15/11/2018: Mass or interaction, but not both

If upcoming direct searches discover the elusive dark matter in the universe, they may be able to measure the mass of the particle or the way it interacts with ordinary matter, but can only do both if we’re lucky, researchers from the UvA Institute of Physics argue.

It is one of the great open questions of modern-day physics and astronomy: what is the mysterious dark matter in the universe? Astronomers suspect that the universe contains much more matter than they can see through there telescopes – simply because there is much more gravity than visible matter can account for. So far, however, nobody has been able to find particles that this dark matter can be made of.

Rare interactions

Yet, many astronomers and particle physicists are optimistic that a dark matter candidate particle can be found soon, in the next generation of experiments and observations. While this may be true, Amsterdam researchers now point out that even if such a new dark matter particle is found, this does not automatically mean that we will immediately know all of its properties.

In their investigation, the researchers looked at planned underground detectors which aim to detect dark matter by looking for its rare interactions with ordinary atomic nuclei. The as yet undiscovered dark matter particle has an unknown mass (how heavy it is) and an unknown cross section (how strongly it interacts with nuclei).

Using new statistical tools, inspired by a concept known as ‘information geometry’ that the same researchers developed earlier this year, the physicists mapped out what a discovery would look like, without assuming a particular dark matter particle mass or cross section – allowing to explore a wide range of these dark matter properties.

New materials and techniques

It was found that a discovery using multiple different target materials that the dark matter particle can interact with, will substantially improve the measurement of the dark matter properties. However, even with multiple detectors, it will be hard to measure the mass of heavy dark matter particles and at the same time understand their precise interactions. Only over a narrow range of properties can both of these things be measured simultaneously.

This result, which was accepted for publication in Physical Review Letters last week, should spur the dark matter community to explore new detector materials and techniques which will improve the prospects for pinning down the properties of the dark matter particle in the event of a future discovery.


Assessing near-future direct dark matter searches with benchmark-free forecasting, Thomas D. P. Edwards, Bradley J. Kavanagh, and Christoph Weniger, Physical Review Letters 2018. (arXiv preprint)

05/10/2018: A new era in the quest for dark matter

In a Nature review article published this week, physicists Gianfranco Bertone (GRAPPA, UvA) and Tim Tait (UvA and UC Irvine) discuss the past accomplishments and the current status of dark matter search experiments and how they will shape the future efforts for dark matter searches.

More information can be found at the IOP news.
The nature article can be found here and the pre-print version can be found here.

06/08/2018: Another blow for the dark matter interpretation of the Galactic Center Excess

For almost ten years, astronomers have been studying a mysterious diffuse radiation coming from the center of our Galaxy. Originally, it was thought that this radiation could originate from the elusive dark matter particles that many researchers are hoping to find. However, physicists from the University of Amsterdam and the Laboratoire d’Annecy-le-Vieux de Physique Théorique have now found further evidence that rapidly spinning neutron stars are a much more likely source for this radiation.

Observations of the gamma-ray radiation from the Galactic center region with the Fermi Large Area Telescope have revealed a mysterious diffuse and extended emission. Discovered almost 10 years ago, this emission generated a lot of excitement in the particle physics community, since it had all the characteristics of a long-sought-after signal from the self-annihilation of dark matter particles in the inner Galaxy. Finding such a signal would confirm that dark matter, a substance that so far has only been observed through its gravitational effects on other objects, is made out of new fundamental particles. Moreover, it would help to determine the mass and other properties of these elusive dark matter particles. However, recent studies show that arguably the best astrophysical interpretation of the excess emission is a new population in the Galactic bulge of thousands of rapidly spinning neutron stars called millisecond pulsars, which have escaped observations at other frequencies up to now.

Figure 1. Observed gamma-ray emission from the Galactic disk, with the bulge region indicated. The insets show the expected profiles of excess radiation coming from dark matter and stars respectively. The researchers were able to show that the stars profile matches the measurements much better than the dark matter profile.

Where there are stars, there is radiation
‘Understanding in detail the morphology [the location and shape] and spectrum [the combined frequencies] of the excess emission is of vital importance for discriminating between the dark matter and astrophysical interpretations of the Galactic Center excess radiation.’, says Christoph Weniger, one of the researchers that conducted the study. A new study by researchers at the University of Amsterdam and the Laboratoire d’Annecy-le-Vieux de Physique Théorique, a research unit of the French Centre National de la Recherche Scientifique, found strong evidence that the emission actually seems to come from regions where there is also a large amount of stellar mass in the Galactic bulge (the ‘boxy bulge’) and center (the ‘nuclear bulge’). Furthermore, the researchers found that the light-to-mass ratio in the Galactic bulge and center are mutually consistent, so that the gamma-ray GeV emission is a surprisingly accurate tracer of stellar mass in the inner Galaxy – see figure 2. This study was based on a new analysis tool, SkyFACT (Sky Factorization with Adaptive Constrained Templates), developed by the researchers themselves, which combines physical modeling with image analysis.

Figure 2. Comparison of the stellar mass (horizontal axis) and gamma-ray luminosity (vertical axis) for the “boxy bulge” (in blue) and for the “nuclear bulge” (in green). The prediction for a population of millisecond pulsars in the Galactic disk (in red) and the bulge of the nearby Andromeda galaxy (M31, in pink) are also shown. Stellar mass and luminosity are proportional to each other in the inner Galaxy (dashed line), which shows that the mysterious excess radiation very likely has a stellar origin and is not coming from dark matter.

The findings support the millisecond pulsar interpretation of the excess emission, since neither a dark matter signal nor other astrophysical interpretations are expected to show such a correlation. ‘The results will help guide upcoming radio searches for this hidden population of millisecond pulsars in the Galactic bulge with MeerKAT and the future Square Kilometre Array’, said Francesca Calore, another of the paper’s authors. ‘This makes these upcoming searches even more promising.’

R. Bartels, E. Storm, C. Weniger and F. Calore, The Fermi-LAT GeV excess traces stellar mass in the Galactic bulge, Nature Astronomy 2018.

31/05/2018: TeVPA 2018

This year’s TeVPA will be hosted in Berlin, Germany from 27 – 31 August, 2018. TeVPA is a five day conference which aims to bring together leading scientists in the field to discuss recent advances in Astroparticle Physics. Early bird registration closes on July 7, 2018.

31/05/2018: Welcome, Samaya Nissanke!

