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Torun, Poland, 26-29 September 2006

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. My conclusions. Most powerful ULX sources should be detectable with VLBI,

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Torun, Poland, 26-29 September 2006

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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

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  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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