Multispacecraft observations of the hard X-ray emission from the giant solar flare on 2003 November 4

Abstract

Abstract. The hard X-ray emission from the "giant" solar flare on 4 November 2003 (∼1947 UT) was observed by the hard X-ray/gamma ray spectrometer on the Ulysses spacecraft located at ∼114 degrees west of the Sun-Earth line at a distance of 5.28 AU from the Sun. A "small" hard X-ray burst during the early rise of the giant flare and a part of the decay of the hard X-ray emission associated with the giant flare were also observed by the hard X-ray imager on the RHESSI satellite located near the Earth. The maximum of the hard X-ray emission during the giant flare could not be observed by the RHESSI instrument because of satellite night. The flare view angles for Ulysses and RHESSI were ∼31• West and 83 • East respectively. The H-α flare (importance 3B) was located at S19 W83 in the active region NOAA 10486. GOES observations of the associated soft X-ray emission saturated during the period 1943-1958 UT. It has been estimated that the soft X-ray maximum occurred at ∼1947 UT with peak flux equivalent to NOAA class > = X28. OVSA radio observations show that the flare produced intense microwave emission, the peak flux at 15.4 GHz being ∼60 000 sfu at ∼1945 UT. Intense type II, III and IV radio bursts have also been reported at metric and decimetric wavelengths. RHESSI has provided 10-100 keV X-ray images and spectra for 1930-1936 UT (the early rise of the flare) and 10-30 keV images and spectra for 2016-2114 UT (a part of the late decay of the flare). Ulysses observed an increase in 25-150 keV X-rays from 1933 UT to 2015 UT with the maximum at ∼1944 UT, almost simultaneously with the maximum in 15.4 GHz radio emission and ∼3 min before the maximum in the soft X-ray emission. This indicates that the X-ray emission observed by Ulysses was mostly non-thermal. An assumed hard X-ray spectrum of ∼E −3.5 photons cm −2 s −1 keV −1 for >20 keV photons leads to an energy dissipation rate of ∼6.4 × 10 31 erg s −1 at the time of the hard X-ray maximum. The total energy in >20 keV electrons released during the flare is estimated to be ∼1.3 × 10 34 erg.

The Ulysses Catalog of Solar Hard X-Ray Flares

“…Column 5 gives the non-normalized maximum GRB count rate after correction for dead time and rollover, and columns 6 and 7 give the inferred GOES X-class intensity and its uncertainty, derived from the scaling law in Section 4.2. The Ulysses observing time range overlapped with that of RHESSI, which gives us an opportunity for direct photometric comparisons of specific events (e.g., Kane, McTiernan, and Hurley, 2005). We have done a comparison for one well-observed flare, the GOES X8.3 of 2 November 2003.…”

“…During the last (Cycle 22) and the present (23) solar cycles, Ulysses GRB successfully recorded the most energetic solar flares (Kane et al, 1995), among which the major flare of 4 November 2003, was the most notable (Kane, McTiernan, and Hurley, 2005). Kane, McTiernan, and Hurley (2005) and others have used the term "giant flare" to describe these top few flares, typically at GOES level X10 or above; they speculated that such flares utilize the bulk of the magnetically stored energy.…”

“…Kane, McTiernan, and Hurley (2005) and others have used the term "giant flare" to describe these top few flares, typically at GOES level X10 or above; they speculated that such flares utilize the bulk of the magnetically stored energy. We do not now regard a "giant flare" as a physically distinct category and believe that many of the reported properties of these events result from the thermal feed-through mechanism described in Section 3 and in Appendix A.…”

Diagnostics from three rising submillimeter bursts

“…After a dramatic increase at ∼11:02:30 UT, enormous peak flux densities of 25,000 and 11,000 sfu were reached (Kaufmann et al 2004). It was associated with an X ≥28 flare (Kane et al 2005), which may have been the largest X-ray event since…”

Astrophysics in 2005

“…Since the strength of RHESSI lies in (1) the first imaging at high energies, (2) the high spectral resolution that allows one to resolve most of the gamma-ray lines, and (3) the high-resolution spectroscopy also at lower hard X-ray energies, we summarize some new RHESSI results in the same order: (1) imaging with RHESSI revealed the evolution of progressing reconnection along a flare loop arcade (Grigis & Benz 2005a;Li et al 2005a), the so far unexplained loop-top altitude decrease in the initial phase of flares (Veronig et al 2005a), and the obscured view of a giant flare with an energy of ≈10 34 ergs (Kane et al 2005); (2) gamma-ray line modeling with RHESSI showed us a 511 keV e ϩ /e Ϫ annihilation line that is so broad that the ambient ionized medium needs a temperature of 10 5 K, instead of the expected much lower chromospheric value (Share et al 2004);and (3) high-resolution spectroscopy with RHESSI gave us new insights into the energy partition of thermal, nonthermal, CMEmechanical, and nonpotential magnetic energies (Emslie et al 2004(Emslie et al , 2005Saint-Hilaire & Benz 2005), the soft-hard-soft evolution of hard X-ray spectra compared with acceleration models (Grigis & Benz 2004, the low-energy cutoff of the electron spectrum (Sui et al 2005), the physics of the Neupert effect, i.e., the correlation between the thermal soft X-ray and the integral of the hard X-ray time profiles (Veronig et al 2005b), and the size dependence of solar flare spectral properties (Battaglia et al 2005). Other exciting RHESSI discoveries are the quasi-periodic hard X-ray pulsations that could be explained in terms of the MHD kink mode, which supposedly modulates the electron injection in a multiple flare-loop system .…”