Trobat l'accelerador de partícules en la radiogalàxia Messier 87

Un equip internacional d'investigadors, dirigit per l'Institut de Física d'Altes Energies (IFAE), adscrit a la UAB, i de l'Institut Max Planck, ha descobert la localització exacta de la regió d'acceleració de partícules en la veïna radiogalàxia gegant Messier 87.Un equipo internacional de investigadores, dirigido por el Instituto de Física de Altas Energías (IFAE), adscrito a la UAB y del Instituto Max Planck, ha descubierto la localización exacta de la región de aceleración de partículas en la vecina radiogaláxia gigante Messier 87, un núcleo galáctico activo situado a unos 55 millones de años luz de la Tierra

Descobreixen un nou sistema binari de raigs-gamma a la nostra galàxia

L'equip de col∙laboració del telescopi espacial Fermi-LAT, integrat entre altres pels científics de l'Institut de Ciències de l'Espai (CSIC-IEEC), amb seu a la UAB, Andrea Caliandro, Daniela Hadasch i Diego Torres, ha descobert un nou sistema binari de raigs gamma en els voltants del centre Galàctic. El descobriment ha merescut la publicació de l'estudi a la prestigiosa revista Science ja que a dia d'avui, només es coneixen uns quants sistemes que emeten en raigs gamma.El equipo de colaboración del telescopio espacial Fermi-LAT, integrado entre otros por los científicos del Instituto de Ciencias del Espacio (CSIC-IEEC), ubicado en el campus de la UAB, Andrea Caliandro, Daniela Hadasch y Diego Torres, han descubierto un nuevo sistema binario de rayos gamma en los inmediaciones del Centro Galáctico tal descubrimiento ha merecido la publicación del estudio en la prestigiosa revista Science ya que a día de hoy, solo se conocen un puñado de sistemas que emiten en rayos gamma

MAGIC VHE Gamma-Ray Observations Of Binary Systems

There are several types of Galactic sources that can potentially accelerate charged particles up to GeV and TeV energies. We present here the results of our observations of the source class of gamma-ray binaries and the subclass of binary systems known as novae with the MAGIC telescopes. Up to now novae were only detected in the GeV range. This emission can be interpreted in terms of an inverse Compton process of electrons accelerated in a shock. In this case it is expected that protons in the same conditions can be accelerated to much higher energies. Consequently they may produce a second component in the gamma-ray spectrum at TeV energies. The focus here lies on the four sources: nova V339 Del, SS433, LS I +61 303 and V404 Cygni. The binary system LS I +61 303 was observed in a long-term monitoring campaign for 8 years. We show the newest results on our search for superorbital variability, also in context with contemporaneous optical observations. Furthermore, we present the observations of the only super-critical accretion system known in our galaxy: SS433. Finally, the results of the follow-up observations of the microquasar V404 Cygni during a series of outbursts in the X-ray band and the ones of the nova V339 Del will be discussed in these proceedings.Comment: Proceedings of the 35th International Cosmic Ray Conference (ICRC 2017), Bexco, Busan, Korea (arXiv:1708.05153

Simultaneous multi-frequency observation of the unknown redshift blazar PG1553+113 in March-April 2008

5 páginas, 2 figuras, 3 tablas.-- El Pdf del artículo es la versión pre-print: arXiv: arXiv:0911.1088.-- MAGIC Collaboration: et al.The blazar PG 1553+113 is a well known TeV γ-ray emitter. In this paper we determine its spectral energy distribution through simultaneous multi-frequency data to study its emission processes. An extensive campaign was carried out between March and April 2008, where optical, X-ray, high-energy (HE) γ-ray, and very-high-energy (VHE) γ-ray data were obtained with the KVA, Abastumani, REM, RossiXTE/ASM, AGILE and MAGIC telescopes, respectively. We combine the data to derive the source's spectral energy distribution and interpret its double-peaked shape within the framework of a synchrotron self-Compton model.Major support from Germany’s Bundesministerium f¨ur Bildung, Wissenschaft, Forschung und Technologie and Max-Planck-Gesellschaft, Italy’s Istituto Nazionale di Fisica Nucleare (INFN) and Istituto Nazionale di Astrofisica (INAF), and Spain’s Ministerio de Ciencia e Innovacion is gratefully acknowledged. The work was also supported by Switzerland’s ETH Research grant TH34/043, Poland’s Ministertwo Nauki i Szkolnictwa Wy˙zszego grant N N203 390834, and Germany’s Young Investigator Program of the Helmholtz Gemeinschaft. This work was also supported by Georgian National Science Foundation grant GNSF/ST07/4-180. EP acknowledges support from the Italian Space Agency through grants ASI-INAF I/023/05/0 and ASI I/088/06/0.Peer reviewe

