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A Catalog of Quasar Proper Motions to Detect the Secular Aberration Drift and Measure the Collapse of Large-Scale Structure.

Event Details

Event Dates: 

Friday, July 21, 2017 - 12:00pm

Seminar Location: 

  • JILA 10th Floor - Foothills Room

Speaker Name(s): 

Alex Truebenbach

Speaker Affiliation(s): 

CASA
Seminar Type/Subject

Scientific Seminar Type: 

  • Astrophysics Lunch Seminar

Event Details & Abstract: 

We present our paper on a catalog of quasar proper motions created using archival VLBI data and our own VLBA astrometry. The catalog contains 713 proper motions, with average uncertainties of ~ 24 microarcseconds / yr. We add 40 new or improved proper motion measurements using relative astrometry with the VLBA. The phase referenced observations were conducted in X-band and yielded positions with uncertainties ~ 70 microarcseconds. The resulting proper motions are accurate to within ~ 38 microarcseconds / yr. We also add 10 new redshifts using spectroscopic observations taken at Apache Point Observatory and Gemini North. With our proper motion catalog, we detect the secular aberration drift - the apparent motion of extragalactic objects caused by the solar system's rotation around the Galactic center - at a 6.3 sigma significance. The dipole signal, with an amplitude of 1.69 microarcseconds / yr and an apex at (275.2 +\- 10.0 degrees, -29.4 +\- 8.8 degrees), is in close agreement with the predicted signal and is detected at a higher significance than previous studies (e.g., Titov et al. 2013). In a future paper, we subtract the aberration drift from our quasar proper motions in order to detect cosmological proper motions, including the Hubble expansion and the colla