Improved VLBI measurement of the solar system acceleration

Titov, Oleg; Lambert, S.

doi:10.1051/0004-6361/201321806

Cited by 45 publications

(57 citation statements)

References 19 publications

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“…Two other E-mode dipolar proper motions of interest in this work are the secular aberration drift and the peculiar proper motion dipole caused by LSS. The former is a distance-independent dipole that has been previously detected using quasar proper motions from very long baseline interferometry (Titov & Lambert 2013;Truebenbach & Darling 2017). The secular aberration drift amplitude is ∼ 5µas yr −1 , which will dominate dipolar proper motions for galaxies at distances of approximately 16 Mpc or greater.…”

Section: Characterizing the Proper Motion Vector Fieldmentioning

confidence: 85%

“…The largest expected contributions to the proper motion are the peculiar velocities caused by gravitational interactions with large-scale structure (LSS) and the secular arXiv:1912.11935v1 [astro-ph.CO] 26 Dec 2019 aberration drift caused by the solar system barycenter acceleration about the Galactic center. Secular aberration drift is observed as a distance-independent dipole with amplitude of ∼ 5 µas yr −1 (Titov & Lambert 2013;Truebenbach & Darling 2017), which should be separable from a distance dependent dipole. LSS, however, induces distance-dependent proper motions at all angular scales with amplitudes comparable to secular parallax (Hall 2019).…”

Section: Introductionmentioning

confidence: 92%

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Secular Extragalactic Parallax: Measurement Methods and Predictions for Gaia

Paine

Darling

Graziani

et al. 2020

ApJ

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Secular extragalactic parallax caused by the solar system's velocity relative to the cosmic microwave background rest frame may be observable as a dipole proper motion field with amplitude 78 µas yr −1 Mpc. Nearby galaxies also exhibit proper motions caused by their transverse peculiar velocities that prevent detection of secular parallax for any single galaxy, although a statistical detection may be made instead. Such a detection could constrain the local Hubble parameter. We present methods to measure secular parallax using correlated extragalactic proper motions and find a first limit on the secular parallax amplitude using proper motions of 232 nearby galaxies from Gaia Data Release 2. The recovered dipole has insignificant upper limit of 3500 µas yr −1 Mpc. This measurement will be improved by larger sample size and reduced proper motion uncertainties in future data releases. Using the local peculiar velocity field derived from Cosmicflows-3, we simulate galaxy proper motions and predict that a significant detection (5 − 10σ) of the secular parallax amplitude will be possible by Gaia's end of mission. The detection is contingent on proper motions of nearby (< 5 Mpc), bright (G < 15 mag) galaxies, and corresponds to an insignificant upper limit on the Hubble parameter. We further investigate the implications of our simulations for the study of transverse peculiar velocities, which we find to be consistent with large scale structure theory. The peculiar velocity field additionally results in low-multipole correlated proper motions on the order of 0.3 µas yr −1 that may be confounded with other cosmological proper motion measurements, such as limits on the gravitational wave background and the anisotropy of the Hubble expansion.

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Section: Characterizing the Proper Motion Vector Fieldmentioning

confidence: 85%

Section: Introductionmentioning

confidence: 92%

Secular Extragalactic Parallax: Measurement Methods and Predictions for Gaia

Paine

Darling

Graziani

et al. 2020

ApJ

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“…Part of the observed glide component may be caused by the apparent proper motion of quasars induced by the galactocentric acceleration of the solar system barycentre (Fanselow 1983;Bastian 1995;Sovers et al 1998;Kovalevsky 2003;Titov & Lambert 2013). This effect should produce a gradually increasing distortion of the ICRF2 positions in the form of a glide vector directed towards the Galactic Centre and with an amplitude proportional to the time elapsed since the mean epoch of the VLBI observations.…”

Section: Large-scale Systematic Differencesmentioning

confidence: 99%

GaiaData Release 1

Mignard

Klioner

Lindegren

et al. 2016

A&A

133

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Context. As part of the data processing for Gaia Data Release 1 (Gaia DR1) a special astrometric solution was computed, the so-called auxiliary quasar solution. This gives positions for selected extragalactic objects, including radio sources in the second realisation of the International Celestial Reference Frame (ICRF2) that have optical counterparts bright enough to be observed with Gaia. A subset of these positions was used to align the positional reference frame of Gaia DR1 with the ICRF2. Although the auxiliary quasar solution was important for internal validation and calibration purposes, the resulting positions are in general not published in Gaia DR1. Aims. We describe the properties of the Gaia auxiliary quasar solution for a subset of sources matched to ICRF2, and compare their optical and radio positions at the sub-mas level. Methods. Descriptive statistics are used to characterise the optical data for the ICRF sources and the optical-radio differences. The most discrepant cases are examined using online resources to find possible alternative explanations than a physical optical-radio offset of the quasars. Results. In the auxiliary quasar solution 2191 sources have good optical positions matched to ICRF2 sources with high probability. Their formal standard errors are better than 0.76 milliarcsec (mas) for 50% of the sources and better than 3.35 mas for 90%. Optical magnitudes are obtained in Gaia's unfiltered photometric G band. The Gaia results for these sources are given as a separate table in Gaia DR1. The comparison with the radio positions of the defining sources shows no systematic differences larger than a few tenths of a mas. The fraction of questionable solutions, not readily accounted for by the statistics, is less than 6%. Normalised differences have extended tails requiring case-by-case investigations for around 100 sources, but we have not seen any difference indisputably linked to an optical-radio offset in the sources. Conclusions. With less than a quarter of the data expected from the nominal mission it has been possible to obtain positions at the sub-mas level for most of the ICRF sources having an optical counterpart brighter than 20.5 mag.

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“…A new astrometric reference frame based on the optical counterparts of the ICRF radio sources is being built, assuming that quasar parallaxes are zero (Michalik & Lindegren 2016). These new data will also test for the presence and magnitude of the dipole proper motion reported by and Titov & Lambert (2013), as well as any higher-order systematics. The alignment of radio and optical reference frames demands a reliable optical identification of the radio sources and, if possible, a redshift to confirm the identification.…”

Section: Introductionmentioning

confidence: 88%

Optical Spectra of Candidate International Celestial Reference Frame (ICRF) Flat-spectrum Radio Sources. III.

Titov

Pursimo

Johnston

et al. 2017

Self Cite

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In extending our spectroscopic program, which targets sources drawn from the International Celestial Reference Frame (ICRF) Catalog, we have obtained spectra for ∼160 compact, flat-spectrum radio sources and determined redshifts for 112 quasars and radio galaxies. A further 14 sources with featureless spectra have been classified as BL Lac objects. Spectra were obtained at three telescopes: the 3.58 m European Southern Observatory New Technology Telescope, and the two 8.2 m Gemini telescopes in Hawaii and Chile. While most of the sources are powerful quasars, a significant fraction of radio galaxies is also included from the list of non-defining ICRF radio sources.

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Improved VLBI measurement of the solar system acceleration

Cited by 45 publications

References 19 publications

Secular Extragalactic Parallax: Measurement Methods and Predictions for Gaia

Secular Extragalactic Parallax: Measurement Methods and Predictions for Gaia

GaiaData Release 1

Optical Spectra of Candidate International Celestial Reference Frame (ICRF) Flat-spectrum Radio Sources. III.

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