Studying MWG structure with VERA Mareki Honma Mizusawa VLBI - - PowerPoint PPT Presentation

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Studying MWG structure with VERA Mareki Honma Mizusawa VLBI - - PowerPoint PPT Presentation

Mar 20, 2023 102 likes •340 views

Studying MWG structure with VERA Mareki Honma Mizusawa VLBI Observatory, NAOJ Milky Way & VERA Ogasawara station contents Galaxy scale astrometry with VERA + some more topics future prospect VERA and optical astrometry (GAIA/JASMIEN)

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Studying MWG structure with VERA

Mareki Honma Mizusawa VLBI Observatory, NAOJ

Milky Way & VERA Ogasawara station

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contents

  • Galaxy‐scale astrometry with VERA

+ some more topics future prospect VERA and optical astrometry (GAIA/JASMIEN) Sgr A* observations

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VLBI Astrometry Arrays

  • VERA, VLBA, EVN, in the Northern

hemisphere.

  • LBA, only one in the South
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VERA : VLBI Exploration of Radio Astrometry

Ishigaki-jima Ogasawara Iriki Mizusawa

Target sources : Galactic masers (H2O@22GHz, SiO@43GHz & CH3OH@6.7GHz) New aspect: dual-beam for phase-referencing

Construction completed in 2002 Regular parallax measurement from 2007

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Galaxy‐scale maser astrometry

Galaxy’s center D= 8 kpc π= 125 μas Galaxy scale astrometry requires 10μas accuracy Galaxy scale astrometry = frontier in 21st century (c.f., astrometric missions like GAIA, JASMINE)

Sun

Galaxy Center

Parallax

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VERA’s result: distance to Orion KL

Astrometry of H2O masers in Orion KL

Hirota et al. (2007) D = 437 +/- 19 pc pi = 2.29 +/- 0.1 mas

Orion nebula with Subaru

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Perseus molecular cloud

  • NGC 1333 (Hirota+ 2007)
  • L1448C (Hirota+ 2011)

c.f. IC 348 at 320 pc seeing depth ?

Sun+(2006)

Hirota+(2011)

HIPPARCOS de Zeeuw +(1999) 318+/-27 pc

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AGB stars and PL relation

  • AGB stars can be

another standard candle

  • Combination with

AGB survey at opt/IR will enable us to trace Galaxy’s structure.

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Mira’s PL relation (Nakagawa+2014)

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Another AGB star: R Aqr

  • Symbiotic star: MIRA + compact star (WD ?)
  • Showing multi‐λ activity
  • Astrometry provides distance and orbital information

Min+(2015) D ~ 218 pc Radial velocity (~100 yr, including VERA/NRO etc) Orbital motion on the sky‐plane (~10 yr)

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Galaxy’s fundamental constants

  • Combined with VLBA/EVN data, we have determined

Galactic parameters using 52 sources. First Galactic parameter analysis by using more than 50 sources with VLBI astrometry (Honma et al. 2012)

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Fundamental Constants

  • R0 = 8.0 +/‐ 0.5 kpc (26100 +/‐ 1600 ly)

(curent IAU standard 8.5 kpc、 27700 ly)

  • Theta_0 = 240 +/‐ 14 km/s

（IAU standard 220 km/s） Larger rotation velocity → 20% larger mass → more dark matter

(Honma et al. 2012)

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Impact on Direct Dark Matter search

  • Dark matter is though to be elementary particle, and

there are on‐going experiments to directly detect DM (Xmass, Xenon 100, DAMA, ...)

  • To reveal the nature of DM particle, Galactic

parameters (galactic rotation speed and DM density) are crucial.

  • High‐precision VLBI astrometry can impact

not only on Galactic astronomy but also on fundamental physics

Xmass detector

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More recent results

  • Reid+(2014)

103 sources R0 = 8.34+/-0.16 kpc Θ0 = 240 +/- 8 km/s

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Galactic constants

Reid+ (2009) Honma+ (2012) Reid+ (2014) Nsrc 18 52 103 R0 (kpc) 8.4 (+/- 0.6) 8.05 (+/- 0.45) 8.34 (+/- 0.16) Θ0 (km/s) 247 (+/- 16) 238 (+/- 14) 240 (+/- 8)

Galactic constants are already measured at a few percent level !

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Most updated data as of 2015

114 sources from VLBA/VERA/EVN (40 sources from VERA)

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Spiral structure seen with VLBI astrometry

  • Systematic deviation from circular rotation seen
  • Lag behind the rotation + inward motion

Comparison with theories will discriminate if the spiral arms are density wave or material wave (e.g., Sakai et al. 2015, submitted)

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Future plan

  • ~60 sources /yr, with a monitoring period of

1.5 – 2 yr

  • 30 – 40 sources / yr
  • 250 ~ 300 sources between 2015 – 2022
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Future: East Asia VLBI Network (EAVN)

: JVN : KVN : CVN : VERA TVN @Chiangmai

KaVA+JVN KaVA+JVN+CVN

X‐band 3C84 SHAO 65m KVN 21m x3 Cost‐effective upgrade of VERA to achive better resolution and sensitivity

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  • The first parallax with LBA obtained

Krishnan+(2015), G339.88

  • LBA + AuScope maser project

(under discussion with Au, US, Europe & Japan)

  • SKA

future radio interferometer in 2020’s (in SA and Au)

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What to do with Southern sky ?

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Toward GAIA/JASMINE era

  • Tracing both gaseous and stellar components are fundamental

(gas: collisional, star: collision‐less)

  • Also important is to compare with simulation

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Stellar orbit in spiral potential (non‐closed) Gas orbit in spiral potential (closed)

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Sgr A* & Event Horizon Telescope (sub‐mm VLBI)

Earth‐size VLBI operating at ~1mm or shorter To directly image the event‐horizon‐scale of black holes (Sgr A*)

Hawaii CARMA SMTO Pico Veleta

Green land ALMA LMT

ALMA (NRAO/ESO/NAOJ)

ALMA Phase-up Project is nearly done and ready. Will directly image the black hole shadow soon !?

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Concluding remarks

  • MWG Research is and will be wonderful !
  • Collaboration between people with different

background should be fundamental. radio / opt‐IR / X theory and simulation

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