Veritas Observations of the Nova in V407 Cygni

Aliu, E.; Archambault, S.; Arlen, T.; Aune, T.; Beilicke, M.; Benbow, W.; Bouvier, A.; Bradbury, S. M.; Buckley, J. H.; Bugaev, V.; Byrum, K.; Cannon, A.; Cesarini, A.; Ciupik, L.; Collins-Hughes, E.; Connolly, Michael; Cui, Wei; Decerprit, G.; Dickherber, R.; Duke, C.; Dumm, J.; Dwarkadas, Vikram V.; Errando, M.; Falcone, A.; Feng, Q.; Finley, J. P.; Finnegan, G.; Fortson, L.; Furniss, A.; Galante, N.; Gall, D.; Godambe, S.; Griffin, S.; Grube, J.; Gyuk, G.; Hanna, D.; Holder, J.; Huan, Hao; Hughes, G.; Humensky, T. B.; Kaaret, Philip; Karlsson, N.; Kertzman, M.; Khassen, Y.; Kieda, D.; Krawczynski, H.; Krennrich, F.; Lang, M. J.; Lee, K.; Maier, G.; Majumdar, P.; McArthur, S.; McCann, A.; Millis, J.; Moriarty, P.; Mukherjee, R.; Nuñez, Paul D.; Ong, R. A.; Orr, M.; Otte, A. N.; Pandel, D.; Park, N.; Perkins, J. S.; Pohl, M.; Prokoph, H.; Quinn, J.; Ragan, K.; Reyes, Luis; Reynolds, P. T.; Roache, E.; Rose, H. J.; Ruppel, J.; Saxon, D. B.; Schroedter, M.; Sembroski, G. H.; Skole, C.; Smith, A. W.; Staszak, D.; Telezhinsky, I.; Tešić, G.; Theiling, M.; Thibadeau, S.; Tsurusaki, K.; Tyler, J.; Varlotta, A.; Vincent, S.; Vivier, M.; Wakely, S. P.; Ward, J. E.; Weekes, T. C.; Weinstein, A. J.R.; Weisgarber, T.; Welsing, R.; Williams, D. A.; Zitzer, B.

doi:10.1088/0004-637x/754/1/77

Cited by 38 publications

(49 citation statements)

References 27 publications

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“…MAGIC Collaboration et al (2015) presented upper limits on ∼ 0.1−1 TeV emission from V339 Del, which lie a factor of ∼ 10 below the extrapolated Fermi LAT spectrum. Similar TeV upper limits on the symbiotic nova V407 Cyg were reported by VERITAS (Aliu et al 2012). These observed cutoffs may result from an intrinsic steepening in the accelerated ion or electron spectrum, which in hadronic scenarios requires a break in the accelerated proton spectrum above E ∼ 10 − 100 GeV.…”

Section: Introductionsupporting

confidence: 85%

Novae as Tevatrons: prospects for CTA and IceCube

Metzger

Caprioli

Vurm

et al. 2016

Mon. Not. R. Astron. Soc.

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The discovery of novae as sources of ∼ 0.1 − 1 GeV gamma-rays highlights the key role of shocks and relativistic particle acceleration in these transient systems. Although there is evidence for a spectral cut-off above energies ∼ 1 − 100 GeV at particular epochs in some novae, the maximum particle energy achieved in these accelerators has remained an open question. The high densities of the nova ejecta (∼ 10 orders of magnitude larger than in supernova remnants) render the gas far upstream of the shock neutral and shielded from ionizing radiation. The amplification of the magnetic field needed for diffusive shock acceleration requires ionized gas, thus confining the acceleration process to a narrow photo-ionized layer immediately ahead of the shock. Based on the growth rate in this layer of the hybrid non-resonant cosmic ray current-driven instability (considering also ion-neutral damping), we quantify the maximum particle energy, E max , across the range of shock velocities and upstream densities of interest. We find values of E max ∼ 10 GeV -10 TeV, which are broadly consistent with the inferred spectral cut-offs, but which could also in principle lead to emission extending to higher energies ∼ > 100 GeV accessible to atmosphere Cherenkov telescopes, such as the planned Cherenkov Telescope Array (CTA). Detecting TeV neutrinos with IceCube in hadronic scenarios appears to be more challenging, although the prospects are improved for a particularly nearby event (distance ∼ < kpc) or if the shock power during the earliest, densest phases of the nova outburst is higher than is implied by the observed GeV light curves, due to downscattering of the gamma-rays by electrons within the ejecta. Novae provide ideal nearby laboratories to study magnetic field amplification and the onset of cosmic ray acceleration, because other time-dependent sources (e.g. radio supernovae) typically occur too distant to detect as gamma-ray sources.

