1. Spectrum Analysis of SGR 1900+14 in quiescent (2nd edition) Bubu 2002/12/12&18

2. Contents About SGR 1900+14 My job Show time!! Current results Conclusion (and next step)

3. About SGR1900+14 One of the 4+1 SGRs In the galactic plane Spin-down energy problem More correct position: “ 19 07 14.1, 09 19 01 ” Models for it in quiescent: No really serious one!! History: discover:1979 giant flare: 1998/8/27 Similar to AXPs

4. My job At present, most papers fit the spectrum of SGRs in quiescence with a “ power law ” From the data of AXPs, we may use two or more blackbody plus a power law to fit its spectrum. This gives us a hint that maybe we can fit the spectrum of SGRs in the same way. The result, will provide some constraints and hints about what SGRs and AXPs are. These help a more correct and detailed physical explanation.

5. Flow chart of my job: ftp.asdc.asi /anonymous

6. In spec analysis, we need …… *.pha *.rmf (response matrix file) *.arf (ancillary response file) Background files (Make it by yourself!)

7. “ Channel type ” PHA The device which measures the energy of a photon, often used to the refer to the raw numbers measured by the device. PI Pulse invariant. PHA values corrected for spatial and temporal changes in gain.

8. Next, Before show time ………

9. Header of MECS2_70249001.evt Naxis2=10926 /number of rows in table CONTENT= ‘ EVENT LIST ’ TELESCOP= ‘ SAX ’ INSTRUME= ‘ MECS2 ’ OBJECT= ‘ SGR 1900+14 ’ RA_OBJ= 286.8125 DEC_OBJ=9.3225 DATE-OBS= ‘ 1997-05-12 ’ TIME-OBS= ’ 01:21:50.000 ’ /(HH:MM:SS) DATA-END= ‘ 1997-05-13 ’ TIME-END= ’ 01:05:26.0000 ’ And ………

10. Some points …… : SAOimage: How to determine the center and the radius of the region? Xselect: How to filter time and region (and pha_cutoff), then extract spectrum? Xspec: What models should we consider? How to choose a model? How we say a fitting is good or not? BeppoSAX MECS2: What steps will it influence? Go!!

11. In Xspec analysis, we need …… *.pha *.rmf (response matrix file) *.arf (ancillary response file) Background files (Make it by yourself!!)

12. One way to make a background file (blank field) : 2.8279E-03 counts/sec 5.2428E-03 counts/sec 4.7622E-03 counts/sec Note: in DETX DETY coordinate (5.2428+4.7622)/2.8279=5 corfile cornorm

13. Current results: data "bubu.pha" Backgrnd & corfile “ bubu_bgd.pha" response "mecs2_sep97.rmf " arf "mecs2_4_sep97.arf " ignore 1-37 227-**

14. In Xspec, there are two basic kinds of model components: Additive model components (sources) Multiplicative model components (mixing, convolution, pile up) There must be least one additive component in a model

15. About bbody (Additive) A blackbody spectrum. ------------------------------------------------------------------- A(E) = K 8.0525 E**2 dE / ((par1)**4 (exp(E/par1)-1)) ------------------------------------------------------------------- where : par1 = temperature kT in keV K = L39/(D10)**2, where L39 is the source luminosity in units of 10**39 ergs/sec and D10 is the distance to the source in units of 10 kpc

16. About bremss (Additive) A thermal bremsstrahlung spectrum based on the Kellogg, Baldwin & Koch(ApJ 199, 299) polynomial fits to the Karzas & Latter numerical values. A routine from Kurucz is used for low temperatures. The He abundance is assumed to be 8.5% by number. par1 = plasma temperature in keV K = (3.02e-15/4/pi/D^2) Int n_e n_I dV where n_e is the electron density (cm^-3), n_I is the ion density (cm^-3), and D is the distance to the source (cm).