We are delighted to welcome Samaya Nissanke as a faculty member at GRAPPA, shared between IHEF and API. Samaya’s current research focuses on the detection, measurement and interpretation of gravitational waves, the astrophysics of compact object (black holes, neutron stars and white dwarfs) binaries, and general relativity.
Samaya expressed her excitement by stating, “I am very excited to be joining the GRAPPA department and building a new dynamic gravitational wave and multi-messenger astrophysics group here. It is an incredible time to be working in strong-field gravity astrophysics thanks to the recent gravitational wave detections, time-domain electromagnetic surveys and astroparticle experiments, and recent advances in cosmology and computational astrophysics. I am greatly looking forward to the many scientific adventures here, and working with the excellent students, postdocs and staff members in both the physics and astronomy departments at UvA, as well as the nearby Nikhef institute.”
Samaya will start her first day at GRAPPA on June 15. We look forward to her contributions to our intellectual community for many years to come.

25/04/2018: Mini-Workshop “Empirical Status of Cosmology”

On April 25, we will host a mini-workshop on the empirical status of cosmology, with the following programme:
When: Wednesday, April 25 at 2.30pm
Where: Room C4.174
– 2.30pm: Jeroen van Dongen “Introduction: Philosophy, cosmology and the empirical in modern physics”
– 2.45pm: Joe Silk “The limits of cosmology”
– 3.05pm: Daniel Baumann “Empirical status of inflation”
– 3.25pm: Ben Freivogel “Multiverse”
– 3.45pm-4.30pm: Discussion
For more information please contact Gianfranco Bertone or Jeroen van Dongen.

11/11/2017: New Jobs

GRAPPA, the center of excellence in Astroparticle Physics of the University of Amsterdam, is a joint effort between the Institute for High Energy Physics, the Anton Pannekoek Institute, and the Institute for Theoretical Physics. It consists of eight faculty members – S. Ando, D. Baumann, G. Bertone (spokesperson), M.P. Decowski, B. Freivogel, S. Markoff, J. Vink and C. Weniger – whose research interests include black holes, cosmic rays, neutrinos, dark matter, dark energy, early universe cosmology, and string theory. In addition, there are about 15 affiliated GRAPPA faculty who are involved with experimental work on Antares/KM3NeT, ATLAS, CTA, LIGO/VIRGO, LOFAR and XENON100/XENON1T, as well as theory.
We invite applications for one or more postdoctoral positions in the fields of particle and astroparticle physics. One of the successful candidates will work in an interdisciplinary team led by G. Bertone. We are looking in particular for candidates who have experience in applying machine learning methods to particle and astroparticle physics problems. Candidates who have shown excellence in other relevant fields and are willing to broaden their research interests are also encouraged to apply. Additional postdoctoral positions might become available in the group of Christoph Weniger. All candidates will be automatically considered for those positions.

The appointment is for two years (with a possible extension to a third year), with a salary set by Dutch labor law, including generous benefits. Candidates should preferably have obtained a PhD in a field related to the group’s research interests after December 2013, or expect to obtain it by September 2018.

11/11/2017: GRAPPA public lecture and planetarium show at ARTIS

Artis Planetarium and GRAPPA are proud to present an evening on The Dark Universe.

Gianfranco Bertone (IoP/ GRAPPA), Hiranya Peiris (UCL) and Jocelyn Monroe (Royal Holloway, University of London) will give talks and answer questions on different aspects of the Dark Universe, moderated by popular science writer Govert Schilling.

The discussion will be followed by a screening of the film The Dark Universe, which was made by researchers at the American Museum of Natural History in New York for their exhibition on the same subject.

This event forms part of the social programme for GRAPPA@5, a conference organised in celebration of GRAPPA’s 5th anniversary. The evening will be aimed at a general audience and will be given in English.


The evening will take place at Artis Planetarium:
Plantage Kerklaan 38-40
1018 CZ Amsterdam


19:30: Doors Open & Welcome Drink

20:00: Discussion Session

21:00: Coffee Break

21:30: Screening of The Dark Universe

21:55: End

Further Information

Admission for the evening costs €20 and tickets should be bought in advance via the Artis website.

Attendance of this event is free to participants of GRAPPA@5.

Further Information & Tickets

11/11/2017: New job: Assistant professor in gravitational-wave astrophysics

A tenure track position in the field of gravitational waves astrophysics is available in our group.

We are looking for a candidate with an exceptionally strong research program and a strong interest in excellent teaching in the areas of interest of GRAPPA, with a strong preference for candidates working in gravitational-wave astrophysics. For a balanced composition of GRAPPA, we also have a strong preference for female candidates.

The candidate is required to have a PhD in (astro-)physics, an excellent scientific track record, and the proven capability to attract funding. The candidate should have the capabilities to build up a research group of internationally outstanding level and to initiate and carry out scientific research. The candidate should also be able to develop and provide allotted cohesive academic course components for a wide range of target groups, based on the faculty’s curriculum, so that students may meet the course objectives in terms of knowledge, understanding, skills, competence and attitude.

The initial appointment will be for a period of six years. Based on performance indicators agreed on at the start of the appointment, the tenure track position will lead to a tenured position in a period of maximally 5 years. In the fifth year of the appointment the tenure decision will be taken. These conditions can be tailored appropriately for candidates that have somewhat greater seniority. Exceptional candidates may be directly considered for a tenured position.

For more information, please follow this link.

28/08/2017: GRAPPA @ 5

We cordially invite you to “GRAPPA @ 5”, a symposium on astroparticle physics to be held in Amsterdam from 16 – 18 October 2017.

In 2012 the University of Amsterdam started Gravitation Astroparticle Physics Amsterdam (GRAPPA), its new excellence center for astroparticle physics. After five years GRAPPA has become an household name in astroparticle physics, and a thriving place to do astroparticle physics research, involving around 50 researchers.

In order to celebrate the 5 years of GRAPPA we are organising a symposium devoted to astroparticle physics. We have an impressive list of invited speakers who will inform you about the current state of astroparticle physics: John Beacom, Lars Bergström, Esra Bulbul, Luke Drury, Stefan Funk, Francis Halzen, Stavros Katsanevas, Matthew Kleban, Nergis Mavalvala, Jocelyn Monroe, Hiranya Peiris and Tim Tait. Apart from a host of excellent invited speakers we also have a number of open slots for interesting contributions in the field of astroparticle physics.

In addition to the symposium we will have a welcome reception on October 16, and a dinner/party on October 17 at two very interesting locations!! Thanks to contributions from several sponsors the contribution fee will be only 55 euro.

Please register here: https://indico.cern.ch/event/608844/. The poster for the symposium is also available for download on the conference website.

Registration deadline is August 31!!

We hope to see many of you in Amsterdam!

03/07/2017: GRAPPA researchers devise new strategy to search for ancient black holes

An interdisciplinary team of physicists and astronomers at the University of Amsterdam’s GRAPPA Center of Excellence for Gravitation and Astroparticle Physics has devised a new strategy to search for ‘primordial’ black holes produced in the early universe. Such black holes are possibly responsible for the gravitational wave events observed by the Laser Interferometer Gravitational-Wave Observatory. In a paper that appeared in Physical Review Letters this week, the researchers specifically show that the lack of bright X-ray and radio sources at the center of our galaxy strongly disfavours the possibility that these objects constitute all of the mysterious dark matter in the universe.

