First NuSTAR Limits on Quiet Sun Hard X-Ray Transient Events
| Autor: | William W. Craig, Andrew J. Marsh, Säm Krucker, Lindsay Glesener, David M. Smith, Paul J. Wright, Fiona A. Harrison, Stephen M. White, Amir Caspi, Iain G. Hannah, Charles J. Hailey, Brian W. Grefenstette, Steven E. Boggs, Matej Kuhar, Finn Erland Christensen, Kristin K. Madsen, Hugh S. Hudson, Daniel Stern, William W. Zhang |
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| Jazyk: | angličtina |
| Rok vydání: | 2017 |
| Předmět: |
Solar minimum
X-ray transient Photon 010504 meteorology & atmospheric sciences Astrophysics::High Energy Astrophysical Phenomena FOS: Physical sciences Astrophysics 01 natural sciences law.invention Telescope Physics - Space Physics law 0103 physical sciences Astrophysics::Solar and Stellar Astrophysics 010303 astronomy & astrophysics Solar and Stellar Astrophysics (astro-ph.SR) 0105 earth and related environmental sciences High Energy Astrophysical Phenomena (astro-ph.HE) Physics Solar flare flares - sun: X-rays [Sun] Gamma rays Gamma ray Astronomy and Astrophysics Space Physics (physics.space-ph) Physics - Plasma Physics Plasma Physics (physics.plasm-ph) Astrophysics - Solar and Stellar Astrophysics 13. Climate action Space and Planetary Science QUIET Physics::Space Physics Satellite Astrophysics::Earth and Planetary Astrophysics Astrophysics - High Energy Astrophysical Phenomena |
| Zdroj: | Marsh, A J, Smith, D M, Glesener, L, Hannah, I G, Grefenstette, B W, Caspi, A, Krucker, S, Hudson, H S, Madsen, K K, White, S M, Kuhar, M, Wright, P J, Boggs, S E, Christensen, F E, Craig, W W, Hailey, C J, Harrison, F A, Stern, D & Zhang, W W 2017, ' First NuSTAR Limits on Quiet Sun Hard X-Ray Transient Events ', Astrophysical Journal Supplement Series, vol. 849, no. 2, 131 . https://doi.org/10.3847/1538-4357/aa9122 |
| ISSN: | 1538-4357 |
| DOI: | 10.3847/1538-4357/aa9122 |
| Popis: | We present the first results of a search for transient hard X-ray (HXR) emission in the quiet solar corona with the \textit{Nuclear Spectroscopic Telescope Array} (\textit{NuSTAR}) satellite. While \textit{NuSTAR} was designed as an astrophysics mission, it can observe the Sun above 2~keV with unprecedented sensitivity due to its pioneering use of focusing optics. \textit{NuSTAR} first observed quiet Sun regions on 2014 November 1, although out-of-view active regions contributed a notable amount of background in the form of single-bounce (unfocused) X-rays. We conducted a search for quiet Sun transient brightenings on time scales of 100 s and set upper limits on emission in two energy bands. We set 2.5--4~keV limits on brightenings with time scales of 100 s, expressed as the temperature T and emission measure EM of a thermal plasma. We also set 10--20~keV limits on brightenings with time scales of 30, 60, and 100 s, expressed as model-independent photon fluxes. The limits in both bands are well below previous HXR microflare detections, though not low enough to detect events of equivalent T and EM as quiet Sun brightenings seen in soft X-ray observations. We expect future observations during solar minimum to increase the \textit{NuSTAR} sensitivity by over two orders of magnitude due to higher instrument livetime and reduced solar background. 11 pages, 7 figures; accepted for publication in The Astrophysical Journal |
| Databáze: | OpenAIRE |
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