Erlangen Centre for Astroparticle Physics

ECAP Seminar: Thorsten Enßlin
2019-05-02 12:00 - 13:00 (Europe/Berlin) | ECAP, room 307, Erwin-Rommel-Str 1, Erlangen, 91058, Germany
Information field theory – turning data into images
Charting the Universe from measurements is a challenging information theoretical problem. The finite data provided by instruments is never able to constraint the infinite degrees of freedom of the physical fields we are interested in astronomy or other areas. Additional information like physical laws and empirical correlations has to be folded into the field inference. Information field theory (IFT) is information theory for field inference enabling the consistent fusion of measurement data and theoretical concepts exploiting techniques developed for quantum field theory. IFT provides optimal methods to generate images exploiting all available information. Existing applications of IFT in astrophysics are galactic tomography, gamma- and radio- astronomical imaging, and the analysis of cosmic microwave background data. Applications in preparation are inferring the dynamics of an observed field and the fusion of measurements from complementary instruments into coherent pictures.

ECAP Seminar: Lee Thompson
2019-06-06 12:00 - 13:00 | ECAP, room 307, Erwin-Rommel-Str 1, Erlangen, 91058, Germany
HyperKamiokande: a next generation long baseline neutrino experiment in Japan

The seminar will present the HyperKamiokande (HyperK) project which will build a large volume water Cerenkov detector for long baseline neutrino oscillation studies in Japan. A brief historical resume of the discovery of neutrino oscillations will be provided. The presentation will give an overview of the design of the HyperK detector and its main technical features. Details of the scientific programme to be undertaken will also be discussed. The prospects for the project to determine fundamental measurements such as CP violation and mass hierarchy will also be presented.

ECAP Seminar: Christian Glaser
2019-06-13 12:00 - 13:00 | ECAP, room 307, Erwin-Rommel-Str 1, Erlangen, 91058, Germany
Radio detection of ultra-high energy neutrinos
High energy neutrino astronomy is a powerful tool to study the high-energy universe. Neutrinos can escape dense source environments and point back to their sources with sub-degree accuracy. In particular, multi-messenger analyses that combine neutrino detection with electromagnetic (e.g. gamma ray) and gravitational-wave observations bear huge potential to probe the sources of neutrinos and cosmic rays. The detection of neutrinos is challenging because of their small flux and cross-section, and requires the instrumentation of huge volumes. Ultra-high energy neutrinos (E > 1e16 eV) can be efficiently measured using the radio technique, and the cold Antarctic ice is an optimal target material.
Before discussing the radio detection of neutrinos, I will briefly present the radio detection of cosmic rays, highlighting what we can learn from this mature field for neutrino detection. Then, I will report on the pilot neutrino detectors installed on the Ross ice shelf and at the South Pole, discuss how neutrinos can be measured with a radio detector and how their properties can be reconstructed from the short radio flash. At the end, I will present plans for a large-scale radio neutrino detector and discuss its prospects.

ECAP Seminar: Andreas Haungs
2019-06-27 12:00 - 13:00 | ECAP, room 307, Erwin-Rommel-Str 1, Erlangen, 91058, Germany
Cosmic rays between the knee and the ankle
Investigations of the energy spectrum as well as the mass composition of cosmic rays in the energy range of PeV to EeV are important for understanding both, the origin of the galactic and the extragalactic cosmic rays. The multi-detector arrangement of KASCADE and its extension KASCADE-Grande was designed for observations of cosmic ray air showers in this energy range. Most important result from KASCADE is the proof that the knee feature at several PeV is due to a decrease in the flux of light atomic nuclei of primary cosmic rays. Results of KASCADE-Grande have now shown two more spectral features: a knee-like structure in the spectrum of heavy primaries at around 90 PeV and a hardening of the spectrum of light primaries at energies just above 100 PeV. These features are meanwhile confirmed by other experiments like Tunka, IceCube/IceTop, or TA/TALE. In this seminar the recent results on energy spectrum and composition are compared to each other and with astrophysical models for the energy range, where the transition from galactic to extragalactic origin of cosmic rays are expected. In addition, the effects of using different hadronic interaction models for interpreting the measured air-shower data will be discussed. Finally, the KASCADE Cosmic Ray Data Centre (KCDC) is discussed, which is a web-based platform to provide astroparticle physics data for the general public. The main purpose of KCDC is to archive original data to offer long-term scientific data for the high-energy astroparticle physics community as well as for students and the interested public via a sophisticated web portal. However, KCDC can only be a first step into a global analysis and data centre for multi-messenger astroparticle physics.

