X-rays from nova explosions

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1 X-rays from nova explosions Margarita Hernanz Institute of Space Sciences, ICE (CSIC-IEEC) Bellaterra (Barcelona) Spanish X-ray Astronomy Santander 3-5 June 2015 M. Hernanz 1

2 Scenario of nova explosions: white dwarfs in close binary systems Cataclysmic variable: WD + Main Sequence Roche lobe overflow Classical nova Hydrogen burning in degenerate conditions on top of the WD Spanish X-ray Astronomy Santander 3-5 June 2015 M. Hernanz 2

3 Scenario of nova explosions: white dwarfs in close binary systems Cataclysmic variable: WD + Main Sequence Roche lobe overflow Classical nova Hydrogen burning in degenerate conditions on top of the WD P rec ~ yr; P orb ~hr-day a~few 10 5 km~ few cm rate ~35/yr in Galaxy Spanish X-ray Astronomy Santander 3-5 June 2015 M. Hernanz 3

) Classical nova Hydrogen burning in degenerate conditions on top of the WD Recurrent symbiotic nova Credit: R.

4 Scenario of nova explosions: white dwarfs in close binary systems Cataclysmic variable: WD + Main Sequence Symbiotic system: WD + Red Giant Roche lobe overflow Accretion from a red giant wind (+disk?) Classical nova Hydrogen burning in degenerate conditions on top of the WD Recurrent symbiotic nova Credit: R. Corradi, IAC P rec ~ yr; P orb ~hr-day a~few 10 5 km~ few cm rate ~35/yr in Galaxy P rec <100 yrs; P orb ~100 s days a ~ cm rate ~10 known in Galaxy (now more) Spanish X-ray Astronomy Santander 3-5 June 2015 M. Hernanz 4

5 Recurrent novae as a potential scenario of SNIa In recurrent novae, initial mass of the WD should be very large (close to Chandrasekhar mass), to drive such frequent outbursts è Feasible scenario of type Ia supernova explosions, provided that less mass is ejected than accreted in each explosion è X-ray observations: way to study if WD mass grows or diminishes after each nova explosion Solve the controversy between single degenerate and double degenerate scenarios of type Ia supernovae. Probably both can coexist Spanish X-ray Astronomy Santander 3-5 June 2015 M. Hernanz 5

6 Origin of X-ray emission Residual steady H-burning on top of the white dwarf: photospheric emission from the hot WD: T eff ~ (2-10)x10 5 K (L~10 38 erg/s) supersoft X-rays Ø duration related to H-burning turn-off time: traces remnant H-mass on top of WD after explosion Spanish X-ray Astronomy Santander 3-5 June 2015 M. Hernanz 6

7 Origin of X-ray emission Residual steady H-burning on top of the white dwarf: photospheric emission from the hot WD: T eff ~ (2-10)x10 5 K (L~10 38 erg/s) supersoft X-rays Ø duration related to H-burning turn-off time: traces remnant H-mass on top of WD after explosion Internal (external) shocks in the ejecta heat the ejecta, which emits soft and hard X-rays through thermal bremsstrahlung Ø detected early after explosion Ø also detected later Spanish X-ray Astronomy Santander 3-5 June 2015 M. Hernanz 7

8 Origin of X-ray emission Residual steady H-burning on top of the white dwarf: photospheric emission from the hot WD: T eff ~ (2-10)x10 5 K (L~10 38 erg/s) supersoft X-rays Ø duration related to H-burning turn-off time: traces remnant H-mass on top of WD after explosion Internal (external) shocks in the ejecta heat the ejecta, which emits soft and hard X-rays through thermal bremsstrahlung Ø detected early after explosion Ø also detected later Reestablished accretion: emission CV-like Ø non magnetic WD: accretion disk Ø magnetic WD: accretion through a truncated disk or directly onto the WD surface (magnetic poles) Ø soft and hard X-ray emission Spanish X-ray Astronomy Santander 3-5 June 2015 M. Hernanz 8

Origin of X-ray emission Residual steady H-burning on top of the white dwarf: photospheric emission from the hot WD: T eff ~ (2-10)x10 5 K (L~10 38 erg/s) supersoft X-rays Ø duration related to

