40 Years of MicroquasarsRalph 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.

Gregoryet al 1972

Oct 1972 John starts PhD

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 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– 106 times closer

• Mirabel et al. 1992

1E1740.7-2942

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

• GRS1915+105

• Cygnus X-2

Cygnus X-3• 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

• 10 Msun WR star and 2.4 Msun BH Zdziarski et al. 2013

Fender et al 1996

7 103 7.5 10

3 8 103 8.5 10

3 9 103

0

5

10

15

20

Cygnus X-3 Green Bank Interferometer S-band data

MJD

Flu

x de

nsity

Jy

Si

Ti

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

MERLIN+EVN 18 cm June 1998Stirling 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. 2011

Fit to ephemeris including nutation suggests deceleration at 0.04c/yr Stirling et al. 2004More observations needed!

Cygnus X-1 – a radio jet in a persistent black hole XRB

VLBA 8.4 GHzAugust 1998-discovery of jet in Cyg X-1 on ~15 mas scale(Stirling et al 2001)

VLBA 15 GHzShowing compact jet~3 mas long

(in low/hard X-ray state)

Also a weak compact jet in the soft state (Rushton et al 2012

15 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 imageGallo et al 2005

Cyg X-1 Nebula

GRS1915+10510 Msun BH +2 Msun companion

Superluminal expansionMirabel & Rodriguez 1994

Fender et al 1999 0.9c, 11kpc

Radio emission in plateau states (Migliari & Belloni 2003 Xray state χ)

Rushton et al 2010

Typically 1-3 months

0.2-0.4 Jy Flaresand 0.05-0.1 Jyplateaus

Flares decay in 3-4 days, followed by a suppressed flux before recoveringOccurs 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 BinarySpencer et al. MNRAS 435L, 48, 2013

Horizontal Branch (HB) -jet launched here

Normal Branch (NB) -mass accretion rate increases

Flaring Branch (FB) -unstable nuclear burningon the neutron star

Z-track on hardness-intensity diagram

6 cm EVN 22 Feb 2013

23 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 starand 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 Starcompanion

wind

disk

0.3c

>0.3c

HardX-rays

Radio

ReflectedX-rays

Magnetic loops

Hot e+- plasma lifted by unstable loops formed by magnetic rotational instability

Miller et al. 2012 model for CygX-1

GRS1915 evolutionHigh Soft X-ray stateNo radio

Low Hard X-rays

Weak inner jet Stronger inner jet

Flaring outburst withrelativistic ejection

Inner disk instability leads tomajor 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!!