WG 4 Summary

1
WG 4 Summary
Monday 26th July 1100 1300     WG4 session
1 Introductions, planning, updates 1430
1800     WG4 session 2 The events of Oct/Nov
2003 Tuesday 27th July 0900 1030     WG4
session 3 Iron Line Complex Studies 1100
1300    WG4 session 4 Joint with WG2/3 on Oct
28 2003 1430 1600 Inter-group sessions WG4
atmospheric response inversions, acceleration
theory 1630 1800 WG4 session 5 Microflares
(joint with WG3) Wednesday 28th July 0900
1300 WG4 session 6 Footpoints continued, and
coronal sources
Thanks to Hugh Hudson for assiduous
note-taking http//sprg.ssl.berkeley.edu/hhudson/
workshop/rhessiparis/
2
Energetics
Berlicki et al. (22 Oct 2002) heating in
gradual phase ? looking for gradual non-thermal
component to HXR flux, non-thermal to thermal
energy ratio Li (20 October 2003) non-thermal
to thermal energy ratio Hudson SORCE ability
to give bolometric luminous energy for flare
3
Thermal and non-thermal component during the
gradual phase
a) Thermal energy of plasma
b) Energy contained in the non-thermal electrons
(thin target model) (Hudson et al. 1978,
Sol. Phys. 60, 137)
(for ECUT-OFF 10 keV)
? - power-law index B(x,y) beta function ?10
X-ray flux at 10 keV photons cm-2 s-1 keV-1
4
BERLICKI
Thermal non-thermal Fe/Ni line complex (6.7
8 keV)
5
Spectral Analysis (4)
Li
MODEL Thermal broken power law
6
Li results (20 keV cutoff)

• Energy composition
• Enontherm/Ethermlt 0.38 (thick, Ecutoff 20keV)
• Enontherm/Ethermlt 0.13 (thin, Ecutoff 20keV)
• (very dependent on Ecutoff, fraction increases
  Ecutoff, as decreases)

Berlicki results (10keV cutoff)
7
Hudson

• SORCE spacecraft makes precise irradiance
  measurements
• Total Irradiance Monitor (TIM) sees essentially
  all of the radiant energy (total over event 6 x
  1032 ergs)

8
Iron Line Studies
Fe/Ni complex in principle provides independent
temperature measurement which can be used to test
assumptions of isothermality and help constrain
fits. Caspi Comparing temperatures derived
from thermal component of spectral fit and that
from looking at Fe/FeNi complexes Dennis
Thermal and nonthermal contributions to the solar
X-ray flux
9
Fe Fe/Ni line complexes
CASPI

• Assume isothermal
• Fit with thermal plus single power-law plus 2
  Gaussians to approximate Fe Fe/Ni line
  complexes
• ? T from thermal fit
• ? line ratio as function of T predicted from
  theory

10
Flux ratio vs. Temperature
CASPI
11
Flux ratio vs. Temperature
CASPI

• Is the flare isothermal? What about low E cutoff?

12
Centroids of emission
CASPI

• Higher energy emission from higher in the looptop
• Strongly implies multi-thermal distribution

13
Fe-line Energy, equivalent width vs. Temperature
DENNIS
Equiv. width vs T Different abundance models
Centroid energy vs T
14
Equivalent Width vs. Temperature
DENNIS
Attenuator States A0 - early rise o A1 - peak ?
A3 - 1st peak ? A1 - decay x A0 - late decay
15
Equivalent Width vs. Temperature
DENNIS
Attenuator States A0 - early rise o A1 - peak ?
A3 - 1st 2nd peaks ? A1 - decay x A0 - late
decay
16
October 28th
Gallagher overview of active regions in Oct/Nov
2003 events Demoulin Mandrini overall
magnetic configuration Van Driel Benz radio from
100 4000 MHz Hudson SORCE bolometric increase
17
Oct 28 TRACE RHESSI
KRUCKER
18
Magnetic field evolution
(Demoulin, Mandrini, van Driel)

Emerging active region in an old AR successive
emergences of bipoles creating a complex d region
(AR 10486)
19
DMV
Outline of flare events (Demoulin, Mandrini, van
Driel)
1. 1005-1056 UT Local reconnection due to
emerging flux region (small-scale) 2.
1014-1018 UT and 1047-1058 UT Four ribbons
, global quadrupolar reconnection
(large-scale) 3. 1101 UT X 17 flare with two
ribbons
20
DMV
Outline of flare events
1. 1005-1056 UT Local reconnection due to
emerging flux region (small-scale) 2.
1014-1018 UT and 1047-1058 UT Four ribbons
, global quadrupolar reconnection
(large-scale) 3. 1101 UT X 17 flare with two
ribbons
21
DMV
Global quadrupolar reconnection
2 min. before the flare
Four ribbons between 1012-1019 UT between
1047-1058 UT
DMV
22
DMV
Outline of flare events
1. 1005-1056 UT Local reconnection due to
emerging flux region (small-scale) 2.
1014-1018 UT and 1047-1058 UT Four ribbons
, global quadrupolar reconnection
(large-scale) 3. 1101 UT X 17 flare with two
ribbons
Modelling of main event remains to be done
DMV
23
BENZ
24
Microflares joint with WG3
RHESSI microflare spectra hard to fit (low
counts) 2 approaches full fitting with
SPEX/OSPEX - ratio of two channels ?
temperature, and/or spectral index EASIER TO
AUTOMATE! Christe distributions of RHESSI
microflares ratios of peak rates in 2 channels ?
temperature or spectral index Hannah individual
microflares and distributions ratio technique ?
temp, then spectral index from high energy Kundu
RHESSI and radio imaging Benz
mean-energy/time relation, and micro vs nano
flares
25
Flare examples
CHRISTE
Size - S
26
8-13 and 13-20 keV Peak Rate
CHRISTE
27
Distribution of g and Temp.
CHRISTE

• Superhot components with Tgt20 MK do occur though
  usually only associated with large flares (Hudson
  Nitta 1996).
• For small bursts, a typical temperature is 10 MK.
• Therefore emission is most likely nonthermal.