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Section: Introductionsupporting

confidence: 85%

Novae as Tevatrons: prospects for CTA and IceCube

Metzger

Caprioli

Vurm

et al. 2016

Mon. Not. R. Astron. Soc.

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“…Hence, no more than a few events like V407 Cyg can reasonably be expected in the Fermi/LAT remaining 5−10 years of operations. In any case, our analysis suggests that novae in symbiotic systems are unlikely to be a class of TeV-emitters (Aliu et al 2012). …”

Section: The Population Of Novae In Symbiotic Systemsmentioning

confidence: 73%

Particle acceleration and non-thermal emission during the V407 Cygni nova outburst

Martin

Dubus

2013

A&A

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Context. On March 2010, the symbiotic binary V407 Cyg erupted as a result of a nova explosion. The event gave rise to a two-week long burst of ≥100 MeV γ-rays detected by Fermi/LAT, a unique observation testifying to particle acceleration in the system. Aims. The outburst can be considered a scaled-down supernova, with short dynamical time scale, and thus can constitute a test case for theories of the origin of Galactic cosmic rays. We aim at determining the properties of the accelerated particles and identifying the origin of the high-energy radiation. Methods. We developed a model for diffusive shock acceleration and non-thermal emission in V407 Cyg, complemented by an evaluation of the thermal emission from the shocked plasma. We considered both leptonic and hadronic contributions to the non-thermal processes, and investigated the effect of many binary and nova parameters.Results. The γ-ray emission is mostly of leptonic origin and arises predominantly from inverse-Compton scattering of the nova light. Matching the light curve requires gas accumulation in the vicinity of the white dwarf, as a consequence of wind accretion, while the spectrum imposes particle scattering close to the Bohm limit in the upstream equipartition magnetic field. The nova accelerated protons (respectively electrons) with energies up to 300 GeV (respectively 20 GeV), for a total non-thermal energy 10 43 erg after two weeks, representing 10% of the initial nova kinetic energy. The electron-to-proton ratio at injection is 6%. Conclusions. The V407 Cyg eruption can be understood from the same principles that are invoked for particle acceleration in supernova remnants, although without the need for strong magnetic field amplification. The population of novae in symbiotic systems is a negligible source of Galactic cosmic rays, and most likely not a class of TeV-emitters.

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“…At the highest energies, one can anticipate very high energy (VHE; >0.1 TeV) emission and a transient neutrino signal in the pion-decay scenario for symbiotic novae (Razzaque et al 2010;Aliu et al 2012;Bednarek 2013) and for classical novae (Ahnen et al 2015;Metzger et al 2016). Among the recurrent novae with shorter recurrence times (Schaefer 2010), we may anticipate an explosion from RS Oph during the Fermi mission and in the era of the upcoming Cerenkov Telescope Array.…”

Section: Discussionmentioning

confidence: 99%

Fermi-Lat Gamma-Ray Detections of Classical Novae V1369 Centauri 2013 and V5668 Sagittarii 2015

Cheung

Jean

Shore

et al. 2016

ApJ

108

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We report the Fermi Large Area Telescope (LAT) detections of high-energy (>100 MeV) γ-ray emission from two recent optically bright classical novae, V1369 Centauri 2013 and V5668 Sagittarii 2015. At early times, Fermi target-of-opportunity observations prompted by their optical discoveries provided enhanced LAT exposure that enabled the detections of γ-ray onsets beginning ∼2 days after their first optical peaks. Significant γ-ray emission was found extending to 39-55 days after their initial LAT detections, with systematically fainter and longerduration emission compared to previous γ-ray-detected classical novae. These novae were distinguished by multiple bright optical peaks that encompassed the time spans of the observed γ-rays. The γ-ray light curves and spectra of the two novae are presented along with representative hadronic and leptonic models, and comparisons with other novae detected by the LAT are discussed.

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Veritas Observations of the Nova in V407 Cygni

Cited by 38 publications

References 27 publications

Novae as Tevatrons: prospects for CTA and IceCube

Novae as Tevatrons: prospects for CTA and IceCube

Particle acceleration and non-thermal emission during the V407 Cygni nova outburst

Fermi-Lat Gamma-Ray Detections of Classical Novae V1369 Centauri 2013 and V5668 Sagittarii 2015

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