1. Insight-HXMT observations on type-I &type-II X-ray bursts
Chen Yu-Peng
On behalf of Insight-HXMT team
IHEP, CAS, China

2. outline Introduction Insight-HXMT observations on type-I X-ray bursts
type-II X-ray burst
Insight-HXMT observations on type-I X-ray bursts 4U 4U
Insight-HXMT& Swift/XRT observations on type-II X-ray bursts
Rapid Burster

3. type-I X-ray burst Burst energy thermonuclear
Persistent flux gravitational energy
(much more energy)
Chen Y.-P. et al. 2010, A&A, 510, A81

4. Type-I X-ray burst

5. Rapid burster (MXB 1730-335 ）Bursting Pulsar （GRO J1744-28 ）
type-II X-ray burst
Younes et al. 2015
Rapid burster (MXB ）Bursting Pulsar （GRO J ）

6. spectral softening in decay
X-ray bursters
Frequent Outbursts of s duration with lower, persistent X-ray flux inbetween
Type I bursts (~111 sources)
Thermonuclear
By far most of the bursters
Type II bursts (2 sources)
sudden increases accretion rate
Rapid burster (MXB ） Bursting Pulsar （GRO J ）
Use as handout and maybe project on second screen
spectral softening in decay
a>30 ( the ration between outburst fluence and burst fluence)

7. type-I X-ray burst as a evidence for Disk corona not sphere corona
Chen et al. 2013, ApJL, 777,9
Ji et al. …..

8. Insight-HXMT observations on type-I &type-II X-ray bursts sources
Name
OBSID No ks
Tyep-I X-ray bursts
Type-II X-ray bursts 4U P 17
170 3 4U P 70 1
Rapid Burster
~360
Aql X-1 P 30
Cyg X-2 P 11
320 GS P 40
GX 17+2 P 5
150

9. 4U 1636-536 LMXB Atoll source 6 kpc
The orbit and spin periods are about 3.8 h and 581 Hz
Type-I X-ray burst

10. 4U

14. HE > 25 keV

15. LE&ME &HE top 2 seconds spectra
Soft X-ray excess
Hard X-ray excess
T=2.64 +/-0.13 keV

16. LE&ME&HE effective area

17. Exposure Time: 2 sec
5.291e+02 +/ e+01 (86.0 % total)
5.482e+02 +/ e+01 (63.5 % total)
1.829e+02 +/ e+01 (16.7 % total)
constant factor frozen
wabs nH ^ frozen
bbodyrad kT keV / E-02
bbodyrad norm /
Data group: 2
constant factor / E-02
wabs nH ^ = p2
bbodyrad kT keV = p3
bbodyrad norm = p4
Data group: 3
constant factor /

18. s
6.4*108 ergs/cm2/s
Mean peak PRE (photospheric radius-expansion) burst
(Galloway 2008 , ApJS,179,360)
4.7 *108 ergs/cm2/s 

19. Hard X-ray excess Photon from type-I X-ray burst
As seed photon for comptonization of corona ?

20. Type-I X-ray burst spectra of LE

21. Exposure Time: 40 sec
Net count rate (cts/s) for Spectrum: e+02 +/ e+00 (65.8 % total)
Model wabs<1>*bbodyrad<2> Source No.: 1 Active/On
Model Model Component Parameter Unit Value
par comp
wabs nH ^ E-07 +/ E-02
bbodyrad kT keV / E-02
bbodyrad norm /
_______________________________________________________
Test statistic : Chi-Squared = using 318 PHA bins.
Reduced chi-squared = for degrees of freedom
Null hypothesis probability = e-01

22. 4U (slow burster)

23. angular distance~0.5 degree

24. HXMT/LE & swift/XRT lightcurve

25. 4U type-I X-ray burst

27. Burst spectra ~20 sec xposure Time: 23 sec
Net count rate (cts/s) for Spectrum: e+02 +/ e+00 (50.2 % total)
Exposure Time: 23 sec
Net count rate (cts/s) for Spectrum: e+02 +/ e+00 (28.0 % total)
constant factor frozen
wabs nH ^ /- 0.0
bbodyrad kT keV /- 0.0
bbodyrad norm /- 0.0
Data group: 2
constant factor /- 0.0
Test statistic : Chi-Squared = using 346 PHA bins.
Reduced chi-squared = for degrees of freedom
Null hypothesis probability = e-03

28. MXB 1730-335 NS XRB Rapid Burster 8 kpc B ~4*108 G
Type-I X-ray burst & Type-II X-ray burst

29. HXMT/LE lightcurve (~360 bursts)

30. Swift/XRT type-I X-ray burst
Lightcurve shape Hardness Tbb

31. XRT&LE spectra of type-II X-ray bursts

32. Effective area XRT&LE(small FoV)

33. Exposure Time: sec
Net count rate (cts/s) for Spectrum: e+01 +/ e-01 (94.6 % total)
Exposure Time: 2458 sec
Net count rate (cts/s) for Spectrum: e+01 +/ e-01 (23.6 % total)
Model constant<1>*wabs<2>*nthComp<3> Source No.: 1 Active/On
constant factor frozen
wabs nH ^ /- 0.0
nthComp Gamma /- 0.0
nthComp kT_e keV /- 0.0
nthComp kT_bb keV frozen
nthComp inp_type 0/ frozen
nthComp Redshift frozen
nthComp norm /- 0.0
Data group: 2
constant factor /- 0.0
Reduced chi-squared = for degrees of freedom
Null hypothesis probability = e-02

34. propeller effect
N. Masetti et al A&A
Type-I x-ray burst
Large fraction of accretion drop
on the NS surface after
propeller effect
4E+35 erg/s

35. type-I & type-II X-ray bursts
2012,ApJ,752,158
123 type I and 8458 type II bursts from the RB
Type-II bursts are from disk
type-I & type-II X-ray bursts happened simultaneously
Nthcomp can fit the burst spectra well

36. outline Introduction Insight-HXMT observations on type-I X-ray bursts
type-II X-ray burst
Insight-HXMT observations on type-I X-ray bursts 4U
Hard X-ray excess:
busrt as seed photon for comptonization of corona 4U
Soft X-ray excess?
Insight-HXMT& Swift/XRT observations on type-II X-ray bursts
Rapid Burster
Large fraction of accretion drop on the NS surface after propeller effect
Type-II X-ray burst from disk not the NS surface