Very High Energy Observations of Gamma‐Ray Burst Locations with the Whipple Telescope

Horan, D.; Atkins, R.; Badran, H. M.; Blaylock, G.; Bradbury, S. M.; Buckley, J. H.; Byrum, K.; Çelik, Ö.; Chow, Y. C. K.; Cogan, P.; Cui, Wei; Daniel, M. K.; Pérez, I. de la Calle; Dowdall, C.; Falcone, A.; Fegan, D. J.; Fegan, S. J.; Finley, J. P.; Fortin, P.; Fortson, L.; Gillanders, G. H.; Grube, J.; Gutierrez, K.; Hall, J.; Hanna, D.; Holder, J.; Hughes, Shaun M. G.; Humensky, T. B.; Kenny, G. E.; Kertzman, M.; Kieda, D.; Kildea, J.; Krawczynski, H.; Krennrich, F.; Lang, M. J.; LeBohec, S.; Maier, G.; Moriarty, P.; Nagai, T.; Ong, R. A.; Perkins, J. S.; Petry, D.; Quinn, J.; Quinn, M.; Ragan, K.; Reynolds, P. T.; Rose, H. J.; Schroedter, M.; Sembroski, G. H.; Steele, D.; Swordy, S. P.; Toner, J. A.; Valcarcel, L.; Vassiliev, V. V.; Wagner, R. G.; Wakely, S. P.; Weekes, T. C.; White, R.; Williams, D. A.

doi:10.1086/509567

Cited by 23 publications

(20 citation statements)

References 71 publications

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“…These data are essential for the excellent temporal coverage in the VHE for this campaign. Details on the light curve presented here can be found in Pichel (2009) with the general Whipple analysis technique described in Horan et al (2007) and Acciari et al (2014). The frequencies/wavelengths covered by the campaign are radio (2.6-225 GHz), near-infrared (J, H and K), optical (B, V, g, R and I), UV (Swift/UVOT W1, W2 and M2), X-ray (0.3-195 keV), high-energy (HE) γ rays (0.1-400 GeV) and .…”

Section: The 2009 Multi-wavelength Campaignmentioning

confidence: 99%

The 2009 multiwavelength campaign on Mrk 421: Variability and correlation studies

Aleksić¹,

Ansoldi²,

Antonelli³

et al. 2015

A&A

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105

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Aims. We perform an extensive characterization of the broadband emission of Mrk 421, as well as its temporal evolution, during the non-flaring (low) state. The high brightness and nearby location (z = 0.031) of Mrk 421 make it an excellent laboratory to study blazar emission. The goal is to learn about the physical processes responsible for the typical emission of Mrk 421, which might also be extended to other blazars that are located farther away and hence are more difficult to study. Methods. We performed a 4.5-month multi-instrument campaign on Mrk 421 between January 2009 and June 2009, which included VLBA, F-GAMMA, GASP-WEBT, Swift, RXTE, Fermi-LAT, MAGIC, and Whipple, among other instruments and collaborations. This extensive radio to very-high-energy (VHE; E > 100 GeV) γ-ray dataset provides excellent temporal and energy coverage, which allows detailed studies of the evolution of the broadband spectral energy distribution. Results. Mrk421 was found in its typical (non-flaring) activity state, with a VHE flux of about half that of the Crab Nebula, yet the light curves show significant variability at all wavelengths, the highest variability being in the X-rays. We determined the power spectral densities (PSD) at most wavelengths and found that all PSDs can be described by power-laws without a break, and with indices consistent with pink/red-noise behavior. We observed a harder-when-brighter behavior in the X-ray spectra and measured a positive correlation between VHE and X-ray fluxes with zero time lag. Such characteristics have been reported many times during flaring activity, but here they are reported for the first time in the non-flaring state. We also observed an overall anti-correlation between optical/UV and X-rays extending over the duration of the campaign.Appendix A is available in electronic form at http://www.aanda.org The complete data set shown in Fig. 1 Article published by EDP Sciences A126, page 1 of 18 A&A 576, A126 (2015) Conclusions. The harder-when-brighter behavior in the X-ray spectra and the measured positive X-ray/VHE correlation during the 2009 multiwavelength campaign suggests that the physical processes dominating the emission during non-flaring states have similarities with those occurring during flaring activity. In particular, this observation supports leptonic scenarios as being responsible for the emission of Mrk 421 during nonflaring activity. Such a temporally extended X-ray/VHE correlation is not driven by any single flaring event, and hence is difficult to explain within the standard hadronic scenarios. The highest variability is observed in the X-ray band, which, within the one-zone synchrotron self-Compton scenario, indicates that the electron energy distribution is most variable at the highest energies.