28
HANNAH
RATIO
OSPEX
KeyDataTherm modelNon-therm modelTotal Model
RESIDUALS
29
Time evolution of thermal fit parameters
HANNAH
30
OSPEX Comparison
HANNAH
Ratio Ospex
31
Time Profiles of non-thermal parameter fits
HANNAH
32
Non-Thermal Energy Distribution
HANNAH
Parnell Jupp 2000 method is independent of
bin size. So objectively fits Skew-Laplace
Distribution to log(E) using approximate Maximum
Likelihood method.
For Total Energy only used P with error lt 100.
So smaller events have underestimated energies.
33
KUNDU
Observes 3 RHESSI microflares joint with Nobeyama
(microwave), e.g.
The microflare concerned occurs at 0152 UT
(first row). The RHESSI and NoRH images show
co-located sources superposed on a MDI
magnetogram.
34
KUNDU
..and 2 joint with NANCAY? type III locations,
e.g.
35
Microflares microwave/metric
KUNDU

• The microwave emission comes from the foot points
  (for higher energies), and from the entire small
  (mini) flaring loop (for lower energies).
• The relative positions of microwaves and hard
  X-rays in the higher energy channels are as they
  should be in normal flares. Sometimes the two
  (microwave hard X-ray) sources coincide, at
  other times the two are at opposite ends of the
  mini flaring loop. One sees the mini flaring
  loops clearly in NoRH images.
• The hard X-ray spectrum of microwave associated
  RHESSI micro flares can be fit by a thermal
  component (EM61046 cm-3 at 3-6 keV) at low
  energies and (sometimes) a nonthermal component
  (with slope -3.2) at higher energies.
• At metric wavelengths the type III bursts are
  often spatially associated with RHESSI
  microflares. This must have important
  implications in the propagation of energetic
  electrons up thru the corona.

36
Spectral and spatial
properties of solar microflares
Simnett, G. M. Dennis, B. R.
In its 19th Intern. Cosmic Ray Conf.,
Vol. 4 p 38-41 (SEE N85-34729 23-92)
08/1985 Solar
Physics Solar microflares are studied using
both hard ( 28 keV) and soft (3.5 to 8.0 keV)
X-ray observations. The soft X-ray events have
durations 3 m at 0.1x maximum intensity, and
typically have similar rise and decay times. The
fastest decay observed was 15 s (1/e). Soft and
hard X-ray intensities are uncorrelated. The
events are very compact, consistent with a
projected area approximately 8 x 8 inches.
BENZ
37
BENZ
Decrease of mean photon energy with time
38
BENZ
microflares, active region gt
nanoflares, quiet region gt
Benz Güdel, 1996 Krucker Benz, 2000
39
Footpoints Somov reconnection /
field-stressing model to explain the motion of
HXR footpoints Mrozek energy-height analysis
of HXR centroids
40
SOMOV
Type I motions 5 of events (Yohkoh HXT)
Type II motions 15 of events (Yohkoh HXT)
(and the rest..)
41
Pre-flare Energy Accumulation
SOMOV
Motions only towards neutral line
Shear motions along neutral line
42
MROZEK
PseudoColor picture the TRACE 171 Å
image, obtained after the maximum contours
the TRACE 171 Å images obtained during the
impulsive phase, the times are given
above each frame crosses locations
of centroids of hard X-ray sources, the times are
the same as above, brighter
colours represent the higher energies the solar
limb is overplotted.
43
MROZEK
- Make images in the wide energy range
divided into intervals of few keV,
in steps of 1 keV. - Determine positions of
centroids - Fit the power-law function
The altitude of centroids (asterixs) above a
reference level versus the energy of hard
X-rays. The power-law function fit is
presented with dotted line.
44
MROZEK
Comparision between several models of density
(Aschwanden et al. 2002) and densities obtained
from RHESSI observations.
45
MROZEK
Height distributions 12 s apart Source motion
implies upward speed?
46
Coronal Sources
Veronig Temmer analysis of (moving source HXR
source in) November 3 event Somov collapsing
trap model for production of coronal
sources Hudson November 4th, coronal loops in
white-light
47
VERONIG
48
VERONIG
Evolution of RHESSI footpoints and loop top source
Footpoints 70-100 keV Loop top 20-25 keV
49
VERONIG
RHESSI (0946-1001 UT) and H? (1000-1200 UT)
loop top source evolution
50
Particle Acceleration in a Collapsing Trap
SOMOV

• A magnetic trap between the Super-Hot
  Turbulent-Current Layer (SHTCL) and a Fast
  Oblique Collisionless Shock (FOCS) above magnetic
  obstacle (MO)

Ref. Somov, B.V. and Kosugi, T., ApJ, 485, 859,
1997
51
HUDSON
Thomson scattering -gt WL coronal source -gt mass
estimate 1015g