Matteo Balbo

IGR J11014-6103: a newly discovered pulsar wind nebula?

Context. IGR J11014-6103 is one of the still unidentified hard X-ray INTEGRAL sources, reported for the first time in the 4th IBIS/ISGRI catalog. Aims. We investigated the nature of IGR J11014-6103 by carrying out a multiwavelength analysis of the available archival observations performed in the direction of the source. Methods. We present the results of the timing and spectral analysis of all the X-ray observations of IGR J11014-6103 carried out with ROSAT, ASCA, Einstein ,S wift, andXMM-Newton. We used them to search for possible counterparts to the source in the optical, infrared, radio and γ-ray domain. Results. Our analysis reveals that IGR J11014-6103 is comprised of three different X-ray emitting regions: a point-like source, an extended object, and a cometary-like “tail” (∼4 arcmin). A possible radio counterpart positionally coincident with the source was also identified. Conclusions. Based on these results, we suggest that the emission from IGR J11014-6103 is generated by a pulsar wind nebula produced by a high-velocity pulsar. IGR J11014-6103 might be the first of these systems detected with INTEGRAL IBIS/ISGRI.

HESS J1632-478: an energetic relic

Aims. HESS J1632-478 is an extended and still unidentified TeV source in the galactic plane. Methods. In order to identify the source of the very high energy emission and to constrain its spectral energy distribution, we used a deep observation of the field obtained with XMM-Newton together with data from Molonglo, Spitzer and Fermi to detect counterparts at other wavelengths. Results. The flux density emitted by HESS J1632-478 peaks at very high energies and is more than 20 times weaker at all other wavelengths probed. The source spectrum features two large prominent bumps with the synchrotron emission peaking in the ultraviolet and the external inverse Compton emission peaking in the TeV. HESS J1632-478 is an energetic pulsar wind nebula with an age of the order of 10 4 years. Its bolometric (mostly GeV-TeV) luminosity reaches 10% of the current pulsar spin down power. The synchrotron nebula has a size of 1 pc and contains an unresolved point-like X-ray source, probably the pulsar with its wind termination shock.

Closer view of the IGR J11014-6103 outflows

IGR J11014-6103 (also known as the Lighthouse Nebula) is composed of a bow-shock pulsar wind nebula (PWN) and large-scale X-ray jet-like features, all powered by PSR J1101-6101. Previous observations suggest that the jet features stem from a ballistic jet of relativistic particles. In order to confirm the nature of the jet and the counter-jet, we obtained a new deep 250 ks Chandra observation of the Lighthouse Nebula. We performed detailed spatial and spectral analysis of all X-ray components of the system. The X-ray PWN is now better resolved and shows a peculiar morphology resembling the shape of an arrow. The overall helical pattern of the main jet is confirmed. However, there are large deviations from a simple helical model at small and large scales. Significant extended emission is now detected, encompassing the main jet all along its length. The presence of an apparent gap along the main jet at ~50″ distance from the pulsar is confirmed; however, the surrounding extended emission prevents conclusions on the coherence at this position of the jet. The counter-jet is now detected at high statistical significance. In addition, we found two small-scale arcs departing from the pulsar towards the jets. We also looked for possible bow-shock emission due to the pulsar motion, with a short VLT/FORS2 H- α observation. No clear emission is found, most likely because of the contamination from a diffuse nebulosity. The results of our X-ray analysis show that both a ballistic jet scenario and an alternative scenario involving the diffusion of particles along pre-existing interstellar magnetic field lines are able to satisfactorily explain some of the observational evidence, but cannot fully reproduce the observations.

