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40 Years of Microquasars Ralph Spencer Jodrell Bank Observatory School of Physics and Astronomy University of Manchester Ierapetra June 2014 Radio Emitting X-ray binaries (REXRB) • 1968: discovery of radio emission from Sco X-1 (Andrew and Purton 1968) • 1971: radio emission from X-ray binaries detected by Westerbork Array and GB Interferometer at ~ mJy levels (Braes and Miley 1971, Hjellming and Wade1971) April 1971 John applies to Jodrell Bank for a place on the MSc course, joins in Sept 1971 Cygnus X-3 Goes Bang! • Jan 1972: Detection of Cyg X-3 with GBI (Hjellming and Wade 1972) 0.1-0.3 Jy at 11 and 4 cm • September 1972: –outburst on Cyg X-3 reaching > 20 Jy. Many observatories took part. Oct 1972 John starts PhD Gregory et al 1972 Nova Monoceros 1975 A0620-00 • Rapid increase in X-ray emission reported by Leicester group (Ariel) • Triggered radio obs at JBO (Davis et al. 1975) • Kuulkers et al. 1999 revisited data Oct 1975 John completes PhD X-Ray Binaries • ~300 X-ray emitting binary stars (XRBS) found in our own Milky Way galaxy, detected by X-ray satellites at ~1-10 kev (van Paradis 1995, Liu et al. 2000, 2001 catalogues) • High Mass ~ 10 Msun • Low Mass ~ 1 Msun • .All powered by accretion onto a compact object (neutron star or black hole). • Roche Lobe overflow or wind? • ~20 % have been found to have radio emission Low Mass XRBs • • • • • Companions around 1 Msun, with a neutron star or BHC secondary Neutron star binaries – Type I X-ray bursts – Soft X-ray emission (few kev brightness temp.) – Short orbital period of < 12 hours BHCs : no Type 1 bursts, hard X-rays, transients X-ray colour-colour diagram useful diagnostic Quasi period oscillations in X-ray intensity X-ray bursts from Circ X-1 High Mass X-ray binaries: HMXRB • Indicators: – O, B, Be or Wolf-Rayet stellar spectrum – Strong flaring and absorption variability on a timescale of minutes – Transient outbursts – Hard 1-10 kev spectrum with a power law index at higher energies of ~0-1 • Periods range from 4.8 hrs (Cygnus X-3) to 187 days (Hen 715) • N- star or BHC compact secondaries • Generally wind fed. The discovery of radio jets • SS433 in 1979 • Moving optical lines suggest precessing jets at 0.26 c with a period of 162.5 days (Abell and Margon 1979) • Cambridge 5km observations of compact objects < 1 arcsec, Ryle et al 1978 • Interesting X-ray behaviour – Dennis Walsh suggested we observed it at JB • Discovered extension in PA ~100 deg – jets? (Spencer 1979) Margon and Anderson 1989 MkI-Defford 74-cm 1979 visibility curve SS433 radio jets • Hjellming and Johnston 1981 VLA results • MERLIN 5 GHz Jowett PhD 1999 Stirling et al 2002 Radio Emission • ~50 sources have radio emission • Most radio emitters are Low Mass XRBs with BHC I. Brown 2006 PhD Thesis Microquasars • Term first used by Martin Elvis 1984 “Microquasars and the Xray Background” (Weak AGN) • First used in the context of Xray binaries: Geldzahler, Fomalont and Cohen 1984, “Sco X-1 The Microquasar” • Now thought to be unrelated background sources VLA 4.8 GHZ Microquasars • Why microquasar? – Radio jets – Relativistic velocities – Powered by accretion – 106 times closer • Mirabel et al. 1992 1E1740.7-2942 Number of papers with ‘microquasar’ in the title or abstract No. of papers Year Fundamental plane of black holes • Radio/X-ray correlation found in XRBS can be extended to AGN by the inclusion of a mass term. • Correlation very tight for LLAGN Merloni, Heinz et al. 2003, Falcke, Koerding, Markoff 2004, Koerding et al. 2006 Some Individual Objects • • • • • Cygnus X-3 SS433 Cygnus X-1 GRS1915+105 Cygnus X-2 Cygnus X-3 Cygnus X-3 Green Bank Interferometer S-band data 20 Flux density Jy • Greenbank Interferometer Waltman et al 1995 • 1983 MERLIN 5 GHz – model fitting N-S double showed expansion at 0.3 c Johnston et al. 1983 • Infra red and radio flares Fender, Bell-Burnell, Ogley et al. 1994,1995, 1996, 2001 15 Si 10 5 0 3 710 3 7.510 3 810 Ti MJD • 10 Msun WR star and 2.4 Msun BH Zdziarski et al. 2013 Fender et al 1996 3 8.510 3 910 Relationship to