HAP Workshop | Monitoring the non-thermal Universe

Dec 6, 2016, 6:30 PM → Dec 10, 2016, 6:00 PM Europe/Berlin

Cochem (Mosel), Germany

Alan Marscher (Boston University), Daniela Dorner (Universität Würzburg), Markus Böttcher (North-West Univ. Potchefstroom), Stefan Wagner (LSW Heidelberg), Talvikki Hovatta (Aalto University), Thomas Bretz (RWTH Aachen University)

Towards a global multi-wavelength network

Taken from http://www.hotel-brixiade.de/cms/upload/Hotel/hotel_a/brix_trix_hotel_015_a.jpg

From...
   ...theory to TeV
   ...radio to relativity
   ...polarization to periodicity

Synergy of energy and time series without gaps

Maximizing physics insights from multi-frequency monitoring

Conference Pictures HAP Workshop - Cochem 2016 - Pictures (HiRes).pdf HAP Workshop - Cochem 2016 - Pictures (LoRes).pdf

Conference Poster Poster (HiRes) - Monitoring the non-thermal Universe.pdf Poster (LoRes) - Monitoring the non-thermal Universe.pdf

Evaluation Results HAP Workshop - Cochem 2016 - Evaluation Results.pdf

Tuesday, December 6

Registration

Guided city tour

Wednesday, December 7

Registration

Welcome

1 Welcome

Speaker: Prof. Thomas Bretz (RWTH Aachen University)

Slides Welcome.pdf

Multi-Messenger Astronomy

2 AMON: real-time operations

The Astrophysical Multimessenger Observatory Network (AMON) will link the world’s leading high-energy neutrino, cosmic-ray, gamma-ray and gravitational wave observatories by performing real-time coincidence searches for multimessenger sources from observatories’ subthreshold data streams. The resulting coincidences will be distributed to interested parties in the form of electronic alerts for real-time followup observation. We will present the science case, design elements, current and projected partner observatories, status of the AMON project, and current AMON-enabled analyses. We have deployed new high-uptime servers in February 2016 and started issuing real-time alerts via Gamma-ray Coordinates Network (GCN) since late spring 2016.

Speaker: Gordana Tešić (Penn State University)

Slides AMON: real-time operations

3 Multi-messenger studies with the Pierre Auger Observatory

The Pierre Auger Observatory is the world’s largest cosmic-ray detector, sensitive to cosmic rays with energy exceeding $\sim 10^{17}$ eV. In addition to charged cosmic rays that form the bulk of the cosmic-ray flux at ultra-high energies, Auger is sensitive to ultra-high energy neutral messengers (photons, neutrinos, and neutrons). The later are particularly exciting as they are expected to arrive in spatial, and temporal coincidence with electromagnetic counterparts from the yet unknown sources of ultra-high energy cosmic rays, and can be used for triggering, or follow-up in multi-messenger transient searches. I will review the activities of Auger as partner in multi-messenger searches, focusing on searches for ultra-high energy neutrinos from gravitational wave events, and the contribution of Auger to realtime multi-messenger searches within the Astrophysical Multi-messenger Observatory Network (AMON).

Speaker: Dr Foteini Oikonomou (Penn State)

Slides hap_monitoring_oikonomou_7_12_16.pdf

4 Searching for sources of high-energy neutrinos with Swift

The IceCube high-energy neutrino observatory has reported a 6.5$\sigma$ discovery of the first high-energy astrophysical neutrino candidates. However, the nature of the sources responsible for these neutrinos -- potentially also the sources of the highest-energy cosmic rays -- is still unknown and no high-confidence counterparts to any of the neutrino events have been yet identified. If the sources producing these highest-energy cosmic neutrinos are transient, they may be identifiable in rapid-response observations at Swift. We will present our proposed program that carries out prompt searches for X-ray and UV/optical counterparts to IceCube neutrinos with Swift.

Speaker: Dr Azadeh Keivani (The Pennsylvania State University)

Slides HAP-Keivani.pdf

10:30 AM Coffee Break

Multi-Wavelength Astronomy

5 CTA blazar monitoring program and supporting optical monitoring program

Long term monitoring of blazars is part of the Key Science Programs of the CTA Consortium. In this talk I will describe the foreseen observing program and the supporting optical monitoring observations.

Speaker: Elina Lindfors (Tuorla Observatory, University of Turku)

Slides 01_-_Lindfors_HAP.pdf

6 Monitoring the X-ray Sky with Swift Observations of Active Galactic Nuclei and Other Variable Sources

Due to its ability to rapidly slew, with relatively minimal loss of observing time, Swift is able to look at many targets per day. This efficient pointing, combined with rapid response and the observatory's suite of sensitive telescopes covering multiple wavebands, make Swift an ideal monitoring observatory for the transient and variable sky. Swift regularly monitors a variety of active galactic nuclei (AGN) as part of long-term monitoring campaigns and as part of targeted multiwavelength campaigns with instruments ranging from radio to TeV gamma-rays. Swift is also observing gamma-ray unassociated sources from the Fermi catalog in an effort to identify X-ray counterparts, which are most likely to be AGN. We will report on the wealth of X-ray data that is available from these programs, while also highlighting some other results on variable X-ray sources.

Speaker: Abe Falcone (Penn State University)

Slides 02_-_Falcone_Swift_Xray_Monitoring_Dec2016_noExtra.ppt

7 Studies on the VHE γ-ray/X-ray correlation in high-synchrotron peak BL Lacs

Many multi-wavelength campaigns have been carried out to study high-synchrotron peak BL Lacs (HBL). In particular the activity in the gamma-rays and X-rays seems to be correlated in many observations but, not conclusive results have been achieved yet. In this work we present a robust and comprehensive study of the (VHE) γ-ray/X- ray correlation of Mrk 421 with data taken with different VHE experiments on different time scales and different levels of activity of the source. We show that, independently of the time scale, there exists a robust correlation, consistent between instruments and that can be described as a linear function. However, a breakdown of the correlation is clearly evident at high states of activity with fluxes comparable with three times the one of the Crab at energies above 400 GeV independently of the time scale, observational period or instrument. The breakdown is observed as an arbitrary decrement in the X-ray flux while the source remains in a high state of activity in VHE γ-rays. Even for single flares, the X-ray and VHE γ-ray emissions lie on the correlation until the VHE γ-ray flux reaches values higher than the mentioned above. We present a theoretical interpretation of these results within the leptonic SSC scenario and extend our studies to other HBL.

