searches for dark matter</span></b></p>
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<b><span style="font-size: 28pt; color: rgb(144, 6, 45);">Prof. Louis Strigari, Texas A&M University</span></b><b><span style="font-size: 28pt; color: rgb(31, 73, 125);"></span></b></p>
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<b><span style="font-size: 11pt; font-family: Calibri, sans-serif; color: rgb(31, 73, 125);"> </span></b></p>
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<img align="left" hspace="12" height="245" width="180"><span lang="EN-GB">Dr. Louis Strigari received his Ph.D from The Ohio State University in 2005. He was a Hubble Fellow before joining Texas A&M University.</span>Dark matter, which is deduced through the
motions of stars and gas in galaxies, and large scale observations of gravitational lensing and of the cosmic microwave background, is a well-established aspect of cosmological theory. Though its precise nature is unknown, it has become clear its existence
points directly to new physics, likely in the form of an undiscovered elementary particle that is connected to a theoretical model such as supersymmetry. Dr. Strigari’s research involves understanding astrophysical aspects of dark matter, and connecting these
observations to particle dark matter theories. He works to understand data from high energy astrophysics experiments and from direct dark matter detection experiments. He utilizes numerical simulations and numerical algorithms to model data from dark matter-dominated
galaxies.<b><span lang="EN-GB"></span></b></p>
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<b><i><span lang="EN-GB" style="font-size: 11pt; font-family: Calibri, sans-serif; color: rgb(31, 73, 125);"> </span></i></b></p>
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<b><i><span lang="EN-GB" style="font-size: 14pt;">Abstract:</span></i></b></p>
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For nearly a century, more mass has been measured in all types of galaxies than is contained in the visible matter. Through a variety of observations, it has become clear that the dark matter in galaxies is not comprised of known astronomical objects or baryonic
matter, and that its identification is certain to reveal a profound connection between astrophysics, cosmology, and fundamental physics. In this talk, I discuss the status of searches for particle dark matter using a variety of different experimental techniques.
I conclude by highlighting how in the next several years we will either confirm the leading theoretical model for dark matter, or there will be a paradigm shift in our view of it.</p>
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<span style="color: rgb(31, 73, 125); font-family: 'Times New Roman', serif; font-size: medium;"> </span><font face="Tahoma" size="2" color="#000000" style="color: rgb(0, 0, 0);"><b>From:</b> phas-dept-bounces@tamuc.edu [phas-dept-bounces@tamuc.edu] on behalf
of Carlos Bertulani [Carlos.Bertulani@tamuc.edu]<br>
<b>Sent:</b> Wednesday, October 07, 2015 11:36 AM<br>
<b>To:</b> Physics & Astronomy Department<br>
<b>Subject:</b> [phas-dept] news on dark matter<br>
</font><br>
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<div>I got this email message below from Prof.<span style="color:rgb(0,0,0); font-size:12px"> </span><span style="font-family:Arial,Helvetica,sans-serif; background-color:rgb(255,255,255)">Nicholas Suntzeff (College Station). really exciting news about dark
matter.</span></div>
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<div>Carlos </div>
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<span style="font-weight:bold">From: </span>nsuntzeff <<a href="mailto:nsuntzeff@tamu.edu" target="_blank">nsuntzeff@tamu.edu</a>><br>
<span style="font-weight:bold">Date: </span>Wed, 7 Oct 2015 00:24:15 -0500<br>
<span style="font-weight:bold">To: </span><<a href="mailto:faculty-talk@physics.tamu.edu" target="_blank">faculty-talk@physics.tamu.edu</a>><br>
<span style="font-weight:bold">Cc: </span>"Astrophysics@TAMU" <<a href="mailto:astro@listserv.tamu.edu" target="_blank">astro@listserv.tamu.edu</a>><br>
<span style="font-weight:bold">Subject: </span>[Faculty-talk] Interacting dark matter<br>
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<div class="" style="word-wrap:break-word">Dear All,
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<div class="">The European Southern Observatory has released some photos and analysis that are quite puzzling. See:</div>
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<div class=""><a href="http://www.eso.org/public/images/eso1514a/" class="" target="_blank">http://www.eso.org/public/images/eso1514a/</a></div>
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<div class="">What they have found is that through gravitational lensing, they have mapped out the dark matter content around four interacting galaxies buried deep in the core of a cluster of galaxies. What is strange is that there is one galaxy where the dark
matter appears to have lagged behind the galaxy. This seems to imply that dark matter is interacting in a non-gravitational way, and perhaps is self-interacting. </div>
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<div class="">This is not like the Bullet Cluster where two galaxies passed through each other, and the interaction separated the gas from the stars/dark matter. Here there is no gas and as the galaxies collide, both the stars and the dark matter will pass
through each other. Gravity will slow the components as they pass through each other due to gravitational friction, but the separation of the dark matter and the stars was not expected as seen in the image.</div>
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<div class="">The interpretation is not iron clad at this point, but it is very intriguing.</div>
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<div class="">The picture of the cluster in the article above is also intriguing. I attach the HST image of the cluster. You can see the four elliptical galaxies enveloped in a much larger luminous halo, which is not uncommon in very rich clusters. But if you
look closely into the haze, you can see four images of a single galaxy that looks like a blue loop with a dot in the center. It is this multiply imaged galaxy, along with some other arcs that allow such a reconstruction of the dark matter distribution.</div>
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<div class="">In this image you can see the derived contours of the dark matter (in dark blue lines). The galaxy to the 10 o’clock position of the quartet has the dark matter contours clearly not centered on the galaxy, which they are interpreting as perhaps
due to self interaction of the dark matter. The other three galaxies do not have enough contrast from the lensing to detect such an offset.</div>
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<div class="">cheers nick</div>
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