Simulations of M87 and Sgr A imaging with the Millimetron ...
The Event Horizon Telescope: (sub)mm VLBI of Sgr A* and M87
Transcript of The Event Horizon Telescope: (sub)mm VLBI of Sgr A* and M87
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The Event Horizon Telescope:A (sub)mm-VLBI Network
Shep Doeleman MIT Haystack Observatoryfor the EHT Collaboration
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Big Questions
• Is there an Event Horizon?• Does GR hold near BH?• How does matter accrete/outflow near a BH?• Do Black Holes have spin?• How do Black Holes launch jets?
•EHT addresses ASTRO 2010 questions and discovery areas:• How do black holes work and influence their surroundings?• What controls the mass-energy-chemical cycles within galaxies?• What are the connections between dark and luminous matter?• Time domain Astronomy.
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SgrA*: Best Case for a SMBH
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SgrA*: Best Case for a SMBH• Stellar orbits approaching within 45 AU.
Ghez et al 2005
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SgrA*: Best Case for a SMBH• Stellar orbits approaching within 45 AU. • Proper motions < 1km/s: M>10^5 Msol
(Backer & Sramek 1999, Reid & Brunthaler 2004)
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SgrA*: Best Case for a SMBH• Stellar orbits approaching within 45 AU. • Proper motions < 1km/s: M>10^5 Msol
(Backer & Sramek 1999, Reid & Brunthaler 2004)
• Short time scale X-ray flares (300 sec rise).
Baganoff et al 2001
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SgrA*: Best Case for a SMBH• Stellar orbits approaching within 45 AU. • Proper motions < 1km/s: M>10^5 Msol
(Backer & Sramek 1999, Reid & Brunthaler 2004)
• Short time scale X-ray flares (300 sec rise).• IF flares with
modulation (a>0).
VLT: Genzel et al 2003
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Resolving Rsch-scale structures
Spinning (a=1) Non-spinning (a=0)
FalckeMeliaAgol
• SgrA* has the largest apparent Schwarzschild radius of any BH candidate. • Rsch = 10µas• Shadow = 5.2 Rsch (non-spinning) = 4.5 Rsch (maximally spinning)
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Scattering towards the GC
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ISM Scattering:Θscat ~ λ2
Need to observe withVLBI at short wavelengths.
Expected intrinsic size at 1.3mm is~35 micro arcsec.
7mm: Bower et al3mm: Shen et al
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1.3mmλ Observations of SgrA*
4630km
4030km
908km
Builds on long history of SgrA* VLBI and mmVLBI.
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Determining the size of SgrA*
SMT-CARMA
SMT-JCMT
θOBS = 43µas (+14, -8)
θINT = 37µas (+16, -10)
θOBS = θ INT2 +θSCAT
2
1 Rsch = 10µas
ρ = 1023M
pc−3
JCMT-CARMA
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Alternatives to a MBH• Most condensations of smaller mass objects evaporate on short timescales.Current obs imply Tevap<500 yrs.• Boson Star is a remaining ‘exotic’ possibility where R=Rsch + epsilon.Depends on Boson mass.
Proof of an Event Horizon?•If no EH, then the ‘surface’ will radiate inthe NIR, but none seen. (Broderick, Loeb, Narayan 2009)
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Constraining RIAF Models
Broderick, Fish, Doeleman & Loeb (2009)
SgrA* 10-8 Eddington
Inclination constrainedto be >30 degrees: disk not ‘face-on’.
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Constraining RIAF Models
Broderick, Fish, Doeleman & Loeb (2009)
SgrA* 10-8 Eddington
Inclination constrainedto be >30 degrees: disk not ‘face-on’.
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April 2009: SgrA* Flare on Rsch scales
Fish et al, ApJL, v727, L36, 2011
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Tighter Constraints on BH spin.
11Broderick, Fish, Doeleman & Loeb, arXiv:1011.2770
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Time Variable Structures• Variabilty in NIR, x-ray, submm, radio.• VLBI caught SgrA* ‘before’ and ‘after’ flare.• Probe of metrics near BH, and of BH spin.• Requires non-imaging analysis.• Look for signatures of ‘hot spot’ flare models.
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Hot Spot Model for SgrA* Flares
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Hot Spot Model for SgrA* Flares
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Tracing Black Hole Orbits with VLBI
14Steeger et al
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Measuring Black Hole Orbits with VLBI
Spin = 0.9Hot-spot at ~ 6RgPeriod = 27 min.
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Measuring Black Hole Orbits with VLBI
Spin = 0.9Hot-spot at ~ 6RgPeriod = 27 min.
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Measuring Black Hole Orbits with VLBI
Spin = 0.9Hot-spot at ~ 6RgPeriod = 27 min.
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Measuring Black Hole Orbits with VLBI
Spin = 0.9Hot-spot at ~ 6RgPeriod = 27 min.
