DMWG Seminar
26 events
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Seminar
The effect of the early kinetic decoupling in a fermionic dark matter model
June 12 (Fri) at 10:00 - 11:00, 2020
Tomohiro Abe (Assistant Professor, Kobayashi-Maskawa Institute for the Origin of Particles and the Universe (KMI), Nagoya University)
*Detailed information about the seminar refer to the email
Venue: via Zoom
Event Official Language: English
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Seminar
Characterizing the continuous gravitational-wave signal from boson clouds around Galactic isolated black holes
April 27 (Mon) at 16:00 - 17:00, 2020
Sylvia Zhu (Postdoctoral Researcher, Deutsches Elektronen-Synchrotron DESY, Germany)
Bosons such as axions or axion-like particles can form enormous clouds around black holes via the superradiance instability. As the bosons annihilate in the presence of the black hole, they produce a long-lived, slowly-evolving continuous gravitational-wave signal that is potentially detectable using the current generation of gravitational-wave interferometers.A non-detection can disfavor the existence of axions in certain mass ranges, although this is highly dependent on the Galactic black hole population. In this talk, I will discuss the expected annihilation signal from the population of isolated stellar-mass black holes in the Galaxy, and the prospects for detecting the signal using standard searches for continuous gravitational waves.
Venue: via Zoom
Event Official Language: English
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Seminar
Mining for Dark Matter substructure: Learning from lenses without a likelihood
February 17 (Mon) at 14:00 - 15:30, 2020
Johann Brehmer (Postdoctoral Researcher, New York University, USA)
Dr. Brehmer gives us a talk about a method to deduce DM small structures. Please join us! The subtle imprint of dark matter substructure on extended arcs in strong lensing systems contains a wealth of information about the small-scale distribution of dark matter and, consequently, about the underlying particle physics. However, teasing out this effect is challenging since the likelihood function for realistic simulations of population-level parameters is intractable. Structurally similar problems appear in many other scientific fields ranging from particle physics to neuroscience to epidemiology, which has prompted the development of powerful simulation-based inference techniques based on machine learning. We give a broad overview over these methods, and then apply them to the problem of substructure inference in galaxy-galaxy strong lenses. In this proof-of-principle application to simulated data, we show that these methods can provide an efficient and principled way to simultaneously analyze an ensemble of strong lenses, and can be used to mine the large sample of lensing images deliverable by near-future surveys for signatures of dark matter substructure.
Venue: #424-426, Main Research Building
Event Official Language: English
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Seminar
Weak lensing cosmology by Subaru HSC survey
December 12 (Thu) at 10:30 - 12:00, 2019
Chiaki Hikage (Project Associate Professor, Kavli Institute for the Physics and Mathematics of the Universe (Kavli IPMU), The University of Tokyo)
Place: IPMU seminar room C
Venue: Kavli IPMU Building
Event Official Language: English
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Seminar
Haloes at the low-mass end in wino dark matter
October 21 (Mon) at 13:00 - 15:00, 2019
Toyokazu Sekiguchi (Research Center for the Early Universe (RESCEU), The University of Tokyo)
Neutral wino is a natural candidate of dark matter in split-supersymmetry. Indirect detection is a promising probe of wino dark matter, with its annihilation enhanced non-perturvatively (i.e. Sommerfeld enhancement). In theoretical prediction, halo formation at the low-mass end is a key ingredient. For this purpose, we investigate kinetic decoupling of wino dark matter and consequent dark matter density perturbations. We show that inelastic processes involving charged wino, which are relevant for kinetic equilibrium at late times, shuts off abruptly. This results in boosted acoustic peaks in density power spectrum at horizon scales around the kinetic decoupling. Based on an analytic modeling of subhalo evolution, we estimate the subhalo mass function of (dwarf) galaxy-sized haloes and effects on the annihilation boost factor. We also discuss application of our analysis to SU(2)_L multiplet minimal dark matter.
Venue: Seminar Room #160
Event Official Language: English
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Seminar
A new lamppost in dark matter searches: Composite Dark Matter
October 1 (Tue) at 10:00 - 18:00, 2019
Enrico Rinaldi (Research Part-time Worker, iTHEMS)
In the search for the nature of dark matter many particle physics models are proposed. Models originating from a new strongly coupled dark sector, similar to QCD and Nuclear Physics, give rise to Composite Dark Matter particles. These models are hard to study, but they have a very interesting phenomenology with clear signals that are distinct from the usual WIMP candidates. To make robust predictions in Composite Dark Matter models one often needs to investigate non-perturbative effects due to the strong dynamics. In my talk I will explain how Lattice Field Theory methods and numerical simulations are well suited for this task and contribute to a solid uncertainty quantification. A variety of detection signals can be studied with lattice simulations, from dark matter self interactions to interactions with regular matter and even signals of dark phase transitions generating primordial gravitational waves.
Venue: #424-426, Main Research Building
Event Official Language: English
26 events