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The discovery of GeV gamma-rays from classical novae indicates that shocks and relativistic particle acceleration are energetically key in these events. Further evidence for shocks comes from thermal keV X-ray emission and an early peak in…

High Energy Astrophysical Phenomena · Physics 2016-08-31 Andrey Vlasov , Indrek Vurm , Brian Metzger

Since the Fermi discovery of $\gamma$-rays from novae, one of the biggest questions in the field has been how novae generate such high-energy emission. Shocks must be a fundamental ingredient. Six months of radio observations of the 2012…

Classical novae are shock-powered multi-wavelength transients triggered by a thermonuclear runaway on an accreting white dwarf. V1674 Her is the fastest nova ever recorded (time to declined by two magnitudes is t_2=1.1 d) that challenges…

The radio light curves of novae rise and fall over the course of months to years, allowing for detailed observations of the evolution of the nova shell. However, the main parameter determined by radio models of nova explosions - the mass of…

Gamma-ray emission at energies >100MeV has been detected from nine novae using the Fermi-LAT, and it can be explained by particle acceleration at shocks in these systems. Eight out of these nine objects are classical novae in which…

High Energy Astrophysical Phenomena · Physics 2018-04-18 Pierrick Martin , Guillaume Dubus , Pierre Jean , Vincent Tatischeff , Cyril Dosne

We present radio light curves and spectra of the classical nova V1723 Aql obtained with the Expanded Very Large Array (EVLA). This is the first paper to showcase results from the EVLA Nova Project, which comprises a team of observers and…

We present one-dimensional hydrodynamical simulations including radiative losses, of internal shocks in the outflows from classical novae, to explore the role of shocks in powering multi-wavelength emission from radio to gamma-ray…

High Energy Astrophysical Phenomena · Physics 2020-01-08 Elad Steinberg , Brian D. Metzger

The discovery that many classical novae produce detectable GeV $\gamma$-ray emission has raised the question of the role of shocks in nova eruptions. Here we use radio observations of nova V809 Cep (Nova Cep 2013) with the Jansky Very Large…

Shock interaction in classical novae occurs when a fast outflow from the white dwarf > 1000 km s/s collides with a slower, cooler shell of gas released earlier in the outburst. The shocks radiate across the electromagnetic spectrum, from…

High Energy Astrophysical Phenomena · Physics 2025-06-12 Brian D. Metzger , Lachlan Lancaster , Rebecca Diesing

In recent years, several nova explosions have been detected by Fermi/LAT at E>100 MeV, mainly early after the explosion and for a short period of time. The first evidence of particle acceleration in novae was found in the 2006 eruption of…

High Energy Astrophysical Phenomena · Physics 2019-10-22 Laura Delgado , Margarita Hernanz

Evidence for shocks in nova outflows include (1) multiple velocity components in the optical spectra; (2) keV X-ray emission weeks to months after the outburst; (3) early radio flare on timescales of months, in excess of that predicted from…

High Energy Astrophysical Phenomena · Physics 2015-06-19 Brian D. Metzger , Romain Hascoet , Indrek Vurm , Andrei M. Beloborodov , Laura Chomiuk , J. L. Sokoloski , Thomas Nelson

Novae are now firmly established as a high-energy (>100 MeV) gamma-ray source class by the Fermi Large Area Telescope (LAT). In symbiotic binary systems such as V407 Cyg 2010, there is a firm theoretical framework for the production of…

High Energy Astrophysical Phenomena · Physics 2016-05-05 C. C. Cheung , P. Jean , S. N. Shore , J. E. Grove , M. Leising

The detection of GeV $\gamma$-ray emission from Galactic novae by $Fermi$-LAT has become routine since 2010, and is generally associated with shocks internal to the nova ejecta. These shocks are also expected to heat plasma to $\sim 10^7$…

High Energy Astrophysical Phenomena · Physics 2021-04-14 Alexa C. Gordon , Elias Aydi , Kim L. Page , Kwan-Lok Li , Laura Chomiuk , Kirill V. Sokolovsky , Koji Mukai , Joseph Seitz

Classical novae in the Milky Way have now been well-established as high-energy GeV $\gamma$-ray sources. In novae with main-sequence companions, this emission is believed to result from shocks internal to the nova ejecta, as a later fast…

The Fermi LAT discovery that classical novae produce >100 MeV gamma-rays establishes that shocks and relativistic particle acceleration are key features of these events. These shocks are likely to be radiative due to the high densities of…

High Energy Astrophysical Phenomena · Physics 2015-05-20 Brian D. Metzger , Thomas Finzell , Indrek Vurm , Romain Hascoet , Andrei M. Beloborodov , Laura Chomiuk

We propose a theoretical explanation of absorption/emission line systems in classical novae based on a fully self-consistent nova explosion model. We found that a reverse shock is formed far outside the photosphere ($\gtrsim 10^{13}$ cm)…

Solar and Stellar Astrophysics · Physics 2022-11-30 Izumi Hachisu , Mariko Kato

Context. Numerous classical novae have been observed to emit {\gamma}-rays (E > 100 MeV) detected by the Fermi-LAT. The prevailing hypothesis attributes this emission to the interaction of accelerated particles within shocks in the nova…

High Energy Astrophysical Phenomena · Physics 2025-12-17 P. Fauverge , P. Jean , K. Sokolovsky , C. C. Cheung , M. Lemoine-Goumard , M. -H. Grondin , L. Chomiuk , A. Dickenson , J. D. Linford , K. Mukai , J. L. Sokoloski

The shell of the classical nova V5668 Sgr was resolved by ALMA at the frequency of 230 GHz 927 days after eruption, showing that most of the continuum bremsstrahlung emission originates in clumps with diameter smaller than $10^{15}$ cm.…

Astrophysics of Galaxies · Physics 2023-11-27 Zulema Abraham , Larissa Takeda , Pedro P. B. Beaklini , Marcos Diaz , Kim L. Page , Laura Chomiuk , Justin D. Linford

Classical novae are the most common astrophysical thermonuclear explosions, occurring on the surfaces of white dwarf stars accreting gas from companions in binary star systems. Novae typically expel ~10^(-4) solar masses of material at…

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