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The Dark Side of the Universe (DSU) workshops bring together a wide range of theorists and experimentalists to discuss current ideas on models of the dark side, and relate them to current and future experiments.
The 12th edition of DSU will take place in the colorful Norwegian city of Bergen. Topics include dark matter, dark energy, cosmology, and physics beyond the standard model.
One of the goals of the workshop is to expose in particular students and young researchers to the fascinating topics of dark matter and dark energy, and to provide them with the opportunity to meet some of the best researchers in these areas.
I will briefly review the current status of WIMP indirect dark matter detection, identifying recent progresses and the hurdles to overcome in order to improve sensitivity. Particular attention will be paid to the charged cosmic ray channels, although some considerations will also concern other domains, such as gamma rays. I will then discuss how indirect probes also have some chances in constraining (or possibly detecting) DM models beyond the WIMP scenario, which are often hard to identify at (if not beyond the reach of) direct or collider searches.
Theoretical review on the direct detection search for dark matter.
One of the long-standing challenges in indirect dark matter searches is to understand the origin of the pronounced emission of 1-3 GeV photons that is seen in Fermi LAT data in the Galactic bulge and at the Galactic center. The arguably most exciting interpretation is that it is caused by the annihilation of dark matter particles. However, before making such a claim all possible backgrounds need to be assessed with utmost care. I will here show that in contrast to previous claims millisecond pulsars (MSPs) are a valid and rather likely explanation. What is more, the MSP hypothesis can explain the non-Gaussian noise that we detected in the gamma-ray emission from the inner Galaxy, with at least 10 sigma significance, using a new dedicated wavelet decomposition analysis. The power spectrum of dust-traced gas at small angular scales, as well as the projected density of other Galactic sources is far too low to account for this signal. I will present realistic strategies of how upcoming targeted radio searches and surveys can establish or refute the MSP hypothesis with high statistical significance. If we fail to find bulge MSPs in radio soon, the dark matter interpretation of the Fermi GeV excess will become much more likely again. I will close with an outlook on indirect dark matter searches in the next ten years.
After a brief review of the standard diffusion approach to the propagation of cosmic rays (CR), I discuss as alternative method the calculation of individual CR trajectories. The results obtained with this approach suggest that CR propagate strongly anisotropic, and that the antimatter fluxes observed are dominated by a single local source. Finally, I discuss
different approaches to predict antiproton production and their theoretical uncertainties.
I will give an overview of the current state of dark energy research, from an observational point of view. Current and future probes of dark energy will be discussed; I will examine the latest constraints on dark energy physics from cosmological surveys, and describe future prospects for yet more powerful measurements in the coming decade.
The problem facing us with dark energy has manifested itself through the many theoretical models that have been published, all with the same goal, to explain the late time acceleration of the Universe. I will try and summarise the state of play with the models, recap the original cosmological constant problem which prevents many of us from simply accepting there is a constant energy density driving the acceleration, and discuss some recent attempts to address the problem. Throughout we will see the need for fine tuning which enters with pretty much every model, and we will see how particle physics considerations can have a huge impact on the type of models that are consistent with the data.
The Laser Interferometer Gravitational-wave Observatory (LIGO) recently made the first direct detection of gravitational waves; minute distortions in space-time caused by cataclysmic events far away in the universe. I will talk about the source of the signal we detected, the physics behind the detectors, and prospects for the future of this emerging field.
I will focus on the challenge posed by dark energy and discuss theoretical issues involved in finding an optimal framework to unveil its nature from upcoming high precision measurements of the large scale structure, giving an overview of recent progress.
Model-independent methods in cosmology have become an essential tool in order to deal with an increasing number of theoretical alternatives for explaining the late-time acceleration of the Universe. In principle, this provides a way of testing the Cosmological Concordance (or LambdaCDM) model under different assumptions and ruling out whole classes of competing theories. One such model-independent method is the so-called cosmographic approach, which relies only on the homogeneity
and isotropy of the Universe on large scales. We show that this method suffers from many short-comings, providing biased results depending on the auxiliary variable used in the series expansion and is unable to rule out models or adequately reconstruct theories with higher-order derivatives in either the gravitational or matter sector. Consequently, in its present form, this method seems unable to provide reliable or useful results for cosmological applications.