ECAP Seminar: Iris Gebauer
2019-07-04 12:00 - 13:00 | ECAP, room 307, Erwin-Rommel-Str 1, Erlangen, 91058, Germany
Indirect Dark Matter Searches and Cosmic Ray Transport in the Era of AMS
The Alpha Magnetic Spectrometer (AMS) is installed on the International Space Station (ISS) since May 2011. AMS is a complex particle detector designed to precisely measure the fluxes of cosmic rays between 0.5 GeV and a few TeV. The physics goals of the experiment include the search for possible signals of dark matter annihilation and hints for primordial antimatter in the fluxes of cosmic rays. As of recently, new calorimetric experiments like CALET and DAMPE begin to shed even more light on the matter component in cosmic rays with high statistics measurements up to TeV energies.
A plethora of precision results is emerging from these experiments. Many results challenge our understanding of galactic cosmic ray transport. This talk provides an overview over some of the most exiting and often surprising results from AMS, CALET and DAMPE. I will discuss their impact on our understanding of the origin and transport of galactic cosmic rays and their contribution to indirect dark matter searches.

ECAP Seminar: Sara Buson
2019-07-11 12:00 - 13:00 | ECAP, room 307, Erwin-Rommel-Str 1, Erlangen, 91058, Germany
High-energy neutrinos from AGN?
With the advent of multi-messenger observatories, neutrino astronomy is turning into a helpful tool to investigate and put limits on the contribution of the known astrophysical objects to the diffuse neutrino background. Active Galactic Nuclei (AGN) have long been suggested among the candidate sources of cosmic high-energy neutrinos. If hadronic processes operate in the AGN jets, a lot can be learnt by combining neutrino observations with the putative accompanying electromagnetic information. This is motivated by the fact that both radiations may be pictured in the same astrophysical particle-cascades scenario, cascades that are ultimately originated by cosmic rays. While to date no neutrino point sources have been identified at high confidence, a promising ground for discovery could be the search for transient and variable neutrino/electromagnetic sources, in which case the atmospheric neutrino and muon backgrounds can be reduced by taking advantage of time- and space-coincidence. Recent outcomes in this field will be presented.

ECAP Seminar: Siegfried Glenzer
2019-07-18 12:00 - 13:00 | ECAP, room 307, Erwin-Rommel-Str 1, Erlangen, 91058, Germany
Exploring extreme states of matter with an ultra-bright X-ray free-electron laser
In this talk, we will review recent progress in high-energy density physics using the world’s brightest X-ray source, the Linac Coherent Light Source, SLAC’s free electron X-ray laser. These experiments investigate laser-driven matter in extreme conditions where powerful X-ray scattering and imaging techniques have been applied to resolve ionic interactions at atomic (Ångstrom) scale lengths and to visualize the formation of dense plasma states [1, 2]. The major research areas include dynamic compression experiments of solid targets to determine structural properties and characterize phase transitions at conditions approaching the interior of planets. Another area studies extreme fields produced by high-intensity radiation where fundamental questions of strongly excited solids can be investigated [3]. Each of these areas takes advantage of the unique properties of the probing beam. They include small foci for achieving high intensity or high spatial resolution, high photon or electron flux for dynamic structure factor measurements in single shots, and high spectral bandwidth to resolve plasmon (Langmuir) waves or ion acoustic waves in dense plasmas. We will present new experimental data demonstrating several novel studies that test our fundamental understanding of matter in extreme conditions with data of sufficient accuracy to support or refute theoretical approximations. These advances have led to significant international competition and laid out the path for facility upgrades to explore ever more extreme states of matter.
[1] P. Sperling, E. J. Gamboa, H. K. Chung, E. Galtier, H. J. Lee, Y. Omarbakiyeva, H. Reinholz, G. Röpke, U. Zas- trau, J. Hastings, L. B. Fletcher, and S. H. Glenzer, Phys. Rev. Lett. 115, 115001 (2015).
[2] B. B. L. Witte, L. B. Fletcher, E. Galtier, E. Gamboa, H. J. Lee, U. Zastrau, R. Redmer, S. H. Glenzer, and P. Sperling, Phys. Rev. Lett. 118, 225001 (2017).
[3] M. Mo, Z. Chen, R. K. Li, M. Dunning, B. B. L. Witte, J. K. Baldwin, L. B. Fletcher, J. B. Kim, A. Ng, R. Redmer, A. H. Reid, P Shekhar, X. Z. Shen, M. Shen, K. Sokolowski-Tinten, Y. Y. Tsui, Y. Q. Wang, Q. Zheng, X. J. Wang, and S. H. Glenzer, Science 360, 1451-1454 (2018).

