1 / 10

Refining the time delay in JVAS B0218+357

Refining the time delay in JVAS B0218+357. Andy Biggs UK ATC. 0218 in a nutshell. Time delay: Variable Polarised Resolvable with VLA Modelling Single galaxy lens Known redshifts Extended emission. 0218+357 time delay history. Monitored 4 times with the VLA Oct - Jan 1992/93

major
Télécharger la présentation

Refining the time delay in JVAS B0218+357

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Refining the time delay inJVAS B0218+357 Andy Biggs UK ATC

  2. 0218 in a nutshell • Time delay: • Variable • Polarised • Resolvable with VLA • Modelling • Single galaxy lens • Known redshifts • Extended emission

  3. 0218+357 time delay history • Monitored 4 times with the VLA • Oct - Jan 1992/93 • Corbett et al. (1996) [ = 12 ± 3 days] • Mar - May 1994 • Chris Sykes’ thesis? • Oct - Jan 1996/97 • Biggs et al. (1999) [ = 10.5 ± 0.4 days] • Cohen et al. (2000) [ = 10.1 ± 1.5 days]

  4. Total flux density (1996-1997) ratio (A/B) = 3.73

  5. Polarisation p.a. (1996-1997)  p.a. (AB) = 15.4°

  6. Motivation for re-visiting data • Calibration techniques have improved • gain/elevation correction • Time delay can be found from all data simultaneously • long time baseline • light curves can be combinations of different ‘measures’ • 1993 total flux + 1994 position angle + 1996 polarised flux • many light curves formed in this way • Investigate possible time-variable Faraday rotation • Recent VLA proposals rejected

  7. Monitoring strategy • 3C147/3C48 (not 1996/97) • get approximate flux density of variable 3C84 • 3C84 • set flux scale of each epoch • assume non-variable (!) • calibrate polarisation leakage assuming non-polarised • 3C119 • calibrate polarisation position angle

  8. Preliminary results Corbett data (1992/1993) Polarised flux density Polarisation position angle

  9. Problems with 1994 data Unstable gains Bizarre polarisation behaviour Elongated beam (BnA configuration)

  10. To do • Reduce all data in uniform fashion • Resolve polarisation issue • Decide on model-fitting strategy • Measure time delays for all combinations of data • Derive errors using Monte Carlo simulations

More Related