Fermi acceleration along the orbit of η Carinae

Context. The η Carinae binary system hosts one of the most massive stars, which features the highest known mass-loss rate. This dense wind encounters the much faster wind expelled by the stellar companion, dissipating mechanical energy in the shock, where particles can be accelerated up to relativistic energies and subsequently produce very-high-energy γ -rays. Aims. We aim at comparing the variability of the γ -ray emission of η Carinae along the binary orbit with the predictions of simulations to establish the nature of the emission and of the seed particles. Methods. We have used data from the Fermi Large Area Telescope obtained during its first seven years of observations and spanning two passages of η Carinae at periastron. We performed the analysis using the new PASS8 pipeline and its improved instrument response function, extracting low and high-energy light curves as well as spectra in different orbital phase bins. We also introduced particle acceleration in hydrodynamic simulations of the system, assuming a dipolar magnetic field generated by the most massive star, and compared the γ -ray observations with the predictions of diffuse shock acceleration in a multi-cell geometry. Results. The main source of the γ -ray emission originates from a position compatible with η Carinae and located within the Homunculus Nebula. Two emission components can be distinguished. The low-energy component cuts off below 10 GeV and its flux, modulated by the orbital motion, varies by a factor less than 2. Short-term variability occurs at periastron. The flux of the high-energy component varies by a factor 3–4 but is different during the two periastrons. The variabilities observed at low energy, including some details of them, and those observed at high energy during the first half of the observations, match the prediction of the simulation, assuming a surface magnetic field of 500 G. The high-energy component and the thermal X-ray emission were weaker than expected around the second periastron suggesting a modification of the wind density in the inner wind collision zone. Conclusions. Diffuse shock acceleration in the complex geometry of the wind collision zone of η Carinae provides a convincing match to the observations and new diagnostic tools to probe the geometry and energetics of the system. This demonstrates that Fermi acceleration is at work in the wind collisions and that a few percent of the shock mechanical energy are converted into particle acceleration. Further observations are required to understand the periastron-to-periastron variability of the high-energy component and to associate it firmly with hadronic origin. We estimate that η Carinae is a pevatron at periastron and is bright enough to be detected by IceCube after many years of observations. Orbital modulations of the high-energy component can be distinguished from those of photo absorption by the four large size telescopes of the Cherenkov Telescope Array to be placed in the southern hemisphere.

FACT - Calibration of Imaging Atmospheric Cerenkov Telescopes with Muon Rings

M. Nothe∗, a M. L. Ahnen b, M. Balbo c, M. Bergmann d , C. Bockermann e, A. Biland b, T. Bretz b, K. A. Brugge a, J. Buss a, D. Dorner d , S. Einecke a, J. Freiwald a, C. Hempfling d , D. Hildebrand b, G. Hughes b, W. Lustermann b, K. Mannheim d , K. Meier d , K. Morik e, S. Muller b, D. Neise b, A. Neronov c, A.-K. Overkemping a, A. Paravac d , F. Pauss b, W. Rhode a, F. Temme a, J. Thaele a, S. Toscano c, P. Vogler b, R. Walter c, and A. Wilbert d Email: maximilian.noethe@tu-dortmund.de

FACT-Tools: Streamed Real-Time Data Analysis

K. A. Brügge b∗, M. L. Ahnena, M. Balboc, M. Bergmannd , A. Bilanda, C. Bockermanne, T. Bretza, J. Bussb, D. Dornerd , S. Eineckeb, J. Freiwaldb, C. Hempflingd , D. Hildebranda, G. Hughesa, W. Lustermanna, K. Mannheimd , K. Meierd , K. Morike, S. Müllera, D. Neisea, A. Neronovc, M. Nötheb, A.-K. Overkempingb, A. Paravacd , F. Paussa, W. Rhodeb, F. Temmeb, J. Thaeleb, S. Toscanoc, P. Voglera, R. Walterc, and A. Wilbertd Email: kai.bruegge@tu-dortmund.de

FACT - Status and Experience from Three Years Operation of the First SiPM Camera

A. Biland∗a, M. L. Ahnena, M. Balbob, M. Bergmannc, T. Bretza,1, K. A. Brugged , J. Bussd , D. Dornerc, S. Einecked , J. Freiwaldd , C. Hempflingc, D. Hildebranda, G. Hughesa, W. Lustermanna, K. Mannheimc, K. Meierc, S. Mullera, D. Neisea, A. Neronovb, M. Nothed , A.-K. Overkempingd , A. Paravacc, F. Paussa, W. Rhoded , F. Temmed , J. Thaeled , S. Toscanob, P. Voglera, R. Walterb, and A. Wilbertc aETH Zurich, Institute for Particle Physics Otto-Stern-Weg 5, 8093 Zurich, Switzerland bUniversity of Geneva, ISDC Data Center for Astrophysics Chemin d’Ecogia 16, 1290 Versoix, Switzerland cUniversitat Wurzburg, Institute for Theoretical Physics and Astrophysics Emil-Fischer-Str. 31, 97074 Wurzburg, Germany dTU Dortmund, Experimental Physics 5 Otto-Hahn-Str. 4, 44221 Dortmund, Germany 1also at RWTH Aachen E-mail: biland@phys.ethz.ch