Speaker: Dr Maria Magdalena Gonzalez (Universidad Nacional Autonoma de Mexico)

Slides 03_-_monitoring-cochem-dic16-magda.pdf

8 Multi-waveband study of TeV blazar 1ES1959+650 during a high state in 2016

The nearby TeV Blazar 1ES 1959+650 (z=0. 047) is a high-peaked BL Lacertae object and one of the prime sources which has been monitored at VHE gamma-ray energies by FACT. This source is well known for its orphan flare in June 2002, which makes this an unique source. It was found in a low state of flux since its outburst in 2002 and did not show much of activity during the first three years of FACT monitoring. However, the source had started showing enhanced activity in VHE gamma-rays during summer 2015 and reached a high flux state during summer of 2016. A few very bright flares were observed by FACT in June and July 2016. In the presentation, we will discuss the multiwaveband behavior of 1ES 1959+650 and evolution of the high state. A physical model,with which several flaring episodes can be explained, will also be discussed.

Speaker: Dr Amit Shukla (Institut für Theoretische Physik und Astrophysik, Universität Würzburg)

Slides 04_-_1959_final_hap.pdf

12:55 PM Lunch Break

Just walk down the stairs to the town. You will find enough restaurants close-by.

Gamma-Ray Astronomy: Part I

9 Monitoring the High-Energy Sky: the Fermi Experience

For more than eight years, scientists using the two instruments on the Fermi Gamma-ray Space Telescope have gained significant experience with monitoring the high-energy Universe. The Gamma-ray Burst Monitor (GBM) and Large Area Telescope (LAT) have huge fields of view, and Fermi operates in a scanning mode, allowing the entire gamma-ray sky to be viewed about every three hours. Most of the Fermi results have involved multi-wavelength or multi-messenger cooperation. The keys to successful near-simultaneous multi-wavelength observations are rapid data processing and fast sharing of information. The Fermi mission is continuing, and new analysis approaches are designed to increase the availability of data products useful for cooperative work. Fermi scientists look forward to continuing opportunities to work with multi-wavelength and multi-messenger observers.

Speaker: Dr David Thompson (NASA Goddard Space Flight Center)

Slides HAP_Fermi_Experience.pptx

10 Monitoring the TeV Gamma-Ray Sky with HAWC

The High Altitude Water Cherenkov (HAWC) observatory is a wide field-of-view gamma-ray detector that performs monitoring of two thirds of the sky every day at energies between 0.1 and 100 TeV. Operating in its full configuration since March 2015, with a duty cycle of approximately 90%, HAWC has already accumulated an unprecedented data set of unbiased and evenly sampled daily TeV light curves. We will discuss how we use these results to characterize variability in various sources and focus on the study of flux states for the Blazars Markarian 421 and Markarian 501. With HAWC, we also monitor the gamma-ray flux of selected objects in near real time with flare search algorithms running on the computing infrastructure at the HAWC site. We have started to send out alerts for HAWC flare detections and followed up on external alerts, for example neutrino triggers from IceCube. We will present the highlights of these ongoing multi-wavelength and multi-messenger monitoring efforts.

Speaker: Dr Robert Lauer (University of New Mexico)

Slides rlauer_HAWC_HAP2016.pdf

11 VERITAS Observations of Active Galactic Nuclei

The Very Energetic Radiation Imaging Telescope Array System (VERITAS), located in southern Arizona USA, is an array of four 12-m diameter imaging atmospheric-Cherenkov telescopes dedicated to studying the very-high-energy (VHE, E > 100 GeV) gamma-ray sky. The investigation of Active Galactic Nuclei (AGN) is a key element of the VERITAS long-term science plan, with 34 detected by VERITAS to date. VERITAS regularly monitors known AGN through a program of regular observations, many in coincidence with observations made with the Swift-XRT X-ray telescope and optical telescopes, with the aim to build up large multi-year datasets on these objects with good multi-wavelength coverage. In addition, VERITAS has a target-of-opportunity (ToO) program to conduct intense observations during periods of enhanced activity, whether triggered by the VERITAS monitoring observations themselves or by multi-wavelength alerts. Details of the VERITAS observation program and recent result highlights will be presented.

Speaker: Mr Stephan O'Brien (UCD Dublin)

Slides StephanOBrien_HAP2016.pdf

12 Monitoring of VHE blazars with H.E.S.S.

A key project of the High Energy Stereoscopic System (H.E.S.S.) is the regular monitoring of different types of blazars at very high energies (E>100 GeV). Since the inauguration of H.E.S.S. in 2004 the high-frequency peaked BL Lac object PKS 2155-304 and the radio galaxy M 87 have been observed frequently. The flat spectrum radio quasar PKS 1510-089 has been added to the list of monitored sources after its detection during a flare in 2009. In this talk, recent results of these monitoring efforts will be presented, including evidence that the quiescent and flaring states differ in more than merely flux levels in PKS 2155-304. This points to different processes producing these states. Monitoring with H.E.S.S. phase II of PKS 1510-089 in 2015 revealed for the first time VHE night-by-night variability in this source, implying that the flaring region must be located on the edge or beyond the broad line region.

Speaker: Dr Michael Zacharias (North-West University)

Slides Zacharias_MonWS.pdf

13 Gamma-ray Novae: Rare or Nearby?

Classical Novae were revealed as a surprise source of $\gamma$-rays in *Fermi* LAT observations. During the first 8 years since the LAT was launched, 6 novae in total have been detected to $ > 5\sigma$ in $\gamma$-rays, in contrast to the $69$ discovered optically in the same period. We attempt to resolve this discrepancy by assuming all novae are $\gamma$-ray emitters, and assigning peak one-day fluxes based on a flat distribution of the known emitters to a simulated population. To determine optical parameters, the spatial distribution and magnitudes of bulge and disc novae in M31 are scaled to the Milky Way, which we approximate as a disc with a $20~\rm{kpc}$ radius and elliptical bulge with semi major axis $3~\rm{kpc}$ and axis ratios 2:1 in the xy plane. We approximate Galactic reddening using a double exponential disc with vertical and radial scale heights of $r_{d} = 5~\rm{kpc}$ and $z_{d} = 0.2~\rm{kpc}$, and demonstrate that even such a rudimentary model can easily reproduce the observed fraction of $\gamma$-ray novae, implying that these apparently rare sources are in fact nearby and not intrinsically rare. We conclude that classical novae with $m_{R} \leq 12$ and within $\approx 8~\rm{kpc}$ are likely to be discovered in $\gamma$-rays using the *Fermi* LAT.