ECAP Seminar: Markus Demleitner
2019-07-25 12:00 - 13:00 | ECAP, room 307, Erwin-Rommel-Str 1, Erlangen, 91058, Germany
The VO And Why It Matters To You
In the most technical words, the Virtual Observatory (VO) is an effort to enable uniform and efficient access to astronomical data. With more glitz, it is like the Web and Google, only for data. In this talk I will try to convince you that what sounds tedious and boring in reality is exciting and useful to your research. Thus, after some motivation filling in the gaps in the above definitions, I will go on describing some of the key VO technologies and ways to use them – right now, from your desktop. I will close with an invitation to publish your data to the VO as well.
Slides available at http://docs.g-vo.org/er.pdf.

ECAP Seminar: Sebastian Böser
2019-11-07 12:00 - 13:00 | ECAP, room 307, Erwin-Rommel-Str 1, Erlangen, 91058, Germany
Project 8 – towards a radio frequency measurement of the neutrino mass
While neutrino flavour oscillations are a clear indication that neutrinos do have non-vanishing rest masses, their values have so far not been established experimentally. The state-of-the-art experiment KATRIN has recently set a limit for the effective electron neutrino mass at mβ < 1.1 eV/c² @ 90%CL. However, cosmological observations indicate that Σm𝜈 < 0.12eV/c², well below KATRINs final projected sensitivity at m_𝜈 < 0.2 meV/c². As the MAC-E filter technology employed in KATRIN can not be scaled easily, new technologies are required to measure the neutrino mass in the lab. Towards this goal, the Project 8 collaboration has established Cyclotron Radiation Emission Spectroscopy as a new experimental method. In a four phased approach, this technique is employed in precision endpoint spectroscopy on tritium. For the final stage of the experiment, an atomic tritium setup is envisioned that allows a sensitivity of m_𝜈 < 0.04 meV/c²

ECAP Seminar: Eckhard Sturm
2019-12-05 12:00 - 13:00 | ECAP, room 307, Erwin-Rommel-Str 1, Erlangen, 91058, Germany
The core of the matter – spatially resolving the nuclei of Active Galaxies with VLTI/GRAVITY
One of the most exciting opportunities oﬀered by the new VLT beam combiner GRAVITY is to directly resolve the immediate regions around the super-massive black holes (SMBHs) in the centres of active galaxies (AGN), i.e. the Broad Line Region (BLR) and the hot dust (“torus”) structures. We are exploiting this capability to study the inner workings of AGN in the K-band on unprecedented micro-arcsecond (sub-pc) spatial scales. This has led to the ﬁrst interferometric detection of a BLR (finding ordered rotation and measuring the black hole mass in the quasar 3C273), as well as to the first 0.2 parsec resolution K-band image of the dust sublimation region in the nucleus of the Seyfert 2 galaxy NGC1068 (finding a ring-like structure which is inconsistent with the expected signatures of a geometrically and optically thick torus). After a short introduction to the GRAVITY instrument and the principles of interferometry with GRAVITY, I will summarize these and other recent results, discuss their scientific (and historical) context, and give an outlook how such observations might contribute to the study of the structures and physical processes around SMBHs or to the study of how SMBHs build up their mass across cosmic time.

ECAP Seminar: Jörg Hörandel
2019-12-12 12:00 - 13:00 | ECAP, room 307, Erwin-Rommel-Str 1, Erlangen, 91058, Germany
Measuring the properties of cosmic rays with the radio technique
The radio emission from air showers is now routinely detected to measure the properties of cosmic rays. An overview is given on recent experimental activities, including observations with the LOFAR radio telescope and the Auger Engineering Radio Array at the Pierre Auger Observatory. Recent results will be discussed. We will give an outlook on our ongoing project to equip all surface detectors of the Auger observatory with radio antennas, forming a 3000 km2 radio array.

