<html><head><meta http-equiv="Content-Type" content="text/html charset=utf-8"></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space;" class=""><div class="">Dear all, </div><div class=""><div class=""><br class=""></div><div class="">Astro Journal club starts on Wednesday at 3 p.m. (sharp) in the seminar room F-201 of the Physics Department. </div><div class=""><br class=""></div><div class="">Presenter: Ivan Delvecchio, dr. sc.</div><div class=""><br class=""></div><div class="">Title: An intermediate-mass black hole in the centre of the globular cluster 47 Tucanae</div><div class=""><br class=""></div>Authors: Kiziltan et al. (2017)<br class=""><br class=""><div class="">Abstract: </div><div class=""><div class="">Intermediate mass black holes play a critical role in understanding the evolutionary connection between stellar mass and super-massive black holes. However, to date the existence of these species of black holes remains ambiguous and their formation process is therefore unknown. It has been long suspected that black holes with masses <span tabindex="0" id="MathJax-Element-1-Frame" class="MathJax"><nobr class=""><span id="MathJax-Span-1" class="math" style="width: 6.778em; display: inline-block;"><span style="display: inline-block; position: relative; width: 5.477em; height: 0px; font-size: 15px;" class=""><span style="position: absolute; clip: rect(1.547em, 1005.48em, 2.972em, -1000em); top: -2.597em; left: 0em;" class=""><span id="MathJax-Span-2" class="mrow"><span id="MathJax-Span-3" class="msubsup"><span style="display: inline-block; position: relative; width: 1.429em; height: 0px;" class=""><span style="position: absolute; clip: rect(3.163em, 1000.98em, 4.192em, -1000em); top: -4.009em; left: 0em;" class=""><span id="MathJax-Span-4" class="mn" style="font-family: STIXGeneral;">10</span><span style="display: inline-block; width: 0px; height: 4.009em;" class=""></span></span><span style="position: absolute; top: -4.412em; left: 1em;" class=""><span id="MathJax-Span-5" class="texatom"><span id="MathJax-Span-6" class="mrow"><span id="MathJax-Span-7" class="mn" style="font-size: 10px; font-family: STIXGeneral;">2</span></span></span><span style="display: inline-block; width: 0px; height: 4.009em;" class=""></span></span></span></span><span id="MathJax-Span-8" class="mo" style="font-family: STIXGeneral; padding-left: 0.25em;">−</span><span id="MathJax-Span-9" class="msubsup" style="padding-left: 0.25em;"><span style="display: inline-block; position: relative; width: 1.429em; height: 0px;" class=""><span style="position: absolute; clip: rect(3.163em, 1000.98em, 4.192em, -1000em); top: -4.009em; left: 0em;" class=""><span id="MathJax-Span-10" class="mn" style="font-family: STIXGeneral;">10</span><span style="display: inline-block; width: 0px; height: 4.009em;" class=""></span></span><span style="position: absolute; top: -4.412em; left: 1em;" class=""><span id="MathJax-Span-11" class="texatom"><span id="MathJax-Span-12" class="mrow"><span id="MathJax-Span-13" class="mn" style="font-size: 10px; font-family: STIXGeneral;">4</span></span></span><span style="display: inline-block; width: 0px; height: 4.009em;" class=""></span></span></span></span><span id="MathJax-Span-14" class="msubsup"><span style="display: inline-block; position: relative; width: 1.447em; height: 0px;" class=""><span style="position: absolute; clip: rect(3.186em, 1000.87em, 4.178em, -1000em); top: -4.009em; left: 0em;" class=""><span id="MathJax-Span-15" class="mi" style="font-family: STIXGeneral; font-style: italic;">M<span style="display: inline-block; overflow: hidden; height: 1px; width: 0.039em;" class=""></span></span><span style="display: inline-block; width: 0px; height: 4.009em;" class=""></span></span><span style="position: absolute; top: -3.859em; left: 0.833em;" class=""><span id="MathJax-Span-16" class="texatom"><span id="MathJax-Span-17" class="mrow"><span id="MathJax-Span-18" class="mo" style="font-size: 10px; font-family: STIXGeneral;">⊙</span></span></span><span style="display: inline-block; width: 0px; height: 4.009em;" class=""></span></span></span></span></span><span style="display: inline-block; width: 0px; height: 2.597em;" class=""></span></span></span><span style="display: inline-block; overflow: hidden; vertical-align: -0.323em; border-left-width: 0px; border-left-style: solid; width: 0px; height: 1.476em;" class=""></span></span></nobr></span> should form and reside in dense stellar systems. Therefore, dedicated observational campaigns have targeted globular cluster for many decades searching for signatures of these elusive objects. All candidates found in these targeted searches appear radio dim and do not have the X-ray to radio flux ratio predicted by the fundamental plane for accreting black holes. Based on the