17. About powerlaw (Additive) Simple photon power law. -------------------------------------------------------- A(E) = K (E/1 keV)**(-par1) -------------------------------------------------------- where : par1 = photon index of power law (dimensionless) K = photons/keV/cm**2/s at 1 keV.

18. About phabs (multiplicative) Photoelectric absorption using cross-sections set by the xsect command. The relative abundances are set by the abund command. ------------------------------------------------------------------- A(E) = exp(-par1*sigma(E)) ------------------------------------------------------------------- where sigma(E) is the photo-electric cross-section (NOT including Thomson scattering). Note that the default He cross-section changed in v11. The old version can be recovered using the command xsect obcm. par1 = equivalent hydrogen column (in units of 10**22 atoms/cm**2)

19. I ’ ll fit models for: 1_Phab(po) 2_phab(bb) 3_phab(bb+po) 4_phab(bb+bb) 5_phab(br) 6_phab(bb+br) 7_phab(br+po) 8_phab(bb+br+po)

20. 1_Model: phabs[1]( powerlaw[2] ) Model Fit Model Component Parameter Unit Value par par comp 1 1 1 phabs nH 10^22 1.067 +/- 0.3301 2 2 2 powerlaw PhoIndex 1.987 +/- 0.1283 3 3 2 powerlaw norm 2.9807E-03 +/- 0.9752E-03 --------------------------------------------------------------------------- --------------------------------------------------------------------------- Chi-Squared = 186.4382 using 190 PHA bins. Reduced chi-squared = 0.9969957 for 187 degrees of freedom Null hypothesis probability = 0.498

21. 1_Model: phabs[1]( powerlaw[2] )

22. 2_Model: phabs[1]( bbody[2] ) Model Fit Model Component Parameter Unit Value par par comp 1 1 1 phabs nH 10^22 0.000 +/- -1.000 2 2 2 bbody kT keV 1.110 +/- 0.2619E-01 3 3 2 bbody norm 8.6667E-05 +/- 0.4542E-05 --------------------------------------------------------------------------- --------------------------------------------------------------------------- Chi-Squared = 274.2688 using 190 PHA bins. Reduced chi-squared = 1.466678 for 187 degrees of freedom Null hypothesis probability = 3.317E-05

23. 2_Model: phabs[1]( bbody[2] )

24. 3_Model: phabs[1]( bbody[2] + powerlaw[3] ) Model Fit Model Component Parameter Unit Value par par comp 1 1 1 phabs nH 10^22 2.949 +/- 1.147 2 2 2 bbody kT keV 3.032 +/- 1.579 3 3 2 bbody norm 7.9305E-05 +/- 0.6007E-04 4 4 3 powerlaw PhoIndex 3.364 +/- 0.9279 5 5 3 powerlaw norm 1.7330E-02 +/- 0.1784E-01 --------------------------------------------------------------------------- --------------------------------------------------------------------------- Chi-Squared = 180.8243 using 190 PHA bins. Reduced chi-squared = 0.9774286 for 185 degrees of freedom Null hypothesis probability = 0.573

25. 3_Model: phabs[1]( bbody[2] + powerlaw[3] )

26. 4_Model: phabs[1]( bbody[2] + bbody[3] ) Model Fit Model Component Parameter Unit Value par par comp 1 1 1 phabs nH 10^22 1.092 +/- 0.7154 2 2 2 bbody kT keV 2.318 +/- 0.3807 3 3 2 bbody norm 9.1681E-05 +/- 0.2009E-04 4 4 3 bbody kT keV 0.6055 +/- 0.8454E-01 5 5 3 bbody norm 7.2289E-05 +/- 0.3571E-04 --------------------------------------------------------------------------- --------------------------------------------------------------------------- Chi-Squared = 176.3595 using 190 PHA bins. Reduced chi-squared = 0.9532943 for 185 degrees of freedom Null hypothesis probability = 0.663

27. 4_Model: phabs[1]( bbody[2] + bbody[3] )