The ordinary atoms that make up the known universe, from our bodies and the air we breathe to the planets and stars, constitute only 5% of all matter and energy in the cosmos. The remaining 95% is made up of a recipe of 25% dark matter and 70% dark energy, both nonluminous components whose nature remains a mystery. Freese will recount the hunt for dark matter, from the discoveries of visionary scientists like Knut Lundmark and Fritz Zwicky, the astronomers who coined the term "dark matter" in the 1930's, to the deluge of data today from underground laboratories, satellites in space, and the Large Hadron Collider. Theorists contend that dark matter consists of fundamental particles known as WIMPs, or weakly interacting massive particles. Billions of them pass through our bodies every second without us even realizing it, yet their gravitational pull is capable of whirling stars and gas at breakneck speeds around the centers of galaxies, and bending light from distant bright objects. In this talk Freese will provide an overview of this cosmic cocktail, including the evidence for the existence of dark matter in galaxies. Many cosmologists believe we are on the verge of solving this mystery and this talk will provide the foundation needed to fully fathom this epochal moment in humankind's quest to understand the universe.
I will review evidence for dark matter's existence from astronomical observations. I will focus primarily evidence from dwarf galaxies and galaxy clusters, but also discuss results from cosmological observations of the cosmic microwave background and large scale structure.
Although there is substantial gravitational evidence for the existence of dark matter, its particle nature
remains one of the biggest mysteries in modern physics. The favourite theoretical model, Cold Dark Matter
(CDM), assumes that non-gravitational dark matter interactions are irrelevant for galaxy formation and evolution.
Surprisingly, current astronomical observations allow significant departures from the CDM hypothesis
that have a relevant impact on our understanding of how galaxies form and evolve. Moreover, the observed
properties of the smallest galaxies have been a consistent challenge for the CDM model.
In this talk, I will argue that to explain galaxy formation and evolution in the broadest sense,
an effective dark matter theory must contain a wider range of dark matter particle physics. I will describe the
first steps we have taken towards developing ETHOS and present some of its applications.
Recent observations have revealed the structural properties of the dark
and luminous mass distribution in galaxies from dwarfs to giants. Their study led to the
vision of a new and amazing scenario. The investigation of single and
coadded objects has in fact shown that the rotation curves of spirals
follow, from their centers out to their virial radii, an universal profile
that implies a tuned combination of their stellar disk and dark halo mass
distributions. The mass distribution of ellipticals and dwarf spheroidals
is found similar. This, alongside with accurate mass modeling of
individual galaxies, poses important challenges to the presently
theoretically favored LCDM Cosmology and indicate a surprising direct interaction between
the dark and the luminous components.
Boat Trip from Bergen to Osterøy. The boat departs from the Bergen harbour Dreggekaien.
See separate handout and/or conference webpage for details
Dark matter particles may be produced at the LHC in combination with other particles, typically from initial state radiation. We present results from the ATLAS experiment from searches for phenomena with jets, photons, heavy quarks, electroweak gauge bosons, or Higgs bosons recoiling against large missing transverse momentum. The measurements are interpreted using several theoretical frameworks including simplified models with pair production of Weakly Interacting Massive Particles, effective field theories, and other beyond the Standard Model scenarios. Constraints from dijet searches are compared with results from the “Mono-X” searches to provide a combined interpretation in the context of simplified models.
The existence of dark matter, indicated by astronomical observations, is one of the main proofs of physics beyond the standard model. Despite its abundance, dark matter has not been directly observed yet. This talk reviews the latest results and future plans of searches for dark matter at the CMS experiment at the LHC.
Will discuss issues related to unitarity and gauge invariance of DM interactions, covering both collider searches and indirect detection.
We review model of decaying Dark Matter and other very weakly interacting
DM candidates and present the status of theoretical developments for those
models and DM searches both in indirect detection and at colliders.