Speaker: Mr Paul Morris (University of Oxford)

Slides GamRayNovaeRarity_PJM__HAPconf.pdf

4:15 PM Coffee Break

Radio Astronomy: Part II

14 The University of Michigan Centimeter-band Blazar Monitoring Program: multi-frequency, time-resolved, flux and polarization observations as probes of the physical conditions in blazar jets

The University of Michigan 26-m paraboloid (UMRAO) was dedicated to observations of AGN, primarily of the blazar class, for nearly 40 years providing continuous light curves for hundreds of sources. In 1977 the telescope was placed under automatic computer control permitting nearly round-the-clock operation and systematically-obtained measurements of both linear polarization and total flux density at 4.8, 8, and 14.5 GHz. The sampling probes variations on time scales of weeks to months, with the individual observing cadence selected on the basis of activity; both flux-limited samples and targeted, flaring blazars were observed. During 2002-2012 multi-frequency circular polarization observations were also obtained for a sample of bright (S>5 Jy), flaring sources. Analysis of time segments of the total flux density data have identified characteristic variability time scales of a few years, and quasi-periodicity. Cross-correlations of the UMRAO data with X-ray and gamma-ray light curves have been used for localization of the high energy emission and are most successful in identifying causally-related flares when multi-year data trains containing strong flares are included. The co-spatiality of the optical and radio-band emission has been investigated during contemporaneous GeV-flaring by looking for correlated variations in the optical and 14.5 GHz electric vector position angle light curves indicative of similar local magnetic field orientation; a similar approach has potential for the high energy bands when well-determined, high-cadence polarimetry becomes available. The UMRAO data support a scenario in which the quiescent jet in the blazar zone contains a turbulent magnetic field which is compressed and ordered by propagating shocks during strong flares. Radiative transfer modeling incorporating this scenario is being used to elucidate the intrinsic flow conditions during gamma-ray flaring.

Speaker: Dr Margo Aller (University of Michigan)

Slides M.ALLER_FINAL_Cochem.pptx

15 Radio Monitoring Projects at Metsähovi Radio Observatory

I will present the ongoing blazar monitoring programme and other AGN observing projects of Aalto University Metsähovi Radio Observatory (MRO) in Finland. MRO has been operational for more than 40 years now, and even though we struggle with decreasing funding for basic research just like many other research units nowadays do, our streamlined operations and flexibility allow for a multitude of different kinds of observing projects. The backbone of our observing programme is the dense, long term monitoring of approximately one hundred blazars at 37 GHz (and somewhat less at 22 GHz). But in addition to that, we carry out also many other AGN observing projects, trying to optimally use the observing time between the core monitoring sample, some "high-risk" projects involving faint sources or large samples, as well as Target-of-Opportunity projects that call for a quick response. In recent years, the focus of our research has been in multifrequency studies related to the Planck satellite's extragalactic foreground source programme, and radio to gamma-ray connection in blazars. Currently we are also observing samples of younger radio sources, such as Gigahertz Peaked Spectrum sources and Narrow-Line Seyfert 1 galaxies. I will describe our observing programmes and the science goals which ultimately aim for a better understading of blazar unification and evolution.

Speaker: Dr Merja Tornikoski (Aalto University Metsahovi Radio Observatory)

Slides HAP-2016-tornikoski.pptx

16 OVRO blazar monitoring programs

Since 2008, the 40-m telescope at Owens Valley Radio Observatory in California has been used to monitor a large number of blazars at 15 GHz. The program started with 1158 candidate gamma-ray sources and has been extended now to monitor over 1800 blazars, including all Fermi 1FGL and 2FGL sources and TeV emitters, with twice per week cadence. The data of this program have been used in more than 80 publications showing their value for the blazar community. In May 2014, a new receiver covering 13-18 GHz and capable of spectrometric linear polarization measurements was installed. I will present some recent highlights from the program, and describe a new planned monitoring program where two 10.4-m telescopes previously used in the CARMA array will be used to monitor blazars at 3mm and 1mm wavelengths in full polarization mode.

Speaker: Dr Talvikki Hovatta (University of Turku)

Thursday, December 8

Variability Methods: Part I

17 Time Series Analysis For the Multi-Wavelength Future

Virtually all astronomical sources are variable on some time scale, making studies of variability across different wavelengths a major tool in pinning down the underlying physical processes, for example accretion onto compact objects and cataclysmic explosions like gamma-ray bursts. The new telescopes currently starting operations or coming online in the coming years, including the Square Kilometre Array (SKA) and the Cherenkov Telescope Array (CTA), will open up the sky to transient searches, monitoring campaigns and time series studies with an unprecedented coverage and resolution. But at the same time, they collect extraordinarily large data sets of previously unknown complexity, motivating the necessity for new tools and statistical methods. In this talk, I will review the state-of-the-art of astronomical time series analysis, and show possible future directions of research that will help us address the flood of multiwavelength time series data to come.

Speaker: Dr Daniela Huppenkothen (New York University)

Slides hap_dhuppenkothen.pdf

18 Bimodal radio variability in OVRO-40m-monitored blazars

Blazars are known to show periods of quiescence followed by extreme outbursts seen throughout the electromagnetic spectrum. We present a novel maximum likelihood approach to capturing this bimodal behavior by examining blazar radio variability in the flux-density domain. We separate quiescent and flaring components of a source's light curve by modeling its flux-density distribution as a series of "off" and "on" states. Our modeling allows us to extract information regarding the flaring ratio (S_{on}/S_{off}), duty cycle, and the modulation index in the "off"-state, in the "on"-state, as well as throughout the monitoring period of each blazar. We apply our method to a flux-density-limited subsample from the Owens Valley Radio observatory's 15 GHz blazar monitoring program, and explore differences in the variability characteristics between the different classes of blazars as well as gamma-ray detected and non-detected sources.