28. 5_Model: phabs[1]( bremss[2] ) Model Fit Model Component Parameter Unit Value par par comp 1 1 1 phabs nH 10^22 0.4176 +/- 0.2399 2 2 2 bremss kT keV 9.208 +/- 1.773 3 3 2 bremss norm 2.1056E-03 +/- 0.2931E-03 --------------------------------------------------------------------------- --------------------------------------------------------------------------- Chi-Squared = 190.5356 using 190 PHA bins. Reduced chi-squared = 1.018907 for 187 degrees of freedom Null hypothesis probability = 0.414

29. 5_Model: phabs[1]( bremss[2] )

30. 6_Model: phabs[1]( bbody[2] + bremss[3] ) Model Fit Model Component Parameter Unit Value par par comp 1 1 1 phabs nH 10^22 2.481 +/- 0.7823 2 2 2 bbody kT keV 2.482 +/- 0.5976 3 3 2 bbody norm 9.1600E-05 +/- 0.2621E-04 4 4 3 bremss kT keV 1.393 +/- 0.4551 5 5 3 bremss norm 1.1180E-02 +/- 0.8392E-02 --------------------------------------------------------------------------- --------------------------------------------------------------------------- Chi-Squared = 178.9737 using 190 PHA bins. Reduced chi-squared = 0.9674256 for 185 degrees of freedom Null hypothesis probability = 0.611

31. 6_Model: phabs[1]( bbody[2] + bremss[3] )

32. 7_Model: phabs[1]( bremss[2] + powerlaw[3] ) Model Fit Model Component Parameter Unit Value par par comp 1 1 1 phabs nH 10^22 2.270 +/- 1.003 2 2 2 bremss kT keV 1.255 +/- 0.7542 3 3 2 bremss norm 9.4088E-03 +/- 0.1118E-01 4 4 3 powerlaw PhoIndex 1.255 +/- 0.7725 5 5 3 powerlaw norm 7.0125E-04 +/- 0.2141E-02 --------------------------------------------------------------------------- --------------------------------------------------------------------------- Chi-Squared = 180.7877 using 190 PHA bins. Reduced chi-squared = 0.9772307 for 185 degrees of freedom Null hypothesis probability = 0.574

33. 7_Model: phabs[1]( bremss[2] + powerlaw[3] )

34. 8_Model: phabs[1]( bbody[2] + powerlaw[3] + bremss[4] ) Model Fit Model Component Parameter Unit Value par par comp 1 1 1 phabs nH 10^22 3.379 +/- 6.896 2 2 2 bbody kT keV 2.985 +/- 2.273 3 3 2 bbody norm 7.0254E-05 +/- 0.7403E-04 4 4 3 powerlaw PhoIndex 3.494 +/- 3.013 5 5 3 powerlaw norm 2.2387E-02 +/- 0.9565E-01 6 6 4 bremss kT keV 0.1548 +/- 0.1014 7 7 4 bremss norm 43.67 +/- 0.1629E+05 --------------------------------------------------------------------------- --------------------------------------------------------------------------- Chi-Squared = 181.1675 using 190 PHA bins. Reduced chi-squared = 0.9899863 for 183 degrees of freedom Null hypothesis probability = 0.524

35. 8_Model: phabs[1]( bbody[2] + powerlaw[3] + bremss[4] )

36. Null hypothesis probability of these models are: 1_Phab(po) 2_phab(bb) 3_phab(bb+po) 4_phab(bb+bb) 5_phab(br) 6_phab(bb+br) 7_phab(br+po) 8_phab(bb+br+po) 0.498 3.317E-05 0.573 0.663 0.414 0.611 0.574 0.524

37. But …… Astro-ph/9912061

38. Conclusion (& next step): error, recornrm α=2.2?? Reasonable!! Try MECS and LECS data. Compare with more results. Uncertainties??......

39. It’s a long road……”\|O.o|/” It’s a long road……”\|O.o|/”