Discovery of an FRII microquasar Manfred Pakull (Strasbourg Observatory) Jess Broderick (Southampton) Stephane Corbel (Université Paris 7 and CEA Saclay ) Fabien Grise’ (University of Iowa) Christian Motch (Strasbourg Observatory) Roberto Soria (University College London)
Outline Energetics of S26: the most powerful microquasar known to date Introduction: ULX bubbles NGC 7793 S26: multiband study X-ray core + X-ray/radio lobes + ionized bubble Radio loud and radio quiet states
Holmberg IX X1 Pakull & Mirioni 2002 Grise’ et al 2008 IC342 X1 (“foot nebula”) Pakull & Mirioni 2002 Feng & Kaaret 2008 HHHH HST No radio nebula (F <~ 0.1 mJy) No radio nebula? L x ~ 1—2 E 40 erg/s L mech ~ 1 E 40 erg/s L x ~ 1 E 40 erg/s L mech ~ few E 39 erg/s
NGC1313 X2 Grise’ et al 2008 Grise’ et al 2011 in prep No radio nebula (F <~ 0.1 mJy) L mech ~ few E 39 erg/s L x ~ 0.5—2 E 40 erg/s
Holmberg II X1 Miller, Mushotzky & Neff 2005 NGC5408 X1 Kaaret et al 2003 Soria et al 2006 Lang et al 2007 ULX radio bubbles found in:
…and of course SS433 in our Galaxy L jet ~ 1 E 39 erg/s
S26 nebula discovered by Blair & Long 1997 Previously interpreted as an SNR (Pannuti et al 2002) NGC 7793 (d ~ 3.9 Mpc)
M Pakull discovers a triple X-ray source from Chandra data (2007)
L x ~ 1.2E37 erg/s L x ~ 6E36 erg/s thermal plasma kT ~ 0.3—0.9 keV thermal plasma kT ~ 0.3—0.9 keV L x ~ 7E36 erg/s Power-law ~ 1.5 L x ~ 6E36 erg/s thermal plasma kT ~ 0.5 keV
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)
Radio spectral index: ~ -0.8 in the lobes (opt thin synchrotron) ~ -0.8 in the lobes (opt thin synchrotron) ~ 0 in the bubble (free-free from ionized gas) ~ 0 in the bubble (free-free from ionized gas)
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 Bubble = shocked gas at T ~ 30,000 K and density ~ 1/cm3
VLA long-slit spectrum shows velocity structure: expanding bubble + jet entrainment shows velocity structure: expanding bubble + jet entrainment
Energetics of S26 (Castor et al 1975, Weaver et al 1977) From observations, we get: (expansion velocity from H line width) (shock velocity from H HeII 4686) Alternative estimate from radiative shock models observed (~ 10 times that of SS433)
Mass swept up in the shell ~ 2E38 g Total energy in the cavity ~ 1E53 erg Assume magnetic field ~ in equipartition with relativistic energy density After reverse shock, jet energy transferred to: relativistic electrons ( ~ 1—1E5) relativistic electrons ( ~ 1—1E5) non-relativistic electrons ( ~ 1) non-relativistic electrons ( ~ 1) relativistic protons and He nuclei relativistic protons and He nuclei thermal gas thermal gas Calculate synchrotron emission and radio flux density only a few E(-3) of the jet power is given to relativistic electrons Energetics of S26 Compare with observed radio flux density We obtain that: Characteristic age ~ 200,000 yrs
1. Estimate the energy required to inflate the bubble Get direct estimate of mechanical power From [p x V] of X-ray cavity (eg, 4pV = enthalpy of relativistic gas) (eg, 4pV = enthalpy of relativistic gas) From optical line emission From free-free radio emission 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 S26 is a rare object with direct estimates of both proxies (eg, Willott et al 1999)
