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Gamma-rays from the quiet Sun

Gamma-rays from the quiet Sun. Nicola Omodei Stanford. SolarTutorial. Get the needed files: https://www.dropbox.com/sh/s8io1bq5yvk966j/3F6Rq3xTI4 Unpack the SolarTutorial_src.tgz and SolarTutorial_data.tgz file into the tools directory. tools/SolarTutorial should look like:

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Gamma-rays from the quiet Sun

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  1. Gamma-rays from the quiet Sun Nicola Omodei Stanford

  2. SolarTutorial • Get the needed files: • https://www.dropbox.com/sh/s8io1bq5yvk966j/3F6Rq3xTI4 • Unpack the SolarTutorial_src.tgz and SolarTutorial_data.tgz file into the tools directory. • tools/SolarTutorial should look like: • XSPEC/ (models for XSPEC) • lleBackground/ (tool for extracting the LLE background) • src/ (python code) • data/ (data, FT1, FT2 and LLE, template file for likelihood analysis, isotropic model and galactic diffuse model)

  3. Direct Download -> Save File

  4. γ p Quite Sun gamma-ray emission Sun is bright in gammas due to interactions of Galactic cosmic rays (CR) • Inverse Compton (IC) emission from the Sun • idea and theory: Moskalenko et al. 2006, Orlando & Strong 2007, 2008 e- e- η < radial e- > p γ < Galactic CRs + 2) Solar disk emission due to interactions of CR particles with solar atmosphere model : Seckel 91, upper-limit detection: Thompson 97 First detection (EGRET): Orlando & Strong, 2008 FERMI/LAT: high statistical significance for a clear separation of the components! 2011ApJ...734..116A

  5. Solar Activity (SA) and Cosmic rays (CR) Solar gamma-ray flux depends on CRs flux Max SA -> min CR flux Min SA -> max CR flux • - SA was in its minimum during the period analyzed in the Fermi LAT paper • SA is now increasing and expected to peak around 2013

  6. Fermi paper: LAT data selection • 18 months data • Analysis in Sun-centered system • Zenith angle < 105° (to avoid the Earth’s emission) • Galactic Plane Cut (|b|>30°) (to reduce the background) • Moon-Sun angular separation >40° • Avoided the brightest sources, F(>100 MeV) above 2e-7 cm-2s-1 • Only a small percentage of the data survives Counts map >100 MeV 7

  7. Ephemerides in a nutshell #!/usr/bin/env python import pyLikelihood as pl import os from math import * def d(x): return degrees(x) def r(x): return radians(x) def getJD(met): if met > 252460801: met-=1 # 2008 leap second if met > 157766400: met-=1 # 2005 leap second if met > 362793601: met-=1 # 2012 leap second return (pl.JulianDate.seconds(pl.JulianDate_missionStart())+met)/pl.JulianDate.secondsPerDay def _jd_from_met(met): jd = pl.JulianDate(getJD(met)) return jd def getSunPosition( met ): os.environ['TIMING_DIR']=os.path.join(os.environ['HEADAS'],"refdata") sun=pl.SolarSystem(pl.SolarSystem.SUN) return sun.direction(_jd_from_met(met)) def rotation(x,y,p): xr=r(x) yr=r(y) pr=r(p) x1= d(atan2(sin(xr)*cos(pr) + tan(yr)*sin(pr), cos(xr))) y1 = d(asin(sin(yr)*cos(pr) - cos(yr)*sin(xr)*sin(pr))) return x1,y1 def equatorial2ecliptic(ra,dec): EPS = 23.439292 # THIS IS THE OBMIQUITY AS J2000 (lon,lat)=rotation(ra,dec,EPS) if lon<0: lon+=360 return (lon,lat) ./sunpos.py 376358403.0 Difference from USNO position: 0.0007530°

  8. Sun Centered coordinates • At each instant, the rotation brings • RA,DEC -> ecliptic lon-Sun lon, ecliptic latitude. • The idea is to replace the RA,DEC with the new coordinates: • FT1 file (RA,DEC) • FT2 file: (RA_ZENITH, DEC_ZENITH), (RA_SCZ,DEC_SCZ),(RA_SCX, DEC_SCX) ./suncenter.py –ft1 ft1fileName ./suncenter.py –ft2 ft2fileName

  9. Background determination • Galactic and extragalactic emission along the ecliptic • 2 methods for evaluating the background: • Based on data • Based on simulations

  10. Based on data:Fake source method • A fake source follows the path of the real source but many degrees away (integrated along the ecliptic)