Primordial black holes
The existence of black holes tens of times more massive than our Sun was confirmed recently by the observation of gravitational waves, produced by the merger of pairs of massive black holes, with the LIGO interferometer. The origin of these objects is unclear, but one exciting possibility is that they originated in the very early universe, shortly after the Big Bang. It has been suggested that these ‘primordial’ black holes may constitute all of the universe’s dark matter – the mysterious substance that appears to permeate all astrophysical and cosmological structures, and that is fundamentally different from the matter made of atoms that we are familiar with.

An interdisciplinary team of UvA physicists and astronomers proposed to search for primordial black holes in our galaxy by studying the X-ray and radio emission that these objects would produce as they wander through the galaxy and accrete gas from the interstellar medium. The researchers have shown that the possibility that these objects constitute all of the dark matter in the galaxy is strongly disfavoured by the lack of bright sources observed at the galactic center.

Collective effort
‘Our results are based on a realistic modelling of the accretion of gas onto the black holes, and of the radiation they emit, which is compatible with current astronomical observations. These results are robust against astrophysical uncertainties’, says Riley Connors, PhD student at the UvA and an expert in black hole astrophysics. ‘What’s even more interesting”, adds Daniele Gaggero, first author of the publication, ‘is that with more sensitive future radio and X-ray telescopes, our proposed search strategy may allow us to discover a population of primordial black holes in our galaxy, even if their contribution to the dark matter is small.’

‘A convincing implementation of our original idea was possible thanks to the collective effort of an interdisciplinary team of scientists at the GRAPPA Center of Excellence for Astroparticle Physics’, says Gianfranco Bertone, GRAPPA spokesperson. ‘This includes theorists studying dark matter and the formation of black holes, astrophysicists modelling the subsequent accretion process, and astronomers working on radio and X-ray observations.’

The new findings are expected to shed light on the formation and origin of primordial black holes as well as of standard astrophysical black holes that are formed when stars collapse.

Searching for Primordial Black Holes in the radio and X-ray sky, Daniele Gaggero, Gianfranco Bertone, Francesca Calore, Riley M.T. Connors, Mark Lovell, Sera Markoff and Emma Storm, Phys. Rev. Lett. 118, 241101 [arXiv: 1612.00457].

18/04/2017: Shin’ichiro Ando receives prestigious young scientist grant

Physicist Shin’ichiro Ando was awarded the prestigious Japanese Grant-in-Aid for Young Scientists. Ando, a member of the center of excellence for Gravitation and Astroparticle Physics Amsterdam, will use the grant for his research in astroparticle physics, high-energy astrophysics, and cosmology.

Next to his full-time position at UvA, Ando has also been affiliated to the Kavli Institute for the Physics and Mathematics of the Universe (Kavli IPMU) at the University of Tokyo since the fall of 2016. The Grant-in-Aid for Young Scientists is the biggest Japanese grant for young individual researchers, similar to the Vidi grant in the Netherlands. The grant, awarded through Kavli IPMU, consists of an amount equivalent to €200,000, and can be spent over the next four years on travel, equipment and postdoc salaries. Ando will also take this as an opportunity to facilitate exchange of knowledge and people between Amsterdam and Tokyo.

02/03/2017: How did dark matter come to matter?

The nature of dark matter is one of the most important open problems in today’s physics. When, how and why did scientists accept that most matter in the universe is actually invisible and unknown to us? An interdisciplinary collaboration of historians and physicists at the Institute of Physics, the GRAPPA Center of Excellence, and the Vossius Center has revisited these questions. Their results inform us about past and current practices in cosmology.

PhD student Jaco de Swart, astroparticle physicist Gianfranco Bertone and historian of science Jeroen van Dongen study the history of ‘how dark matter came to matter’. Their first results are published in an article in Nature Astronomy this week.

Forty years of darkness
Dark Matter has a long history. In the 1930s, first observations suggested that galaxies in clusters are moving so rapidly that their velocities cannot be understood by familiar and visible matter. Still, it took 40 years before consensus on this conclusion was reached. ‘[A] lot of things were not understood about masses of astronomical objects on the scales of galaxies and larger’, eminent physicist Jim Peebles recalled in an interview with Jaco de Swart. Peebles played a central role in the 1970s in convincing the scientific community that most of the matter in the universe is unknown to us: it is literally ‘dark’. But why did it take so long for scientists to realize this?

Cosmological turn
De Swart, Bertone and Van Dongen studied original sources, interviewed pioneering scientists and reconstructed the historical context of the dark matter hypothesis. In their paper, they show that newly observed phenomena, as well as institutional developments, partly driven by the Cold War, led astronomers and physicists to focus on cosmological problems. A quest to determine the mass density of the universe began: it is this mass density which decides the ultimate fate of the universe. In the search for the universe’s mass, galactic dynamics was finally taken to imply that 85% of the universe’s matter is missing.

History for the future
Collaborations between physicists, historians and philosophers are necessary to deepen our understanding of cosmology and dark matter. What kind of arguments and inferences are used in cosmology? When does data turn into evidence for astrophysicists? Answers to these questions will inform today’s heated debates on the nature of dark matter and the proper practice of cosmology.

How dark matter come to matter – Jaco de Swart, Gianfranco Bertone, and Jeroen van Dongen

19/12/2016: Most precise analysis of fluctuations in gamma-ray sky

MattiaFornasa_smallResearchers from the University of Amsterdam’s (UvA) GRAPPA Center of Excellence have just published the most precise analysis of the fluctuations in the gamma-ray background to date. By making use of more than six years of data gathered by the Fermi Large Area Telescope, the researchers found two different source classes contributing to the gamma-ray background. No traces of a contribution of dark matter particles were found in the analysis. The collaborative study was performed by an international group of researchers and is published in the latest edition of the journal Physical Review D.

Gamma rays are particles of light, or photons, with the highest energy in the universe and are invisible to the human eye. The most common emitters of gamma rays are blazars: supermassive black holes at the centers of galaxies. In smaller numbers, gammy rays are also produced by a certain kind of stars called pulsars and in huge stellar explosions such as supernovae.

In 2008 NASA launched the Fermi satellite to map the 2015-02-26 04.22.58 pmgamma-ray universe with extreme accuracy. The Large Area Telescope, mounted on the Fermi satellite, has been taking data ever since. It continuously scans the entire sky every three hours. The majority of the detected gamma rays is produced in our own Galaxy (the Milky Way), but the Fermi telescope also managed to detect more than 3000 extragalactic sources (according to the latest count performed in January 2016). However, these individual sources are not enough to explain the total amount of gamma-ray photons coming from outside our Galaxy. In fact, about 75% of them are unaccounted for.