Speaker: Mr Ioannis Liodakis (University of Crete, FORTH)

Slides Liodakis_HAP.pdf

19 Detecting transient and periodic phenomena in astrophysical sources

Time domain astronomy and astrophysics are concerned with studying the temporal characteristics of the light from distant astrophysical sources that our instruments detect. Consequently, time domain studies are aimed at the detection and characterisation of variability: periodic variability, aperiodic or stochastic variability, and transient events. In this presentation, I propose to introduce and discuss the fundamental elements of statistical data analysis involved in searching for transient phenomena and weak periods in noisy or sparse data. The concepts and techniques I will present apply equally to binned and unbinned time series data. However, given that the primary focus in this workshop is on high energies, special emphasis will be placed on the treatment of event data.

Speaker: Dr Guillaume Belanger (European Space Agency)

Slides periodsAndTransients.key

20 Multi-frequency blazar variability from decades to minutes

The typical shape of blazar lightcurves' power spectra is a power-law, $P(f) = A f^{-\beta}$, where A is the normalization and $\beta$ is the slope, indicating that the variability is generated by the underlying $\it stochastic$ processes which is of colored noise type (i.e., $\beta \simeq 1-3$). Here we present the results of power spectral analysis of 5 blazars utilizing the $\it Fermi$-LAT survey at high energy $\gamma-$rays, $\it Swift$-XRT and $\it RXTE$-PCA data at X-rays, several ground based observatories and Kepler data at optical and single-dish radio telescopes operating at GHz frequencies (UMRAO and OVRO programmes). The novelty of our approach is that at optical regime, by combining long-term (historical optical light curves) and densely sampled intra-night lightcurves, the PSD characterisitics are investigated for temporal frequencies ranging over 7 orders of magnitude. Our analysis reveals that : (1) nature of processes generating flux variability at optical/radio frequencies is different from those at GeV freqeuncies ($\beta \sim $ 2 and 1, respectively); this could imply, that $\gamma-$ray variability, unlike the Synchrotron (radio-to-optical) one, is generated by superposition of two stochastic processes with different relaxation timescales, (2) the main driver behind the optical variability is same on years, months, days, and hours timescales ($\beta \sim 2$), which argues against the scenario where different drivers behind the long-term flux changes and intra-night flux changes are considered, such as internal shocks due to the jet bulk velocity fluctuation (long-term flux changes) versus small-scale magnetic reconnection events taking place at the jet base (intra-night flux changes). Implications of these results are discussed in the context of blazar emission models.

Speaker: Dr Arti Goyal (Astronomical observatory of the Jagiellonian University)

Slides AG_psd.pdf

10:30 AM Coffee Break

Variability Methods: Part II

21 Multiwaveband Variability of AGN

Most of our understanding of the processes that power AGN has been gained not from single-epoch observations, but from monitoring over long periods and, usually, in more than waveband. In this talk I will describe the results of combined X-ray/UV/optical monitoring of Seyfert galaxies which have shown that UV/optical variability on short timescales is largely driven by reprocessing of high energy. However whether that emission is X-ray emission from the central corona or far-UV emission from the inner edge of the disc is unclear. I will also discuss combined X-ray and radio monitoring of 'radio quiet AGN', ie Seyferts. There is a very weak correlation, indicating that normal Seyferts are probably not the analogues of 'soft state' X-ray binaries but contain low luminosity synchrotron jets. I will also show the results of the more radio-loud LINER galaxies, where rapid, large amplitude, radio variability is seen which is also correlated with the X-ray emission. The perturbations which drive the X-ray variations may also propagate down the jet to drive the radio variability. If time permits I will indicate some similarities with the much more powerful blazars. I will try to suggest a few areas in which future multiband monitoring may be productive.

Speaker: Dr Ian McHardy

Slides mchardy_hap16_seyferts_liners.pdf

22 The location of the gamma-ray emission site in blazars from radio and gamma-ray monitoring

I will discuss our efforts to determine the location of the gamma-ray emission site in blazars with the ongoing OVRO 40 meter telescope blazar monitoring program. This program started in 2008 and is currently monitoring about 1800 blazars at 15 GHz with twice a week cadence for a sample including most of the bright blazars north of declination -20 degrees. A summary of previous findings and preliminary results on our analysis of 8 years of Fermi-LAT and OVRO light curves for the brightest sources will be presented. The emphasis will be on the characterization of the variability in the radio band, and its correlation to gamma-ray emission as observed with Fermi-LAT. The study of these correlations can provide constrains on the location of the gamma-ray emission region, but require careful consideration of the statistics that we will also discuss.

Speaker: Walter Max-Moerbeck (Max-Planck-Institut für Radioastronomie)

Slides wmax_talk_no_anim.pdf

23 High Energy Astrophysics with Novel Observables

Despite intensive research over a few decades facilitated by highly sensitive multiwavelength (MWL) telescopes, fundamental characteristics of active galactic nuclei (AGNs) are still open. With respect to physics of individual AGNs, the location and mechanisms of particle acceleration, their connection to flaring, relative importance of hadronic and leptonic processes in specific sources and in general, and finally the fundamental features of variability are up for debate. As a population too, the frequency of flaring in AGNs at different wavelengths and characteristic patterns that are source independent is a subject of ongoing research. In this situation, quantifying characteristics such as variability in terms of novel statistical observables as the power spectral density and the flux probability distribution provides complementary constraints to the traditional energy spectrum, morphology and MWL lightcurve. In this presentation, I demonstrate the potential of using such statistical observables based on time-series methods simultaneously at different wavelengths as a means of both probing fundamental processes in individual AGNs as well as transient studies on their population. Limitations due to observational cadence are explored. Extending from individual MWL observations to population studies at specific wavelengths, prospects of transient and variability pattern detection are evaluated. Finally, mechanisms of particle acceleration and radiative processes leading to observed PSD and PDF are discussed.

Speaker: Dr Nachiketa Chakraborty (Max Planck Institute for Nuclear Physics)

Slides HAPWorkshop_NC_NO.pdf

24 DSEA - A Data Mining Approach to Unfolding

Obtaining energy spectra of incident particles such as neutrinos or gamma-rays is a common challenge in neutrino- and Air-Cherenkov astronomy, as the particle's energy cannot be observed directly but has to be inferred from other observables e.g. energy losses of secondary particles utilized for detection. The task is further made difficult by the fact that the production of secondaries, e.g. in a neutrino-nucleon interaction is governed by stochastical processes. Mathematically this corresponds to an inverse problem, which is described by the Fredholm integral equation of the first kind. Several algorithms for solving inverse problems exist, which are, however, somewhat limited, for example in the number of input variables or in the sense that only the unfolded distribution is returned and information on individual events is lost. We present the Dortmund Spectrum Estimation Algorithm (DSEA), which aims at overcoming the afore mentioned obstacles by treating the inverse problem as a multinominal classification task. Within DSEA the final spectrum is obtained by summing the class-confidences of the individual events. DSEA, therefore, offers the advantage that any learning algorithm can be used as long as it returns the confidences of the individual classes. This results in a modular and highly flexible algorithm that can easily be tailored to a problem at hand. To avoid a potential bias on the class distribution used for the training of the learner, DSEA can be used iteratively using a uniform class-distribution as input.

