Solar Physics

, Volume 290, Issue 12, pp 3625–3639 | Cite as

Soft X-Ray Pulsations in Solar Flares

  • P. J. A. Simões
  • H. S. Hudson
  • L. Fletcher
Solar and Stellar Flares


The soft X-ray emissions (>1.5 keV) of solar flares mainly come from the bright coronal loops at the highest temperatures normally achieved in the flare process. Their ubiquity has led to their use as a standard measure of flare occurrence and energy, although the overwhelming bulk of the total flare energy goes elsewhere. Recently Dolla et al. (Astrophys. J. Lett. 749, L16, 2012) noted quasi-periodic pulsations (QPP) in the soft X-ray signature of the X-class flare SOL2011-02-15, as observed by the standard photometric data from the GOES (Geostationary Operational Environmental Satellite) spacecraft. In this article we analyse the suitability of the GOES data for this type of analysis and find them to be generally valuable after September, 2010 (GOES-15). We then extend the result of Dolla et al. to a complete list of X-class flares from Cycle 24 and show that most of them (80 %) display QPPs in the impulsive phase. The pulsations show up cleanly in both channels of the GOES data, making use of time-series of irradiance differences (the digital time derivative on the 2-s sampling). We deploy different techniques to characterise the periodicity of GOES pulsations, considering the red-noise properties of the flare signals, finding a range of characteristic time scales of the QPPs for each event, but usually with no strong signature of a single period dominating in the power spectrum. The QPP may also appear on somewhat longer time scales during the later gradual phase, possibly with a greater tendency towards coherence, but the sampling noise in GOES difference data for high irradiance values (X-class flares) makes these more uncertain. We show that there is minimal phase difference between the differenced GOES energy channels, or between them and the hard X-ray variations on short time scales. During the impulsive phase, the footpoints of the newly forming flare loops may also contribute to the observed soft X-ray variations.


Flares, impulsive phase Oscillations, solar X-ray bursts, hard X-ray bursts, soft 



We would like to thank the anonymous referee for the comments and suggestions that helped to improve the paper. We would like to thank Marie Dominique and Rodney Viereck for helpful discussions. HSH thanks NASA for support under contract NAS 5-98033 for RHESSI, and acknowledges warm hospitality at the University of Glasgow. The research leading to these results has received funding from the European Community’s Seventh Framework Programme (FP7/2007-2013) under grant agreement no. 606862 (F-CHROMA) (PJAS, LF), from STFC grant ST/I001808/1 (PJAS, LF) and ST/L000741/1 (LF).


