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Cosmological supernovae as neutrino and gravitational wave sources

Astrophysical Gravitational Wave Backgrounds. Cosmological supernovae as neutrino and gravitational wave sources mHz gravitational wave background from inspiral of compact objects embedded in AGN accretion discs. G ü nter Sigl APC (Astroparticule et Cosmologie), Université Paris 7

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Cosmological supernovae as neutrino and gravitational wave sources

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  1. Astrophysical Gravitational Wave Backgrounds • Cosmological supernovae as neutrino and gravitational wave sources • mHz gravitational wave background from inspiral of compact objects embedded in AGN accretion discs. Günter Sigl APC (Astroparticule et Cosmologie), Université Paris 7 and GReCO, Institut d’Astrophysique de Paris, CNRS http://www2.iap.fr/users/sigl/homepage.html

  2. 1 ¡ j = ( j ) [ ( ( ) ) ( ) ] h h h l f l d d l d f h f f d d l l d d ¯ l d d b h I T T G W S N R H i i i i i i i i i i i i i 1 t t t t t t t t t t t t t t + n e e e c r s m g a n s r a a o c c e o o r s n s m o o c s e o g r y a o a m p z u e o a n z n o r v z s n u g a a e e n e v v e e n a n n s e s v s e n r e e n a r a e e e p y o e r c o e m e n o v e r n g y g = c ( ) ( = ) ( ) l d f h l d d d f f d l h f R G E W i i i i i i t t t t t t t e v m o u m e e p e z r r e q u e e n m c y e - a n v e e r r v a a g e e n e r g y e n s y p e r o g a r m c r e q u e n c y g w , , f 2 ( ) h f Z l m a x i i t n e r v a s 2 c d l f S N R ¯ ¯ n ( ) 1 d = d d Z 2 R E ( ) t d E 2 1 1 + ½ z ; f S z ¯ ¯ g w g w ( ) ( ) 2 g w f d f f ( ) [ ( ) ] f h f f 1 n + z = i z ¯ ¯ = m n z z : d l f d d f 2 ; 1 c 2 + d d f n z z ¯ ¯ ¼ 0 L ( ) h f h d b d S i i t t t t w e r e s e e e c o r s n o s e u g e n . h d h l d i i i i t t t w e r e s e u m n o s y s a n c e L . Individual and Diffuse Signals

  3. h h d l f b l h l h d h h h T T E i i i i i i i i t t t t t t t t t t e e e v u e n y c r y a c e e a s s s g e e v n e n r o y m m u a r p y s n g e n e g r a n w e c o e r e n c e m e ( ) [ ( ) ] l f 1 1 t + + s c a e z z : h c o 2 ( ) ( ) 1 1 d Z Z R V 4 z ¼ r z ( ) d d ¡ R z z z = = : ( ) ( ) 2 d H ( ) [ ( ) ] 1 1 1 f Z + + 4 1 t + z z z z ¼ r z z h 0 0 c o ( ) l d D R t ' u y c y c e z z : ( ) H z 0 ( ) ( ) h h d d d i i i 1 t t t t + w r z e c o m o v n g c o o r n a e r z = , . Event rates and Duty Cycles

  4. Onion structure of a supernova Janka, Mueller Convection, turbulence

  5. Supernovae as Neutrino and Gravitational Wave Sources Anisotropic mass motion and neutrino emission in collapse of massive stars leads to gravitational wave emission. At low frequencies anisotropic neutrino emission of luminosity Lν(t) and anisotropy q(t) dominates and leads to the dimensionless strain at distance D Individual supernovae (SN) in our Galaxy can give prominent signals in neutrinos in Super-Kamiokande, Amanda, ICECUBE, Uno… and in gravitational waves in Virgo/EGO, LIGO…, but are rare events. However, backgrounds from cosmological SN may soon be detectable by gadolinium upgrade of Super-K in neutrinos and by gravitational wave detectors such as the Big Bang Observatory (BBO).