Speaker: Dr Tim Ruhe (TU Dortmund)

Slides DSEA_HAP_Cochem_v3.pdf

12:45 PM Lunch Break

Modelling

25 Turbulence Acceleration Model for the Broad Band Blazar Spectra

The curved spectra seen in blazar emission can be explained by the curved electron spectra predicted by the stochastic acceleration process via turbulence. In this slow acceleration process, the time-dependent treatment is essential. In this talk I present our results of the time-dependent simulations of the acceleration and emission in blazars. The model naturally explains the hard and curved spectra. Our results prefer the hard sphere scattering to reconcile the spectral feature. Also taking into account the obtained low magnetic field, the particle scattering is likely due to the compressible waves.

Speaker: Dr Katsuaki Asano (Institute for Cosmic Ray Research, The University of Tokyo)

Slides コッヘム16.pdf コッヘム16.pptx

26 Time-dependent radiation signatures of relativistic reconnection in blazar jets

Magnetic reconnection is one of the most promising mechanisms of dissipation and particle acceleration in relativistic jets of blazars. Magnetic reconnection is a complex physical phenomenon that by nature is very difficult for analytical and experimental studies. Rapid progress in understanding relativistic reconnection has been made over the past several years thanks to numerical kinetic plasma simulations. Of particular interest to the multiwavelength community of blazar observers is the capability of the kinetic particle-in-cell codes to incorporate the effects of radiation reaction on the energy distribution of particles, as well as to calculate time-dependent radiation signatures (synchrotron and inverse Compton) of particle acceleration in relativistic reconnection. I will discuss the latest simulation results and current limitations on making a direct connection between numerical predictions and observational data.

Speaker: Krzysztof Nalewajko (Nicolaus Copernicus Astronomical Center)

Slides nalewajko_cochem16.pdf

27 The Blazar Sequence and Accretion Disk Winds.

Adopting the hypothesis that the nonthermal emission of blazars is primarily due to the acceleration of electrons, we construct a simple leptonic model in order to explain the Blazar Sequence. The acceleration process is assumed to be of the first order Fermi type and the injected electrons and photons in the emitting region of the blazar are described by spatially averaged kinetic equations. According to the leptonic scenario, the spectral energy distributions of blazars have two basic components: a low frequency component, peaking in the optical through X-rays, from synchrotron emission; and a high frequency one, peaking in the γ rays, probably originating from Compton scattering of some seed photon source, either internal (synchrotron self-Compton) and/or external to the jet (external Compton). The origin of external photons is generally undetermined, attributed to BLR cloud emission. Motivated by recent works suggesting the presence of accretion disk winds with density profiles $n \propto 1/r$ and normalization proportional to $\dot m^2$( the normalized to Eddington mass flux in the wind), that allow the isotropization of the accretion disk photons over radii as large as $\sim 1$ pc, we compute blazar SEDs for different values of $\dot m$. We find that the Blazar Sequence can then be represented adequately in terms of a single parameter, namely $\dot m$.

Speaker: Ms Stella Boula (University of Athens)

Slides presentation_boula_cochem.pdf

28 Polarization Variability in Leptonic and Hadronic Blazar Models

We present results of time-dependent flux and polarization calculations in the framework of an internal-shock model for blazars. Both a leptonic and hadronic model are considered. It is shown that polarization-angle swings, accompanied by multi-wavelength flares, are a natural consequence of an internal shock in a jet pervaded by a helical magnetic field, without the need for bent or otherwise asymmetric jet features. However, if the high-energy emission is dominated by hadronic processes, such PA wings do not occur. Coupled MHD plus time- and polarization-dependent radiation-transfer simulations of such internal shocks will be shown for both leptonic and hadronic scenarios.

Speaker: Prof. Markus Boettcher (North-West University)

Slides HAP2016_Boettcher.pdf HAP2016_Boettcher.pptx

3:55 PM Coffee Break

Optical Astronomy

29 The RoboPol Optical Polarization Monitoring Program

Optical Synchrotron emission from blazars is significantly polarized and the polarization probes the magnetic field structure in the jet. Rotations of the polarization angle in blazars reveal important information about the evolution of disturbances responsible for blazar flares. The RoboPol program for the polarimetric monitoring of statistically complete samples of blazars was developed in 2013 to systematically study this class of events. RoboPol is a collaboration between the University of Crete, Caltech, the Max-Planck Institute for Radio Astronomy, the Inter-University Centre for Astronomy and Astrophysics in India, and the Nicolaus Copernicus University in Poland. Using a novel polarimeter operating at the 1.3m telescope of the Skinakas Observatory in Crete, it has succeeded in its 4 years of operation in taking optopolarimetric rotations of blazars from novelty status to a well-studied phenomenon that can be used to answer long-standing questions in our theoretical understanding of jets. I will review the RoboPol program and its most important results in the classification of the optopolarimetric properties of blazars, the statistical properties of polarization rotations, and their relation to gamma-ray activity in blazar jets.

Speaker: Prof. Vasiliki Pavlidou (University of Crete)

Slides 01_-_Pavlidou_RoboPol_HAPWorkshop_2016.pptx

30 Blazar Optical Sky Survey - BOSS project (2013-2016) and the long-term optical variability monitoring

Blazar Optical Sky Survey (BOSS) Project is a dedicated observational survey with the aim of monitoring known blazars in optical wavelengths. The project was initiated in March 2013 at the University of Athens Observatory (UOAO), performing ground-based optical photometric observations in parallel with orbital (SWIFT/XRT, FERMI/LAT) X-ray observatories. BOSS project has immediately met international attention, attracting the interest of several collaborators worldwide. It is currently running as an international collaboration of the National University of Athens, utilizing the robotic and remotely controlled telescope at the UOAO. Several targets of interest are monitored in the frame of BOSS Project, such as highly variable blazars and AGNs. The targets are continuously observed on a daily basis, with the aim to achieve dense temporal coverage in optical wavelengths. In parallel, simultaneous observations in high and low energy bands are cross-correlated with BOSS database. In this presentation, the main achievements after the first 4 years of operation of the BOSS Project are given, while the advantage of small, robotic and remotely controlled telescopes is highlighted.