Isotropic gamma-ray background

As far back as the late 1960s, orbiting observatories found a diffuse background of gamma rays streaming from all directions in the universe. If you had gamma-ray vision, and looked at the sky, there would be no place that would be dark.

2015-02-26 04.26.22 pmThe source of this so-called isotropic gamma-ray background has hitherto remained unknown.  This radiation could be produced by unresolved blazars, or other sources too faint to be detected with the Fermi telescope. Parts of the gamma-ray background might also hold the fingerprint of the illustrious dark matter particle, a so-far undetected particle held responsible for the missing 80% of the matter in our universe. If two dark matter particles collide, they can annihilate and produce a signature of gamma-ray photons.


Together with colleagues, Dr Mattia Fornasa, an astroparticle physicist at the UvA and lead author of the paper, performed an extensive analysis of the gamma-ray background by using 81 months of data gathered by the Fermi Large Area Telescope – much more data and with a larger energy range than in previous studies. By studying the fluctuations in the intensity of the gamma-ray background, the researchers were able to distinguish two different contributions to the gamma-ray background. One class of gamma-ray sources is needed to explain the fluctuations at low energies (below 1 GeV) and another type to generate the fluctuations at higher energy – the signatures of these two contributions is markedly different.

In their paper the researchers suggest that the gamma rays in the high-energy ranges – from a few GeV up – are likely originating from unresolved blazars. Further investigation into these potential sources is currently being carried out by Fornasa, fellow UvA researcher Shin’ichiro Ando and colleagues from the University of Torino, Italy. However, it seems much harder to pinpoint a source for the fluctuations with energies below 1 GeV. None of the known gamma-ray emitters have a behaviour that is consistent with the new data.

Constraints on dark matter

To date, the Fermi telescope has not detected any conclusive indication of gamma-ray emission originating from dark-matter particles. Also, this latest study showed no indication of a signal associated with dark matter. Using their data, Fornasa and colleagues were even able to rule out some models of dark matter that would have produced a detectable signal.

‘Our measurement complements other search campaigns that used gamma rays to look for dark matter and it confirms that there is little room left for dark matter induced gamma-ray emission in the isotropic gamma-ray background’, says Fornasa.


The data that were analysed in the work described here. Fluctuations in the isotropic gamma-ray background, based on 81 months of data. Emission from our own Galaxy, the Milky Way, is masked in grey. (Credits: Mattia Fornasa, UvA/Grappa)

Publication details

Mattia Fornasa, Alessandro Cuoco, Jesús Zavala, Jennifer M. Gaskins, Miguel A. Sánchez-Conde, German Gomez-Vargas, Eiichiro Komatsu, Tim Linden, Francisco Prada, Fabio Zandanel and Aldo Morselli: ‘The Angular Power Spectrum of the Diffuse Gamma-ray Emission as Measured by the Fermi Large Area Telescope and Constraints on its Dark Matter Interpretation’ in Physical Review D. D 94, 123005, 9 December 2016.


GRAPPA (GRavitation and AstroParticle Physics in Amsterdam) is a center of excellence of the University of Amsterdam. GRAPPA brings together theoretical physicists, astronomers and particle physicists in order to answer some of the most profound questions in particle astrophysics and cosmology: What is the so-called dark matter? How was the universe created? Where do cosmic rays originate? What bounds the smallest particles? The GRAPPA members who contributed to this research paper are Mattia Fornasa (lead author), Jennifer M. Gaskins and Fabio Zandanel.

19/12/2016: ERC Consolidator Grant for Ben Freivogel

ben-freivogelThe European Research Council has awarded a prestigious Consolidator Grant to GRAPPA researcher Ben Freivogel, for the project “Quantifying Quantum Gravity Violations of Causality and the Equivalence Principle”

Freivogel’s ERC project intends to accurately identify the circumstances and scales where quantum-mechanical effects of gravity become relevant. Although these quantum effects are typically believed to be extremely tiny on scales that can be probed experimentally, recent results of Freivogel and others suggest that under certain circumstances quantum gravity effects can become large and perhaps even observable on much larger, macroscopic, length scales. This could in particular have major consequences for the possibility to probe quantum gravity through cosmology.


17/11/2016: New Job: joint postdoctoral position at Amsterdam/Leiden

We invite applications for a joint postdoctoral position at the GRAPPA center of excellence in Astroparticle Physics at the U. of Amsterdam, and at the Lorentz Institute at the U. of Leiden. Preference will be given to candidates with expertise in the application of advanced statistical methods and/or machine learning, to astronomy and/or particle physics. The appointment is for two years with a starting date in the Fall 2017.

Instructions to apply: Interested candidates should submit the application material through the general GRAPPA postdoctoral search at https://academicjobsonline.org/ajo/jobs/8324.

(No action needed from applicants who have already submitted their material through the link above, as they will automatically considered for all positions open at GRAPPA)

For further details please contact Gianfranco Bertone (g.bertone@uva.nl) or Alexey Boyarsky (boyarsky@lorentz.leidenuniv.nl).

17/11/2016: Delta-ITP grant awarded to G. Bertone and A. Boyarsky

The Delta-Institute of Theoretical Physics has awarded a grant to Gianfranco Bertone and Alexey Boyarsky (Leiden) to hire a joint postdoctoral research associate at GRAPPA (Amsterdam) and the Lorentz Institute (Leiden). The successful candidate will conduct research work on the application of advanced statistical methods and/or machine learning to astronomy and/or particle physics. 

All positions open at GRAPPA, and instructions on how to apply, can be found on our Jobs page. 


04/11/2016: ISAPP PhD School Texel, 26 June – 5 July 2017, Registration Open

We would like to draw your attention to the next ISAPP Doctoral School which will be held next summer in Texel (The Netherlands):

ISAPP 2017 (Texel): The Dark and Visible Side of the Universe

26 June – 5 July 2017

De Krim Holiday Park, de Cocksdorp, Texel (The Netherlands)

Web page: http://indico.cern.ch/e/isapp2017

Email: isapp.texel.2017@gmail.com

We invite you to forward this message to potentially interested students and young postdocs.

Every year, the ISAPP European network (http://isapp.ba.infn.it) organizes doctoral schools addressed to students – theorists, experimentalists and observers – in the astroparticle physics domain.  This school is organized by the GRAPPA Institute at University of Amsterdam and by the Radboud University in Nijmegen. It will be held on the beautiful island of Texel, located off the northern coast of The Netherlands.

The school is dedicated to the particle and astroparticle aspects of dark matter in the Universe as well as high-energy astrophysics with a multi-messenger approach. The lectures cover a wide range of relevant topics including sources, acceleration, propagation and detection of cosmic rays, gamma-ray and neutrino astrophysics, astroparticle statistics, the production and distribution of dark matter, and the current status of indirect and other dark matter searches. They will cover both the theoretical/phenomenological and experimental/observational aspects, in order to give an exhaustive overview of this complex field.