9 Origin of X-ray emission Residual steady H-burning on top of the white dwarf: photospheric emission from the hot WD: T eff ~ (2-10)x10 5 K (L~10 38 erg/s) supersoft X-rays Ø duration related to H-burning turn-off time: traces remnant H-mass on top of WD after explosion Internal (external) shocks in the ejecta heat the ejecta, which emits soft and hard X-rays through thermal bremsstrahlung Ø detected early after explosion (see Laura Delgado s talk) Ø also detected later Reestablished accretion: emission CV-like Ø non magnetic WD: accretion disk Ø magnetic WD: accretion through a truncated disk or directly onto the WD surface (magnetic poles) Ø soft and hard X-ray emission Spanish X-ray Astronomy Santander 3-5 June 2015 M. Hernanz 9

10 Super Soft X-ray emission as a tracer of post-outburst nuclear burning Photospheric emission from the hot WD related to residual H- burning on top of the white dwarf : supersoft X-rays Ø detected by ROSAT/PSPC in only 3 classical novae, out of 39 observed up to 10 years after explosion (Orio et al. 2001): GQ Mus 1983: 9 yrs, N Cyg 1992 (1.5 yrs), N LMC 1995 (8 yrs) Spanish X-ray Astronomy Santander 3-5 June 2015 M. Hernanz 10

11 V1974 Cyg (1992): soft X-ray light curve - ROSAT Krautter et al & Balman et al. 1998, ApJ rise: until day increasing transparency of expanding ejecta plateau: 18 months steady H-burning decline: nuclear fuel (H) exhausted Spectra: BB fits not good à need of WD atmospheres models Spanish X-ray Astronomy Santander 3-5 June 2015 M. Hernanz 11 [MacDonald & Vennes, Rauch (NLTE, static), Van Rossum (exp.)]

12 Super Soft X-ray emission as a tracer of post-outburst nuclear burning Photospheric emission from the hot WD related to residual H- burning on top of the white dwarf : supersoft X-rays Ø detected by ROSAT/PSPC in only 3 classical novae, out of 39 observed up to 10 years after explosion (Orio et al. 2001): GQ Mus 1983: 9 yrs, N Cyg 1992 (1.5 yrs), N LMC 1995 (8 yrs) Ø Duration of the SSS phase: related to turn-off of nuclear burning - max. 13 yrs; typical < 2 yrs. Can be much shorter (weeks). Swift/XRT (2004-): monitoring campaigns Spanish X-ray Astronomy Santander 3-5 June 2015 M. Hernanz 12

13 XMM-Newton - AO1 Cycle -Summary XMM-Newton (pre-swift) campaign Target N Sco 1997 V1141 Sco N Sgr 1998 V4633 Sgr N Oph 1998 V2487 Oph N Sco 1998 V1142 Sco N Mus 1998 LZ Mus Discovery date June 5 March 22 June 15 Date of observation Time after outburst Oct. 11, d, 3.4yr Mar. 24, d, 3.8yr Sep. 7, d, 4.3yr Oct. 11, d, 2.6yr Mar. 9, d, 3.0yr Sep. 7, d, 3.5yr Feb. 25, d, 2.7 yr Sep. 5, d, 3.2 yr Feb d, 3.7yr Sept. 24, d, 4.3yr October 21 Oct. 11, d, 2.0 yr Mar. 24, d, 2.4 yr Sep. 7, d, 2.9 yr December 29 Dec. 28, d, 2.0 yr Jun. 26, d, 2.5 yr Dec. 26, d 3.0 yr Detection NO YES but no SSS YES but no SSS 2.6± ± ±0.2 (10-2 cts/s) NO? Hernanz & Sala No supersoft X-ray emission related to residual H-burning detected all novae had already turned-off 3 out of 5 were emitting [thermal plasma (+ BB)] spectrum ejecta/accretion 13 Spanish X-ray Astronomy Santander 3-5 June 2015 M. Hernanz 13

Target N Oph 1998 V2487 Oph N Cyg 2005 V2361 Cyg N Sgr 2005a V5115 Sgr N Sgr 2005b V5116 Sgr N Cyg 2006 V2362 Cyg N Oph 2006a V2575 Oph N Oph 2006b V2576 Oph Discovery date June 15 February 10 March

4, 2009 49 months Mar. 20, 2007 20 months Mar. 13, 2009 44 months May 5, 2007 13 months affected by bkg AO6 Dec. 22, 2008 32 months February 9 Sep. 4, 2007 19 months AO6 April 6 Oct.

