2011/7/12

Yuuki Moritani (Kyoto Univ.)
Collaborators:

D. Nogami(1), A. T. Okazaki(2), A. Imada(3), E. Kambe(3),S. Honda(1) and O. Hashimoto(4)(1): Kyoto Univ., (2): Hokkai-gakuen Univ.,(3): OAO/NAOJ, (4): GAOBeXRB 2011 in Valencia

Drastic Spectroscopic Variability of the Be/X-ray
Binary A0535+262/V725 Tau during and after the2009 Giant Outburst

1/20

Contents
1. Brief introduction of A0535+262
2. Observations
3. Results and discussions
1.
2.
3.

Line profile variability
Equivalent width
Intensity of normalized flux

4. Conclusion

2/20

A0535+262/V725 Tau

Roche lobe of A0535+262(Okazaki & Negueruela 2001)• One of the most famous Be/X-ray binaries• Parameters• O9.7IIIe + NS, V = 8.9 mag• orbital eccentricity: ～ 0.47, orbital period: 110.2 days
• NS: 103-sec pulsar• Up to now, 8 giant outbursts have been observed• in 1975, 1977, 1980, 1989, 1994, 2005, 2009, 2011

• Bright enough to perform high-dispersion spectroscopy in optical

X-ray history of A0535+262 (Camero-Arranz et al. 2011)3/20Outbursts in 2009 - 2011
• Giant outburst in Nov./Dec. 2009
• Precursors in Oct. (Sugizaki+ 2009, Atel. #2277)• Rapid brightening at 30 Nov. (JD 2455166)• 3.1 Crab at the peak in 15-50 keV (Krimm+ 2009, Atel. #2336)• Normal outbursts after the giant outburst• Precursor … outbursts in Mar. and July 2010
• No precursor? … outburst in Oct. 2010
• X-ray peak shift: Mar. and July 2010

• Giant outburst again in Feb. 2011MAXI light curve (2 – 10 keV)

4/20

Motivation:
To understand the mechanism• Okayama Astrophysical Observatory of Be phenomena in both short(< 1 orbit) and long (> 1 orbit)• 188cm telescope/ HIDES, 350 – 680 nm time scale

Observations (1)• Gunma Astronomical Observatory• 1.5m telescope/ GAOES, 480 – 670 nm• R ～ 50,000, S/N ～ 100 @ Hα

Detailed analysis of variations
can be dealt with• We were very lucky to perform monitoring during the giant
outburst in 2009

188cm tel. @OAO

1.5m tel. @GAO

4/20

Motivation:
To understand the mechanism• Okayama Astrophysical Observatory of Be phenomena in both short(< 1 orbit) and long (> 1 orbit)• 188cm telescope/ HIDES, 350 – 680 nm time scaleObservations (1)• Gunma Astronomical Observatory• 1.5m telescope/ GAOES, 480 – 670 nm• R ～ 50,000, S/N ～ 100 @ Hα

Detailed analysis of variations
can be dealt with• We were very lucky to perform monitoring during the giant
10outburst in 2009
cnt s-1 cm-2 (2-10keV)

1100
10-1
10-2
10-3
55100

188cm tel. @OAO

55200

55300

55400
55500
JD - 2400000

55600

55700

1.5m tel. @GAO

5/20

Results (1)• Representative spectra of
Hα, He I λ 5876
• Before the giant outburst 2009
• Hα line profile: characterized by a strongly redshifted triple peak and a broad
hump in the blue wing
• He I λ5876 line profile: more or less a typical double peaked seen in many Bestars
Triple peak2
1.8

Blue hump

1.6

A
2009.10.18
2455123.143
φX = 0.645

Fλ/Fc

1.4
1.2
10.8
0.6

A-400 -300 -200 -100

0100 200 300 400 500

wevelength [km/s]

5/20

Results (1)• Representative spectra of
Hα, He I λ 5876
• Before the giant outburst 2009
• Hα line profile: characterized by a strongly redshifted triple peak and a broad
hump in the blue wing
• He I λ5876 line profile: more or less a typical double peaked seen in many Bestars
5Triple peak 4.5 2009.08.31
2455075.264
φX = 0.211

