J-Net Galactic-Plane Survey of VLBI Radio Sources for VLBI Exploration of Radio Astrometry (VERA)

Honma, Mareki; Oyama, Tomoaki; Hachisuka, Kazuya; Sawada-Satoh, Satoko; Sebata, Kouichi; Miyoshi, Makoto; Kameya, Osamu; Manabe, S.; Kawaguchi, Noriyuki; Sasao, Tetsuo; Kameno, Seiji; Fujisawa, Kenta; Shibata, Katsunori M.; Bushimata, Takeshi; Miyaji, Takeshi; Kobayashi, Hideyuki; Inoue, Makoto; Imai, Hiroshi; Araki, Hiroshi; Hanada, Hideo; Iwadate, Kenzaburo; Kaneko, Yoshihisa; Kuji, Seisuke; Sato, Katsuhisa; Tsuruta, Seiitsu; Sakai, Satoshi; Tamura, Yoshiaki; Horiai, K.; Hara, T.; Yokoyama, Kôichi; Nakajima, Jun; Kawai, Eiji; Okubo, Hiroshi; Osaki, Hiroshi; Koyama, Yasuhiro; Sekido, Mamoru; Suzuyama, Tomonari; Ichikawa, Ryuichi; Kondo, Tetsuro; Sakai, Kensei; Wada, Koh; Harada, Naohiko; Tougou, Norihiro; Fujishita, M.; Shimizu, Rie; Kawaguchi, Shoichiro; Yoshimura, Akane; Nakamura, Masakazu; Hasegawa, Wataru; Morisaki, Satoshi; Kamohara, Ryuichi; Funaki, Tomoe; Yamashita, Naoko; Watanabe, Takehisa; Shimoikura, Tomomi; Nishio, Makoto; Omodaká, Toshihiro; Okudaira, Atuya

doi:10.1093/pasj/52.4.631

Cited by 18 publications

(4 citation statements)

References 8 publications

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“…They have therefore been used by numerous authors to constrain the properties of the Milky Way (e.g., Reid et al 2009a;McMillan & Binney 2010;Bovy et al 2009;Bobylev & Bajkova 2013;Reid et al 2014, Paper I). Reid et al (2014) summarised the work of a number of groups, most notably the Bar and Spiral Structure Legacy survey (BeSSeL, Brunthaler et al 2011) and VLBI Exploration of Radio Astronomy (VERA, Honma et al 2000), which have determined the parallaxes, proper motions and line-of-sight velocities of 103 Galactic HMSFRs. This represents an increase by more than a factor of 4 over the number of HMSFRs with known parallaxes used in Paper I.…”

Section: Maser Observationsmentioning

confidence: 99%

The mass distribution and gravitational potential of the Milky Way

McMillan

2016

Mon. Not. R. Astron. Soc.

838

615

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We present mass models of the Milky Way created to fit observational constraints and to be consistent with expectations from theoretical modelling. The method used to create these models is that demonstrated in McMillan (2011), and we improve on those models by adding gas discs to the potential, considering the effects of allowing the inner slope of the halo density profile to vary, and including new observations of maser sources in the Milky Way amongst the new constraints. We provide a best fitting model, as well as estimates of the properties of the Milky Way. Under the assumptions in our main model, we find that the Sun is R 0 = (8.20 ± 0.09) kpc from the Galactic Centre, with the circular speed at the Sun being v 0 = (232.8 ± 3.0) km s −1 ; that the Galaxy has a total stellar mass of (54.3 ± 5.7) × 10 9 M ⊙ , a total virial mass of (1.30±0.30)×10 12 M ⊙ and a local dark-matter density of 0.38±0.04 GeV cm −3 , where the quoted uncertainties are statistical. These values are sensitive to our choice of priors and constraints. We investigate systematic uncertainties, which in some cases may be larger. For example, if we weaken our prior on R 0 , we find it to be (7.97 ± 0.15) kpc and that v 0 = (226.8 ± 4.2) km s −1 . We find that most of these properties, including the local dark-matter density, are remarkably insensitive to the assumed power-law density slope at the centre of the dark-matter halo. We find that it is unlikely that the local standard of rest differs significantly from that found under assumptions of axisymmetry. We have made code to compute the force from our potential, and to integrate orbits within it, publicly available.

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Section: Maser Observationsmentioning

confidence: 99%

The mass distribution and gravitational potential of the Milky Way

McMillan

2016

Mon. Not. R. Astron. Soc.

