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Science from e-VLBI

Discover the exciting potential of electronic Very Long Baseline Interferometry (e-VLBI) for studying black hole binaries and other rapidly variable objects in the universe. Rapid response and high-resolution imaging allow for the observation of small-scale analogs of supermassive black holes, offering insights into feedback mechanisms and galaxy formation. See the first science results and future prospects of e-VLBI in this informative article.

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Science from e-VLBI

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  1. Science from e-VLBI Rob Fender (University of Southampton, UK and Universiteit van Amsterdam, NL) On behalf of Valeriu Tudose, Anthony Rushton, Zsolt Paragi, Mike Garrett, Ralph Spencer, Arpad Szomoru, James Miller-Jones, Guy Pooley and many others…

  2. Why e-VLBI is exciting for science • Need to know what is going on at the smallest angular scales (close to the central engine e.g. black hole) • Objects are rapidly variable so we need rapid response to observing requests, and rapid analysis of data • Coordination with current and future observatories (e.g. LOFAR, Chandra, GLAST)

  3. Test cases: black holes in outburst • Data processing took 1-2 weeks with first images within 48 hours • Publication took less than 2 months

  4. Observing black holes within our galaxy ‘hard’ X-ray spectrum ‘soft’ X-ray spectrum

  5. The companion star The corona (T > 100 MK ?} The accretion disc (1000 K < T < 10,000,000 K) The jet (v ~ c)  Radio Emission

  6. All of these accreting sources produce radio-emitting outflows: high energy processes are always associated with radio emission MERLIN (daily images) GRS 1915+105: ~15 solar mass black hole in 33 day orbit Jets moving at >0.99c Associated with outbursts Carrying a huge amount of energy There are several hundred such objects in the galactic plane. e-VLBI has ten times better angular resolution! receding

  7. WHY DO THIS ? These objects are small-scale analogs of supermassive black holes We can use them to study the evolution of feedback and galaxy formation over cosmic time The varying feedback of accretion power which has shaped our modern universe over millions of years can be observed in weeks in X-ray binaries

  8. Two years in the life of the black hole X-ray binary GX 339-4 (compressed to two minutes  one second = six days) Luminosity Spectral changes (‘mode’ of accretion) ‘Light curve’ here

  9. What exactly is happening to the jet? As the spectrum changes the jet becomes powerful and unstable At the vertex, before the spectral change begins, there is a steady, small-scale jet At the end of the transition the jet is switched off These changes occur on a timescale of ~one week  we need rapid-response high-resolution radio imaging

  10. First production science with e-EVN Target: Cygnus X-3 – highly variable black hole binary system 6 antennae : Onsala (SW), Torun (PL), Jodrell Bank (UK), Cambridge (UK), Medicina (IT) and Westerbork (NL) Frequency: 5 GHz Data transfer: 128 Mb/s Three observations: March 16 : no useable data April 20 : 7 hr on-source May 18 : 12 hr on-source

  11. No data Epoch I Epoch II Major radio outburst – implying relativistic accretion and ejection events, based on monitoring at 15 GHz with Ryle Telescope (i.e. external trigger)

  12. Cygnus X-3 Tudose, Fender et al. (2007) peak flux : 3.4 mJy/beam rms noise : 0.03 mJy/beam contour levels: (-15,15,25,35,45,55,65,75,85,95) x rms peak flux : 18.2 mJy/beam rms noise : 0.2 mJy/beam contour levels: (-15,15,25,35,45,55,65,75,85,95) x rms

  13. Cygnus X-3 Not only continuum but excellent polarisation results  diagnostics of relativistic shocks Fractional linear polarization Distribution of the electric vector PAs

  14. GRS1915, from April 2006 GRS 1915+105: e-VLBI obervations of a black hole in a quiet state Provides a measure of the physical size of the relativistic outflow in ‘dormant’ states (by far the most common state) Rushton et al. (2007)

  15. What did we learn from these observations: • How rapidly energy is transported from the black hole to the surrounding environment, and how rapidly the flow of energy switches off • Relativistic shocks in the interstellar gas  dissipation of jet kinetic energy into the interstellar medium • e-VLBI works ! • (and is published - • Two journal papers • Tudose et al. • and • Rushton et al.)

  16. Cygnus X-3 GRS 1915+105 More rapid tracking of these events will broaden our understanding of the relation between inflow and outflow  need rapid (days) response to observing requests Once a major outflow / shock etc is detected we need to trigger additional observations  need rapid analysis

  17. What the observers would like : • More possibility for ad-hoc e-VLBI sessions. • The most exciting events are necessarily rare and unpredictable so we need to be able to get VLBI images very rapidly ( e-VLBI) on short timescales (days) • Future scientific prospects: • e-VLBI is a superb development. We look forward to further observations of high-energy, rapidly-variable transients. This includes proposed coordination with e.g. • - GLAST burst monitor • - LOFAR Radio Sky Monitor • Spectrum-RG Lobster THE END

  18. Australian e-VLBI – ‘PAM(H)ELA’ – first science results

  19. Circinus X-1 First Australian e-VLBI observations Detection of radio ‘core’ following a phase of radio flaring Compact nature of core (unlike Cygnus X-3) supports interpretation that radio-emitting jet is pointing directly at us This system contains a neutron star which seems to behave like the black holes !

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