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Section: The 2009 Multi-wavelength Campaignmentioning

confidence: 99%

The 2009 multiwavelength campaign on Mrk 421: Variability and correlation studies

Aleksić¹,

Ansoldi²,

Antonelli³

et al. 2015

A&A

Self Cite

105

View full text Add to dashboard Cite

show abstract

“…Atkins et al 2005;Albert et al 2007;Horan et al 2007;Aharonian et al 2009), but some of the components discussed above may be eventually observed by current ground-based facilities such as MAGIC (II), HESS (II), VERITAS, CANGAROO III, or the future projects CTA, AGIS, HAWC, etc. For example, MAGIC may detect the luminous proton synchrotron emission for ǫ B /ǫ e = 100 in Figure 5 at 0.1 TeV beyond z ∼ 1, assuming E γ,iso = 10 53 erg and the latest estimates of intergalactic γγ absorption (Albert et al 2008).…”

Section: Observational Implicationsmentioning

confidence: 99%

Prompt High-Energy Emission From Proton-Dominated Gamma-Ray Bursts

Asano

Inoue

Mészáros

2009

ApJ

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The prompt emission of gamma-ray bursts (GRBs) is widely thought to be radiation from accelerated electrons, but an appreciably larger amount of energy could be carried by accelerated protons, particularly if GRBs are the sources of ultra-high-energy cosmic rays (UHECRs). We model the expected photon spectra for such "proton-dominated" GRBs in the internal shock scenario through Monte Carlo simulations, accounting for various processes related to high-energy electrons and protons. Besides proton and muon synchrotron components, emission from photomeson-induced secondary pair cascades becomes crucial, generally enhancing the GeV-TeV and/or eV-keV photons and offering a signature of UHE protons. In some cases, it can overwhelm the primary electron component and result in GRBs peaking in the 10 MeV -1 GeV range, which may be relevant to some bursts discussed in a recent re-analysis of EGRET TASC data. The dependence of the spectra on key quantities such as the bulk Lorentz factor, magnetic field and proton-to-electron ratio is nontrivial due to the nonlinear nature of cascading and the interplay of electron-and proton-induced components. Observations by Fermi, ground-based telescopes and other facilities should test these expectations and provide critical constraints on the proton acceleration efficiency.

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“…Although GeV emission was detected from several GRBs by EGRET (Dingus 2003 and references therein), firm detections have yet to be achieved at TeV energies (e.g., Atkins et al 2005;Albert et al 2007;Horan et al 2007;Tam et al 2007). Theoretical expectations for the high-energy component depend strongly on the emission mechanism and the physical parameters.…”

Section: Introductionmentioning

confidence: 99%

Detectability of Pair Echoes from Gamma-Ray Bursts and Intergalactic Magnetic Fields

Takahashi

Murase

Ichiki

et al. 2008

ApJ

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High-energy emission from gamma-ray bursts (GRBs) can give rise to pair echoes, i.e., delayed inverse Compton emission from secondary electron-positron pairs produced in photon-photon interactions with intergalactic background radiation. We investigate the detectability of such emission with modern-day gamma-ray telescopes. The spectra and light curves are calculated for a wide range of parameters, applying the formalism recently developed by Ichiki et al. The flux depends strongly on the unknown magnitude and coherence length of intergalactic magnetic fields, and we delineate the range of field strength and redshift that allow detectable echoes. Relevant uncertainties such as the high-energy cutoff of the primary gamma-ray spectrum and the intensity of the cosmic infrared background are addressed. GLAST and MAGIC may be able to detect pair echo emission from GRBs with redshift Շ1 if the primary spectra extend to ∼10 TeV, offering a unique probe of intergalactic magnetic fields.

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Very High Energy Observations of Gamma‐Ray Burst Locations with the Whipple Telescope

Abstract: Gamma-ray burst (GRB) observations at very high energies (VHE, E > 100 GeV) can impose tight constraints on some GRB emission models. Many

Cited by 23 publications

References 71 publications

The 2009 multiwavelength campaign on Mrk 421: Variability and correlation studies

The 2009 multiwavelength campaign on Mrk 421: Variability and correlation studies

Prompt High-Energy Emission From Proton-Dominated Gamma-Ray Bursts

Detectability of Pair Echoes from Gamma-Ray Bursts and Intergalactic Magnetic Fields

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