838

615

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“…VERA (Honma et al 2000), VLBA (Reid 2008;Hachisuka et al 2009), and EVN (Rygl et al 2008) are radio VLBI arrays that are conducting ∼ 10µas astrometric observations for water and/or methanol masers. Compared to our M-giant sample, water masers have the advantage as targets that most of them lie in star-forming regions very close to the Galactic plane.…”

Section: Radio Vlbi Arraysmentioning

confidence: 99%

“…Three innovations in observations promise to dramatically improve our understanding of the phase-space structure of our Galactic disk: (1) large-scale photometric surveys, both existing (the Two Micron All Sky Survey (2MASS) and the Sloan Digital Sky Survey) and planned (PanSTARRS and LSST), together with methods of deriving accurate photometric parallaxes for stars in these surveys (Majewski et al 2003;Jurić et al 2008). (2) high-precision (few to 10's of µas) astrometry from radio observations of masers e.g., VERA (Honma et al 2000), VLBA (Reid 2008;Hachisuka et al 2009) and the European VLBI Network (Rygl et al 2008) and optical observations of stars (NASA's SIM Lite-Space Interferometry Mission Lite and ESA's GAIA-Global Astrometric Interferometer for Astrophysics, see Unwin et al 2007 1 ;Perryman 2002); and (3) large-scale, high-resolution spectroscopic surveys, such as the ongoing Radial Velocity Experiment (RAVE; Steinmetz et al 2006) and the SEGUE project of the Sloan Digital Sky Survey (Beers et al 2004) as well as the planned Apache Point Observatory Galactic Evolution Experiment (APOGEE; Allende Prieto et al 2008), HERMES instrument for the Anglo Australian Telescope and Wide Field Multi-Object Spectrograph (WFMOS) for the Gemini telescope. It is clear that any or (better yet) all of these advances will significantly improve our knowledge of the Galaxy.…”

Section: Introductionmentioning

confidence: 99%

Probing the Galactic Potential With Next-Generation Observations of Disk Stars

Sumi

Johnston

Tremaine

et al. 2009

ApJ

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Our current knowledge of the rotation curve of the Milky Way is remarkably poor compared to other galaxies, limited by the combined effects of extinction and the lack of large samples of stars with good distance estimates and proper motions. Near-future surveys promise a dramatic improvement in the number and precision of astrometric, photometric, and spectroscopic measurements of stars in the Milky Way's disk. We examine the impact of such surveys on our understanding of the Galaxy by "observing" particle realizations of nonaxisymmetric disk distributions orbiting in an axisymmetric halo with appropriate errors and then attempting to recover the underlying potential using a Markov Chain Monte Carlo (MCMC) approach. We demonstrate that the azimuthally averaged gravitational force field in the Galactic plane-and hence, to a lesser extent, the Galactic mass distribution-can be tightly constrained over a large range of radii using a variety of types of surveys so long as the error distribution of the measurements of the parallax, proper motion, and radial velocity are well understood and the disk is surveyed globally. One advantage of our method is that the target stars can be selected nonrandomly in real or apparent-magnitude space to ensure just such a global sample without biasing the results. Assuming that we can always measure the line-of-sight velocity of a star with at least 1 km s −1 precision, we demonstrate that the force field can be determined to better than ∼1% for Galactocentric radii in the range R = 4 − 20 kpc using either: (1) small samples (a few hundred stars) with very accurate trigonometric parallaxes and good proper-motion measurements ( uncertainties δ p,tri 10 µas and δ µ 100 µas yr −1 respectively); (2) modest samples (∼ 1000 stars) with good indirect parallax estimates (e.g., uncertainty in photometric parallax δ p,phot ∼ 10%-20%) and good proper-motion measurements (δ µ ∼ 100 µas yr −1 ); or (3) large samples (∼ 10 4 stars) with good indirect parallax estimates and lower accuracy propermotion measurements (δ µ ∼ 1 mas yr −1 ). We conclude that near-future surveys, like SIM Lite, Gaia, and VERA, will provide the first precise mapping of the gravitational force field in the region of the Galactic disk.

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“…One such problem was observational noise from the VLBI antenna. The VERA Ishigakijima station, which is equipped with a 20-m-diameter parabolic antenna, is one of four VLBI stations that belong to the VERA project (e.g., Honma et al 2000). The distance between the VLBI antenna and the SG is approximately 35 m. When the antenna begins to move, step noise (gravity increasing) is recorded in the gravity signal (Fig.…”

Section: Introductionmentioning

confidence: 99%

Effects of horizontal acceleration on the superconducting gravimeter CT #036 at Ishigakijima, Japan

Imanishi

Nawa

Tamura

et al. 2018

Earth Planets Space

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In the gravity sensor of a superconducting gravimeter, a superconducting sphere as a test mass is levitated in a magnetic field. Such a sensor is susceptible to applied horizontal as well as vertical acceleration, because the translational degrees of freedom of the mass are not perfectly limited to the vertical direction. In the case of the superconducting gravimeter CT #036 installed at Ishigakijima, Japan, horizontal ground acceleration excited by the movements of a nearby VLBI antenna induces systematic step noise within the gravity recordings. We investigate this effect in terms of the static and dynamic properties of the gravity sensor using data from a collocated seismometer. It is shown that this effect can be effectively modeled by the coupling between the horizontal and vertical components in the gravity sensor. It is also found that the mechanical eigenfrequency for horizontal translation of the levitating sphere is approximately 3 Hz.

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J-Net Galactic-Plane Survey of VLBI Radio Sources for VLBI Exploration of Radio Astrometry (VERA)

Cited by 18 publications

References 8 publications

The mass distribution and gravitational potential of the Milky Way

The mass distribution and gravitational potential of the Milky Way

Probing the Galactic Potential With Next-Generation Observations of Disk Stars

Effects of horizontal acceleration on the superconducting gravimeter CT #036 at Ishigakijima, Japan

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