ECAP Seminar: Klaus Desch
2020-01-09 12:00 - 13:00 | ECAP, room 307, Erwin-Rommel-Str 1, Erlangen, 91058, Germany
Axions from Sun? Exploring the low-energy frontier with the IAXO experiment
Axions are ultralight hypothetical particles originally postulated to explain the observed smallness of the neutron´s electric dipole moment and its connection with the so-called strong CP-problem, i.e. the fact that QCD allows for CP violation while Nature apparently does not. Meanwhile it is clear that axions, and more generally axion-like particles (ALPs), may also serve as interesting candidates for the observed Dark Matter and may explain certain astrophysical anomalies. If axions exist, they are copiously produced in our Sun and may be detected through their small effective coupling to electro-magnetic fields. A promising approach is their conversion into soft X-ray photons in strong magnetic fields and subsequent detection.
In the talk, I will lay out the experimental scene of axion searches around the globe and then focus on a new proposal, the International Axion Observatory (IAXO) and its smaller predecessor, BabyIAXO to be constructed at DESY in Hamburg. I will discuss the layout of the experiment, ongoing R&D towards its realization and its sensitivity and discovery potential as well the time scale towards realization.

ECAP Seminar: Jim Hinton
2020-01-16 12:00 - 13:00 | ECAP, room 307, Erwin-Rommel-Str 1, Erlangen, 91058, Germany
HAWC
[abstract not available yet]

ECAP Seminar: Brian Reville
2020-01-23 12:00 - 13:00 | ECAP, room 307, Erwin-Rommel-Str 1, Erlangen, 91058, Germany
Cosmic-ray acceleration – limits and laboratories
I will review the current theoretical status of shock acceleration at supernova type shocks, with an emphasis on the plasma theory and implications for limitation on maximum energy. The current hypotheses will be put to the test in a surprising scaled down laboratory, the binary system Eta Carinae.

ECAP Seminar: Dieter Horns
2020-06-18 12:00 - 13:00 | Zoom
The Crab nebula and pulsar – particle acceleration at the limit
The Crab Nebula is the front-page object of multi-wavelength astrophysics and an excellent object to study non-thermal emission and particle acceleration. The Crab Pulsar powers the extreme accelerator regions that inject an ultra-relativistic plasma into the surrounding nebula. The exceptionally well-defined spectral energy distribution has been measured from the lowest accessible frequencies to the highest photon energies beyond 100 TeV. In this talk, I will provide an overview on the recent first-time measurements of spatial extension of the nebula from several GeV to TeV energies and the implications to the magnetic field strength and its spatial dependence in the Nebula. Besides the spatially resolved structure of the nebular emission, we have found episodes of dimming of the synchrotron emission, indicating that the highest energy electrons are confined to a compact region that we tentatively identify with the inner knot close to the pulsar’s position.

ECAP Seminar: Muhammad Kasim
2020-07-02 12:00 - 13:00 | Zoom
Up to two billion times acceleration of scientific simulations with deep neural architecture search
Computer simulations are invaluable tools for scientific discovery. However, accurate simulations are often slow to execute, which limits their applicability to extensive parameter exploration, large-scale data analysis, and uncertainty quantification. A promising route to accelerate simulations by building fast emulators with machine learning requires large training datasets, which can be prohibitively expensive to obtain with slow simulations. Here we present a method based on neural architecture search to build accurate emulators even with a limited number of training data. The method successfully accelerates simulations by up to 2 billion times in 10 scientific cases including astrophysics, climate science, biogeochemistry, high energy density physics, fusion energy, and seismology, using the same super-architecture, algorithm, and hyperparameters. Our approach also inherently provides emulator uncertainty estimation, adding further confidence in their use. We anticipate this work will accelerate research involving expensive simulations, allow more extensive parameters exploration, and enable new, previously unfeasible computational discovery.