14 Target N Oph 1998 V2487 Oph N Cyg 2005 V2361 Cyg N Sgr 2005a V5115 Sgr N Sgr 2005b V5116 Sgr N Cyg 2006 V2362 Cyg N Oph 2006a V2575 Oph N Oph 2006b V2576 Oph Discovery date June 15 February 10 March 28 July 4 April 2 XMM-Newton campaign Date of observation Time after outburst Mar. 24, yr AO6 long exposure May 13, mo bkg Oct. 20, months AO5 Sep. 27, months Apr. 4, months Mar. 20, months Mar. 13, months May 5, months affected by bkg AO6 Dec. 22, months February 9 Sep. 4, months AO6 April 6 Oct. 3, months AO6 Detection YES but no SSS -- YES marginal: (4.0±0.8)x10-3 cts/s YES supersoft source YES but no SSS YES supersoft source YES but no SSS YES but no SSS YES but no SSS Supersoft X-ray emission related to residual H-burning found in 2 novae from 2005 (V5115 Sgr & V5116 Sgr) novae had not Spanish X-ray Astronomy Santander 3-5 June 2015 M. Hernanz 14 turned-off yet NO NO 5116 Sgr 2005b: see Gloria Sala s talk 14

15 Swift/XRT campaign: searching novae in the SSS phase Swift/XRT observations of 52 Galactic / Magellanic Cloud novae + 10 additional novae obs. with other satellites Ø 26 with Super Soft X-ray emission (19 from Swift) Schwarz et al. 2011, ApJS hard soft Spanish X-ray Astronomy Santander 3-5 June 2015 M. Hernanz 15

16 Swift/XRT campaign: searching novae in the SSS phase Schwarz et al. 2011, ApJS Spanish X-ray Astronomy Santander 3-5 June 2015 M. Hernanz 16

17 Models - Super soft X-rays: turn-off time of nuclear burning Wolf et al 2013, ApJ MESA code Spanish X-ray Astronomy Santander 3-5 June 2015 M. Hernanz 17

18 Models - Super soft X- rays: turn-off time of nuclear burning Wolf et al 2013, ApJ MESA code Spanish X-ray Astronomy Santander 3-5 June 2015 M. Hernanz 18

19 Super soft X-ray emission as a tracer of post-outburst nuclear burning Photospheric emission from the hot WD related to residual H- burning on top of the white dwarf : supersoft X-rays Ø detected by ROSAT/PSPC in only 3 classical novae, out of 39 observed up to 10 years after explosion (Orio et al. 2001): GQ Mus 1983: 9 yrs, N Cyg 1992 (1.5 yrs), N LMC 1995 (8 yrs) Ø Duration of the SSS phase: related to turn-off of nuclear burning - max. 13 yrs; typical < 2 yrs. Can be much shorter (weeks). Swift/XRT (2004-): monitoring campaigns Ø BeppoSAX: discovery of emission lines contemporaneous with photospheric WD emission - N Vel 1999 Ø Chandra, XMM-Newton (1999-): first grating observations Spanish X-ray Astronomy Santander 3-5 June 2015 M. Hernanz 19

20 Nova V4743 Sgr 2002 NLTE hot WD atmospheres Rauch et al., ApJ 2010 Spanish X-ray Astronomy Santander 3-5 June 2015 M. Hernanz 20

21 Emission line spectrum + WD photosphere - Nova V382 Vel 1999 Ness et al., MNRAS 2005 Previous observation with Beppo/ SAX (Orio et al. 2001,2002, MNRAS): 1st time lines and atmospheric emission seen simultaneously in a nova Spanish X-ray Astronomy Santander 3-5 June 2015 M. Hernanz 21

22 Observations of Super Soft X-ray emission from novae in M31: spatial distribution Henze et al. 2010, 2011,2014, A&A Spanish X-ray Astronomy Santander 3-5 June 2015 M. Hernanz 22

23 Observations of Super Soft X-ray emission from novae in M31: population studies Spanish X-ray Astronomy Santander 3-5 June 2015 M. Hernanz 23 Henze et al. 2014, A&A

24 X-ray observations of post-outburst novae: recovery of accretion è tracing the properties of the binary system (CV, symbiotic) hosting the nova explosion Spanish X-ray Astronomy Santander 3-5 June 2015 M. Hernanz 24

25 XMM-Newton observations of V2487 Oph = Nova Oph 1998 (post-outburst) 1st observed in XMM-Newton was not available in 1998 Target Discovery date Date of observation Time after outburst Detection N Oph 1998 V2487 Oph June 15 Feb. 25, d, 2.7 yr Sep. 5, d, 3.2 yr Feb d, 3.7yr Sept. 24, d, 4.3yr YES but no SSS N Oph 1998 V2487 Oph June 15 Mar. 24, yr AO6 long exposure YES but no SSS Very fast nova optical light curve with t 2 = 6.3 d and t 3 = 9.5 d Spanish X-ray Astronomy Santander 3-5 June 2015 M. Hernanz 25