Speaker: Dr Kosmas Gazeas (University of Athens)

Slides 161208_Kosmas_Gazeas_Cochem_Germany.pdf

31 Counterpart candidates to unassociated gamma-ray sources: the case of 3FGL J0133.3+5930

The identification of high energy sources in the Galactic Plane is often a difficult but rewarding task as it can lead to the discovery of exotic stellar accelerators, such as gamma-ray binaries and microquasars. Here, we report a multi-wavelength analysis of the unassociated Fermi source 3FGL J0133.3+5930 at low galactic latitude. Two candidate counterparts have been identified inside its 95% confidence ellipse. One of them is the AGN source 2MASS 01325529+5932158 at a redshift $z=0.1143$. This object could be a low-luminosity blazar although this point remains to be confirmed. The other one is the bright Be star LS I+59 79 ($V=$10.7), also known as TYC 3683-985-1, whose eclipsing binary nature is reported in this work. With a photometric period of 1.94 d, its multi-colour light curves are apparently consistent with a semi-detached binary system with two early-type components. Possible gamma-ray emission mechanisms are tentatively proposed in a stellar context that, at present, does not fully match a typical gamma-ray binary scenario. However, this situation could change when further spectroscopic data are available that better constrain the nature of the system components.

Speaker: Prof. Josep Martí (University of Jaén)

Slides Marti_Cochem_2016.pdf

7:30 PM Conference Dinner

The conference dinner will take place in the castle of Cochem. Included is a guided tour through the castle and some dinner. Participation is highly recommended.

Friday, December 9

Gamma-Ray Astronomy: Part II

32 Blazar Monitoring with FACT

The First G-APD Cherenkov Telescope (FACT) is pioneering the usage of solid state photo sensors (G-APD aka SiPM) for measuring the dim flashes of Cherenkov light initiated by the interaction of a high energetic particles or photons with the atmosphere. One advantage of these sensors is that they donot degrade even when exposed to bright light. Therefore, FACT can operate with standard setup also under strong moonlight conditions. In the past five years, the operation of FACT has been very smooth and got automatized to a large extent, resulting in a data taking efficiency reaching 95% if weather permits. Temperature dependencies of the sensors are well under control without the need of any temperature stabilization system, resulting in very stable data taking conditions. This makes FACT an ideal device for unbiased long-term monitoring of variable sources of very high-energy gamma-ray emission. While the sensitivity of FACT is limited by the small mirror area of ~9.5m$^2$, it is sufficient to measure the emission from the brightest Blazars like Mrk421, Mrk501 and 1ES1959 and alerting the community in case of bright flares. While Mrk421 and Mrk501 showed several flaring episodes over the last years, 1ES1959+650 was in a low state for the first three years. In 2015 an increase of the flux was observed, and in 2016, several bright outbursts have been recorded. In this presentation, the results of five year of unbiased Blazar monitoring will be presented.

Speaker: Mr Jens Buß (Tu Dortmund, Exp. Physik 5b)

Slides 2016_FACT_HAP.pdf 2016_FACT_HAP.pptx

33 DWARF Network

The variability of the very high energy (VHE) emission from blazars seems to be connected with the feeding and propagation of relativistic jets and with their origin in supermassive black hole binaries. The key to understanding their properties is measuring well-sampled gamma-ray lightcurves, revealing the typical source behavior unbiased by prior knowledge from other wavebands. Using ground-based gamma-ray observatories with exposures limited by dark-time, a global network of several telescopes is needed to carry out full-time measurements. Obviously, such observations are time-consuming and, therefore, cannot be carried out with the present state of the art instruments. The FACT telescope on the Canary Island of La Palma is dedicated to monitoring observations. It has been set up, employing a cost-efficient and robotic design. A future aim is the construction of a distributed network of small telescopes. The physical motivation of VHE long-term monitoring will be outlined in detail and the perspective for a network for 24/7 VHE gamma-ray observations will be presented.

Speaker: Dr Michael Backes

Slides M.Backes-DWARF-HAP-final.pptx

34 Monitoring the Sky at soft Gamma-ray Energies with CGRO/COMPTEL for nine Years

The COMPTEL experiment aboard Compton Gamma-Ray Observatory (CGRO) explored the MeV sky (0.75 - 30 MeV) for more than 9 years between April 1991 and June 2000, providing a wealth of discoveries. Now, more than 16 years after the deorbit of CGRO, the COMPTEL data are still the forefront of our knowledge on the non-thermal soft gamma-ray sky (1 - 30 MeV), because no successor is operating. The COMPTEL source catalog (Schönfelder et al. 2000) lists 32 steady sources, which raised to more than 40 sources up to now, the majority in source type are blazars. We will summarise the observational status (source counts, spectra, light curves) of COMPTEL sources at soft MeV energies with emphasis on blazars, including multifrequency spectra for selected sources. We'll also present new developments in the still ongoing COMPTEL data analyses, focusing on polarization and state-of-the-art imaging techniques, and their scientific perspectives.

Speaker: Dr Werner Collmar (MPE)

Slides collmar_cochem_talk.pdf

10:35 AM Coffee Break

Radio Astronomy: Part II

35 VLBI monitoring and Dynamic SEDs of southern blazars

Speaker: Dr Felicia Krauss (GRAPPA & API, UvA)

Slides sedtalk.pdf

36 F-GAMMA program: multi-frequency radio monitoring of Fermi blazars

Motivated by the advent of Fermi gamma-ray space telescope and the potential of multi-energy studies of AGN, we initiated in January 2007 a monthly multi-frequency radio monitoring of almost 100 gamma-ray blazars. The observations were being conducted primarily wit the Effelsberg 100-m, the IRAM Pico Veleta 30-m and less regularly the APEX 12-m telescopes in the frequency range from 2.6 to 345 GHz. The resulting dataset is characterized by an effective cadence of a measurement every 1.3 months with a coherence of the resulting radio SEDs of better than 10 days. The monitoring has been conducted in linear and circular polarization mode. This effort which culminated in January 2015 with the completion of the nominal operation of the program resulted a vast dataset that is being explored. In this talk I aim at reviewing the program and discuss some of the most noteworthy findings, such as: - the detection of a statistically rigorous correlation between gamma-rays and radio flux densities - the detection of a correlation of radio and gamma-ray light curves which allowed us to constrain the location of the gamma-ray production site - the unification of the spectral variability patterns to small number of classes all of which are explainable with the operation of shocks in the jet - the modeling of the multi-frequency circular and linear polarization light curves with full-Stokes radiative transfer - the detection of blazar-like jets from Narrow Line Seyfert galaxies