  6. 9 ¡ % l l l d F D M M i i i i i 2 0 4 5 1 5 3 1 0 t t t t £ < > u a y v e r a g e a x s q y m m e r c r o a n g p r o g e n o r r e e a s e n » » ¯ ¯ , : , d l G W i i i t u r n g s m u a o n Illustration for a particular rotating core collapse model by Mueller et al., Astrophys. J. 603 (2004) 221. time dependent q

  7. 5 1 0 ¡ ¡ l l k d F D M i i i 2 3 1 0 1 6 1 0 t t t t t t £ £ < > u a y v e r a g a e x s y q m m e r c n o n - r o a n g n a e p r o o - n e u r o n s a r » » ¯ , , : l d d l G W i i i i t r e e a s e n u r n g s m u a o n However, note dependence on progenitor model

  8. SN rate + very massive PopIII stars at z≥15 future input from SWIFT… + s i m u l a t i o n s ≥100Msun PopIII ordinary SN gravitational wave spectra neutrino spectra

  9. => diffuse neutrino spectra stochastic gravitational wave background Ando and Sato, astro-ph/0410061 Buonanno, Sigl, Raffelt, Janka, Mueller, Phys.Rev.D 72 (2005) 084001

  10. At low frequency gravitational wave spectrum always dominated by anisotropic neutrino emission. At high frequency f > 100 Hz convective mass motion dominates. • Note that simulations stop after ~250 msec, during which only about 1/6 of the • total 3x1053 erg in neutrinos radiated during cooling phase has been emitted • Possible enhancement factors in the GW amplitude between ~√6 and ~6 (bands in previous figure) • Red vs blue band are different type II SN redshift evolutions

  11. The rate of ordinary supernovae is R ~ 1/sec. For Pop III events related to a few hundred solar mass stars the rate RIII is related to the fraction of baryons converted into Pop III stars fIII by For events with rate R and processes that loose phase coherence after one cycle, at frequencies f < R the signal becomes « stochastic », or « gaussian », i.e. more than one event is « on » at any given time. Individual events are also unresolvable at such frequencies because SNR < 1. If metals are released, fIII has to be <10-5. However, there are speculations that an observed infrared background exess could be explained by efficient Pop III formation correponding to fIII~0.1. Metallicity constraints in this case must be circumvented by fall into black hole.

  12. reionization Uncertainties in star formation rates at high redshift

  13. By using more optimistic SFR, Sandick et al, Phys.Rev.D 73 (2006) 104024 obtain more optimistic estimates

  14. SN and PopIII Compare this with upper limits, sensitivities, and cosmological predictions BBO BBO correlated By the way: Accelerated expansion could decrease conventional inflation signal by factor 100 ! This makes astrophysical sources more important. Giovannini

  15. Sensitivities of existing and future ground-based gravitational wave detectors (uncorrelated)

  16. f µ ¶ M ´ g w c o 3 8 1 ¡ f L L L f f L L L 1 2 5 1 0 £ ´ » » ´ e r g s X » » » b l d d d d d d E E E g w g w c o a c c : o e m a c c : f M ´ X ¯ e m Active Galactic Nuclei as Photon and Gravitational Wave Sources The bolometric luminosity Lbol of an AGN with central black hole of mass M is related to the accretion rate Lacc and the Eddington rate LEdd by of which a fraction fX is in X-rays between 2 and 10 keV, LX= fX Lbol. Assume that a fraction fco of accretion is in the form of compact objects of typical mass m ~ 100 Msun. These objects release a fraction α ~ 0.2 of their mass m in gravitational waves during inspiral to the last stable orbit: Thus, from the observed X-ray luminosity function dn/dLX for AGNs, we can compute the cosmological gravitational wave background.

  17. For ΩSMBH = fraction of critical density in SMBHs, Ωacc = fraction of critical density in accreted gas, ΩX = fraction of critical density of X-rays in the 2-10 keV band, facc = fraction of SMBH mass due to accreted gas, fobsc = fraction of obscured emission ~ 0.3, one has faccΩSMBH ~ (1 – ηem) Ωacc ΩX ~ <(1+z)-1> fobsc fX ηem Ωacc Since ΩX/ΩSMBH ~ 1.3x10-3, <(1+z)-1> ~ 0.4from AGN evolution data, one obtains the condition fobscfaccfXηem ~ 3x10-3 • Observations suggest that ηem is not much smaller than 0.1, and that • SMBH build-up is dominated by accretion facc ~ 1 and NOT by mergers • fX ~ 0.1: bolometric emission dominated by infrared. This will be our standard case.

