About

About

Currently I am focussing on two main topics: ReSnap, which I cofounded, and a PhD in machine learning & high energy physics. My focus currently is on single page app development (in React + Redux), serverless backend development and machine learning (mainly computer vision). I apply this on both satellite data for solving the dark matter problem, and to predict subjective features in photos such as ‘perceived beautifulness’. My main interests are AI (technical as well as philosophical), physics, quantum computing and blockchain applications. This blog serves as an outlet of stuff I find interesting.

Highlights & talks

2018

2017

2016

  • September: I started my PhD in machine learning & dark matter

2015

2014

  • I was one of Sprout’s “25 under 25“, an award that recognises young entrepreneurial talent in the Netherlands

Popular science

I was active in popular science for a while. Unfortunately due to ReSnap and my PhD I don’t have enough time anymore to be active in this area, although I do still have the ambition to write about physics and technology on a simple level. I wrote a book together with Rob Walrecht about the higgs particle in Dutch, which can be found here: https://www.bol.com/nl/p/higgs-gevonden/9200000009552066/

Media

Scientific publications

Implications of the Fermi-LAT Pass 8 Galactic Center excess on supersymmetric dark matter

The Fermi Collaboration has recently updated their analysis of gamma rays from the center of the Galaxy. They reconfirm the presence of an unexplained emission feature which is most prominent in the region of 1–10 GeV, known as the Galactic Center GeV excess (GCE). Although the GCE is now firmly detected, an interpretation of this emission as a signal of self-annihilating dark matter (DM) particles is not unambiguously possible due to systematic effects in the gamma-ray modeling estimated in the Galactic Plane. In this paper we build a covariance matrix, collecting different systematic uncertainties investigated in the Fermi Collaboration’s paper that affect the GCE spectrum. We show that models where part of the GCE is due to annihilating DM is still consistent with the new data. We also re-evaluate the parameter space regions of the minimal supersymmetric Standard Model (MSSM) that can contribute dominantly to the GCE via neutralino DM annihilation. All recent constraints from DM direct detection experiments such as PICO, LUX, PandaX and Xenon1T, limits on the annihilation cross section from dwarf spheroidal galaxies and the Large Hadron Collider limits are considered in this analysis. Due to a slight shift in the energy spectrum of the GC excess with respect to the previous Fermi analysis, and the recent limits from direct detection experiments, we find a slightly shifted parameter region of the MSSM, compared to our previous analysis, that is consistent with the GCE. Neutralinos with a mass between 85–220 GeV can describe the excess via annihilation into a pair of W-bosons or top quarks. Remarkably, there are models with low fine-tuning among the regions that we have found. The complete set of solutions will be probed by upcoming direct detection experiments and with dedicated searches in the upcoming data of the Large Hadron Collider. Read more

Analyzing γ-rays of the Galactic Center with Deep Learning

We present a new method to interpret the γ-ray data of our inner Galaxy as measured by the Fermi Large Area Telescope (Fermi LAT). We train and test convolutional neural networks with simulated Fermi-LAT images based on models tuned to real data. We use this method to investigate the origin of an excess emission of GeV γ-rays seen in previous studies. Interpretations of this excess include γ-rays created by the annihilation of dark matter particles and γ-rays originating from a collection of unresolved point sources, such as millisecond pulsars. Our new method allows precise measurements of the contribution and properties of an unresolved population of γ-ray point sources in the interstellar diffuse emission model. Read more

Comparing Galactic Center MSSM dark matter solutions to the Reticulum II gamma-ray data

Observations with the Fermi Large Area Telescope (LAT) indicate a possible small photon signal originating from the dwarf galaxy Reticulum II that exceeds the expected background between 2 GeV and 10 GeV . We have investigated two specific scenarios for annihilating WIMP dark matter within the phenomenological Minimal Supersymmetric Standard Model (pMSSM) framework as a possible source for these photons. We find that the same parameter ranges in pMSSM as reported by an earlier paper to be consistent with the Galactic Center excess, are also consistent with the excess observed in Reticulum II, resulting in a J-factor of log(10)(J(α(int)=0.5(o))) simeq (20.3−20.5)(+0.2)(−)(0.3) GeV(2)cm(−)(5). This J-factor is consistent with log(10)(J(α(int)=0.5(o))) = 19.6(+1.0)(−)(0.7) GeV(2)cm(−)(5), which was derived using an optimized spherical Jeans analysis of kinematic data obtained from the Michigan/Magellan Fiber System (M2FS). Read more

A description of the Galactic Center excess in the Minimal Supersymmetric Standard Model

Observations with the Fermi Large Area Telescope (LAT) indicate an excess in gamma rays originating from the center of our Galaxy. A possible explanation for this excess is the annihilation of Dark Matter particles. We have investigated the annihilation of neutralinos as Dark Matter candidates within the phenomenological Minimal Supersymmetric Standard Model (pMSSM) . An iterative particle filter approach was used to search for solutions within the pMSSM . We found solutions that are consistent with astroparticle physics and collider experiments, and provide a fit to the energy spectrum of the excess. The neutralino is a Bino/Higgsino or Bino/Wino/Higgsino mixture with a mass in the range 84–92 GeV or 87–97 GeV annihilating into W bosons. A third solutions is found for a neutralino of mass 174–187 GeV annihilating into top quarks. The best solutions yield a Dark Matter relic density 0.06 < Ω h(2) <0.13. These pMSSM solutions make clear forecasts for LHC, direct and indirect DM detection experiments. If the pMSSM explanation of the excess seen by Fermi-LAT is correct, a DM signal might be discovered soon. Read more. Read news article on Nature news