Speakers: Dr Emmanouil Angelakis (Max-Planck-Institut für Radioastronomie), Dr Ioannis Myserlis (Max Planck Institut für Radioastronomie)

Slides HAP-angelakis.pdf

37 Physics of extragalactic plasma elements through multi-frequency linear and circular radio polarization monitoring

The radio emission of active galactic nuclei (AGN) jets is polarized due to the incoherent synchrotron radiation mechanism. The linear and circular polarization parameters are directly related with the physical conditions (magnetic field strength and topology, particle density and plasma composition) both in the jet as well as any magnetized plasma regions along the line of sight. However, detecting their polarization properties is a challenging endeavor due to their low levels and possible depolarization effects. We have developed an end-to-end data analysis methodology to recover the polarization properties of unresolved sources with high accuracy. It has been applied to recover the linear and circular polarization of 87 AGNs measured by the F-GAMMA monitoring program from July 2010 to January 2015 with a mean cadence of 1.3 months. Their linear polarization was recovered at four frequencies between 2.64 and 10.45 GHz and the circular polarization at 4.85 and 8.35 GHz. The physical conditions required to reproduce the observed polarization properties and the processes which induce their variability were investigated with a polarized radiative transfer code which emulates the synchrotron emission of modeled jets. Here we present our first results on modeling the full-Stokes variability of the blazar 3C 454.3, assuming that it can be attributed to evolving internal shocks propagating downstream.

Speaker: Dr Ioannis Myserlis (Max Planck Institut für Radioastronomie)

Slides HAP-myserlis.pdf

12:30 PM Lunch Break

MWL and Multi-Messenger: Part I

38 Blazar studies with ASTROSAT

Blazars are a subclass of Active Galactic Nuclei (AGN) characterized by non-thermal emission extending from radio to high energies. The broadband radiation originates within a relativistic jet that is oriented very close to the line of sight. Radiative processes of Blazars can be studied using ASTROSAT. ASTROSAT is India's first multi-wavelength astronomy satellite in a 650-km, near-equatorial orbit. ASTROSAT has five onboard payloads for simultaneous multi-band observations at X-ray and UV energies. These instruments cover an energy range from UV to hard X-rays. Detecting accretion disk emission during the low state from the blazar is another goal. I will present some of the possible observational prospects for blazar studies in my talk.

Speaker: Dr Amit Shukla (Institut für Theoretische Physik und Astrophysik, Universität Würzburg)

Slides ASTROSAT_HAP2016.pdf

39 Multimessenger Studies of Blazars

Active galactic nuclei often show relativistic outflows of matter, called jets. We study their simultaneous radio to gamma-ray spectral energy distributions (SEDs) from the TANAMI sample, with over 80 SEDs for 22 sources. The large amount of monitoring data from the TANAMI project allows us to construct dynamic SEDs, highlighting spectral changes in varying flux states. With the data, we can further address key questions in AGN jet physics like the existence of the blazar sequence and the Fermi blazar's divide, the fundamental plane of black hole masses and the origin of the "big blue bump". In high flux states the sources do not seem to follow the blazar sequence, suggesting a change in the jet. We find disagreements with the Big Blue Bump originating in thermal emission from the accretion disk. We further observe that the fundamental plane does not work well as an estimator of the black hole mass, or the black hole mass is severely overestimated by SED fitting for some of the sources.

Speaker: Dr Felicia Krauss (GRAPPA & API, UvA)

Slides neutrino_krauss.pdf

40 On the direct correlation between gamma-rays and PeV neutrinos from blazars

We study the frequently used assumption in multi-messenger astrophysics that the gamma-ray and neutrino fluxes are directly connected because they are assumed to be produced by the same photohadronic production chain. An interesting candidate source for this test is the flat-spectrum radio quasar PKS B1424-418, which recently called attention of a potential correlation between an IceCube PeV-neutrino event and its burst phase. We simulate both the multi-waveband photon and the neutrino emission from this source using a self-consistent radiation model. We demonstrate that a simple hadronic model cannot adequately describe the spectral energy distribution for this source, but a lepto-hadronic model with sub-dominant hadronic component can reproduce the multi-waveband photon spectrum observed during various activity phases of the blazar. As a conclusion, up to about 0.3 neutrino events may coincide with the burst, which implies that the leptonic contribution dominates in the relevant energy band. We also demonstrate that the time-wise correlation between the neutrino event and burst phase is weak.

Speaker: Dr Shan Gao (DESY)

Slides GAO_pksb1424418A.pdf

3:00 PM Coffee Break

MWL and Multi-Messenger: Part II

41 INTEGRAL search for gamma-ray counterparts of gravitational wave and neutrino events

Observations of the INTErnational Gamma-Ray Astrophysics Laboratory (INTEGRAL) allow us to put upper limits on the gamma-ray and hard X-ray emission associated with the gravitational wave events, reported by LIGO/Virgo collaboration, as well as with exceptional high energy neutrino events detected by IceCube. Large duty cycle of INTEGRAL, stable background, and quasi-omnidirectional sensitivity of INTEGRAL/SPI-ACS and IBIS prove to be especially valuable in searches for counterparts of multi-messenger transients. We also discuss the potential of INTEGRAL for performing pointed observations of the GW and high-energy neutrino sources. INTEGRAL high-energy imaging instruments, IBIS, SPI, and JEM-X, give an opportunity to search for both prompt and long-lasting electromagnetic counterparts of various transient events over 3 decades in energy, from 5 keV to 8 MeV.

