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Vera Nievas - Very-high-energy gamma-rays from the Universe's middle age: detection of B0218+357 and PKS1441+25 with the MAGIC telescopes
Toggle Cloak Cloak Flat Spectrum Radio Quasars (FSRQs) remain uncommon members of the Very High Energy (VHE, E$>$100GeV) source family. The reason is twofold. First, they typically have strong emission in the optical-UV coming from the Broad Line Region, which can interact with the gamma-rays, determining a strong absorption. Second, their spectrum is typically soft and may exhibit intrinsic cut-offs.
The FSRQs B0218+357 (z=0.944) and PKS1441+25 (z=0.940) were first detected at VHE with MAGIC in July 2014 and April 2015 respectively, and are the most distant VHE blazars known to date. The detection of this new z~1 blazar class by the MAGIC telescopes gives us a chance to study the processes that allow a typically VHE-obscured blazar to emit sub-TeV photons when strong flares occur and set limits on the EBL density at redshift ~1 for the first time with the Cherenkov technique.
The VHE observations of both blazars were triggered after a high-state alert coming from Fermi-LAT in the High Energy band (HE, 100MeV$<$E$<$100GeV). For B0218+357, a known gravitationally lensed blazar with two image components separated by ~0.3 arcsec and with a delay of 10-12 days, MAGIC observations were scheduled for the trailing pulse after a strong flare in July 2014 and resulted in a detection during only 2 nights. For PKS1441+25, the long-lasting flare allowed the MAGIC collaboration to cover the highest activity state and its gradual decay to the quiescent state.Stephan O’Brien - TeV Observations of Hard Spectrum BL Lac objects with VERITAS
Toggle Cloak Cloak High-Frequency-Peaked BL Lac objects (HBLs) are the most-intense sources of VHE emission, dominating the extragalactic VHE (E > 100 GeV) night sky. HBLs have been observed to vary across all wavelengths and on timescales ranging from minutes to years. VHE observations of a number of HBLs made with the VERITAS telescope array will be reported. Combined data taken between 2007 and 2016 will be used to derive time-averaged spectra, compare spectral models and determine the highest energies probed by the observations. This will be done using advanced forward-folding spectral reconstruction methods. Flux variability will also be investigated on nightly and seasonal timescales. Methods for combining the VHE spectra with Fermi-LAT data, allowing constraints to be placed on the extragalactic background light (EBL), will also be discussed.
- Zhaoqiang Shen
Mon., June 6
Nicolas Vasquez - Developing Water Cherenkov Detectors in Quito, Ecuador
Toggle Cloak Cloak The Ecuadorian Andes located around zero latitude offers altitudes over 3000 m.a.s.l. which is an advantage to the detection of astroparticles. The aim of this work is to present the progress done by our research team on the developing WCD. Starting with an introduction of astroparticle detection, we present the simulations in CORSIKA of atmospheric extensive showers originated from primary particles with energies within 10 GeV and 100 TeV in Quito. We continue with the instrumentation used in our detectors to finally present some results of the muon detection in our city.
Sara Coutiño - Extragalactic background light study with HAWC
Toggle Cloak Cloak The extragalactic background light (EBL) is all the electromagnetic energy released by resolved and unresolved extragalactic sources since the recombination era. Its intensity and spectral shape provide information about the evolution of galaxies throughout cosmic history. Since direct observations of the EBL are very difficult to perform, the study of the interaction between the low energy EBL photons and high energy photons from distant extragalactic sources becomes relevant to constrain the EBL intensity. The main goal of this study is to investigate the opacity of the EBL to gamma rays by observing a sample of active galactic nuclei (AGN) with the High Altitude Water Cherenkov (HAWC) Gamma-Ray Observatory. Current gamma-ray observations up to 20 TeV performed by Imaging Atmospheric Cherenkov Telescopes (IACTs) have constrained the EBL intensity in the 0.150 μm region. HAWC, which monitors the gamma-ray sky in the 100 GeV to 100 TeV energy range, will be able to detect about 10 AGN with the first year of HAWC data based on the extrapolation of steady-state spectra from the GeV band to TeV, and thus constrain the EBL in the poorly measured 1100 μm range.
- Yuanzhu Wang
- Yongbo Yu
- Christian Johnson
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