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 S26 K=1
How does a microquasar jet with average P ~ a few E 40 erg/s fit with canonical BH states? fit with canonical BH states? Radio loud and radio quiet accretion Low/hard state Radio loud FRI galaxies microquasars High/soft state Radio quiet Radio-quiet QSOs VH state ULX states Radio loud? (steady or flaring?) FRII galaxies Radio-loud QSOs S26? No jet Possible scheme
Three cases at accretion rates >~ Edd ? Radio loud and radio quiet accretion Ultraluminous, radio-loud state quasars: PKS (L ~ P ~ 1E47 erg/s) quasars: PKS (L ~ P ~ 1E47 erg/s) 3C14 (P ~ 5E45 erg/s, L ~ 3E45 erg/s) 3C14 (P ~ 5E45 erg/s, L ~ 3E45 erg/s) ULXs: Holmberg II X1 (L ~ P ~ 2E40 erg/s) ULXs: Holmberg II X1 (L ~ P ~ 2E40 erg/s) NGC5408 X1 (L ~ P ~ 1E40 erg/s) NGC5408 X1 (L ~ P ~ 1E40 erg/s) Kinetically-dominated ultra-high state quasars: 3C82 (P ~ 1E47 erg/s, L ~ 1E46 erg/s) quasars: 3C82 (P ~ 1E47 erg/s, L ~ 1E46 erg/s) 3C9 (P ~ 1E47 erg/s, L ~ 3E46 erg/s) 3C9 (P ~ 1E47 erg/s, L ~ 3E46 erg/s) 3C455 (P ~ 7E45 erg/s, L ~ 4E44 erg/s) 3C455 (P ~ 7E45 erg/s, L ~ 4E44 erg/s) microquasars: S26 (P ~ 5E40 erg/s >> L) microquasars: S26 (P ~ 5E40 erg/s >> L) Ultraluminous, radio-quiet state Most quasars Many (most?) ULXs? (Punsly 2008, Punsly & Tingay 2007)
Radio loud and radio quiet accretion Kinetically-dominated ultra-high state quasars: 3C82 (P ~ 1E47 erg/s, L ~ 1E46 erg/s) quasars: 3C82 (P ~ 1E47 erg/s, L ~ 1E46 erg/s) 3C9 (P ~ 1E47 erg/s, L ~ 3E46 erg/s) 3C9 (P ~ 1E47 erg/s, L ~ 3E46 erg/s) 3C455 (P ~ 7E45 erg/s, L ~ 4E44 erg/s) 3C455 (P ~ 7E45 erg/s, L ~ 4E44 erg/s) microquasars: S26 (P ~ 5E40 erg/s >> L) microquasars: S26 (P ~ 5E40 erg/s >> L) Mechanical feedback > radiative feedback Allows quasars to grow more quickly May require high-spin BH and extraction of energy from BH spin
Conclusions ULX bubbles have mechanical power ~ 1E39—1E40 erg/s S26 in NGC 7793 is first example of collimated jets Most of the jet power used to inflate the bubble Only ~ 1E38 erg/s go into synchrotron-emitting electrons Largest and most powerful microquasar (160 x 290 pc) Linear size ~ 2.5 x SS433 Linear size ~ 2.5 x SS433 Radio luminosity ~ 3 x Cas A Radio luminosity ~ 3 x Cas A Jet power ~ a few E 40 erg/s Jet power ~ a few E 40 erg/s 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)
Work in progress HST imaging observations already approved, scheduled for July 2011 Re-apply for Chandra time to determine accurate position and spectrum of the hot spots 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) to determine mass and age of the optical counterpart (B ~ 23 mag) (and maybe mass function in the future?) (and maybe mass function in the future?) Find a more appealing name than “NGC 7793 S26” ( suggestions to ( suggestions to Study polarization and Faraday rotation from new ATCA radio data REFERENCES: Pakull, Soria & Motch 2010, Nature Soria, Pakull, Broderick, Corbel & Motch 2010, MNRAS