40 Years of Microquasars Ralph Spencer Jodrell Bank Observatory School of Physics and Astronomy University of Manchester Ierapetra June 2014

Contents REXRB X-ray binaries Discovery of jets Microquasars Individual objects Radio/Xrays Future

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) Jy at 11 and 4 cm September 1972: –outburst on Cyg X-3 reaching > 20 Jy. Many observatories took part. Gregory et al 1972 Oct 1972 John starts PhD

Nova Monoceros 1975 A Rapid increase in X-ray emission reported by Leicester group (Ariel) Triggered radio obs at JBO (Davis et al. 1975) Kuulkers et al 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 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 X- ray Background” (Weak AGN) First used in the context of X- ray 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 –10 6 times closer Mirabel et al E

Year No. of papers Number of papers with ‘microquasar’ in the title or abstract

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 GRS Cygnus X-2

Cygnus X-3 Greenbank Interferometer Waltman et al MERLIN 5 GHz – model fitting N-S double showed expansion at 0.3 c Johnston et al Infra red and radio flares Fender, Bell-Burnell, Ogley et al. 1994,1995, 1996, Msun WR star and 2.4 Msun BH Zdziarski et al Fender et al 1996

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 hard X-rays and γ-rays suppressed just before a major flare

Cygnus X-3 Images Mioduszewski et al 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) NB 90 deg rotation

EVN at 5 GHZ 1 st 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 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 MERLIN+EVN 18 cm June 1998 Stirling et al 2004 VLA, MERLIN VLBA 6 cm March 1998 Blundell et al 2001 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 Fit to ephemeris including nutation suggests deceleration at 0.04c/yr Stirling et al More observations needed!

Cygnus X-1 – a radio jet in a persistent black hole XRB VLBA 8.4 GHz August discovery of jet in Cyg X-1 on ~15 mas scale (Stirling et al 2001) VLBA 15 GHz Showing compact jet ~3 mas long (in low/hard X-ray state) Also a weak compact jet in the soft state (Rushton et al Msun Black hole +19 Msun O star companion

Optical line emission White: continuum Red: Ha Green: O[III] (Russell, Fender et al. 2007) 1.4 GHz Westerbork image Gallo et al 2005 Cyg X-1 Nebula

GRS Msun BH +2 Msun companion Superluminal expansion Mirabel & Rodriguez 1994 Fender et al c, 11kpc

Radio emission in plateau states (Migliari & Belloni 2003 Xray state χ) Rushton et al 2010

Typically 1-3 months Jy Flares and Jy plateaus

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 Normal Branch (NB) - mass accretion rate increases Flaring Branch (FB) - unstable nuclear burning on the neutron star Z-track on hardness- intensity diagram 6 cm EVN 22 Feb Feb 2013 Hard Apex - Jet ejected SWIFT hardness – intensity diag. Source in HB 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

O Star companion wind disk 0.3c >0.3c Hard X-rays Radio Reflected X-rays Magnetic loops Hot e+- plasma lifted by unstable loops formed by magnetic rotational instability Miller et al model for CygX-1

GRS1915 evolution High Soft X-ray state No radio Low Hard X-rays Weak inner jet Stronger inner jet Flaring outburst with relativistic ejection Inner disk instability leads to major ejection Dominated by radiation form disk Hot corona and jet formed - Blandford Znajek 1977 mechanism Plateau state X-ray Intensity Hardness

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!!

Typical jet luminosities suggest B~ 10^8 gauss or more The Power of Spin Blandford and Znajek 1977 Fender, Gallo and Russell 2010 No correlation of radio luminosity with spin Narayan and McClintock 2012 Peak radio luminosity correlates with spin! Problems: 1) spin measurement 2) Jet power RES version 2 high points are the continuous jet sources CygX-1, GRS

Field Clean-Up Tchechovskoy et al 2010 Thorne et al 1986