lack of an electromagnetic counterpart upper limits of <span tabindex="0" id="MathJax-Element-2-Frame" class="MathJax"><nobr class=""><span id="MathJax-Span-19" class="math" style="width: 4.237em; display: inline-block;"><span style="display: inline-block; position: relative; width: 3.444em; height: 0px; font-size: 15px;" class=""><span style="position: absolute; clip: rect(1.744em, 1003.44em, 2.972em, -1000em); top: -2.597em; left: 0em;" class=""><span id="MathJax-Span-20" class="mrow"><span id="MathJax-Span-21" class="mn" style="font-family: STIXGeneral;">2060</span><span id="MathJax-Span-22" class="msubsup"><span style="display: inline-block; position: relative; width: 1.447em; height: 0px;" class=""><span style="position: absolute; clip: rect(3.186em, 1000.87em, 4.178em, -1000em); top: -4.009em; left: 0em;" class=""><span id="MathJax-Span-23" class="mi" style="font-family: STIXGeneral; font-style: italic;">M<span style="display: inline-block; overflow: hidden; height: 1px; width: 0.039em;" class=""></span></span><span style="display: inline-block; width: 0px; height: 4.009em;" class=""></span></span><span style="position: absolute; top: -3.859em; left: 0.833em;" class=""><span id="MathJax-Span-24" class="texatom"><span id="MathJax-Span-25" class="mrow"><span id="MathJax-Span-26" class="mo" style="font-size: 10px; font-family: STIXGeneral;">⊙</span></span></span><span style="display: inline-block; width: 0px; height: 4.009em;" class=""></span></span></span></span></span><span style="display: inline-block; width: 0px; height: 2.597em;" class=""></span></span></span><span style="display: inline-block; overflow: hidden; vertical-align: -0.323em; border-left-width: 0px; border-left-style: solid; width: 0px; height: 1.233em;" class=""></span></span></nobr></span> and <span tabindex="0" id="MathJax-Element-3-Frame" class="MathJax"><nobr class=""><span id="MathJax-Span-27" class="math" style="width: 3.616em; display: inline-block;"><span style="display: inline-block; position: relative; width: 2.936em; height: 0px; font-size: 15px;" class=""><span style="position: absolute; clip: rect(1.752em, 1002.94em, 2.972em, -1000em); top: -2.597em; left: 0em;" class=""><span id="MathJax-Span-28" class="mrow"><span id="MathJax-Span-29" class="mn" style="font-family: STIXGeneral;">470</span><span id="MathJax-Span-30" class="msubsup"><span style="display: inline-block; position: relative; width: 1.447em; height: 0px;" class=""><span style="position: absolute; clip: rect(3.186em, 1000.87em, 4.178em, -1000em); top: -4.009em; left: 0em;" class=""><span id="MathJax-Span-31" class="mi" style="font-family: STIXGeneral; font-style: italic;">M<span style="display: inline-block; overflow: hidden; height: 1px; width: 0.039em;" class=""></span></span><span style="display: inline-block; width: 0px; height: 4.009em;" class=""></span></span><span style="position: absolute; top: -3.859em; left: 0.833em;" class=""><span id="MathJax-Span-32" class="texatom"><span id="MathJax-Span-33" class="mrow"><span id="MathJax-Span-34" class="mo" style="font-size: 10px; font-family: STIXGeneral;">⊙</span></span></span><span style="display: inline-block; width: 0px; height: 4.009em;" class=""></span></span></span></span></span><span style="display: inline-block; width: 0px; height: 2.597em;" class=""></span></span></span><span style="display: inline-block; overflow: hidden; vertical-align: -0.323em; border-left-width: 0px; border-left-style: solid; width: 0px; height: 1.224em;" class=""></span></span></nobr></span> have been placed on the mass of a putative black hole in 47 Tucanae (NGC 104) from radio and X-ray observations respectively. Here we show there is evidence for a central black hole in 47 Tuc with a mass of </div><div class="">M<span tabindex="0" id="MathJax-Element-4-Frame" class="MathJax"><nobr class=""><span id="MathJax-Span-35" class="math" style="width: 6.27em; display: inline-block;"><span style="display: inline-block; position: relative; width: 5.081em; height: 0px; font-size: 15px;" class=""><span style="position: absolute; clip: rect(1.752em, 1005.08em, 2.972em, -1000em); top: -2.597em; left: 0em;" class=""><span id="MathJax-Span-36" class="mrow"><span id="MathJax-Span-37" class="msubsup"><span style="display: inline-block; position: relative; width: 0.322em; height: 0px;" class=""><span style="position: absolute; clip: rect(3.839em, 1000em, 4.178em, -1000em); top: -4.009em; left: 0em;" class=""><span id="MathJax-Span-38" class="mi"></span><span style="display: inline-block; width: 0px; height: 4.009em;" class=""></span></span><span style="position: absolute; top: -3.859em; left: 0em;" class=""><span id="MathJax-Span-39" class="texatom"><span id="MathJax-Span-40" class="mrow"><span id="MathJax-Span-41" class="mo" style="font-size: 10px; font-family: STIXGeneral;">∙</span></span></span><span style="display: inline-block; width: 0px; height: 4.009em;" class=""></span></span></span></span><span id="MathJax-Span-42" class="mo" style="font-family: STIXGeneral; padding-left: 0.313em;">∼</span><span id="MathJax-Span-43" class="mn" style="font-family: STIXGeneral; padding-left: 0.313em;">2300</span><span id="MathJax-Span-44" class="msubsup"><span style="display: inline-block; position: relative; width: 1.447em; height: 0px;" class=""><span style="position: absolute; clip: rect(3.186em, 1000.87em, 4.178em, -1000em); top: -4.009em; left: 0em;" class=""><span id="MathJax-Span-45" class="mi" style="font-family: STIXGeneral; font-style: italic;">M<span style="display: inline-block; overflow: hidden; height: 1px; width: 0.039em;" class=""></span></span><span style="display: inline-block; width: 0px; height: 4.009em;" class=""></span></span><span style="position: absolute; top: -3.859em; left: 0.833em;" class=""><span id="MathJax-Span-46" class="texatom"><span id="MathJax-Span-47" class="mrow"><span id="MathJax-Span-48" class="mo" style="font-size: 10px; font-family: STIXGeneral;">⊙</span></span></span><span style="display: inline-block; width: 0px; height: 4.009em;" class=""></span></span></span></span></span><span style="display: inline-block; width: 0px; height: 2.597em;" class=""></span></span></span><span style="display: inline-block; overflow: hidden; vertical-align: -0.323em; border-left-width: 0px; border-left-style: solid; width: 0px; height: 1.224em;" class=""></span></span></nobr></span><span tabindex="0" id="MathJax-Element-5-Frame" class="MathJax"><nobr class=""><span id="MathJax-Span-49" class="math" style="width: 2.431em; display: inline-block;"><span style="display: inline-block; position: relative; width: 1.976em; height: 0px; font-size: 15px;" class=""><span style="position: absolute; clip: rect(-0.013em, 1001.98em, 1.607em, -1000em); top: -1.016em; left: 0em;" class=""><span id="MathJax-Span-50" class="mrow"><span id="MathJax-Span-51" class="msubsup"><span style="display: inline-block; position: relative; width: 1.974em; height: 0px;" class=""><span style="position: absolute; clip: rect(3.839em, 1000em, 4.178em, -1000em); top: -4.009em; left: 0em;" class=""><span id="MathJax-Span-52" class="mi"></span><span style="display: inline-block; width: 0px; height: 4.009em;" class=""></span></span><span style="position: absolute; clip: rect(3.353em, 1001.97em, 4.207em, -1000em); top: -4.382em; left: 0em;" class=""><span id="MathJax-Span-53" class="texatom"><span id="MathJax-Span-54" class="mrow"><span id="MathJax-Span-55" class="mo" style="font-size: 10px; font-family: STIXGeneral;">+</span><span id="MathJax-Span-56" class="mn" style="font-size: 10px; font-family: STIXGeneral;">1500</span></span></span><span style="display: inline-block; width: 0px; height: 4.009em;" class=""></span></span><span style="position: absolute; clip: rect(3.353em, 1001.62em, 4.278em, -1000em); top: -3.687em; left: 0em;" class=""><span id="MathJax-Span-57" class="texatom"><span id="MathJax-Span-58" class="mrow"><span id="MathJax-Span-59" class="mo" style="font-size: 10px; font-family: STIXGeneral;">−</span><span id="MathJax-Span-60" class="mn" style="font-size: 10px; font-family: STIXGeneral;">850</span></span></span><span style="display: inline-block; width: 0px; height: 4.009em;" class=""></span></span></span></span></span><span style="display: inline-block; width: 0px; height: 1.016em;" class=""></span></span></span><span style="display: inline-block; overflow: hidden; vertical-align: -0.588em; border-left-width: 0px; border-left-style: solid; width: 0px; height: 1.715em;" class=""></span></span></nobr></span> when the dynamical state of the globular cluster is probed with pulsars. The existence of an intermediate mass black hole in the centre of one of the densest clusters with no detectable electromagnetic counterpart suggests that the black hole is not accreting at a sufficient rate and therefore contrary to expectations is gas starved. This intermediate mass black hole might be a member of electromagnetically invisible population of black holes that are the elusive seeds leading to the formation of supermassive black holes in galaxies. </div><div class=""><br class=""></div><div class="">Link to paper: <a href="https://arxiv.org/abs/1702.02149" class="">https://arxiv.org/abs/1702.02149</a></div><div class=""> </div></div><div class="">If you have recently read interesting astrophysics paper you would like to present, please contact me via e-mail: <a href="mailto:lceraj@phy.hr" class="">lceraj@phy.hr</a></div><div class=""><br class=""></div><div class="">See you on Wednesday.</div><div class=""><br class=""></div><div class="">Cheers,</div><div class="">Lana</div></div></body></html>