42

3.5
3
2.5

1.6

2

1.4

Fλ/Fc

Blue hump

Fλ/Fc

1.8

1.2

A
2009.10.18
2455123.143
φX = 0.645

1.5
10.5

1-400 -300 -200 -1000.80100 200 300 400 500wevelength [km/s]

0.6

A-400 -300 -200 -100

0100 200 300 400 500

wevelength [km/s]

6/20

Results (1)• Representative spectra of
Hα, He I λ 5876
• Precursor of the giant outburst 2009
• The intensity of normalized flux, E/C, of both lines significantly increased• The blue hump became more outstanding

B

6/20

Results (1)• Representative spectra of
Hα, He I λ 5876
• Precursor of the giant outburst 2009
• The intensity of normalized flux, E/C, of both lines significantly increased• The blue hump became more outstanding
54.542009.11.232455150.289
φX = 0.9731

Fλ/Fc

3.5
32.5
21.5
10.5
-400 -300 -200 -100

0100 200 300 400 500

wevelength [km/s]

54.54

2009.11.142455150.289
φX = 0.8913

Fλ/Fc

3.5
32.5
21.5

B

10.5
-400 -300 -200 -100 0 100 200 300 400 500
wevelength [km/s]

7/20

Results (1)• Representative spectra ofHα, He I λ 5876
• during the giant outburst 2009
• In Hα line profile, a bright “shoulder” appeared ～ 0 km s −1 in the blue wing
• A similar, bright feature was seen in the central part of the He I λ5876 line
profile (between -50 km s−1 and +50 km s−1).
Blue shoulder

CBright feature8/20

Results (1)• Representative spectra of
Hα, He I λ 5876
• during the giant outburst 2009
• The blue bright “shoulder” in Hα line and bright feature in He I λ 5876 hasgoneD

9/20

Results (1)• Representative spectra of
Hα, He I λ 5876
• during the giant outburst 2009
• The E/C ratio gradually increased until 22 December 2009 and then decreasedin fading phase

E

9/20

Results (1)• Representative spectra of
Hα, He I λ 5876
• during the giant outburst 2009
• The E/C ratio gradually increased until 22 December 2009 and then decreasedin fading phase

54.5
42009.12.22
2455188.223
φX = 0.2354

Fλ/Fc

3.5
3
2.5
2
1.5

E

1
0.5
-400 -300 -200 -100 0 100 200 300 400 500
wevelength [km/s]

10/20Results (1)• Representative spectra of
Hα, He I λ 5876
• after the giant outburst 2009 to the normal
outburst in March 2010
• the double peak of the Hα line continued to growDouble peakF

11/20Results (1)• Representative spectra of
Hα, He I λ 5876
• after the giant outburst 2009 to the normal
outburst in March 2010
• the double peak of the Hα line reached the highest intensityG12/20Results (1)• Representative spectra of
Hα, He I λ 5876
• during the normal outburst in March 2010
• The blue “shoulder” seems to reappear

Blue shoulder
54.5
4H
2010.03.1755272.960
φX = 0.0041

Fλ/Fc

3.5
32.5
2
1.5
1H0.5-400 -300 -200 -100

0100 200 300 400 500

wevelength [km/s]

13/20Results (1)• Representative spectra of
Hα, He I λ 5876
• during the normal outburst in March 2010
• In the Hα line, the strongly redshifted double peak weakened and a huge,broad shoulder appeared in the blue wing and Hα line profile became like a
top-hat profile• In the He I λ5876 line, a bright component appearedI13/20Results (1)• Representative spectra of
Hα, He I λ 5876
• during the normal outburst in March 2010
• In the Hα line, the strongly redshifted double peak weakened and a huge,broad shoulder appeared in the blue wing and Hα line profile became like a
top-hat profile• In the He I λ5876 line, a bright component appeared
54.5
4H
2010.03.1755272.960
φX = 0.0041

Fλ/Fc

3.5

Broad shoulder

32.5
2
1.5
15
0.5

4.5
4

2010.03.262455281.982
φX = 0.0859

Fλ/Fc

3.5
3
2.5
21.5

I

10.5
-400 -300 -200 -100 0 100 200 300 400 500
wevelength [km/s]-400 -300 -200 -1000100 200 300 400 500

wevelength [km/s]