High-energy gamma rays are one of the most promising tools to constrain or reveal the nature of Dark Matter (DM), in particular the Weakly Interacting Massive Particles (WIMP) models. During the almost eight years of the Fermi satellite mission, the data from its Large Area Telescope (LAT) were used to set constraints on the WIMP annihilation cross section which cut well into the theoretically-motivated region of parameter space for WIMP masses below 100 GeV. At the same time, the Cherenkov Telescope Array (CTA) is well into its prototyping phase and will soon offer a chance to probe a complementary parameter space of heavier dark matter (from O(200 GeV) up to several tens of TeV ), with unprecedented sensitivity.
In this talk I will describe methods used to search for evidence of dark matter with the LAT, and review the status of the searches. I will discuss projections of the expected sensitivities with continued LAT data taking, together with the latest sensitivity predictions on the various targets with CTA.
There are several reasons supersymmetric models are appealing as
a candidate for beyond the standard models physics. These include help with
gauge coupling unification, the gauge hierarchy problem, the stabilization of the
electroweak vacuum, radiative electroweak symmetry breaking, dark matter, and perhaps
an improvement to low energy phenomenology.
The lack of evidence for low energy supersymmetry at the LHC implies a
supersymmetry scale in excess a TeV. While this is consistent (and even helpful) with
a Higgs boson mass at $\approx$ 125 GeV, simple supersymmetric models with scalar
and gaugino mass universality are being pushed into strips of parameter space.
In contrast, non-supersymmetric grand unified theories such as SO(10) may
provide equivalent benefits to all of the above issues normally associated with
supersymmetry, including a dark matter candidate. Because of the presence of an intermediate scale,
these theories may unify gauge couplings, provide for neutrino masses and a suitably long lived proton.
The construction of SO(10) dark matter models
will be discussed.
The µνSSM solves the µ-problem of SUSY models simply using right-handed neutrinos ν’s, while simultaneously explains the origin of neutrino masses. In this context, novel signatures of SUSY at the LHC are present through the new states of the model. On the other hand, since R parity is broken, a decaying gravitino turns out to be an interesting candidate for dark matter which can be searched through gamma-ray observations such as those of the Fermi Large Area Telescope.
I review recent progress in the construction of modified gravity models as alternatives to dark energy as well as the development of cosmological tests of gravity. Einstein's theory of General Relativity (GR) has been tested accurately within the local universe i.e. the Solar System, but this leaves the possibility open that it is not a good description of gravity at the largest scales in the Universe. In 1998, astronomers made the surprising discovery that the expansion of the Universe is accelerating, not slowing down. Within the framework of GR, the acceleration would originate from an unknown dark energy. Alternatively, it could be that there is no dark energy and GR itself is in error on cosmological scales.
In this talk, I first give an overview of recent developments in modified gravity theories. I then focus on common properties these models share, such as screening mechanisms they use to evade the stringent Solar System tests. Once armed with a theoretical knowledge of modified gravity models, I move on to discuss how we can test modifications of gravity on cosmological scales. Since screening mechanisms leave distinct signatures in the non-linear structure formation, I review novel astrophysical tests of gravity using clusters, dwarf galaxies and stars.
I will review motivations for the existence of self interacting dark matter and discuss possible astrophysical observables.
Self-interactions of dark matter particles can potentially lead to an observable separation between the dark matter halo
and the stars of a galaxy moving through a region of large dark matter density. Such a separation has recently been
observed in a galaxy falling into the core of the galaxy cluster Abell 3827.
I discuss the DM self-interaction cross section needed to reproduce the observed effects.
I will review attempts to address the small-scale problems of Lambda-CDM using a combination of dark matter self-interactions and dark matter interactions with a dark radiation-like species. We will see that most models are rather tightly constrained. New results outlining the role of non-perturbative corrections to these interactions will be presented.
In this talk I will briefly review the tensions and anomalies
in current cosmological data that hint for possible extensions
to the "concordance" LCDM model.