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| Formato: | Preprint |
| Publicado: |
2025
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| Acceso en línea: | https://arxiv.org/abs/2511.20582 |
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| _version_ | 1866912729028100096 |
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| author | Biggs, A. D. |
| author_facet | Biggs, A. D. |
| contents | We have measured a time delay of 25.3 +/- 2.0 d (1-sigma confidence) in the Einstein ring gravitational lens system PKS 1830-211 from an analysis of archival VLA and ATCA monitoring data observed between 1997 and 2004. A small portion of the ATCA data was previously used to determine a time delay and our result is consistent with the previous value, but with an uncertainty that is smaller by more than a factor of two. The long time-baseline of the monitoring reveals that the flux density ratio is smoothly varying on a time-scale of years, an effect which we attribute to millilensing by massive objects (>>1 M_sun) in the lensing galaxy. Image A is unpolarized in the VLA monitoring, but VLBI observations show that this is partly due to beam dilution by an unpolarized counter-jet that is only present in that image. Based on the identification of this feature as a counter-jet, we conclude that its unexpected prominence in image A is a consequence of lensing and that more detailed modelling is required in order to reconcile the VLBI morphology of each image. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2511_20582 |
| institution | arXiv |
| publishDate | 2025 |
| record_format | arxiv |
| spellingShingle | An improved time delay from VLA and ATCA monitoring of the gravitational lens system PKS 1830-211 Biggs, A. D. Cosmology and Nongalactic Astrophysics We have measured a time delay of 25.3 +/- 2.0 d (1-sigma confidence) in the Einstein ring gravitational lens system PKS 1830-211 from an analysis of archival VLA and ATCA monitoring data observed between 1997 and 2004. A small portion of the ATCA data was previously used to determine a time delay and our result is consistent with the previous value, but with an uncertainty that is smaller by more than a factor of two. The long time-baseline of the monitoring reveals that the flux density ratio is smoothly varying on a time-scale of years, an effect which we attribute to millilensing by massive objects (>>1 M_sun) in the lensing galaxy. Image A is unpolarized in the VLA monitoring, but VLBI observations show that this is partly due to beam dilution by an unpolarized counter-jet that is only present in that image. Based on the identification of this feature as a counter-jet, we conclude that its unexpected prominence in image A is a consequence of lensing and that more detailed modelling is required in order to reconcile the VLBI morphology of each image. |
| title | An improved time delay from VLA and ATCA monitoring of the gravitational lens system PKS 1830-211 |
| topic | Cosmology and Nongalactic Astrophysics |
| url | https://arxiv.org/abs/2511.20582 |