Surveying the X-ray Behavior of Novae as They Emit $\gamma$-rays

Abstract

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 $\sim 10^7$ K, resulting in detectable X-ray emission. In this paper, we investigate 13 $\gamma$-ray emitting novae observed with the Neil Gehrels $Swift$ Observatory, searching for 1-10 keV X-ray emission concurrent with $\gamma$-ray detections. We also analyze $\gamma$-ray observations of novae V407 Lup (2016) and V357 Mus (2018). We find that most novae do eventually show X-ray evidence of hot shocked plasma, but not until the $\gamma$-rays have faded below detectability. We suggest that the delayed rise of the X-ray emission is due to large absorbing columns and/or X-ray suppression by corrugated shock fronts. The only nova in our sample with a concurrent X-ray/$\gamma$-ray detection is also the only embedded nova (V407 Cyg). This exception supports a scenario where novae with giant companions produce shocks with external circumbinary material and are characterized by lower density environments, in comparison with novae with dwarf companions where shocks occur internal to the dense ejecta.

23 pages, 19 figures, submitted to ApJ

References in corpus (19)

• An online repository of Swift/XRT light curves of GRBs
• Gamma-Ray Emission Concurrent with the Nova in the Symbiotic Binary V407 Cygni
• Fermi Establishes Classical Novae as a Distinct Class of Gamma-Ray Sources
• X-Ray Emitting Blast Wave from the Recurrent Nova RS Ophiuchi
• The Super-Soft X-ray Phase of Nova RS Ophiuchi 2006
• Gamma-ray novae as probes of relativistic particle acceleration at non-relativistic shocks
• Shocks in nova outflows. I. Thermal emission
• A Nova Outburst Powered by Shocks
• Constraints on the space density of intermediate polars from the Swift-BAT survey
• Early spectral evolution of classical novae: consistent evidence for multiple distinct outflows
• The Radio Light Curve of the Gamma-Ray Nova in V407 Cyg: Thermal Emission from the Ionized Symbiotic Envelope, Devoured from Within by the Nova Blast
• NuSTAR Detection of X-rays Concurrent with Gamma Rays in the Nova V5855 Sgr
• The Distance to Nova V959 Mon from VLA Imaging
• X-ray Spectroscopy of the gamma-ray Brightest Nova V906 Car (ASASSN-18fv)
• The 2019 eruption of recurrent nova V3890 Sgr: observations by Swift, NICER and SMARTS
• The sustained post-outburst brightness of Nova Per 2018, the evolved companion, and the long orbital period
• Early multiwavelength analysis of the recurrent nova V745 Sco
• Fermi-LAT Observations of V549 Vel 2017: a Sub-Luminous Gamma-Ray Nova?
• Near-infrared studies of V5558 Sgr: an unusually slow nova with multiple outbursts

Cited by in corpus (25)

• New Insights into Classical Novae
• Classical Novae at Radio Wavelengths
• Evidence for multiple shocks from the $\gamma$-ray emission of RS Ophiuchi
• The first nova eruption in a novalike variable: YZ Ret as seen in X-rays and gamma-rays
• The multi-wavelength view of shocks in the fastest nova V1674 Her
• A strong shock during a nova outburst: an origin of multiple velocity systems in optical spectra and of high-energy emissions
• Transients from the Cataclysmic Deaths of Cataclysmic Variables
• An update on Fermi-LAT transients in the Galactic plane, including strong activity of Cygnus X-3 in mid-2020
• Interpretation of the light curve of GeV-TeV emission from the 2021 outburst of the recurrent nova RS Ophiuchi
• Search for sub-TeV Neutrino Emission from Novae with IceCube-DeepCore
• Lepto-hadronic interpretation of 2021 RS Ophiuchi nova outburst
• Optical and NIR data and modelling of nova V5668 Sgr
• $\gamma$-ray Emission from Classical Nova V392 Per: Measurements from Fermi and HAWC
• Investigation of a likely orbital periodicity of Nova Hercules 2021 in X-rays and gamma-rays
• Classical Novae in the ASKAP Pilot Surveys
• Possible evidence for the 478 keV emission line from ${}^7$Be decay during the outburst phases of V1369 Cen
• For how long are particles accelerated in shells of recurrent Novae ?
• What determines the $\gamma$-ray luminosities of classical novae?
• Persistent nuclear burning in Nova Sgr 2016 N.4 (= V5856 Sgr = ASASSN-16ma) six years past its outburst
• Evidence of the gamma-ray counterpart from nova FM Cir with Fermi-LAT
• X-ray emission mechanisms in accreting white dwarfs
• Multi-wavelength study for gamma-ray nova V1405 Cas
• Discovery and Detailed Study of the M31 Classical Nova AT 2023tkw: Evidence for Internal Shocks
• Viability of novae as sources of Galactic lithium
• AT 2019qyl in NGC 300: Internal Collisions in the Early Outflow from a Very Fast Nova in a Symbiotic Binary