  11. Photon density profile >100 MeV Sun Fake-Sun background

  12. Angular profiles: evidence of extended emission • Sun Data • BKG • IC • Disk + Bkg+IC > 500 MEV Good description of the background Zoom in Angular distribution well fitted by both disk and IC components. 13

  13. Disk SED s.i.=-2 SED for the disk emission compared with model predictions.

  14. Analysis method • Model “Independent” Fit for the IC Component • IC-ring models with Pls (RINGS: 5-11-20°) • Model for Disk point-like Component • Point source modeled with a PL2 • Model for background Component • spatially uniform nested rings, (RINGS 10-14-17.3-20°) spectrum from fake sun

  15. IC: Results IC flux IC differential spectrum

  16. Disk results Energy

  17. Including the quite sun in Solar flare analysis <source name=”SunDisk" type="PointSource"> <!-- point source units are cm^-2 s^-1 MeV^-1 --> <spectrum type="PowerLaw2"> <parameter free=”0" max="1000.0" min="1e-05" name="Integral" scale="1e-06" value=”0.463"/> <parameter free=”0" max="-1.0" min="-5.0" name="Index" scale="1.0" value="-2.11"/> <parameter free="0" max="200000.0" min="20.0" name="LowerLimit" scale="1.0" value="20.0"/> <parameter free="0" max="200000.0" min="20.0" name="UpperLimit" scale="1.0" value="2e5"/> </spectrum> <spatialModel type="SkyDirFunction"> <parameter free="0" max="360." min="-360." name="RA" scale="1.0" value=”0"/> <parameter free="0" max="90." min="-90." name="DEC" scale="1.0" value=”0"/> </spatialModel> </source> This is for Sun Center coordinates, otherwise replace with R.A. and Dec. of the Sun • The Sun is a faint source of gamma-rays, not detected on hour long time scale. • Depending on its position, can be detected in few days.

  18. Take at home • Calculate the position of the Sun (sunpos.py) • Calculate the sun-centered FT1 and FT2 (suncenter.py) • For long duration flares > 6 hr you will need to work in sun centered coordinates.

  19. SolarTutorial • Get the needed files: • https://www.dropbox.com/sh/s8io1bq5yvk966j/3F6Rq3xTI4 • Unpack the SolarTutorial_src.tgz and SolarTutorial_data.tgz file into the tools directory. • tools/SolarTutorial should look like: • XSPEC/ (models for XSPEC) • lleBackground/ (tool for extracting the LLE background) • src/ (python code) • data/ (data, FT1, FT2 and LLE, template file for likelihood analysis, isotropic model and galactic diffuse model)

  20. What’s in there • ProgressBar.py* (helper function to display a progress bar…) • SFLARE110307_analysis.py* (executable, run the analysis in different TIME bins, in equatorial coordinates) • SFLARE110307_analysis_SC.py* (executable run the analysis in 1 time bin, in sun-centered coordinates) • analysis.py (this is the script containing the analysis steps) • makeProfileLikelihood.py* (Used to draw a profile likelihood, once the analysis is finished) • myscripts.py (wrapper around ST) • plotSED.py* (plot the SED) • setup.sh (you can use to setup your environment (ignore for now) • suncenter.py* (compute the sun center ft1 and ft2 files) • sunpos.py* (compute the position of the sun) • xspec_cmd.tcl (example of xspec command)

  21. BACKUP

  22. Inverse Compton models • Uncertainty in the solar modulation of electrons close to the Sun • Force field approximation for e- spectrum modulation (Gleeson & Axford 68) • Starting from the Fermi electron spectrum at 1AU, 3 MODELS with Φ0(1AU)=400MV, but different formulations of Φ(r): MODEL 1 and MODEL 2 assume additional modulation <1AU, MODEL 3 assumes the e- spectrum constant <1AU. E- spectrum at r=1AU as measured by Fermi Modulation potential LIS

  23. Electron spectra for IC models LIS galprop AMS 02 Fermi LIS 1AU At 0.3AU MODEL3 e- constant <1AU MODEL1 (400MV) MODEL2 (400MV)

  24. Quiet Solar emission: pion decay • Solar disk emission due to interactions of CR particles with solar atmosphere Seckel ‘91 NAIVE: no B Mirrored showers, reflected by B back to the surface NOMINAL: includes CR diffusion Cascade developpement in forward direction F(> 100MeV) = (0.22−0.65) 10−7 cm-2 s-1 for nominal

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