FACT - TeV Flare Alerts Triggering Multi-Wavelength Observations

D. Dorner∗a, M. L. Ahnenb, M. Balbod , M. Bergmanna, A. Bilandb, T. Bretzb1, K. A. Bruggec, J. Bussc, S. Eineckec, J. Freiwaldc, C. Hempflinga, D. Hildebrandb, G. Hughesb, W. Lustermannb, K. Mannheima, K. Meiera, S. Mullerb, D. Neiseb, A. Neronovd , M. Nothec, A.-K. Overkempingc, A. Paravaca, F. Paussb, W. Rhodec, F. Temmec, J. Thaelec, S. Toscanod , P. Voglerb, R. Walterd , and A. Wilberta aUniversitat Wurzburg, Institute for Theoretical Physics and Astrophysics Emil-Fischer-Str. 31, 97074 Wurzburg, Germany bETH Zurich, Institute for Particle Physics Otto-Stern-Weg 5, 8093 Zurich, Switzerland cTU Dortmund, Experimental Physics 5 Otto-Hahn-Str. 4, 44221 Dortmund, Germany dUniversity of Geneva, ISDC Data Center for Astrophysics Chemin d’Ecogia 16, 1290 Versoix, Switzerland 1also at RWTH Aachen E-mail: dorner@astro.uni-wuerzburg.de

First study of combined blazar light curves with FACT and HAWC

For studying variable sources like blazars, it is crucial to achieve unbiased monitoring, either with dedicated telescopes in pointing mode or survey instruments. At TeV energies, the High Altitude Water Cherenkov (HAWC) observatory monitors approximately two thirds of the sky every day. It uses the water Cherenkov technique, which provides an excellent duty cycle independent of weather and season. The First G-APD Cherenkov Telescope (FACT) monitors a small sample of sources with better sensitivity, using the imaging air Cherenkov technique. Thanks to its camera with silicon-based photosensors, FACT features an excellent detector performance and stability and extends its observations to times with strong moonlight, increasing the duty cycle compared to other imaging air Cherenkov telescopes. As FACT and HAWC have overlapping energy ranges, a joint study can exploit the longer daily coverage given that the observatories’ locations are offset by 5.3 hours. Furthermore, the better sensitivity of FACT adds a ...

FACT - Novel mirror alignment using Bokeh and enhancement of the VERITAS SCCAN alignment method

S. Muller∗a, M. L. Ahnena, M. Balbob, M. Bergmannc, A. Bilanda, T. Bretza,1, K. A. Brugged , J. Bussd , D. Dornerc, S. Einecked , J. Freiwaldd , C. Hempflingc, D. Hildebranda, G. Hughesa, W. Lustermanna, K. Mannheimc, K. Meierc, D. Neisea, A. Neronovb, M. Nothed , A.-K. Overkempingd , A. Paravacc, F. Paussa, W. Rhoded , F. Temmed , J. Thaeled , S. Toscanob, P. Voglera, R. Walterb, and A. Wilbertc aETH Zurich, Institute for Particle Physics Otto-Stern-Weg 5, 8093 Zurich, Switzerland bUniversity of Geneva, ISDC Data Center for Astrophysics Chemin d’Ecogia 16, 1290 Versoix, Switzerland cUniversitat Wurzburg, Institute for Theoretical Physics and Astrophysics Emil-Fischer-Str. 31, 97074 Wurzburg, Germany dTU Dortmund, Experimental Physics 5 Otto-Hahn-Str. 4, 44221 Dortmund, Germany 1also at RWTH Aachen E-mail: sebmuell@phys.ethz.ch