Speaker: Dr Volodymyr Savchenko (APC)

Slides Cochem_INTEGRAL.pdf

42 Photon searches with the Pierre Auger Observatory and the connection to TeV gamma-ray observations

The Pierre Auger Observatory, located in Argentina, provides an unprecedented integrated aperture for the search of photons with energy above 100 PeV. In this contribution recent results are presented with a focus on directional searches for photon point sources. The derived limits are of considerable astrophysical interest: Diffuse limits place severe constraints on top-down models and start to touch the predicted GZK photon flux range while directional limits can exclude the continuation of the electromagnetic flux from measured TeV sources with a significance of more than 5$\sigma$ and set upper limits on the maximum cutoff energy of the source. By taking into account multi-wavelength information the sensitivity can be further increased.

Speaker: Daniel Kuempel (RWTH Aachen University)

Slides HAPCochemPhoton_V2.pdf

Summary

43 Summary

Speaker: Prof. Stefan Wagner (LSW)

44 Closing

Speaker: Prof. Thomas Bretz (RWTH Aachen University)

Slides GoodBye.pdf

Saturday, December 10

AMON Workshop: Welcome, A. KEIVANI

45 "Welcome"

Speaker: Dr Azadeh Keivani (The Pennsylvania State University)

AMON Workshop: Theory: "High-Energy Neutrinos from Gamma-Ray Bursts and Blazar Flares", S. GAO

46 High-Energy Neutrinos from Gamma-Ray Bursts and Blazar Flares

Gamma-ray bursts (GRB) and blazars are luminous point sources in gamma-rays and candidate sources for IceCube neutrinos. The potential spatial and temporal correlations between the IceCube neutrinos and the gamma-ray flares from those sources have called attention and extensive studies. Due to the low statistics of neutrino events, it is important to interpret the results based on accurate modeling of the sources. Here I will summarize the recent developments on theoretical models of GRBs and blazars and the correlation between their neutrino and gamma-ray emissions.

Speaker: Dr Shan Gao (DESY)

Slides GAO_nugrbblz.pdf

AMON Workshop: "Status of the AMON network", G. TEŠIĆ

47 "Status of the AMON network"

Speaker: Gordana Tešić (Penn State University)

Slides Status of the AMON network

AMON Workshop: "IceCube multimessenger program", T. KINTSCHER

48 "IceCube multimessenger program"

Speaker: Thomas Kintscher (DESY)

Slides 2016-12-10_-_AMON_Workshop.pdf

AMON Workshop: "The Auger contribution to AMON", F. OIKONOMOU

49 "The Auger contribution to AMON"

Speaker: Dr Foteini Oikonomou (Penn State)

Slides amon_cochem_oikonomou.pdf

10:35 AM Coffee Break

AMON Workshop: Gamma rays: "Multimessenger studies with HAWC ", R. LAUER

50 "Multimessenger studies with HAWC"

Speaker: Dr Robert Lauer (University of New Mexico)

Slides lauer_amon2016.pdf

AMON Workshop: "Multimessenger follow-up with FACT", D. DORNER

51 "Multimessenger follow-up with FACT"

Speaker: Dr Daniela Dorner (Universität Würzburg)

Slides fact_amon.pdf

AMON Workshop: "The H.E.S.S. Multi-Messenger Program", F. SCHÜSSLER

52 The H.E.S.S. Multi-Messenger Program

In this contribution I will present the H.E.S.S. programs to follow up on multi-wavelength and multi-messenger observations and alerts. I will show first results from searches for high-energy gamma-ray emission in spatial coincidence with neutrino events detected by the IceCube and ANTARES neutrino telescopes and discuss recent extensions towards a fully integrated real-time alert system between neutrino telescopes and the H.E.S.S. gamma-ray observatory. Ongoing activities searching for high-energy gamma-ray emission in coincidence with Gamma Ray Bursts, recent extensions to Fast Radio Bursts and Gravitational Waves are going to be discussed as well.

Speaker: Dr Fabian Schüssler (IRFU / CEA-Saclay)

Slides AMON2016_HESSmultimessenger_Schussler.pdf

AMON Workshop: "Multimessenger Follow-up with MAGIC", K. SATALECKA

53 "Multimessenger Follow-up with MAGIC"

Speaker: Konstancja Satalecka (DESY Zeuthen)

Slides KSatalecka_MAGIC_AMON2016.pdf

12:30 PM Lunch

AMON Workshop: "Multimessenger Transients and the Liverpool Telescope", C. COPPERWHEAT

54 Multimessenger Transients and the Liverpool Telescope

The Liverpool Telescope is a 2-metre clear aperture, fully robotic telescope based at the Observatorio Del Roque De Los Muchachos on the Canary island of La Palma. Robotic telescopes are powerful tools for the exploration of the time variable sky, and their rapid reaction and flexible scheduling capabilities provide them with an important role in the multimessenger era. In this talk I will provide an overview of the telescope and its contribution to programmes of transient follow-up, focusing in particular on our participation in the first Advanced LIGO science run. I will also give a brief introduction to our proposed new facility, the 4-metre Large Robotic Telescope, which we intend to be one of the world's leading time domain facilities in the coming decade.

Speaker: Dr Chris Copperwheat (Astrophysics Research Institute, Liverpool John Moores University)

Slides 161210_copperwheat.pdf

AMON Workshop: "Multimessenger Follow-up with MASTER", V. LIPUNOV

55 "Multimessenger Follow-up with MASTER"

Speaker: Prof. Vladimir Lipunov (Lomonosov Moscow State University)

AMON Workshop: "LOFAR/AERA", J. HÖRANDEL

56 "LOFAR/AERA"

Speaker: Jörg Hörandel (Radboud University Nijmegen)

Slides jrh-lofar-aera.pdf

3:00 PM Coffee Break

AMON Workshop: Analysis: "Multimessenger studies of blazars", F. KRAUSS

57 Multimessenger studies of blazars

The IceCube Collaboration has published results on a neutrino flux significantly in excess of the atmospheric background. Due to low atmospheric background at PeV energies, the highest energy events are the most likely ones to be of extraterrestrial origin. We use broadband spectra in the IceCube integration period to calculate the maximum expected number of neutrinos assuming a pion photoproduction model. We show that blazars as a class are capable of explaining the first two observed neutrino events at PeV energies. For the third event at PeV energies we find a flaring blazar in positional and temporal agreement. The energy output of PKS B1424-418 alone can explain the neutrino event, indicative of a physical association.

Speaker: Dr Felicia Krauss (GRAPPA & API, UvA)

Slides neutrino_krauss2.pdf

AMON Workshop: Discussion