The schedule is organized in slots of 1.5 hours lectures (intended as 75 min of teaching, followed by 15 min of discussion with the students). Discussion sessions, placed at the end of most of the lecture days, as well as various student projects, are further devoted to stimulate dialogue amongst students and between students and teachers. Details on the program will be available on the School webpage.

Students are encouraged to bring posters showing their own research work, which will be presented and discussed in dedicated poster sessions.

The School is addressed to PhD students and early postdocs working in the field of dark matter, particle physics, high energy astrophysics and astroparticle physics in general.  A letter from each registrant’s advisor is required to finalize the registration process.

Attendance is limited to 48 participants.  Applications should be sent through the registration form on the School webpage before 1st February 2017.


Shin’ichiro Ando

Gianfranco Bertone

Nicolao Fornengo

Jörg Hörandel

Sergio Pastor

Christoph WenigerISAPPTexel Poster A3

21/10/2016: We’re hiring 1 or more postdoctoral candidate to start around Fall 2017

The GRAPPA center of excellence in Astroparticle Physics and Gravitation (grappa.amsterdam) invites applications for 1 or more postdoctoral positions to start around Fall 2017. The group has wide research interests, including dark matter phenomenology, cosmic rays, high-energy astrophysics, cosmology, black holes physics, gravitational waves, and string theory, and it includes experimental physicists active in the
Antares/KM3NeT, ATLAS, CTA, LOFAR, and XENON1T collaborations.

Go to grappa.amsterdamjobs/ for more information

03/10/2016: First GRAPPA Ph.D. Defense Ceremony – Hamish Silverwood

Next Wednesday October 5th, Hamish Silverwood – first Ph.D. Student of the GRAPPA Institute – will defend his thesis with title The Dark that Shapes the Light (Supervisors: Prof. J. de Boer, Dr. G. Bertone).

For decades, detectors and satellites have been searching for dark matter, mysterious particles whose existence is inferred by gravitational effects but which have never been observed. Hamish investigated new methods for improving the analyses of detectors and predicting the density of local dark matter. The aim is to improve our chances of eventually observing dark matter.

Good luck to Hamish and farewell!

14/06/2016: CTA select headquarters and data management centre

Anther step ahead for the Cherenkov Telescope Array collaboration! On 13 June 2016, the governing body of the Cherenkov Telescope Array Observatory gGmbH (CTAO gGmbH), the CTA Council, selected Bologna as the host site of the CTA Headquarters and Berlin – Zeuthen for the Science Data Management Centre (SDMC) from five site candidates.

The Council, composed of shareholders from nine countries (Austria, Czech Republic, France, Germany, Italy, Japan, Spain, Switzerland and the United Kingdom) in consultation with associate members (Netherlands, South Africa and Sweden), made the decision after careful consideration of the proposals against criteria that included infrastructure, services and access requirements.


Figure. Right: Computer rendering of CTA Headquarters Building, Bologna (Credit: Bologna University Project Office). Left: Architectural rendering of CTA Science Data Management Centre Building, Zeuthen (Credit: Dahm Architekten & Ingenieure, Berlin).

The CTA Headquarters will be the central office responsible for the overall administration of Observatory operations. Approximately two dozen personnel will provide technical coordination and support, and the main administrative services for the governing bodies and users of the Observatory. The headquarters will be located within the Istituto Nazionale di Astrofisica (INAF) premises in a new building shared with the Bologna University Department of Physics and Astronomy. This location gives CTA a home in a word-class scientific environment with state‐of‐the-art facilities, in one of Italy’s most attractive and historic cultural centres.

The Science Data Management Centre will coordinate science operations and make CTA’s science products available to the worldwide community. An estimated 20 personnel will manage CTA’s science coordination including software maintenance and data processing forthe Observatory, which is expected to generate approximately 100 petabytes (PB) of data by the year 2030. (One PB is equal to 1015 bytes of data or one million gigabytes.) The SDMC will be located in a new building complex on the Deutsches Elektronen-Synchrotron (DESY) campus in Zeuthen, which is conveniently located just outside Berlin – one of Europe’s primary capital cities. This location provides extensive access to well-established infrastructure services and a powerful computing centre.

Link to the full press release by CTA.

19/03/2016: A “power house” at the Milky Way centre accelerates PeV protons

An international team of scientists, including David Berge, Jacco Vink, David Salek, Rachel Simoni and Mark Bryan at GRAPPA (University of Amsterdam), has discovered a source accelerating Galactic cosmic rays to energies never observed before in the Milky Way. The researchers suspect that the black hole at the centre of our galaxy can be held responsible. The findings of the scientists, united in the H.E.S.S. collaboration, were published in Nature on 16 March.

For over thirty years a collaboration of 42 institutes in 12 countries, including scientists of the UvA GRAPPA, Anton Pannekoek Institute for Astronomy, and the Institute of Physics, has been mapping the centre of our galaxy in very-high-energy gamma rays. A detailed analysis of the latest data reveals for the first time a source of this cosmic radiation at energies never observed before in the Milky Way: the supermassive black hole at its centre.

Cosmic rays

The Earth is constantly bombarded by high-energy particles (protons, electrons and atomic nuclei) of cosmic origin, particles that comprise the so-called “cosmic radiation”. Since more than a century, the origin of these cosmic rays remains one of the most enduring mysteries of science. The particles, such as protons, electrons and atomic nuclei are electrically charged, and are hence strongly deflected by the interstellar magnetic fields that pervade our galaxy. Fortunately, cosmic rays interact with light and gas in the neighbourhood of their sources and thereby produce gamma rays. These gamma rays travel in straight lines, undeflected by magnetic fields, and can therefore be traced back to their origin.

The source of gamma rays

Researchers of the High Energy Stereoscopic System-consortium (H.E.S.S.-consortium) used their telescopes in Namibia for the measurement. Ten years ago, they had already uncovered a very powerful point source of gamma rays in the galactic centre region, but the nature of the source remained a mystery. Possible objects capable of producing cosmic rays of high energy were supernova remnant, a pulsar wind nebula, and a compact cluster of massive stars.

Deeper observations made it now possible to pinpoint the black hole at the centre of the Milky Way as the source of the particles. This cosmic accelerator is about 100 times as powerful as the LHC at CERN, the largest terrestrial particle accelerator. The black hole is the first discovery of an astrophysical source capable of accelerating protons to energies of about one petaelectronvolt.


Artist’s impression of the giant molecular clouds surrounding the Galactic Centre, bombarded by very high energy protons accelerated in the vicinity of the central black hole and subsequently shining in gamma rays. © Dr Mark A. Garlick/ HESS Collaboration

The scientists have published their findings on 16 March in the journal Nature. Jacco Vink, David Berge, David Salek, Rachel Simoni and Mark Bryan have contributed to the research. Berge, the coordinator of the galactic science program of H.E.S.S., says: “It is great that we as a team finally found the source of gamma rays in the galactic centre region, after years of measuring and modelling.”