MAGIC observation of the GRB 080430 afterglow

6 páginas, 1 figura.-- El Pdf del artículo es la versión pre-print: arXiv:1004.3665v2.-- MAGIC Collaboration: et al.[Context]: Gamma-ray bursts are cosmological sources emitting radiation from the gamma-rays to the radio band. Substantial observational efforts have been devoted to the study of gamma-ray bursts during the prompt phase, i.e. the initial burst of high-energy radiation, and during the long-lasting afterglows. In spite of many successes in interpreting these phenomena, there are still several open key questions about the fundamental emission processes, their energetics and the environment. [Aims]: Independently of specific gamma-ray burst theoretical recipes, spectra in the GeV/TeV range are predicted to be remarkably simple, being satisfactorily modeled with power-laws, and therefore offer a very valuable tool to probe the extragalactic background light distribution. Furthermore, the simple detection of a component at very-high energies, i.e. at ~100 GeV, would solve the ambiguity about the importance of various possible emission processes, which provide barely distinguishable scenarios at lower energies. [Methods]: We used the results of the MAGIC telescope observation of the moderate resdhift (z ~ 0.76) GRB 080430 at energies above about 80 GeV, to evaluate the perspective for late-afterglow observations with ground based GeV/TeV telescopes. [Results]: We obtained an upper limit of F95% CL = 5.5 × 10-11 erg cm-2 s-1 for the very-high energy emission of GRB 080430, which cannot set further constraints on the theoretical scenarios proposed for this object also due to the difficulties in modeling the low-energy afterglow. Nonetheless, our observations show that Cherenkov telescopes have already reached the required sensitivity to detect the GeV/TeV emission of GRBs at moderate redshift (z ≲ 0.8), provided the observations are carried out at early times, close to the onset of their afterglow phase.The support of the German BMBF and MPG, the Italian INFN and Spanish MICINN is gratefully acknowledged. This work was also supported by ETH Research Grant TH 34/043, by the Polish MNiSzW Grant N N203 390834, and by the YIP of the Helmholtz Gemeinschaft.Peer reviewe

Development of the photomultiplier tube readout system for the first Large-Sized Telescope of the Cherenkov Telescope Array

The Cherenkov Telescope Array (CTA) is the next generation ground-based very high energy gamma-ray observatory. The Large-Sized Telescope (LST) of CTA targets 20 GeV -- 1 TeV gamma rays and has 1855 photomultiplier tubes (PMTs) installed in the focal plane camera. With the 23 m mirror dish, the night sky background (NSB) rate amounts to several hundreds MHz per pixel. In order to record clean images of gamma-ray showers with minimal NSB contamination, a fast sampling of the signal waveform is required so that the signal integration time can be as short as the Cherenkov light flash duration (a few ns). We have developed a readout board which samples waveforms of seven PMTs per board at a GHz rate. Since a GHz FADC has a high power consumption, leading to large heat dissipation, we adopted the analog memory ASIC "DRS4". The sampler has 1024 capacitors per channel and can sample the waveform at a GHz rate. Four channels of a chip are cascaded to obtain deeper sampling depth with 4096 capacitors. After a trigger is generated in a mezzanine on the board, the waveform stored in the capacitor array is subsequently digitized with a low speed (33 MHz) ADC and transferred via the FPGA-based Gigabit Ethernet to a data acquisition system. Both a low power consumption (2.64 W per channel) and high speed sampling with a bandwidth of $>$300 MHz have been achieved. In addition, in order to increase the dynamic range of the readout we adopted a two gain system achieving from 0.2 up to 2000 photoelectrons in total. We finalized the board design for the first LST and proceeded to mass production. Performance of produced boards are being checked with a series of quality control (QC) tests. We report the readout board specifications and QC results.Comment: In Proceedings of the 34th International Cosmic Ray Conference (ICRC2015), The Hague, The Netherlands. All CTA contributions at arXiv:1508.0589

A population of gamma-ray emitting globular clusters seen with the Fermi Large Area Telescope

Globular clusters with their large populations of millisecond pulsars (MSPs) are believed to be potential emitters of high-energy gamma-ray emission. Our goal is to constrain the millisecond pulsar populations in globular clusters from analysis of gamma-ray observations. We use 546 days of continuous sky-survey observations obtained with the Large Area Telescope aboard the Fermi Gamma-ray Space Telescope to study the gamma-ray emission towards 13 globular clusters. Steady point-like high-energy gamma-ray emission has been significantly detected towards 8 globular clusters. Five of them (47 Tucanae, Omega Cen, NGC 6388, Terzan 5, and M 28) show hard spectral power indices $(0.7 < \Gamma <1.4)$ and clear evidence for an exponential cut-off in the range 1.0-2.6 GeV, which is the characteristic signature of magnetospheric emission from MSPs. Three of them (M 62, NGC 6440 and NGC 6652) also show hard spectral indices $(1.0 < \Gamma < 1.7)$, however the presence of an exponential cut-off can not be unambiguously established. Three of them (Omega Cen, NGC 6388, NGC 6652) have no known radio or X-ray MSPs yet still exhibit MSP spectral properties. From the observed gamma-ray luminosities, we estimate the total number of MSPs that is expected to be present in these globular clusters. We show that our estimates of the MSP population correlate with the stellar encounter rate and we estimate 2600-4700 MSPs in Galactic globular clusters, commensurate with previous estimates. The observation of high-energy gamma-ray emission from a globular cluster thus provides a reliable independent method to assess their millisecond pulsar populations that can be used to make constraints on the original neutron star X-ray binary population, essential for understanding the importance of binary systems in slowing the inevitable core collapse of globular clusters.Comment: Accepted for publication in A&A. Corresponding authors: J. Kn\"odlseder, N. Webb, B. Pancraz

Resource-aware Research on Universe and Matter: Call-to-Action in Digital Transformation

Given the urgency to reduce fossil fuel energy production to make climate tipping points less likely, we call for resource-aware knowledge gain in the research areas on Universe and Matter with emphasis on the digital transformation. A portfolio of measures is described in detail and then summarized according to the timescales required for their implementation. The measures will both contribute to sustainable research and accelerate scientific progress through increased awareness of resource usage. This work is based on a three-days workshop on sustainability in digital transformation held in May 2023.Comment: 20 pages, 2 figures, publication following workshop 'Sustainability in the Digital Transformation of Basic Research on Universe & Matter', 30 May to 2 June 2023, Meinerzhagen, Germany, https://indico.desy.de/event/3748