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Beam: 0.43x0.21 mas 0.2mas = 0.016pc = 60Rs 1mas/yr = 0.25c
VLBA Movie of M87 @ 43 GHz (7 mm)Craig Walker et al. 2008
6.4 billion solar mass BH, FERMI & TeV source
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Beam: 0.43x0.21 mas 0.2mas = 0.016pc = 60Rs 1mas/yr = 0.25c
VLBA Movie of M87 @ 43 GHz (7 mm)Craig Walker et al. 2008
6.4 billion solar mass BH, FERMI & TeV source
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Magnetically driven jet launching ?Magnetically Driven Jets
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Building the Event Horizon TelescopeAstro2010 Roadmap Phase I
• Adding Telescopes: 7 station array.• VLBI backends/recorders that support > 16Gb/s.• Central wideband correlator (up to 64Gb/s) [ATI prop].• Phased Array processors (SMA, ALMA, PdeBure, CARMA) [MRI prop]• Leverage ALMA receivers for EHT [AAG prop]. • Procure Hydrogen Masers.• Recording media for 7-station 8Gb/s array• New site studies• Turn-key operations: remote operations• Project management, operations.
• Endorsed by RMS Panel of US Decadal Review
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New (sub)mm VLBI Sites
Current: ARO/SMT + CARMA + SMA + JCMT + CSOPhase 1: 7 Telescopes (+ IRAM, PdB, LMT, Chile/ALMA)Phase 2: 9 Telescopes (+ Spole, Haystack) Phase 3: 13 Telescopes (+ NZ, Africa,SEST)
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New (sub)mm VLBI Sites
Current: ARO/SMT + CARMA + SMA + JCMT + CSOPhase 1: 7 Telescopes (+ IRAM, PdB, LMT, Chile/ALMA)Phase 2: 9 Telescopes (+ Spole, Haystack) Phase 3: 13 Telescopes (+ NZ, Africa,SEST)
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New (sub)mm VLBI Sites
Current: ARO/SMT + CARMA + SMA + JCMT + CSOPhase 1: 7 Telescopes (+ IRAM, PdB, LMT, Chile/ALMA)Phase 2: 9 Telescopes (+ Spole, Haystack) Phase 3: 13 Telescopes (+ NZ, Africa,SEST)
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New (sub)mm VLBI Sites
Current: ARO/SMT + CARMA + SMA + JCMT + CSOPhase 1: 7 Telescopes (+ IRAM, PdB, LMT, Chile/ALMA)Phase 2: 9 Telescopes (+ Spole, Haystack) Phase 3: 13 Telescopes (+ NZ, Africa,SEST)
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New (sub)mm VLBI Sites
Current: ARO/SMT + CARMA + SMA + JCMT + CSOPhase 1: 7 Telescopes (+ IRAM, PdB, LMT, Chile/ALMA)Phase 2: 9 Telescopes (+ Spole, Haystack) Phase 3: 13 Telescopes (+ NZ, Africa,SEST)
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New (sub)mm VLBI Sites
Current: ARO/SMT + CARMA + SMA + JCMT + CSOPhase 1: 7 Telescopes (+ IRAM, PdB, LMT, Chile/ALMA)Phase 2: 9 Telescopes (+ Spole, Haystack) Phase 3: 13 Telescopes (+ NZ, Africa,SEST)
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Progression to an Image
GR Model 7 Stations 13 Stations
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Phasing Arrays: SMA, CARMA this month.
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TextSMA: Weintroub, Primiani, et al
CARMA: Wright, McMahon, Dexter, et al
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Phasing ALMA• Single most important objective for EHT.• Increases resolution by x2, sensitivity by x10.• Allows detection in 10s to all other EHT sites.
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Phasing ALMA• Single most important objective for EHT.• Increases resolution by x2, sensitivity by x10.• Allows detection in 10s to all other EHT sites.
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Event Horizon Telescope CollaborationMIT Haystack: Shep Doeleman, Alan Rogers, Vincent Fish, et alU. Arizona Steward Obs: Lucy Ziurys, Robert Freund, Dan MarroneHarvard CfA: Jonathan Weintroub, Jim Moran, Ray Blundell, et alCARMA: Dick Plambeck, Mel Wright, David Woody, Geoff BowerNRAO: John Webber, Ray Escoffier, Rich LacasseCaltech Submillimeter Observatory: Richard ChamberlinUC Berkeley SSL: Dan WerthimerMPIfR: Thomas Krichbaum, Anton Zensus, Alan Roy, et alIRAM: Michael Bremer, Karl SchusterAPEX: Karl Menten, Michael LindqvistJames Clerk Maxwell Telescope: Remo Tilanus, Per FribergASIAA: Paul Ho, Makoto InoueNAOJ: Mareki Honma
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Summary• EHT results confirm Rsch structures in SgrA* and M87. • EHT has detected SgrA* closure phase and variability.• Technical path for Phase I of EHT clear.• New science results at each phase of the project: March/April ’11 - ARO/SMT, CARMA, Mauna Kea, APEX, IRAM30m.• Transformative enhancements in EHT within 3/4 years.• Imaging an Event Horizon and observing BH orbits are within reach in <5 years.• Creates a fundamentally new telescope without building new dishes.• Tailored for this decade (beginning of the ALMA era).