Discovery of non-thermal emission from the classical nova V2491 CygniDai Takei (Rikkyo University)
ESAC Faculty Seminar, 2009.06.18
2/33
Agradecimientos
Muchas gracias !!!
Point of View: X-rays
• Hard X-rays (from shock of the ejecta ?) - Fast evolution - Weak source - Many emission lines in the spectrum
• Photospheric Super-Soft X-rays from WD - SS time scale depends on WD mass - Many emission and absorption lines
• Behavior unpredictable - Observations difficult to schedule
4/33
at white dwarf surface
Mixing?
TNR
Mixing?
TNR

• WD mass is important !! • Increase or Decrease ... ? • Novae (only CO-type) may be
Type Ia
SN progenitors ... ?
Galactic Distribution
A large number of classical novae in the Galaxy !! Detected frequency : 3 yr -1
Estimated frequency : 73±24 yr -1
(Liller & Mayer 1987)
Energy Resolution 130 eV @ 6 keV 4.0 keV (PIN)
Time Resolution 8 sec 61μsec
2
PSF (FWHM) 5 6″ N/A 1.4 2.0″
Energy Resolution 150 eV @ 6.4 keV 0.025 A @ 1 keV 350 (Power)
Time Resolution 1.75 ms / 0.03 ms 0.6 sec 0.5 sec
http://xmm.esac.esa.int/external/xmm_user_support/documentation/technical/EPIC/index.shtml http://imagine.gsfc.nasa.gov/Images/bios/cottam/RGS_array.jpg
2.
Observations
a.
Observatories
b.
Results
3.
Summary
14/33
Discovery of SSXS Suzaku J0105-72 (2005.08) - Takei et al. (2008), PASJ, 60, S231
Observations of Novae
Spectroscopy of V458 Vul (2007.08) - Tsujimoto et al. (2009), PASJ, 61, S69
Spectroscopy of V2491 Cyg (2008.04) - Takei et al. (2009), ApJL, 697, 54 - Takei et al. (2009), in prep.
ROSAT ALL-Sky X-ray Background Survey (0.73-1.56 keV) http://skyview.gsfc.nasa.gov/cgi-bin/query.pl
15/33
Position reconstructed; Outside of the XIS FoV.
Takei et al. 2008, PASJ, 60, S231
Serendipitous discovery of a transient source during a series of routine calibration observations of 1E0102.2-7219.
16/33
Takei et al. 2008, PASJ, 60, S231
17/33
Suzaku (XIS)Decline of the brightness...
Chandra (ACIS)
18/33
1037
.-
19/33
Discovery of SSXS Suzaku J0105-72 (2005.08) - Takei et al. (2008), PASJ, 60, S231
Observations of Novae
Spectroscopy of V458 Vul (2007.08) - Tsujimoto et al. (2009), PASJ, 61, S69
Spectroscopy of V2491 Cyg (2008.04) - Takei et al. (2009), ApJL, 697, 54 - Takei et al. (2009), in prep.
ROSAT ALL-Sky X-ray Background Survey (0.73-1.56 keV) http://skyview.gsfc.nasa.gov/cgi-bin/query.pl
20/33
-
-
Swift detected X-rays on day 70 (Ness et al. 2009, AJ, 137, 4160)
http://www.ztv.ne.jp/web/K.Nakajima/image/Nova2007Vul(07.08.09).jpg
21/33
Day 88
23/33
Discovery of SSXS Suzaku J0105-72 (2005.08) - Takei et al. (2008), PASJ, 60, S231
Observations of Novae
Spectroscopy of V458 Vul (2007.08) - Tsujimoto et al. (2009), PASJ, 61, S69
Spectroscopy of V2491 Cyg (2008.04) - Takei et al. (2009), ApJL, 697, 54 - Takei et al. (2009), in prep.
ROSAT ALL-Sky X-ray Background Survey (0.73-1.56 keV) http://skyview.gsfc.nasa.gov/cgi-bin/query.pl
24/33
-
-
-
-
X-rays were detected in the pre-nova phase (Ibarra et al. 2009, A&A, 497, L5)
http://www.astroarts.jp/news/2008/04/12nova_cyg/v2491cyg.jpg
25/33
V2491 Cygni : Light Curve
The optical data were provided by the variable star observations from the AAVSO International Database and the VSOLJ Observation Database contributed by observers worldwide and used in this research.
Day 9
Day 29
Takei et al. ,2009, ApJL, 697, 54
The highest energy photons up to 70 keV ever detected from a nova !!
(Takei et al. 2009, ApJL, 697, 54)
(Γ = 0.1)
Flat power-law spectrum -
1.1
28/33
2.0) (e.g., Blandford & Ostriker 1980, ApJ, 237, 793)
• Flat population (P ≤
1.1) cannot be explained (Takei et al. 2009, ApJL, 697, L54)
Diffusive Shock Acceleration
30/33
• Ne
X line clearly blue-shifted on day 29 (... and not shifted on day 39)
• Fe K lines grow stronger in the later phase • Fe fluorescence line appears on day 50
We are still thinking about it ... do you have any good ideas ?!?
32/33
Three recent classical novae were observed
WD mass was estimated (Suzaku J0105-72) Plasma abundances were constrained (V458 Vul) Non-thermal X-rays were discovered (V2491 Cyg)
My PhD thesis will be bright, like these novae !!!
Thank you very much !!
Agradecimientos
Discussion
V2491 Cygni : Evolution
Summary: Emission Lines