26 V2487 Oph (1998): 1 st nova seen in X-rays before its explosion (ROSAT) Positional correlation with a source previously discovered by ROSAT (RASS) in 1990 suggests that the host of the nova explosion had been seen in X-rays before the outburst (Hernanz & Sala 2002, Science) à new case: V2491 Cyg (2008): previous ROSAT, XMM and SWIFT detections (Ibarra et al. 2009, A&A) Restablishment of accretion clearly seen in X-rays yrs after eruption Fe K alpha fluorescence line at 6.4 kev Spanish X-ray Astronomy Santander 3-5 June 2015 M. Hernanz 26

27 N Oph 1998 = V2487 Oph - 8.8yr post outburst BB+ 2T APEC gaussian 6.4 kev Spanish X-ray Astronomy Santander 3-5 June 2015 M. Hernanz 27

28 Nova Oph 1998 = V2487 Oph neutral Fe Kα fluorescence line 6.4 kev 6.7 kev Fe XXV 6.97 kev FeXXVI Identification of three Fe Kα emission lines: ~neutral Fe: 6.4 kev He-like Fe: 6.68 kev H-like Fe: 6.97 kev Fluorescent Fe Kα line at 6.4 kev reveals reflection on cold matter (disk and/or WD): accretion Spanish X-ray Astronomy Santander 3-5 June 2015 M. Hernanz 28

29 Nova Oph 1998 = V2487 Oph neutral Fe Kα fluorescence line 6.4 kev 6.7 kev Fe XXV 6.97 kev FeXXVI Identification of three Fe Kα emission lines: ~neutral Fe: 6.4 kev He-like Fe: 6.68 kev H-like Fe: 6.97 kev If T high ~ (10-20) kev, He-like and H-like lines well reproduced & only 6.4 kev fluorescent line added Fluorescent Fe Kα line at 6.4 kev reveals reflection on cold matter (disk and/or WD): accretion Ø If complex absorption -partial covering absorber- low (ISM)+ high N H à T high ~(10-20) kev Spanish X-ray Astronomy Santander 3-5 June 2015 M. Hernanz 29

30 N Oph 1998 = V2487 Oph - 8.8yr post outburst d=10 kpc L abs[ kev] = 7x10 34 erg/s N H =2.6x10 21 cm -2 T bb =117±2 ev L bb = 1.2±0.2)x10 35 erg/s T low =0.24±0.01 kev EM low =(7±1)x10 56 cm -3 Covf=0.54±0.01 T high =20±1 kev N PCA H =(21±2)x10 22 cm -3 EM high =(2.2±0.7)x10 57 cm -3 red. chisq=1.08 (1674/1548) C. Ferri, PhD Thesis, 2011 L BB ~ 50% L TOT [0.2-10] kev - f (emitting surface/wd surface)~ (hot spots?) Ø Luminosity, spectral shape.. Intermediate polar? need P spin vs. P orb Spanish X-ray Astronomy Santander 3-5 June 2015 M. Hernanz 30

31 Nova Oph 1998 = V2487 Oph - Hard X-rays Detection with INTEGRAL/IBIS survey in the kev band (Barlow et al. 2006, MNRAS): kt=25 kev ; flux compatible with our XMM-Newton results, but the IBIS spectrum has low S/N Ø large M WD from large T high but T high not well constrained Spanish X-ray Astronomy Santander 3-5 June 2015 M. Hernanz 31

32 Nova Oph 1998 = V2487 Oph - Hard X-rays INTEGRAL IBIS/ISGRI data reduction: courtesy of S. Paltani Spanish X-ray Astronomy Santander 3-5 June 2015 M. Hernanz 32

33 Nova Oph 1998 = V2487 Oph - Hard X-rays Detection with INTEGRAL/IBIS survey in the kev band (Barlow et al. 2006, MNRAS): kt=25 kev ; flux compatible with our XMM-Newton results, but the IBIS spectrum has low S/N Ø large M WD from large T high but T high not well constrained Also detected with RXTE/PCA (Butters et al, 2011) as a possible IP, but not clear periodicities found Hints for large M WD also from the optical light curve (Hachisu & Kato, 2002, ApJ) Spanish X-ray Astronomy Santander 3-5 June 2015 M. Hernanz 33