  1. Ackermann, M., Ajello, M., Albert, A., Allafort, A., Baldini, L., Barbiellini, G., Bastieri, D., Bechtol, K., Bellazzini, R., Bissaldi, E., Bonamente, E., Bottacini, E., Bouvier, A., Brandt, T.J., Bregeon, J., Brigida, M., Bruel, P., Buehler, R., Buson, S., Caliandro, G.A., Cameron, R.A., Caraveo, P.A., Cecchi, C., Charles, E., Chekhtman, A., Chen, Q., Chiang, J., Chiaro, G., Ciprini, S., Claus, R., Cohen-Tanugi, J., Conrad, J., Cutini, S., D’Ammando, F., de Angelis, A., de Palma, F., Dermer, C.D., Desiante, R., Digel, S.W., Di Venere, L., Silva, E.d.C.e., Drell, P.S., Drlica-Wagner, A., Favuzzi, C., Fegan, S.J., Focke, W.B., Franckowiak, A., Fukazawa, Y., Funk, S., Fusco, P., Gargano, F., Gasparrini, D., Germani, S., Giglietto, N., Giordano, F., Giroletti, M., Glanzman, T., Godfrey, G., Grenier, I.A., Grove, J.E., Guiriec, S., Hadasch, D., Hayashida, M., Hays, E., Horan, D., Hughes, R.E., Inoue, Y., Jackson, M.S., Jogler, T., Jóhannesson, G., Johnson, W.N., Kamae, T., Kawano, T., Knödlseder, J., Kuss, M., Lande, J., Larsson, S., Latronico, L., Lemoine-Goumard, M., Longo, F., Loparco, F., Lott, B., Lovellette, M.N., Lubrano, P., Mayer, M., Mazziotta, M.N., McEnery, J.E., Michelson, P.F., Mizuno, T., Moiseev, A.A., Monte, C., Monzani, M.E., Moretti, E., Morselli, A., Moskalenko, I.V., Murgia, S., Murphy, R., Nemmen, R., Nuss, E., Ohno, M., Ohsugi, T., Okumura, A., Omodei, N., Orienti, M., Orlando, E., Ormes, J.F., Paneque, D., Panetta, J.H., Perkins, J.S., Pesce-Rollins, M., Petrosian, V., Piron, F., Pivato, G., Porter, T.A., Rainò, S., Rando, R., Razzano, M., Reimer, A., Reimer, O., Ritz, S., Schulz, A., Sgrò, C., Siskind, E.J., Spandre, G., Spinelli, P., Takahashi, H., Takeuchi, Y., Tanaka, Y., Thayer, J.G., Thayer, J.B., Thompson, D.J., Tibaldo, L., Tinivella, M., Tosti, G., Troja, E., Tronconi, V., Usher, T.L., Vandenbroucke, J., Vasileiou, V., Vianello, G., Vitale, V., Werner, M., Winer, B.L., Wood, D.L., Wood, K.S., Wood, M., Yang, Z.: 2014, High-energy gamma-ray emission from solar flares: Summary of Fermi large area telescope detections and analysis of two M-class flares. Astrophys. J. 787, 15.  DOI. ADS. CrossRefADSGoogle Scholar
  2. Asai, A., Shimojo, M., Isobe, H., Morimoto, T., Yokoyama, T., Shibasaki, K., Nakajima, H.: 2001, Periodic acceleration of electrons in the 1998 November 10 solar flare. Astrophys. J. Lett. 562, L103.  DOI. ADS. CrossRefADSGoogle Scholar
  3. Aschwanden, M.J., Fletcher, L., Schrijver, C.J., Alexander, D.: 1999, Coronal loop oscillations observed with the Transition Region and Coronal Explorer. Astrophys. J. 520, 880.  DOI. ADS. CrossRefADSGoogle Scholar
  4. Chamberlin, P.C., Woods, T.N., Eparvier, F.G., Jones, A.R.: 2009, Next generation X-ray sensor (XRS) for the NOAA GOES-R satellite series. In: SPIE CS-7438.  DOI. ADS. Google Scholar
  5. Dennis, B.R., Zarro, D.M.: 1993, The Neupert effect – What can it tell us about the impulsive and gradual phases of solar flares? Solar Phys. 146, 177.  DOI. ADS. CrossRefADSGoogle Scholar
  6. Dolla, L., Marqué, C., Seaton, D.B., Van Doorsselaere, T., Dominique, M., Berghmans, D., Cabanas, C., De Groof, A., Schmutz, W., Verdini, A., West, M.J., Zender, J., Zhukov, A.N.: 2012, Time delays in quasi-periodic pulsations observed during the X2.2 solar flare on 2011 February 15. Astrophys. J. Lett. 749, L16.  DOI. ADS. CrossRefADSGoogle Scholar
  7. Fletcher, L., Hudson, H.S.: 2008, Impulsive phase flare energy transport by large-scale Alfvén w aves and the electron acceleration problem. Astrophys. J. 675, 1645.  DOI. ADS. CrossRefADSGoogle Scholar