X-rays • Ryle telescope and RXTE (Pooley) • Quenching of radio before outburst • Hardening of X-rays Radio/Hard X and γ-ray Quenching • Corbel et al 2012- hard X-rays and γ-rays suppressed just before a major flare Cygnus X-3 Images • Mioduszewski et al 2001 • 15 GHz VLBA • Evolving N-S jet • 2-sided N-S structure also seen in 5 GHz VLA images (AM). • Expansion at ~0.5 c (Marti et al 2002) www.aoc.nrao.edu/~amiodusz/ NB 90 deg rotation • EVN at 5 GHZ 1st e-VLBI observations at 5 GHz Complex changes in the core- more to do! SS433 • • • • • Another WR star and compact companion 24 Msun WR and 16 Msun BH 162.5 d precession period 13 d binary period Proper motion if at 0.26 c gives distance of 4.6 kpc VLA 5 GHz Blundell and Bowler 2004 The Ruff – Equatorial emission VLA, MERLIN VLBA 6 cm March 1998 Blundell et al 2001 MERLIN+EVN 18 cm June 1998 Stirling et al 2004 Present in ~25% of images, no obvious relationship to jet knots and PA Spencer 2006 W50 and SS433 – the jets slow down? Velocity of filaments in the ears < 0.04c Goodhall et al. 2011 More observations needed! Fit to ephemeris including nutation suggests deceleration at 0.04c/yr Stirling et al. 2004 Cygnus X-1 – a radio jet in a persistent black hole XRB 15 Msun Black hole +19 Msun O star companion VLBA 8.4 GHz August 1998 -discovery of jet in Cyg X-1 on ~15 mas scale (Stirling et al 2001) VLBA 15 GHz Showing compact jet ~3 mas long Also a weak compact jet in the soft state (Rushton et al 2012 (in low/hard X-ray state) Optical line emission Cyg X-1 Nebula White: continuum Red: Ha Green: O[III] (Russell, Fender et al. 2007) 1.4 GHz Westerbork image Gallo et al 2005 GRS1915+105 10 Msun BH +2 Msun companion Superluminal expansion Mirabel & Rodriguez 1994 Fender et al 1999 0.9c, 11kpc Radio emission in plateau states (Migliari & Belloni 2003 Xray state χ) Rushton et al 2010 0.2-0.4 Jy Flares and 0.05-0.1 Jy plateaus Typically 1-3 months Flares decay in 3-4 days, followed by a suppressed flux before recovering Occurs during plateau state as well as at beginning or end GRS1915 – log normal flux distribution Compare with power law for Cyg X-3 A Radio Jet in the Cyg X-2 Neutron Star X-ray Binary Spencer et al. MNRAS 435L, 48, 2013 Horizontal Branch (HB) jet launched here Z-track on hardnessintensity diagram Normal Branch (NB) mass accretion rate increases Flaring Branch (FB) unstable nuclear burning on the neutron star 6 cm EVN 22 Feb 2013 Jet ejected SWIFT hardness – intensity diag. Source in HB 23 Feb 2013 Hard Apex - Jet ejected X-ray, UV and radio vs time 1.7 Msun neutron star and a 0.6 Msun companion To summarise so far • Radio emission can be relatively steady or in flares • Flaring often associated with the formation of relativistic jets on > 100 mas scales • Steady mas (10’s au) jets can also occur • At least one object shows precessing jets • Strong association with X-ray emission: jet-disk coupling • Changing accretion conditions have a causal relationship with the radio jets q- diagram or Turtles Head Gallo, Fender et al 2005 Miller et al. 2012 model for CygX-1 Radio Reflected X-rays Hard X-rays Magnetic loops >0.3c wind 0.3c disk O Star companion Hot e+- plasma lifted by unstable loops formed by magnetic rotational instability GRS1915 evolution High Soft X-ray state No radio X-ray Intensity Flaring outburst with relativistic ejection Dominated by radiation form disk Hot corona and jet formed - Blandford Znajek 1977 mechanism Hardness Low Hard X-rays Inner disk instability leads to major ejection Weak inner jet Stronger inner jet Plateau state Future • Do all galactic XRBs have radio emission at some level? Need much better sensitivity to bring the 20% detections up! • Microquasars in other galaxies e.g. M31 (Middleton et al 2013), IC10 (Bernard et al 2008), NGC300 (Crowther et al. 2010) – should be lots, especially in star forming galaxies. • E.g. an equivalent 10 Jy flare in IC10 from a CygX-3 type object would give 240 microJy on Earth – can be studied with JVLA and e-MERLIN, but not quiescent emission • Relationship to ULXs – extending the fundamental plane • Need the SKA!!