– Publication details: H.E.S.S. collaboration, corresponding authors: F. Aharonian, S. Gabici, E. Moulin and A. Viana; “Acceleration of petaelectronvolt protons in the Galactic Centre” Nature, 16 March 2016.

02/03/2016: NWO-M grant for David Berge

The CTA group around David Berge at the University of Amsterdam received a NWO-M grant (http://www.nwo.nl/en/funding/our-funding-instruments/nwo/investment-grant-nwo-medium/index.html) worth 356k Euro to build the core of the Clock Distribution and Trigger time Stamping (CDTS) system, the precision timing backbone, for CTA. CTA, The Cherenkov Telescope Array (https://www.cta-observatory.org) is one of the major future facilities of the field of astroparticle physics and high-energy astrophysics, dedicated to exploring the high-energy universe with gamma rays. Planned to start full operation in the early 2020’s, it will address important scientific topics, such as the origin of cosmic rays and their interaction with their environment, the energetic output of accreting black holes and the existence of dark matter.

The video below is an animation of what the telescope is to look like when finished.

CTA will be an observatory with arrays of telescopes on two sites, one in Spain on the Canary Island of La Palma for the Northern hemisphere, one at the European Southern Observatory (ESO) in Paranal in Chile for the Southern hemisphere, with 100 and 20 telescopes in the South and North, respectively.

CTA employs the Imaging Atmospheric Cherenkov Technique to measure cosmic gamma rays by recording the 10-ns long Cherenkov light flashes emitted in air showers induced by these gamma rays in the Earth’s atmosphere. Precise nanosecond timing is therefore mandatory for CTA to correctly tag and identify these short light flashes in the various telescopes.

The CDTS system that dr. Berge is working on, including a common timing card in every telescope, is based on “White Rabbit” (http://www.ohwr.org/projects/white-rabbit/wiki). This is an extension of the Ethernet protocol that distributes timing signals with nanosecond precision in optical networks.

17/02/2016: Vici grant for Sera Markoff

Congratulations to Dr Sera Markoff, Associate Professor at the UvA Anton Pannekoek Institute for Astronomy and a GRAPPA memberhe GRAPPA Center of Excellence. She was awarded a prestigious Vici grant. Markoff receives the grant for her project entitled “From micro- to megascales: understanding how black holes shape the local universe”.


This is primarily a theoretical project, focusing on the very important role black holes play in “recycling” material and subsequently energising their surroundings. Although black holes are famous for sucking up everything in their paths, including light, in reality they manage to convert captured material into other forms with an efficiency that can be orders of magnitude larger than nuclear fusion.

Jets – The most dramatic outputs are immense streams of magnetised plasma moving at near light speed, called jets. Jets from a supermassive black hole like the one in the centre of our Galaxy (luckily not currently ‘active’) can dump the energy equivalent of 100 billion supernovae into their environment, heating the surrounding gas to the point where it cannot collapse to form stars and effectively halting future galaxy growth. The myriad small, stellar-remnant black holes in every galaxy also enact a ‘micro’ version of this feedback, locally affecting star formation. At the moment there is no predictive theory for how this fundamental process occurs. At the same time several new observatories are just about to come online, that will deliver incredibly precise data from thousands of newly discovered black holes, and even make images of (some of) their Event Horizons.

A picture from the X-ray satellites Chandra (NASA) and XMM-Newton (ESA) showing the hot gas trapped in a cluster of galaxies
Image: combined X-ray image from NASA/ESA satellites Chandra and XMM-Newton showing the hot gas trapped within a cluster of galaxies.The image is almost a million light years across, the bright central spot is a galaxy, buried inside is a supermassive black hole that has launched immense jets 100s of millions of times larger than itself, which have inflated symmetric ‘bubbles’ on either side.  Each bubble is many times larger than our Galaxy, and older sets of bubbles show that this process has been driving pressure waves and even weak shocks for millions of years, disrupting and heating the gas on massive scales. Markoff and collaborators seek to understand this process. Credits: NASA.


Research Team – Sera Markoff will use the Vici grant to build a research group of three PhD students and two postdocs to tackle this problem. They will use existing HPC facilities as well as building a local compute cluster to develop models that can be tested against the new, precision observations across the electromagnetic spectrum. There are strong links to astroparticle physics, because Markoff and group will test also against signals from particles like high-energy cosmic rays and now even gravitational waves from merging compact objects.

Finally, Markoff has a project that will focus on science outreach in the Indishe Buurt in Amsterdam, as well as in number of refugee centers.

12/02/2016: Gravitational Waves detected!

ligo20160211_TnFor the first time, scientists have observed ripples in the fabric of spacetime called gravitational waves, arriving at the earth from a cataclysmic event in the distant universe. This confirms a major prediction of Albert Einstein’s 1915 general theory of relativity and opens an unprecedented new window onto the cosmos.

Gravitational waves carry information about their dramatic origins and about the nature of gravity that cannot otherwise be obtained. Physicists have concluded that the detected gravitational waves were produced during the final fraction of a second of the merger of two black holes to produce a single, more massive spinning black hole. This collision of two black holes had been predicted but never observed.

The gravitational waves were detected on September 14, 2015 at 5:51 a.m. Eastern Daylight Time (09:51 UTC) by both of the twin Laser Interferometer Gravitational-wave Observatory (LIGO) detectors, located in Livingston, Louisiana, and Hanford, Washington, USA. The LIGO Observatories are funded by the National Science Foundation (NSF), and were conceived, built, and are operated by Caltech and MIT. The discovery, accepted for publication in the journal Physical Review Letters, was made by the LIGO Scientific Collaboration (which includes the GEO Collaboration and the Australian Consortium for Interferometric Gravitational Astronomy) and the Virgo Collaboration using data from the two LIGO detectors.

Based on the observed signals, LIGO scientists estimate that the black holes for this event were about 29 and 36 times the mass of the sun, and the event took place 1.3 billion years ago. About 3 times the mass of the sun was converted into gravitational waves in a fraction of a second—with a peak power output about 50 times that of the whole visible universe. By looking at the time of arrival of the signals—the detector in Livingston recorded the event 7 milliseconds before the detector in Hanford—scientists can say that the source was located in the Southern Hemisphere.

According to general relativity, a pair of black holes orbiting around each other lose energy through the emission of gravitational waves, causing them to gradually approach each other over billions of years, and then much more quickly in the final minutes. During the final fraction of a second, the two black holes collide into each other at nearly one-half the speed of light and form a single more massive black hole, converting a portion of the combined black holes’ mass to energy, according to Einstein’s formula E=mc2. This energy is emitted as a final strong burst of gravitational waves. It is these gravitational waves that LIGO has observed.