ECAP Seminar: Anita Reimer
2020-07-30 12:00 - 13:00 | Zoom
Identifying sources of high-energy neutrinos of the AGN type: A theoretical approach
Active galactic nuclei (AGN) have long been predicted to emit neutrinos if they host sites of cosmic-ray acceleration to very high energies. Until a few years ago neutrino astrophysics was merely a prediction by (some) cosmic-ray theorists. It became reality with the first discovery of an astrophysical neutrino flux ~7 years ago. Although the origin of these neutrinos remains unclear up to now, jets of AGN remain among the prime candidate sources.
In this presentation I will discuss the multimessenger approach in the framework of hadronic AGN emission models from a theoretical perspective. Special emphasis will be given on external target photon fields.

ECAP mini-series Exploring Gravity: Ira Thorpe
2021-04-12 16:00 - 17:00 | Zoom
LISA – Bringing the Gravitational Wave Revolution to Space
Gravitational Wave (GW) observatories are humanity’s newest tool for studying the universe. After decades of development efforts, terrestrial interferometers such as LIGO and Virgo are now routinely detecting ripples in the fabric of spacetime caused by distant astrophysical cataclysms such as the collision of black holes. Early results from these instruments have already provided answers to long-standing questions in astrophysics and, more importantly, introduced new questions of their own. However, even as instruments on the Earth continue to improve, there will be vast portions of the GW spectrum that will not be accessible due to their limited size and noise in the terrestrial environment. Space-based interferometers a million times larger than their terrestrial cousins will probe the milliHertz GW spectrum, home to a rich variety of astrophysical signals.
In this talk, I will provide an overview of the Laser Interferometer Space Antenna (LISA), an international collaboration to develop the first space-based GW interferometer. I will describe the science applications, the mission concept, and key technologies behind what will be the largest scientific instrument ever constructed. I will also highlight the contributions of LISA Pathfinder, a European-led technology demonstration mission that validated several critical aspects of the LISA concept.

ECAP mini-series Exploring Gravity: Frank Eisenhauer
2021-04-15 16:00 - 17:00 | Zoom
Infrared Interferometry of the Galactic Center Black Hole
The Galactic Center harbors the nearest massive black hole. With a distance of only 8 kpc, it is the closest laboratory to study the astrophysical processes at work in these extreme objects, and to probe Einstein’s general theory of relativity in the regime of strong gravity. Our presentation gives an overview of the GRAVITY infrared interferometry observations leading to the detection of the gravitational redshift and the Schwarzschild precession in the orbit of a star orbiting the black hole in a 16 yr orbit, and the observations of orbital motion of hot gas close to the innermost stable orbit. We further present the perspective for future measurements of the spin and quadrupole of the black hole by combining infrared interferometry and spectroscopy form extremely large telescopes, which will then also test the cosmic censorship and no hair theorem of black holes.

ECAP Seminar: Ruben Lopez Coto
2021-04-22 13:00 - 14:00 | Zoom
TeV Halos and their connection to the local Leptonic Cosmic Ray flux
The origin and propagation of cosmic rays (CRs) is one of the most important questions in astroparticle physics nowadays. CRs generated by known sources also serve as background to those putatively generated by more exotic phenomena. Apart from the known electrons of primary origin and positrons of secondary one, pulsars and sources powered by them are one of the main candidates to contribute to the total amount of CR electrons and positrons. TeV halos are sources powered by a central pulsar whose electrons and positrons have escaped from the shock region dominated by the pulsar wind and are freely propagating into the interstellar medium. They have been postulated only a couple of years ago and up to date there are only two confirmed sources. In this talk, I will give a review of the current understanding of TeV halos, the observational status and their contribution to the CR sea in the Galaxy.

ECAP Seminar: Raimund Strauss
2021-04-29 13:00 - 14:00 | Zoom
Coherent neutrino scattering: from experimental challenges to new frontiers in neutrino physics
The detection of coherent-neutrino nucleus scattering (CEvNS) opens a new window to study the fundamental properties of neutrinos and to probe physics beyond the Standard Model of Particle Physics. Given the very low recoil energies (eV – keV) predicted for this weak neutral-current process, it has only recently been observed experimentally. Favorably, due to the coherency of the interaction, the cross-section of CEvNS is typically 2 – 4 orders of magnitude larger than classical neutrino interactions, which leads to a dramatic miniaturization of neutrino detectors: instead of using multi-ton detector apparatuses, neutrino detection with compact devices of kg or even g in total mass is in reach. We have established a new experimental approach for a first measurement of CEvNS at a nuclear reactor – the NUCLEUS experiment. With dedicated cryogenic detectors, for which we have demonstrated world-record energy thresholds of ~20 eV, we will probe neutrino properties and scenarios for new physics at unprecedentedly low energies. In this seminar, I will give an overview of this young and growing research field, and present the status and physics potential of NUCLEUS.

