NuSTAR Detection of X-Rays Concurrent with Gamma-Rays in the Nova V5855 Sgr

Thomas Nelson, Koji Mukai, Kwan-Lok Li, Indrek Vurm, Brian D. Metzger, Laura Chomiuk, J. L. Sokoloski, Justin D. Linford, Terry Bohlsen, Paul Luckas

Research output: Contribution to journalArticle

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Abstract

We report the first detection of hard (>10 keV) X-ray emission simultaneous with gamma-rays in a nova eruption. Observations of the nova V5855 Sgr carried out with the NuSTAR satellite on Day 12 of the eruption revealed faint, highly absorbed thermal X-rays. The extreme equivalent hydrogen column density toward the X-ray emitting region (∼3 × 1024 cm‑2) indicates that the shock producing the X-rays was deeply embedded within the nova ejecta. The slope of the X-ray spectrum favors a thermal origin for the bulk of the emission, and the constraints of the temperature in the shocked region suggest a shock velocity compatible with the ejecta velocities inferred from optical spectroscopy. While we do not claim the detection of nonthermal X-rays, the data do not allow us to rule out an additional, fainter component dominating at energies above 20 keV, for which we obtained upper limits. The inferred luminosity of the thermal X-rays is too low to be consistent with the gamma-ray luminosities if both are powered by the same shock under standard assumptions regarding the efficiency of nonthermal particle acceleration and the temperature distribution of the shocked gas.
Original languageEnglish
Article number86
JournalThe Astrophysical Journal
Volume872
Issue number1
DOIs
Publication statusPublished - 10 Feb 2019

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gamma rays
x rays
shock
luminosity
particle acceleration
volcanic eruptions
detection
rays
volcanic eruption
spectroscopy
hydrogen
slopes
gases
gas
energy
temperature

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Nelson, Thomas ; Mukai, Koji ; Li, Kwan-Lok ; Vurm, Indrek ; Metzger, Brian D. ; Chomiuk, Laura ; Sokoloski, J. L. ; Linford, Justin D. ; Bohlsen, Terry ; Luckas, Paul. / NuSTAR Detection of X-Rays Concurrent with Gamma-Rays in the Nova V5855 Sgr. In: The Astrophysical Journal. 2019 ; Vol. 872, No. 1.
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abstract = "We report the first detection of hard (>10 keV) X-ray emission simultaneous with gamma-rays in a nova eruption. Observations of the nova V5855 Sgr carried out with the NuSTAR satellite on Day 12 of the eruption revealed faint, highly absorbed thermal X-rays. The extreme equivalent hydrogen column density toward the X-ray emitting region (∼3 × 1024 cm‑2) indicates that the shock producing the X-rays was deeply embedded within the nova ejecta. The slope of the X-ray spectrum favors a thermal origin for the bulk of the emission, and the constraints of the temperature in the shocked region suggest a shock velocity compatible with the ejecta velocities inferred from optical spectroscopy. While we do not claim the detection of nonthermal X-rays, the data do not allow us to rule out an additional, fainter component dominating at energies above 20 keV, for which we obtained upper limits. The inferred luminosity of the thermal X-rays is too low to be consistent with the gamma-ray luminosities if both are powered by the same shock under standard assumptions regarding the efficiency of nonthermal particle acceleration and the temperature distribution of the shocked gas.",
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author = "Thomas Nelson and Koji Mukai and Kwan-Lok Li and Indrek Vurm and Metzger, {Brian D.} and Laura Chomiuk and Sokoloski, {J. L.} and Linford, {Justin D.} and Terry Bohlsen and Paul Luckas",
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Nelson, T, Mukai, K, Li, K-L, Vurm, I, Metzger, BD, Chomiuk, L, Sokoloski, JL, Linford, JD, Bohlsen, T & Luckas, P 2019, 'NuSTAR Detection of X-Rays Concurrent with Gamma-Rays in the Nova V5855 Sgr' The Astrophysical Journal, vol. 872, no. 1, 86. https://doi.org/10.3847/1538-4357/aafb6d

NuSTAR Detection of X-Rays Concurrent with Gamma-Rays in the Nova V5855 Sgr. / Nelson, Thomas; Mukai, Koji; Li, Kwan-Lok; Vurm, Indrek; Metzger, Brian D.; Chomiuk, Laura; Sokoloski, J. L.; Linford, Justin D.; Bohlsen, Terry; Luckas, Paul.

In: The Astrophysical Journal, Vol. 872, No. 1, 86, 10.02.2019.

Research output: Contribution to journalArticle

TY - JOUR

T1 - NuSTAR Detection of X-Rays Concurrent with Gamma-Rays in the Nova V5855 Sgr

AU - Nelson, Thomas

AU - Mukai, Koji

AU - Li, Kwan-Lok

AU - Vurm, Indrek

AU - Metzger, Brian D.

AU - Chomiuk, Laura

AU - Sokoloski, J. L.

AU - Linford, Justin D.

AU - Bohlsen, Terry

AU - Luckas, Paul

PY - 2019/2/10

Y1 - 2019/2/10

N2 - We report the first detection of hard (>10 keV) X-ray emission simultaneous with gamma-rays in a nova eruption. Observations of the nova V5855 Sgr carried out with the NuSTAR satellite on Day 12 of the eruption revealed faint, highly absorbed thermal X-rays. The extreme equivalent hydrogen column density toward the X-ray emitting region (∼3 × 1024 cm‑2) indicates that the shock producing the X-rays was deeply embedded within the nova ejecta. The slope of the X-ray spectrum favors a thermal origin for the bulk of the emission, and the constraints of the temperature in the shocked region suggest a shock velocity compatible with the ejecta velocities inferred from optical spectroscopy. While we do not claim the detection of nonthermal X-rays, the data do not allow us to rule out an additional, fainter component dominating at energies above 20 keV, for which we obtained upper limits. The inferred luminosity of the thermal X-rays is too low to be consistent with the gamma-ray luminosities if both are powered by the same shock under standard assumptions regarding the efficiency of nonthermal particle acceleration and the temperature distribution of the shocked gas.

AB - We report the first detection of hard (>10 keV) X-ray emission simultaneous with gamma-rays in a nova eruption. Observations of the nova V5855 Sgr carried out with the NuSTAR satellite on Day 12 of the eruption revealed faint, highly absorbed thermal X-rays. The extreme equivalent hydrogen column density toward the X-ray emitting region (∼3 × 1024 cm‑2) indicates that the shock producing the X-rays was deeply embedded within the nova ejecta. The slope of the X-ray spectrum favors a thermal origin for the bulk of the emission, and the constraints of the temperature in the shocked region suggest a shock velocity compatible with the ejecta velocities inferred from optical spectroscopy. While we do not claim the detection of nonthermal X-rays, the data do not allow us to rule out an additional, fainter component dominating at energies above 20 keV, for which we obtained upper limits. The inferred luminosity of the thermal X-rays is too low to be consistent with the gamma-ray luminosities if both are powered by the same shock under standard assumptions regarding the efficiency of nonthermal particle acceleration and the temperature distribution of the shocked gas.

KW - novae

KW - cataclysmic variables

KW - stars: individual: V5855 Sgr

KW - X-rays: binaries

U2 - 10.3847/1538-4357/aafb6d

DO - 10.3847/1538-4357/aafb6d

M3 - Article

VL - 872

JO - The Astrophysical Journal

JF - The Astrophysical Journal

SN - 0004-637X

IS - 1

M1 - 86

ER -