The existence of gravitational waves was first demonstrated in the 1970s and 80s by Joseph Taylor, Jr., and colleagues. Taylor and Russell Hulse discovered in 1974 a binary system composed of a pulsar in orbit around a neutron star. Taylor and Joel M. Weisberg in 1982 found that the orbit of the pulsar was slowly shrinking over time because of the release of energy in the form of gravitational waves. For discovering the pulsar and showing that it would make possible this particular gravitational wave measurement, Hulse and Taylor were awarded the Nobel Prize in Physics in 1993.

The new LIGO discovery is the first observation of gravitational waves themselves, made by measuring the tiny disturbances the waves make to space and time as they pass through the earth.

“Our observation of gravitational waves accomplishes an ambitious goal set out over 5 decades ago to directly detect this elusive phenomenon and better understand the universe, and, fittingly, fulfills Einstein’s legacy on the 100th anniversary of his general theory of relativity,” says Caltech’s David H. Reitze, executive director of the LIGO Laboratory.

The discovery was made possible by the enhanced capabilities of Advanced LIGO, a major upgrade that increases the sensitivity of the instruments compared to the first generation LIGO detectors, enabling a large increase in the volume of the universe probed—and the discovery of gravitational waves during its first observation run. The US National Science Foundation leads in financial support for Advanced LIGO. Funding organizations in Germany (Max Planck Society), the U.K. (Science and Technology Facilities Council, STFC) and Australia (Australian Research Council) also have made significant commitments to the project. Several of the key technologies that made Advanced LIGO so much more sensitive have been developed and tested by the German UK GEO collaboration. Significant computer resources have been contributed by the AEI Hannover Atlas Cluster, the LIGO Laboratory, Syracuse University, and the University of Wisconsin- Milwaukee. Several universities designed, built, and tested key components for Advanced LIGO: The Australian National University, the University of Adelaide, the University of Florida, Stanford University, Columbia University of the City of New York, and Louisiana State University.

“In 1992, when LIGO’s initial funding was approved, it represented the biggest investment the NSF had ever made,” says France Córdova, NSF director. “It was a big risk. But the National Science Foundation is the agency that takes these kinds of risks. We support fundamental science and engineering at a point in the road to discovery where that path is anything but clear. We fund trailblazers. It’s why the U.S. continues to be a global leader in advancing knowledge.”

LIGO research is carried out by the LIGO Scientific Collaboration (LSC), a group of more than 1000 scientists from universities around the United States and in 14 other countries. More than 90 universities and research institutes in the LSC develop detector technology and analyze data; approximately 250 students are strong contributing members of the collaboration. The LSC detector network includes the LIGO interferometers and the GEO600 detector. The GEO team includes scientists at the Max Planck Institute for Gravitational Physics (Albert Einstein Institute, AEI), Leibniz Universität Hannover, along with partners at the University of Glasgow, Cardiff University, the University of Birmingham, other universities in the United Kingdom, and the University of the Balearic Islands in Spain.

“This detection is the beginning of a new era: The field of gravitational wave astronomy is now a reality,” says Gabriela González, LSC spokesperson and professor of physics and astronomy at Louisiana State University.

LIGO was originally proposed as a means of detecting these gravitational waves in the 1980s by Rainer Weiss, professor of physics, emeritus, from MIT; Kip Thorne, Caltech’s Richard P. Feynman Professor of Theoretical Physics, emeritus; and Ronald Drever, professor of physics, emeritus, also from Caltech.

“The description of this observation is beautifully described in the Einstein theory of general relativity formulated 100 years ago and comprises the first test of the theory in strong gravitation. It would have been wonderful to watch Einstein’s face had we been able to tell him,” says Weiss.

“With this discovery, we humans are embarking on a marvelous new quest: the quest to explore the warped side of the universe—objects and phenomena that are made from warped spacetime. Colliding black holes and gravitational waves are our first beautiful examples,” says Thorne.

Virgo research is carried out by the Virgo Collaboration, consisting of more than 250 physicists and engineers belonging to 19 different European research groups: 6 from Centre National de la Recherche Scientifique (CNRS) in France; 8 from the Istituto Nazionale di Fisica Nucleare (INFN) in Italy; 2 in The Netherlands with Nikhef; the Wigner RCP in Hungary; the POLGRAW group in Poland; and the European Gravitational Observatory (EGO), the laboratory hosting the Virgo detector near Pisa in Italy.

Fulvio Ricci, Virgo Spokesperson, notes that, “This is a significant milestone for physics, but more importantly merely the start of many new and exciting astrophysical discoveries to come with LIGO and Virgo.”

Bruce Allen, managing director of the Max Planck Institute for Gravitational Physics (Albert Einstein Institute), adds, “Einstein thought gravitational waves were too weak to detect, and didn’t believe in black holes. But I don’t think he’d have minded being wrong!”

“The Advanced LIGO detectors are a tour de force of science and technology, made possible by a truly exceptional international team of technicians, engineers, and scientists,” says David Shoemaker of MIT, the project leader for Advanced LIGO. “We are very proud that we finished this NSF-funded project on time and on budget.”

At each observatory, the two-and-a-half-mile (4-km) long L-shaped LIGO interferometer uses laser light split into two beams that travel back and forth down the arms (four-foot diameter tubes kept under a near-perfect vacuum). The beams are used to monitor the distance between mirrors precisely positioned at the ends of the arms. According to Einstein’s theory, the distance between the mirrors will change by an infinitesimal amount when a gravitational wave passes by the detector. A change in the lengths of the arms smaller than one-ten-thousandth the diameter of a proton (10-19 meter) can be detected.

“To make this fantastic milestone possible took a global collaboration of scientists—laser and suspension technology developed for our GEO600 detector was used to help make Advanced LIGO the most sophisticated gravitational wave detector ever created,” says Sheila Rowan, professor of physics and astronomy at the University of Glasgow.

Independent and widely separated observatories are necessary to determine the direction of the event causing the gravitational waves, and also to verify that the signals come from space and are not from some other local phenomenon.

Toward this end, the LIGO Laboratory is working closely with scientists in India at the Inter-University Centre for Astronomy and Astrophysics, the Raja Ramanna Centre for Advanced Technology, and the Institute for Plasma to establish a third Advanced LIGO detector on the Indian subcontinent. Awaiting approval by the government of India, it could be operational early in the next decade. The additional detector will greatly improve the ability of the global detector network to localize gravitational-wave sources.

“Hopefully this first observation will accelerate the construction of a global network of detectors to enable accurate source location in the era of multi-messenger astronomy,” says David McClelland, professor of physics and director of the Centre for Gravitational Physics at the Australian National University.