ECAP Seminar: Maryam Modjaz
2021-05-06 13:00 - 14:00 | Zoom
Stellar Forensics with the Most Powerful Explosions in the Universe
Core-collapse Supernovae (SNe), Long-duration Gamma-ray Bursts (GRBs) and exotic transients are exploding massive stars and constitute the most powerful explosions in the universe. Because they are visible over large cosmological distances, release elements heavier than Helium, and leave behind extreme remnants such as black holes, they are fascinating objects, as well as crucial tools for many areas of astrophysics.However, for many decades the fundamental question of which stellar systems give rise to which kinds of explosions has remained outstanding. I will discuss the exciting recent progress that we have made on this question in key areas by publishing and thoroughly analyzing the largest data sets in the world at the time, as well as by developing sophisticated radiative transfer methods to reconstruct the exploded star. I will conclude with an outlook on how the most promising venues of research – using the existing and upcoming innovative large time-domain surveys such as Zwicky Transient Facility II and Rubin’s LSST – will shed new light on the diverse deaths of stars.

ECAP mini-series Exploring Gravity: Michèle Heurs
2021-05-21 14:00 - 15:00 | Zoom
Gravitational waves in a new light
Ultra-precisely stabilised lasers are the interferometric light sources at the heart of gravitational wave detectors. To achieve ever-higher detection rates for meaningful gravitational wave astronomy, ever-greater detection sensitivity is required. In this talk, I will introduce the principle of interferometric gravitational wave detection, and highlight some of the advanced technologies employed in Advanced LIGO.
Current-generation gravitational wave detectors are already limited by quantum noise of the laser light over wide ranges of their detection band. One sophisticated technique that is already routinely being employed to increase the quantum-limited sensitivity of gravitational wave detectors is the use of non-classical (fixed-quadrature squeezed) light. I will conclude my talk by showing some recent results, as well as options for quantum noise reduction in laser interferometry and the broader field of quantum optics.

ECAP Seminar: Alexander Kappes
2021-06-10 13:00 - 14:00 | Zoom
Recent results from IceCube and the future of neutrino astronomy at the South Pole
The IceCube neutrino observatory at the geographic South Pole has now been operating at full capacity for ten years. Following the first observation of astrophysical neutrinos in the TeV — PeV energy range in 2013, cosmic neutrinos have been established as an important information carrier for exploring the high-energy universe in the context of multi-messenger observations. However, despite a first compelling evidence, the sources of high-energy neutrinos remain largely hidden, indicating a complex neutrino sky.
After an introduction to neutrino astronomy as well as the operation principle of neutrino telescopes and the challenges of building a neutrino detector at the South Pole, the talk will highlight recent results from IceCube. Finally, an outlook on future enhancements of IceCube is given, which aim at addressing the open questions.

ECAP Seminar: Rodrigo Guedes Lang
2021-06-17 13:00 - 14:00 | Zoom
Origin of UHECR: current status of a decades-long open question
Ultra-high-energy cosmic rays (UHECR) are the most energetic known particles of the Universe, being accelerated to energies up to 7 orders of magnitude higher than those achieved in human-made accelerators. Their origins, however, remain an intriguing puzzle even decades after their discovery. In this seminar, the current status of this puzzle will be discussed. The state-of-the-art experiments will be presented as well as a compilation of relevant data collected so far. The power and limitations of phenomenological studies to decipher this question will be discussed, focusing on models to estimate the role of local UHECR sources.