  8. Fletcher, L., Dennis, B.R., Hudson, H.S., Krucker, S., Phillips, K., Veronig, A., Battaglia, M., Bone, L., Caspi, A., Chen, Q., Gallagher, P., Grigis, P.T., Ji, H., Liu, W., Milligan, R.O., Temmer, M.: 2011, An observational overview of solar flares. Space Sci. Rev. 159, 19.  DOI. ADS. CrossRefADSGoogle Scholar
  9. Gruber, D., Lachowicz, P., Bissaldi, E., Briggs, M.S., Connaughton, V., Greiner, J., van der Horst, A.J., Kanbach, G., Rau, A., Bhat, P.N., Diehl, R., von Kienlin, A., Kippen, R.M., Meegan, C.A., Paciesas, W.S., Preece, R.D., Wilson-Hodge, C.: 2011, Quasi-periodic pulsations in solar flares: new clues from the Fermi Gamma-Ray Burst Monitor. Astron. Astrophys. 533, A61.  DOI. ADS. CrossRefADSGoogle Scholar
  10. Hudson, H.S., Warmuth, A.: 2004, Coronal loop oscillations and flare shock waves. Astrophys. J. Lett. 614, L85.  DOI. ADS. CrossRefADSGoogle Scholar
  11. Hudson, H.S., Strong, K.T., Dennis, B.R., Zarro, D., Inda, M., Kosugi, T., Sakao, T.: 1994, Impulsive behavior in solar soft X-radiation. Astrophys. J. Lett. 422, L25.  DOI. ADS. CrossRefADSGoogle Scholar
  12. Inglis, A.R., Ireland, J., Dominique, M.: 2015, Quasi-periodic pulsations in solar and stellar flares: Re-evaluating their nature in the context of power-law flare Fourier spectra. Astrophys. J. 798, 108.  DOI. ADS. CrossRefADSGoogle Scholar
  13. Inglis, A.R., Nakariakov, V.M.: 2009, A multi-periodic oscillatory event in a solar flare. Astron. Astrophys. 493, 259.  DOI. ADS. CrossRefADSGoogle Scholar
  14. Inglis, A.R., Nakariakov, V.M., Melnikov, V.F.: 2008, Multi-wavelength spatially resolved analysis of quasi-periodic pulsations in a solar flare. Astron. Astrophys. 487, 1147.  DOI. ADS. CrossRefADSGoogle Scholar
  15. Ireland, J., McAteer, R.T.J., Inglis, A.R.: 2015, Coronal Fourier power spectra: Implications for coronal seismology and coronal heating. Astrophys. J. 798, 1.  DOI. ADS. CrossRefADSGoogle Scholar
  16. Janssens, T.J., White, K.P. III: 1969, Microwave pulse trains observed before and during a solar flare. Astrophys. J. Lett. 158, L127.  DOI. ADS. CrossRefADSGoogle Scholar
  17. Kallunki, J., Pohjolainen, S.: 2012, Radio pulsating structures with coronal loop contraction. Solar Phys. 280, 491.  DOI. ADS. CrossRefADSGoogle Scholar
  18. Kupriyanova, E.G., Melnikov, V.F., Nakariakov, V.M., Shibasaki, K.: 2010, Types of microwave quasi-periodic pulsations in single flaring loops. Solar Phys. 267, 329.  DOI. ADS. CrossRefADSGoogle Scholar
  19. Mariska, J.T.: 2005, Observations of solar flare Doppler shift oscillations with the Bragg crystal spectrometer on Yohkoh. Astrophys. J. Lett. 620, L67.  DOI. ADS. CrossRefADSGoogle Scholar
  20. Mariska, J.T.: 2006, Characteristics of solar flare Doppler-shift oscillations observed with the Bragg crystal spectrometer on Yohkoh. Astrophys. J. 639, 484.  DOI. ADS. CrossRefADSGoogle Scholar
  21. McTiernan, J.M., Kane, S.R., Loran, J.M., Lemen, J.R., Acton, L.W., Hara, H., Tsuneta, S., Kosugi, T.: 1993, Temperature and density structure of the 1991 November 2 flare observed by the YOHKOH soft X-ray telescope and hard X-ray telescope. Astrophys. J. Lett. 416, L91+.  DOI. ADS. CrossRefADSGoogle Scholar
  22. Meegan, C., Lichti, G., Bhat, P.N., Bissaldi, E., Briggs, M.S., Connaughton, V., Diehl, R., Fishman, G., Greiner, J., Hoover, A.S., van der Horst, A.J., von Kienlin, A., Kippen, R.M., Kouveliotou, C., McBreen, S., Paciesas, W.S., Preece, R., Steinle, H., Wallace, M.S., Wilson, R.B., Wilson-Hodge, C.: 2009, The Fermi Gamma-Ray Burst Monitor. Astrophys. J. 702, 791.  DOI. ADS. CrossRefADSGoogle Scholar
  23. Melnikov, V.F., Reznikova, V.E., Shibasaki, K., Nakariakov, V.M.: 2005, Spatially resolved microwave pulsations of a flare loop. Astron. Astrophys. 439, 727.  DOI. ADS. CrossRefADSGoogle Scholar
