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Constraining Intermediate-Mass Black Hole Masses with VLBI Studies

This study from Torun, Poland in September 2006 explores ultraluminous X-ray sources, their radio studies, and the European VLBI Network. Discoveries include compact radio sources in M82, implications for M82.X-1, and the potential of VLBI in detecting ULX sources. The study investigates VLBI technology limitations, observing data rates, and key findings related to IMBH binaries and ULX production. Results also cover VLBI detections, SNR morphologies, and the radio counterpart of M82.X-1. Gain insights into the structure and significance of radio sources in context with XRBs and IMBHs for a comprehensive understanding of VLBI applications.

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Constraining Intermediate-Mass Black Hole Masses with VLBI Studies

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  1. Constraining IMBH masses with VLBI Paragi Z.1, Garrett M.A.1, Biggs A.D.2 1 Joint Institute for VLBI in Europe 2 United Kingdom Astronomy Technology Centre Torun, Poland, 26-29 September 2006

  2. My conclusions • Most powerful ULX sources should be detectable with VLBI, • if these indeed host intermediate-mass black holes. • The sub-mJy radio source in the CHANDRA error box of • M82 X-1 is unrelated to the ULX (unlike I stated in the abstract) • M82 X-1 is most likely not a ~1000 Msun IMBH Torun, Poland, 26-29 September 2006

  3. Ultraluminous X-ray sources • Einstein observatory survey: bright, compact X-ray sources in nearby • galaxies (Fabbiano et al. 1989) • Off-nuclear, highly variable sources are quite common (Colbert and • Mushotzky 1999, Makishima et al. 2000) • Lx > ~31039 erg/s, Eddington limit for 20 M star. • What are ULX sources? • Normal X-ray binaries with geometrical (King et al. 2001) or • relativistic beaming (Reynolds et al. 1997, Körding et al. 2001) • Two populations of super-Eddington XRBs (King 2002) • Intermediate-mass black holes (Colbert and Mushotzky 1999) • Miller, Fabian & Miller (2004): cool accretion disks in brightest ULXs • (TM1/4) Torun, Poland, 26-29 September 2006

  4. ULX radio studies If accreting sources, is there evidence for compact radio (core-jet) structures? So far only ATCA and VLA detections, resolved sources (e.g. Holmberg II X-1; Miller, Mushotzky and Neff 2005; more recently Soria et al. 2006…) Körding et al. VLA survey (2005): LR1.51017 W/Hz M103 M Is VLBI detection of an ULX possible at all??? Torun, Poland, 26-29 September 2006

  5. The European VLBI Network Very Long Baseline Interferometry: radio telescopes record data on magnetic tapes, and these are later processed in a correlator. Tape limitations: expensive, finite lifetime, parity errors. MkIV system limited to 256 Mbps data rate (512 Mbps using two recording heads). Mark5A: PC based disk recording system. Advantages: cheaper, perfect recording, off the shelf technology. EVN is fully MkV since 2004. Observing data rate 1 Gbps available. May target the 50-100 Jy sky. Torun, Poland, 26-29 September 2006

  6. Lr = 0.60 log Lx + 0.78 log M + 7.33 Merloni, Heinz & Di Matteo (2003) Torun, Poland, 26-29 September 2006

  7. Torun, Poland, 26-29 September 2006

  8. Torun, Poland, 26-29 September 2006

  9. Torun, Poland, 26-29 September 2006

  10. Torun, Poland, 26-29 September 2006

  11. M82 X-1 Lx = 104041 erg/s  M > 500 M (Ptak&Griffith 1999; Kaaret et al. 2001) QPO 0.050.1 Hz  M~ 1001000 M (Strohmayer & Mushotzky 2003) QPO 0.114 Hz + VHS XRB-like spectrum  M~ 50260 M (Dewangan, Titarchuk & Griffiths 2005) Kaaret, Simet & Lang (2006): 62 day periodicity, likely due to orbital motion in an XRB. Roche-lobe overflow from a (super)giant companion? This type of IMBH binary may produce M=10M/yr (Li 2004), sufficient to fuel the ULX. Torun, Poland, 26-29 September 2006

  12. M82 radio sources and ULXs Pedlar et al. (1999) Kaaret et al. (2006) Torun, Poland, 26-29 September 2006

  13. EVN Observations 2005 October 27, 1.6 GHz Cm,Ef,Jb76m,Mc,Nt,On,Tr,Ro,Wb 1024 Mbps, 64 MHz LCP and RCP At 1.6 GHz, 15 hours integration. Phase-referencing to M81, 10 min. duty cycle. Correlation with 256 lags, 1s int., providing ~20 arcsec field of view. Only possible at the EVN MkIV Correlator Firm detection 8 sources on the field. RMS noise 15 Jy/beam, limited by M82. Torun, Poland, 26-29 September 2006

  14. MERLIN archive 1.6 GHz data, 1997 Torun, Poland, 26-29 September 2006

  15. SNR 44.01+596 SNR 41.31+592 M82 X-1 radio counterpart? SNR 45.17+612 Torun, Poland, 26-29 September 2006

  16. EVN 1.6 GHz ~2 pc M82 X-1 radio counterpart? McDonalds et al. 2002 Torun, Poland, 26-29 September 2006

  17. Summary of results I. • Eight compact sources detected with VLBI in M82. • Three of them first VLBI detections. • Seven of the sources show resolved, SNR morphology. • There is a source • within the CHANDRA • error bar of X41.4+60 • (M81 X-1). • No source is detected • at the position of • X42.3+59. Körding et al (2005) Torun, Poland, 26-29 September 2006

  18. Summary of results II. • Main target (41.31+59.6) is resolved. • Seems to have a different structure than the SNRs in M82. • Not an HII region: compact, and has • a steep spectrum (e.g. Allen and Krönberg 1998). • Only firmly established radio source within the CHANDRA • error box  looked to be the radio counterpart of M82 X-1 • for some time... • But! • Deep MERLIN observations indicate it is an SNR (Muxlow, priv. comm.) • A new, variable radio source may have been discovered by • Kaaret et al. (2006) in the field (low SNR detection, not yet confirmed) Torun, Poland, 26-29 September 2006

  19. Kaaret et al. (2006) Torun, Poland, 26-29 September 2006

  20. Summary of results II. (cont.) From the non-detection of a compact radio source (4-5~60Jy upper limit) means MBH <~500 M . A similar upper limit applies to X42.3+59. Although this is just a rough estimate, these observations seem to exclude the possibility of a ~1000 M BH in M82 X-1. Both super-Eddington XRB or (less massive) IMBH is consistent with our data. Torun, Poland, 26-29 September 2006

  21. Network Topology for eVLBI Gbit link Chalmers University of Technology, Gothenburg Network North-West OnsalaSweden Gbit link TorunPoland 150Mbit link Jodrell BankUK WesterborkNetherlands DedicatedGbit link MERLIN Microwave link Dwingeloo DWDM link CambridgeUK MedicinaItaly

  22. Next e-VLBI dates: 26 October 2006 14 December 2006 Information: zparagi@jive.nl Torun, Poland, 26-29 September 2006

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