13/20Results (1)• Representative spectra ofHα, He I λ 5876
• during the normal outburst in March 2010
• In the Hα line, the strongly redshifted double peak weakened and a huge,broad shoulder appeared in the blue wing and Hα line profile became like a
top-hat profile• In the He I λ5876 line, a bright component appeared
21.8
1.6

H
2010.03.17
55272.960
φX = 0.0041

Bright component

1.221

1.8

0.8

1.60.6-400 -300 -200 -100 0 100 200 300 400 500wevelength [km/s]

2010.03.26
2455281.982
φX = 0.0859

1.4

Fλ/Fc

Fλ/Fc

1.4

1.2
10.8

I

0.6-400 -300 -200 -100 0 100 200 300 400 500
wevelength [km/s]

14/20Results (2)• Equivalent width of Hα, He I λ 5876

cnt s-1 cm-2 (2-10keV)

EW(Hα)EW(He I 5876)• Highest in the last five years• Hα and He I λ 5876 lines show similar trend• For Hα, temporarily decreased in precursor phase (October 2009, JD2455140)• Increased for a while until two -2.5days before the peak of the outburst-2He I• At first decreased and-1.5
increased in fading phase-1-0.5• Gradually decreased after
0-18
the giant outburst 2009
Hα-16-14• Increased before normal /-12-10
giant outbursts
-8-6
100
10-1
10-2
10-3
55100

55200

55300

55400
JD - 2400000

55500

55600

55700

15/20Results (3)• E/C (intensity of normalized flux) of Hα, He Iλ5876• Similar trend to Equivalent width• Hα: Highest during giant outburst (> 3.5)
• due to highly redshifted triple peak component … also responsible for
equivalent widthcnt s-1 cm-2 (2-10keV)

E/C(Hα)E/C(He I 5876)

1.6

He I

1.4
1.2
15
4.5
4
3.5
3
2.5
2Hα

100
10-1
10-2
10-3
55100

55200

55300

55400
55500
JD - 2400000

55600

55700

16/20Discussion• High E/C ratio, asymmetric line profile• not only the Be disc has grown denser,
but also a non-axisymmetric bright region has appeared in the disc

• Enhanced Hα profile has a blue hump and a triple peak• Blue shoulder• can be seen only at periastron passage• Blue hump: ～ -100 – 0 km s−1; similar to the velocity of the violet peakof double-peaked profiles that showed the V/R variability (YM+ 2010)

Fλ/Fc

4C

4

3.5

3.5

3

3

2.5

5
2009.12.06
2455172.033
φX = 0.0886

4.5
4

2.5

3
2.5

22

2

1.5

1.5

1

1

1

0.5

0.5

0.5

0100 200 300 400 500-400 -300 -200 -100

wevelength [km/s]

φX = 0.039
Giant outburst rise

0100 200 300 400 500

wevelength [km/s]

φX = 0.072DD
2009.12.122455178.107
φX = 0.143

3.5

1.5-400 -300 -200 -100

φX = 0.808

4.5

Fλ/Fc

B5
2009.11.30
2455166.233
φX = 0.0359

Fλ/Fc

54.5

φX = 0.089
Giant outburst peak-400 -300 -200 -100

0100 200 300 400 500

wevelength [km/s]

φX = 0.143

16/20Discussion• High E/C ratio, asymmetric line profile• not only the Be disc has grown denser,
but also a non-axisymmetric bright region has appeared in the disc

• Enhanced Hα profile has a blue hump and a triple peak
• Blue shoulder• can be seen only at periastron passage• Blue hump: ～ -100 – 0 km s−1; similar to the velocity of the violet peakof double-peaked profiles that showed the V/R variability (YM+ 2010)

Fλ/Fc

4C

4

3.5

3.5

3

3

2.5

5
2009.12.06
2455172.033
φX = 0.0886

4.5
4

2.5

3
2.5

22

2

1.5

1.5

1

1

1

0.5

0.5

0.5

0100 200 300 400 500-400 -300 -200 -100

wevelength [km/s]