  24. Mrozek, T., Tomczak, M.: 2004, Solar impulsive soft X-ray brightenings and their connection with footpoint hard X-ray emission sources. Astron. Astrophys. 415, 377.  DOI. ADS. CrossRefADSGoogle Scholar
  25. Nakariakov, V.M., Melnikov, V.F.: 2009, Quasi-periodic pulsations in solar flares. Space Sci. Rev. 149, 119.  DOI. ADS. CrossRefADSGoogle Scholar
  26. Nakariakov, V.M., Melnikov, V.F., Reznikova, V.E.: 2003, Global sausage modes of coronal loops. Astron. Astrophys. 412, L7.  DOI. ADS. CrossRefADSGoogle Scholar
  27. Nakariakov, V.M., Verwichte, E.: 2005, Coronal waves and oscillations. Living Rev. Solar Phys. 2, 3.  DOI. ADS. CrossRefADSGoogle Scholar
  28. Nakariakov, V.M., Zimovets, I.V.: 2011, Slow magnetoacoustic waves in two-ribbon flares. Astrophys. J. Lett. 730, L27.  DOI. ADS. CrossRefADSGoogle Scholar
  29. Neupert, W.M.: 1968, Comparison of solar X-ray line emission with microwave emission during flares. Astrophys. J. Lett. 153, L59.  DOI. ADS. CrossRefADSGoogle Scholar
  30. O’Dwyer, B., Del Zanna, G., Mason, H.E., Weber, M.A., Tripathi, D.: 2010, SDO/AIA response to coronal hole, quiet Sun, active region, and flare plasma. Astron. Astrophys. 521, A21.  DOI. ADS. CrossRefGoogle Scholar
  31. Paciesas, W.S.: 2011, Fermi GBM: Instrument description and science highlights. In: Florinski, V., Heerikhuisen, J., Zank, G.P., Gallagher, D.L. (eds.) Am. Inst. Phys. CS-1366, 155.  DOI. ADS. Google Scholar
  32. Parks, G.K., Winckler, J.R.: 1969, Sixteen-second periodic pulsations observed in the correlated microwave and energetic X-ray emission from a solar flare. Astrophys. J. Lett. 155, L117.  DOI. ADS. CrossRefADSGoogle Scholar
  33. Reznikova, V.E., Melnikov, V.F., Su, Y., Huang, G.: 2007, Pulsations of microwave flaring emission at low and high frequencies. Astron. Rep. 51, 588.  DOI. ADS. CrossRefADSGoogle Scholar
  34. Schwartz, R.A., Dennis, B., Tolbert, A.K., Murphy, R., Share, G., Fishman, G., Briggs, M., Longo, F., Diehl, R., Wijers, R.: 2010, Fermi GBM and LAT solar flare X ray and γ ray observations. In: Bull. Am. Astron. Soc. 41, #404.06. ADS. Google Scholar
  35. Simões, P.J.A., Graham, D., Fletcher, L.: 2015, Impulsive heating of solar flare ribbons above 10 MK. Solar Phys. submitted. Google Scholar
  36. Simões, P.J.A., Fletcher, L., Hudson, H.S., Russell, A.J.B.: 2013, Implosion of coronal loops during the impulsive phase of a solar flare. Astrophys. J. 777, 152.  DOI. ADS. CrossRefADSGoogle Scholar
  37. Stepanov, A.V., Kopylova, Y.G., Tsap, Y.T., Shibasaki, K., Melnikov, V.F., Goldvarg, T.B.: 2004, Pulsations of microwave emission and flare plasma diagnostics. Astron. Lett. 30, 480.  DOI. ADS. CrossRefADSGoogle Scholar
  38. Švestka, Z.: 1976, Solar Flares, Springer, Berlin. ADS. CrossRefGoogle Scholar
  39. Torrence, C., Compo, G.P.: 1998, A practical guide to wavelet analysis. Bull. Am. Meteorol. Soc., 61. Google Scholar
  40. Vaughan, S.: 2005, A simple test for periodic signals in red noise. Astron. Astrophys. 431, 391.  DOI. ADS. CrossRefADSGoogle Scholar
  41. Vaughan, S.: 2010, A Bayesian test for periodic signals in red noise. Mon. Not. Roy. Astron. Soc. 402, 307.  DOI. ADS. CrossRefADSGoogle Scholar
  42. White, S.M., Thomas, R.J., Schwartz, R.A.: 2005, Updated expressions for determining temperatures and emission measures from GOES soft X-ray measurements. Solar Phys. 227, 231.  DOI. ADS. CrossRefADSGoogle Scholar

Copyright information

© Springer Science+Business Media Dordrecht 2015

Authors and Affiliations

  • P. J. A. Simões
    • 1
  • H. S. Hudson
    • 1
    • 2
  • L. Fletcher
    • 1
  1. 1.SUPA, School of Physics and AstronomyUniversity of GlasgowGlasgowUK
  2. 2.SSLUC BerkeleyBerkeleyUSA

Personalised recommendations