Additional video and image assets can be found here: http://mediaassets.caltech.edu/gwave

04/02/2016: Millisecond pulsars may explain Galactic center gamma-ray excess

The puzzling excess of gamma rays from the centre of the Milky Way probably originate from rapidly rotating neutron stars, or millisecond pulsars, and not from dark matter annihilation, as previously claimed. This is the conclusion of new data analyses by two independent research teams from the University of Amsterdam (UvA) and Princeton University/Massachusetts Institute of Technology. The researchers’ findings were published on Thursday, 4 February in Physical Review Letters.

In 2009 observations with the Fermi Large Area Telescope revealed an excess of high-energetic photons, or gamma rays, around 2 GeV (gigaelectronvolt) at the centre of our Galaxy. It was long speculated that this gamma ray excess could be a signal of dark matter annihilation. If true, it would constitute a breakthrough in fundamental physics and a major step forward in our understanding of the matter constituents of the universe.
However, many other hypotheses have emerged in recent years, suggesting the gamma ray excess in the centre of our Galaxy might have a more ordinary, astrophysical cause. Possible origins for the observed gamma ray excess range from the activity of the supermassive black hole in the centre of our Milky Way and star formation in the central molecular zone to the combined emission of a new dim source population in the galactic bulge.

Millisecond pulsars
New statistical analyses of the Fermi data by Dr Christoph Weniger, assistant professor at the UvA, and a research group from Princeton/MIT, now strongly suggest that the excess emission does indeed originate from unresolved point sources. The best candidates are millisecond pulsars, the researchers conclude.
Millisecond pulsars, or rapidly rotating neutron stars, were often formed billions of years ago. They are among the most extreme objects in the Galaxy. A population of hundreds or thousands of these millisecond pulsars must be lurking in the galactic centre, hidden from detection due to present day instrument sensitivity. Future radio surveys with existing and upcoming telescopes (e.g. Green Bank Telescope, Square Kilometre Array) will be able to further test this hypothesis in the coming years.

Gamma ray picture of the Milky Way, as seen by the NASA Fermi satellite. Inserts: two independent statistical analyses showed that the distribution of photons is clumpy rather than smooth, indicating that the excess gamma rays from the centre of our galaxy are unlikely to be caused by dark matter annihilation.


Image courtesy of Christoph Weniger, UvA , © UvA/Princeton

Win-win situation
In their analyses, the UvA and Princeton/MIT researchers each used a different statistical technique, ‘non-Poissonian noise’ and ‘wavelet transformation’, to analyse the Fermi data. What they found was that the distribution of photons was clumpy rather than smooth, indicating that the gamma rays were unlikely to be caused by dark matter particle collisions.

According to Weniger, lead author of one of the papers, this is a win-win situation. ‘Either we find hundreds or thousands of millisecond pulsars in the upcoming decade, shedding light on the history of the Milky Way, or we find nothing. In the latter case, a dark matter explanation for the gamma ray excess will become much more obvious.’

Mariangela Lisanti, assistant professor at Princeton University and one of the authors of the second paper, adds: ‘The results of our analysis probably mean that what we are seeing is evidence for a new population of astrophysical sources in the centre of the Galaxy. That in itself is something new and surprising.’

Publication details:
Richard Bartels, Suraj Krishnamurthy and Christoph Weniger: ‘Strong support for the millisecond pulsar origin of the Galactic center GeV excess’ in: Physical Review Letters, (February 4, 2016). http://arxiv.org/abs/1506.05104

Samuel K. Lee, Mariangela Lisanti, Benjamin R. Safdi, Tracy R. Slatyer and Wei Xue: ‘Evidence for Unresolved Gamma-Ray Point Sources in the Inner Galaxy’ in: Physical Review Letters, February 4, 2016, http://arxiv.org/abs/1506.05124


03/02/2016: Letter of Intent for KM3NeT 2.0

Scientists of the KM3NeT Collaboration have publicly announced KM3NeT 2.0, their ambition for the immediate future to further exploit the clear waters of the deep Mediterranean Sea for the detection of cosmic and atmospheric neutrinos. The published Letter of Intent details the science performance as well as the technical design of the KM3NeT 2.0 infrastructure.

km3net-geometry-cylinder-exampleThe two major scientific goals of KM3NeT 2.0 are the discovery of astrophysical sources of neutrinos in the Universe with the KM3NeT/ARCA detector and the measurement of the neutrino mass hierarchy using atmospheric neutrinos with the KM3NeT/ORCA detector. Thanks to the flexible KM3NeT design, efficient detection of neutrinos is possible over a wide energy range (GeV to PeV) with an almost identical implementation. The KM3NeT scientists estimate that with the ARCA detector installed at the KM3NeT-It site south of Sicily, Italy, the observation of the cosmic neutrino flux reported by the IceCube Collaboration will be possible within one year of operation. With the ORCA detector installed at the KM3NeT-Fr site south of Toulon, France, they expect to determine neutrino mass hierarchy with at least 3-sigma significance after three years of operation.

Rosa Coniglione, KM3NeT Workgroup leader HE Astrophysics: ”The combination of the cost effective design of the ARCA detector of KM3NeT and state-of-the-art reconstruction software allows for efficient detection of all three neutrino flavours from cosmic origin in a few years.”

Antoine Kouchner, KM3NeT Workgroup leader LE Physics: “With the densely instrumented ORCA detector of KM3NeT we will be able to determine the relative ordering of the neutrino masses, also referred to as the neutrino mass hierarchy.”

The Letter of Intent is now open for scrutiny by the neutrino scientific community and will serve as the reference document for requests for funding by the various stakeholders in Europe and abroad. Pending funding, KM3NeT 2.0 could become reality as early as in 2020.

Uli Katz, KM3NeT Physics and Software manager: “The modular design of KM3NeT with detector blocks for the telescope makes it possible to swiftly react on new scientific developments. With KM3NeT 2.0 we are able to not only perform all-flavour neutrino astroparticle physics but also advance fundamental neutrino particle physics.”

Reference: Letter of Intent for KM3NeT 2.0, arXiv:1601.07459

11/01/2016: GRAPPA will host “DM @ LHC” and the “2nd Anisotopic Universe” workshops

The GRAPPA Institute will host two exiting workshops in March/April.

The 3rd “Dark Matter at the Large Hadron Collider” workshop will be held from 30 March to 1 April 2016 jointly by GRAPPA and Nikhef. The aim of the workshop is to bring together the leading experts in the field of Dark Matter searches in order to review the latest results from both theory and the experiments, especially in the light of the new results from the 2015 LHC data sets.

The 2nd Anisotropic Universe workshop “Unveiling the Anisotropic Universe” will be held from 11 to 13 April 2016 with the aim to exploit the momentum recently gained by the cross-field topic of anisotropies to launch a collaborative effort to unravel fundamental issues in astrophysics and cosmology as, for example, the origin of ultra-high energy cosmic rays and neutrinos, and the nature of dark matter.

Register and stay tuned!