Spectrum Analysis of SGR in quiescent (2nd edition) Bubu 2002/12/12&18

Contents About SGR My job Show time!! Current results Conclusion (and next step)

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

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.

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

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

“ 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.

Next, Before show time ………

Header of MECS2_ evt Naxis2=10926 /number of rows in table CONTENT= ‘ EVENT LIST ’ TELESCOP= ‘ SAX ’ INSTRUME= ‘ MECS2 ’ OBJECT= ‘ SGR ’ RA_OBJ= DEC_OBJ= DATE-OBS= ‘ ’ TIME-OBS= ’ 01:21: ’ /(HH:MM:SS) DATA-END= ‘ ’ TIME-END= ’ 01:05: ’ And ………

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!!

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

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

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

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

About bbody (Additive) A blackbody spectrum A(E) = K 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

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).

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.

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)

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)

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

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

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

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

3_Model: phabs[1]( bbody[2] + powerlaw[3] ) Model Fit Model Component Parameter Unit Value par par comp phabs nH 10^ / bbody kT keV / bbody norm E-05 +/ E powerlaw PhoIndex / powerlaw norm E-02 +/ E Chi-Squared = using 190 PHA bins. Reduced chi-squared = for 185 degrees of freedom Null hypothesis probability = 0.573

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

4_Model: phabs[1]( bbody[2] + bbody[3] ) Model Fit Model Component Parameter Unit Value par par comp phabs nH 10^ / bbody kT keV / bbody norm E-05 +/ E bbody kT keV / E bbody norm E-05 +/ E Chi-Squared = using 190 PHA bins. Reduced chi-squared = for 185 degrees of freedom Null hypothesis probability = 0.663

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

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

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

6_Model: phabs[1]( bbody[2] + bremss[3] ) Model Fit Model Component Parameter Unit Value par par comp phabs nH 10^ / bbody kT keV / bbody norm E-05 +/ E bremss kT keV / bremss norm E-02 +/ E Chi-Squared = using 190 PHA bins. Reduced chi-squared = for 185 degrees of freedom Null hypothesis probability = 0.611

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

7_Model: phabs[1]( bremss[2] + powerlaw[3] ) Model Fit Model Component Parameter Unit Value par par comp phabs nH 10^ / bremss kT keV / bremss norm E-03 +/ E powerlaw PhoIndex / powerlaw norm E-04 +/ E Chi-Squared = using 190 PHA bins. Reduced chi-squared = for 185 degrees of freedom Null hypothesis probability = 0.574

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

8_Model: phabs[1]( bbody[2] + powerlaw[3] + bremss[4] ) Model Fit Model Component Parameter Unit Value par par comp phabs nH 10^ / bbody kT keV / bbody norm E-05 +/ E powerlaw PhoIndex / powerlaw norm E-02 +/ E bremss kT keV / bremss norm / E Chi-Squared = using 190 PHA bins. Reduced chi-squared = for 183 degrees of freedom Null hypothesis probability = 0.524

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

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) E

But …… Astro-ph/

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

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