φX = 0.039
Giant outburst rise

0100 200 300 400 500

wevelength [km/s]

φX = 0.072

DD2009.12.122455178.107
φX = 0.143

3.5

1.5

-400 -300 -200 -100

φX = 0.808

4.5

Fλ/Fc

B5
2009.11.30
2455166.233
φX = 0.0359

Fλ/Fc

54.5

φX = 0.089
Giant outburst peak-100 km/s-400 -300 -200 -100

0100 200 300 400 500

wevelength [km/s]

φX = 0.143

17/20Discussion• Blue shoulder• can be seen only at periastron passage• Blue hump: ～ -100 – 0 km s−1; similar to the velocity of the violet peakof double-peaked profiles that showed the V/R variability (YM+ 2010)• Blue hump arise from…
• The outermost region of the Be disc
• The density is higher than usual, possibly due to a one-armed densitywave• The neutron star passes the periastron,an enhanced mass transfer should takeplace from the dense part of the Be
disk to the neutron star
(blue shoulder)
The NSObserver

Coe + (2006)

18/20Discussion• Triple peak
• Negueruela et al. (2001) : 4U 0115+63• The profile often shows a succession of single-peaked and shell profiles
around a giant outburst• Warped Be disc:• driven by radiation from the central star(Porter 1998)• Tidal warping and precession (Martin et al. 2011)• Such a strong disturbance in the Be disc can shift the phase of maximum
mass transfer toward the neutron star

4U0115+63 Negueruela et al. (2001)

19/20More observe,
more complex …?
• Spectra during giant outburstin 2011
• Before the outburst, Hα line was rather
normal double-peaked profile• Equivalent width (|EW(Hα)| ≲ 9 Å), E/C(Hα) ～ 2.5 is rather small toinvolve in type II outburst?

554.5N

4.5
45O
2011.03.022455622.979
φX = 0.1791

O

4.5
4

3.5

3.5

333

2.5

Fλ/Fc

3.5Fλ/Fc

Fλ/Fc

4N
2011.02.02
2455595.081
φX = 0.9261

2.5
22

1.5

1.5

1.5

111

0.5

-400 -300 -200 -100 0 100 200 300 400 500
wevelength [km/s]

P

2.5

20.5

P
2011.03.28
2455649.017
φX =0.4153

0.5-400 -300 -200 -100 0 100 200 300 400 500
wevelength [km/s]-400 -300 -200 -100 0 100 200 300 400 500
wevelength [km/s]

19/20More observe,
more complex …?
• Spectra during giant outburst
in 2011• Before the outburst, Hα line was rather
normal double-peaked profile• Equivalent width (|EW(Hα)| ≲ 9 Å), E/C(Hα) ～ 2.5 is rather small toinvolve in type II outburst?
54.5
4

2007.12.16
2454451.168
φX = 0.550

3.5

4.5
4N
2011.02.02
2455595.081
φX = 0.9261

N

4.5
45O
2011.03.02
2455622.979
φX = 0.1791

Fλ/Fc

553O

P
2011.03.28
2455649.017
φX =0.4153

4.5

2.5

4P

23.5

3.5

3.5

2.5

32.5
221.51.511Fλ/Fc

3Fλ/Fc

Fλ/Fc

1.5
10.5

-400 -300 -200 -100 0 100 200 300 400 500
wevelength [km/s]

2.5

2-400 -300 -200 -100

0100 200 300 400 500

wevelength [km/s]
1.5
10.5

0.5

30.5
-400 -300 -200 -100 0 100 200 300 400 500
wevelength [km/s]-400 -300 -200 -100 0 100 200 300 400 500
wevelength [km/s]

20/20Conclusions• We observed the giant outburst of the Be/X-ray binary
A0535+262/V725 Tau in Nov./Dec. 2009.
• Observed emission line profiles during the giant outburst imply
active components in the Be disk, which cause significant
variability in the observation period.
• The bright blue shoulder indicates the enhanced gas stream
from the outermost part of the Be disk to the neutron star atperiastron.
• Highly redshifted, enhanced triple-peaked feature in the Hαline profiles is possibly from a warping component.