  18. The universal photon spectrum

  19. Diffuse X-ray background AGN+galaxy clusters Compton thin Compton thick unobscured Comastri, Gilli, Hasinger. astro-ph/0604523

  20. X-ray luminosity function The X-ray background between ~1 and ~100 keV is explained by AGNs.

  21. 7 6 5 f b l l S N R M M M M j i i 1 1 1 0 0 0 1 0 0 t o a o e c s p r a n g ¯ ¯ ¯ ¯ l b l k h l f i i t t n o c e n r a a c o e s o v a r o u s m a s s e s . Individual events Sigl, Schnittman, Buonanno, astro-ph/0610680

  22. f d 1 n c o d d R L = X f d l E L n X X g w h l l E i i t t t w e r e g r a v a o n a w a v e r e e a s e p e r e v e n = g w , d b G R g o v e r e n e y fX = 0.03, ηem = 0.2, (infrared emission dominated, solid line) facc = 1, fco = 0.01, black hole spin a/M = 0.95, for which ηgw ~ 0.2 Confusion noise Noise induced by subtracting resolvable events with SNR > 15 Time-averaged total signal

  23. The duty factor is the event rate times the time tcoh ~ f/(df/dt) ~ f -8/3 spent emitting at frequency f. Sigl, Schnittman, Buonanno, astro-ph/0610680 Below a few milli-Hertz > 1 event contributes at any given time and the signal is gaussian. At higher frequencies one would see individual events at final stages of inspiral. These events also have sufficient SNR to be resolved.

  24. The observable total (solid) and resolvable (dashed) chirp rate as function of frequency f. Sigl, Schnittman, Buonanno, astro-ph/0610680

  25. h f d d l h b d b T i i i i t t t t e r a e o n v u a e v e n s c a n u s e a p p r o x m a e y 2 µ ¶ µ ¶ f M 1 0 ¯ 2 1 3 ¡ ¡ c o ( ) f f f ¡ H 1 0 5 1 0 £ < ' y o r z 0 0 1 m : h h d f h l l d b T i i i i i t t t t n s s c e n a r o e u r a o n o s u c a y p c a e v e n w o u e . = 8 3 2 3 ¡ µ ¶ µ ¶ M H 1 0 1 0 z ¯ ( ) f 0 2 t ' y r h c o : : f m d d l l d h b f l l d h h f h h h I i i i t t t t t n v u a e v e n s c o u u s e o o w e r o u g r e q u e n c y s p a c e w e c a r - f l f l i i i t t t a c e r s c r e q u e n c y e v o u o n o r c o a e s c e n c e . ( ) h b k d b d l f T i 1 t > e a c g r o u n e c o m e s g a u s s a n u y c y c e o r = = 3 4 3 8 2 µ ¶ µ ¶ f M 1 0 ¯ 3 ¡ c o . f f H 2 1 0 £ ' z g a u s s : 0 0 1 m : f f l h b k d b f A i i i 5 1 0 t t t r e q u e n c e s a a c o r - o w e r e a c g r o u n e c o m e s c o n u s o n n o s e , .

  26. Conclusions1 1.) There is a deep connection between neutrino and gravitational wave emission by collapsing massive stars. Both signals have good chances to be seen by future experiments. 2.) Such astrophysical backgrounds could partially mask the inflationary background in the BBO (~0.1 Hz) frequency range. In the ground based frequency range ~100 Hz, these backgrounds would only be detectable by the most advanced third generation detectors. 3.) The supernova type II background is gaussian below ~1 Hz, however the neutron star phase transition background would be pop-corn type.

  27. Conclusions2 4.) The accretion powering Active Galactic Nuclei give rise to electromagnetic emission from the infrared to γ-rays and at the same time to gravitational waves from inspiral of compact objects. 5.) If > 1% of the accreted matter fueling AGNs is in form of compact objects, a continuous background detectable by LISA results below 1 mHz. If the typical compact object masses are > 10 solar masses, individual inspirals should be resolvable above a few mHz with a rate of a few hundred per year.

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