ECAP Seminar: Katharina-Sophie Isleif
2021-06-24 13:00 - 14:00 | Zoom
Light-Shining-Through-A-Wall: The ALPS II experiment at DESY
The ALPS II at DESY in Hamburg is a light-shining-through-a-wall (LSW) experiment searching for axion-like elementary particles in the sub eV mass range, which are motivated by astrophysics and cosmology. ALPS II aims at an axion-photon coupling sensitivity which is several orders of magnitude better than that of previous LSW experiments and will thus investigate a new parameter range. This is achieved by an increased magnetic field interaction length and by optical cavities on both sides of the wall, which further amplify the signal.
In this talk, the working principle of LSW experiments and the uniqueness and technological challenges of the ALPS II experiment will be explained. Interim results of previous investigations will be presented, as well as the current status. By converting axions to photons, we expect a rate of only 1 photon per day. The two sophisticated detector schemes, coherent heterodyne detection and a cryogenic single photon detector, are also presented and their implementation in the ALPS II experiment is discussed. ALPS II is aiming at a first data run in late 2021.

ECAP Seminar: Kay Graf
2021-10-21 13:00 - 14:00 | Zoom
The ECAP Laboratory
The ECAP Laboratory will provide the infrastructure for the experimental-based research of the scientific groups of the institute. The concept of this “Forschungsbau” as well as the timeline for the completion and start of operation will be presented.

ECAP Seminar: Christian Glaser
2021-11-04 13:00 - 14:00 | Zoom
Radio Detection of High Energy Neutrinos and Deep Learning
In this seminar talk, I will present the current status of in-ice radio detection of ultra-high-energy (UHE, E > 10^16 eV) neutrinos and how we use deep learning to improve the trigger system and event reconstruction. UHE neutrinos are connected to the most energetic phenomena in our universe and neutrino astronomy is a powerful tool to study the high-energy universe. Their small flux and cross-section require the instrumentation of huge volumes which can be achieved with a sparse array of radio detector stations installed in polar ice sheets. I will report on the results from the pilot arrays ARA and ARIANNA, the status of the Radio Neutrino Observatory in Greenland (RNO-G) that is currently being deployed and the plans for IceCube-Gen2.
In the second part, I will talk about the usage of deep learning techniques. I will present a pilot study that uses a small convolutional neural network for a real-time rejection of thermal noise which allows to lower the trigger thresholds and leads to an increase in neutrino sensitivity by up to a factor of two. Furthermore, I will present reconstruction algorithms for the neutrino direction, energy and flavor based on deep neural networks, that – for the first time – allowed to quantify the sensitivity to the neutrino flavor.

ECAP Seminar: Georg Lamer
2021-12-02 13:00 - 14:00 | Zoom
Two years of eROSITA all-sky surveys: The variable X-ray sky
The eROSITA telescope onboard the SRG satellite was launched on 13 July 2019. After an initial phase of calibration and performance verification observations eROSITA started its all-sky survey operation in December 2019. Covering the entire sky within 6 months, eROSITA is now close to completing its 4th all-sky survey in the 0.2-10 keV band. With the repeated detection of about 1 Million sources in each of the surveys, the eROSITA surveys are a particularly rich resource for the study of variable X-ray sources.
I will report on selected highlights of the mission such as an accurate distance measurement towards a Black Hole candidate using dust scattering, the observation of isolated neutron stars, or of galaxies caught in the moment of ignition or shut-down of their active nuclei.

ECAP Seminar: Alberto Dominguez
2021-12-17 11:00 - 12:00 | ECAP, room 307, Erwin-Rommel-Str 1, Erlangen, 91058, Germany
Galaxy evolution and cosmology using gamma rays observed with Fermi-LAT
The light emitted by all galaxies across the history of the Universe is encoded in the intensity of the extragalactic background light (EBL), the diffuse cosmic radiation field at ultraviolet, optical, and infrared wavelengths. The EBL is a source of opacity for very high energy gamma rays via pair production, leaving a characteristic attenuation imprint in the spectra of distant gamma-ray sources. In this seminar, I will report on new measurements of the EBL using gamma-ray data from both the Large Area Telescope on board the Fermi Gamma-ray Space Telescope and ground-based Imaging Atmospheric Cherenkov Telescopes. These unprecedented measurements have allowed us to derive the cosmic star-formation history, the number density of faint galaxies during the re-ionization epoch, and also the expansion rate of the Universe and its matter content. These results demonstrate that gamma-ray astrophysics has matured to the point of providing competitive measurements of cosmic properties previously restricted to techniques used by more traditional astronomy.