34 Other Novae in IPs MNRAS, 2008 Spanish X-ray Astronomy Santander 3-5 June 2015 M. Hernanz 34

35 Other Novae in IPs Spanish X-ray Astronomy Santander 3-5 June 2015 M. Hernanz 35

36 Other Novae in IPs Spanish X-ray Astronomy Santander 3-5 June 2015 M. Hernanz 36

37 Nova Oph 1998=V2487 Oph - Recurrent Nova Previous outburst in 1900 June 20, discovered in the Harvard College Observatory archival photograph collection Pagnotta and Schaefer, IAUC 8951, 200; 2009 AJ) à recurrent nova P rec = 98 yrs à M WD very close to M CHANDRA à relevance for the SNIa scenario challenge for theory to get recurrent nova explosions with such short time scales recent recurrent nova in M31 (Henze et al. 2014), with P re =1 yr even more challenging for theory Spanish X-ray Astronomy Santander 3-5 June 2015 M. Hernanz 37

38 Accreted masses to reach H-ignition conditions. M=10-8 M /yr hydro code L ini critical accreted mass does not depend only on M wd M wd very close to M CHANDRA Hernanz & José 2008 Spanish X-ray Astronomy Santander 3-5 June 2015 M. Hernanz 38

39 Recurrence periods of novae. M=10-8 M /yr V2487 Oph 1998: P rec =98 yr L ini * * RS Oph: P rec =21 yr. * M= M /yr & L=10-2 L Hernanz & José 2008 Spanish X-ray Astronomy Santander 3-5 June 2015 M. Hernanz 39

40 Nova Oph 1998=V2487 Oph - Recurrent Nova Previous outburst in 1900 June 20, discovered in the Harvard College Observatory archival photograph collection Pagnotta and Schaefer, IAUC 8951, 200; 2009 AJ) à recurrent nova P rec = 98 yrs à M WD very close to M CHANDRA à relevance for the SNIa scenario challenge for theory to get recurrent nova explosions with such short time scales recent recurrent nova in M31 (Henze et al. 2014), with P re =1 yr even more challenging for theory The nova V2491 Cyg (2008) has also been claimed to be recurrent. It was also a very fast nova, expected to be massive, very luminous in X-rays (Ibarra et al. 2009, A&A). It has also been detected in hard X-rays with Suzaku (Takei et al. 2009) Spanish X-ray Astronomy Santander 3-5 June 2015 M. Hernanz 40

41 CONCLUSIONS (recovery of accretion) X-rays are crucial to study the recovery of accretion in postoutburst novae: type of CV, mass of the WD Magnetic WD: challenge for accretion traditionally assumed to occur through an accretion disk in a non mag. WD. But some magnetic novae are known: V1500 Cyg (1975), V4633 Sgr (1998) asynchronous polars as a consequence of the nova outburst (Lipkin & Leibowitz, 2008) - V2487 Oph (1998) also: V4743 Sgr 2002, M31N b (Pietsch et al. 2011) Massive WD: if T high (plasma) is large and/or the nova is recurrent. Scenario for type Ia supernovae Ø BUT: challenging for theory: narrow parameter range: M wd extremely large & accretion rate large to get P recurrence < 100 yrs Ø BUT: M WD should increase (OK: no mixing & SS emission) Ø main caveat: not CO WDs but ONe (collapse instead of explos.) Spanish X-ray Astronomy Santander 3-5 June 2015 M. Hernanz 41

42 CONCLUSIONS (outburst and post outburst) Analysis of X-ray emission from novae during and after outburst gives unique information about: Ø supersoft X-rays: turnoff of nuclear H burning on top of the WD (related to M WD, chemical composition of accreted envelope ), geometry of the binary system (see next talk) Ø hard X-rays: mass outflow; shocks, acceleration of particles (see next talk). Diffrences between classical and recurrent novae (SNIa scenario) Ø study of nova populations (e.g., M31) Grating instruments fundamental to get good quality spectra needed to do real physics beyond too simplistic fitting Timing also crucial: understand short P fluctuations Spanish X-ray Astronomy Santander 3-5 June 2015 M. Hernanz 42

V2487 Oph 1998: a puzzling recurrent nova observed with XMM-Newton

V2487 Oph 1998: a puzzling recurrent nova observed with XMM-Newton Margarita Hernanz Institute of Space Sciences (CSIC-IEEC) - Barcelona (Spain) Gloria Sala (UPC-IEEC), Nataly Ospina (CSIC-IEEC) V2487