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Discovery of an FRII microquasar

Discovery of an FRII microquasar. Roberto Soria (University College London). Manfred Pakull (Strasbourg Observatory) Jess Broderick (Southampton) Stephane Corbel (Université Paris 7 and CEA Saclay ) Fabien Grise’ (University of Iowa) Christian Motch (Strasbourg Observatory). Outline.

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Discovery of an FRII microquasar

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  1. Discovery of an FRII microquasar Roberto Soria(University College London) Manfred Pakull(Strasbourg Observatory) Jess Broderick (Southampton) Stephane Corbel (Université Paris 7 and CEA Saclay) Fabien Grise’(University of Iowa) Christian Motch(Strasbourg Observatory)

  2. Outline Introduction: ULX bubbles NGC 7793 S26: multiband study X-ray core + X-ray/radio lobes + ionized bubble Energetics of S26: the most powerful microquasar known to date Radio loud and radio quiet states

  3. Holmberg IX X1 Pakull & Mirioni 2002 Grise’ et al 2008 No radio nebula (F <~ 0.1 mJy) Lx ~ 1—2 E 40 erg/s Lmech ~ 1 E 40 erg/s HST IC342 X1 (“foot nebula”) Ha Pakull & Mirioni 2002 Feng & Kaaret 2008 No radio nebula? Lx ~ 1 E 40 erg/s Lmech ~ few E 39 erg/s

  4. NGC1313 X2 Grise’ et al 2008 Grise’ et al 2011 in prep No radio nebula (F <~ 0.1 mJy) Lx ~ 0.5—2 E 40 erg/s Lmech ~ few E 39 erg/s

  5. ULX radio bubbles found in: Holmberg II X1 Miller, Mushotzky & Neff 2005 NGC5408 X1 Kaaret et al 2003 Soria et al 2006 Lang et al 2007

  6. …and of course SS433 in our Galaxy Ljet ~ 1 E 39 erg/s

  7. NGC 7793 (d ~ 3.9 Mpc) S26 nebula discovered by Blair & Long 1997 Previously interpreted as an SNR (Pannuti et al 2002)

  8. M Pakull discovers a triple X-ray source from Chandra data (2007)

  9. Lx ~ 6E36 erg/s thermal plasma kT ~ 0.3—0.9 keV Lx ~ 6E36 erg/s thermal plasma kT ~ 0.5 keV Lx ~ 7E36 erg/s Power-law G ~ 1.5 Lx ~ 1.2E37 erg/s thermal plasma kT ~ 0.3—0.9 keV

  10. Combined hot spots Core Chandra spectra of the X-ray core ( = BH in low/hard state?) and X-ray hot spots (thermal emission, not synchrotron)

  11. Radio spectral index: ~ -0.8 in the lobes (opt thin synchrotron) ~ 0 in the bubble (free-free from ionized gas)

  12. Estimated flux of free-free radio emission in agreement with H-beta flux Bubble = shocked gas at T ~ 30,000 K and density ~ 1/cm3

  13. VLA long-slit spectrum shows velocity structure: expanding bubble + jet entrainment

  14. Energetics of S26 (Castor et al 1975, Weaver et al 1977) From observations, we get: (expansion velocity from Ha line width) (shock velocity from Ha/HeII4686) Alternative estimate from radiative shock models observed (~ 10 times that of SS433)

  15. Energetics of S26 Mass swept up in the shell ~ 2E38 g Total energy in the cavity ~ 1E53 erg Characteristic age ~ 200,000 yrs After reverse shock, jet energy transferred to: relativistic electrons (g ~ 1—1E5) non-relativistic electrons (g ~ 1) relativistic protons and He nuclei thermal gas Assume magnetic field ~ in equipartition with relativistic energy density Calculate synchrotron emission and radio flux density Compare with observed radio flux density We obtain that: only a few E(-3) of the jet power is given to relativistic electrons

  16. 1. Estimate the energy required to inflate the bubble From [p x V] of X-ray cavity (eg, 4pV = enthalpy of relativistic gas) From optical line emission From free-free radio emission Get direct estimate of mechanical power 2. Measure radio synchrotron emission from lobes Estimate (1/k) x jet power where (1/k) = fraction of power transferred to relativistic electrons Calibration of 1/k is long-standing problem also for AGN (eg, Willott et al 1999) S26 is a rare object with direct estimates of both proxies

  17. K=1 S26 Cavagnolo et al 2010: relation between radio lobe luminosity and power injected into the bubble, for a sample of AGN Power in relativistic electrons ~ (1/100)—(1/1000) of the total jet power

  18. Radio loud and radio quiet accretion How does a microquasar jet with average P ~ a few E 40 erg/s fit with canonical BH states? Possible scheme Radio loud Low/hard state FRI galaxies microquasars High/soft state Radio quiet No jet Radio-quiet QSOs VH state ULX states Radio loud? (steady or flaring?) FRII galaxies Radio-loud QSOs S26?

  19. Radio loud and radio quiet accretion Three cases at accretion rates >~ Edd ? (Punsly 2008, Punsly & Tingay 2007) Ultraluminous, radio-quiet state Most quasars Many (most?) ULXs? Ultraluminous, radio-loud state quasars: PKS 0743-67(L ~ P ~ 1E47 erg/s) 3C14(P ~ 5E45 erg/s, L ~ 3E45 erg/s) ULXs: Holmberg II X1(L ~ P ~ 2E40 erg/s) NGC5408 X1(L ~ P ~ 1E40 erg/s) Kinetically-dominated ultra-high state quasars: 3C82(P ~ 1E47 erg/s, L ~ 1E46 erg/s) 3C9(P ~ 1E47 erg/s, L ~ 3E46 erg/s) 3C455(P ~ 7E45 erg/s, L ~ 4E44 erg/s) microquasars: S26 (P ~ 5E40 erg/s >> L)

  20. Radio loud and radio quiet accretion Mechanical feedback > radiative feedback Allows quasars to grow more quickly May require high-spin BH and extraction of energy from BH spin Kinetically-dominated ultra-high state quasars: 3C82(P ~ 1E47 erg/s, L ~ 1E46 erg/s) 3C9(P ~ 1E47 erg/s, L ~ 3E46 erg/s) 3C455(P ~ 7E45 erg/s, L ~ 4E44 erg/s) microquasars: S26 (P ~ 5E40 erg/s >> L)

  21. Conclusions ULX bubbles have mechanical power ~ 1E39—1E40 erg/s S26 in NGC 7793 is first example of collimated jets Largest and most powerful microquasar (160 x 290 pc) Linear size ~ 2.5 x SS433 Radio luminosity ~ 3 x Cas A Jet power ~ a few E 40 erg/s Most of the jet power used to inflate the bubble Only ~ 1E38 erg/s go into synchrotron-emitting electrons Core is an optically bright (B ~ 23 mag) but X-ray faint source (currently in the low/hard state? Fainter than average?) Rare example of kinetically-dominated ultra-high state in the local universe (analogy with recently discovered sample of kinetically dominated quasars)

  22. Work in progress Study polarization and Faraday rotation from new ATCA radio data HST imaging observations already approved, scheduled for July 2011 Re-apply for Chandra time to determine accurate position and spectrum of the hot spots Re-apply for VLT spectroscopy to determine mass and age of the optical counterpart (B ~ 23 mag) (and maybe mass function in the future?) Find a more appealing name than “NGC 7793 S26” (email suggestions to roberto.soria@mssl.ucl.ac.uk) REFERENCES: Pakull, Soria & Motch 2010, Nature Soria, Pakull, Broderick, Corbel & Motch 2010, MNRAS

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