{
  "id": "2309.04285",
  "version": "v1",
  "published": "2023-09-08T12:08:31.000Z",
  "updated": "2023-09-08T12:08:31.000Z",
  "title": "Andromeda's Parachute: Time Delays and Hubble Constant",
  "authors": [
    "Vyacheslav N. Shalyapin",
    "Luis J. Goicoechea",
    "Karianne Dyrland",
    "Håkon Dahle"
  ],
  "comment": "10 pages, 4 figures, 4 tables (full version of Table 2 is only available in electronic form). Accepted for publication in ApJ. arXiv admin note: substantial text overlap with arXiv:2206.09266",
  "categories": [
    "astro-ph.GA"
  ],
  "abstract": "The gravitational lens system PS J0147+4630 (Andromeda's Parachute) consists of four quasar images ABCD and a lensing galaxy. We obtained $r$-band light curves of ABCD in the 2017$-$2022 period from monitoring with two 2-m class telescopes. Applying state-of-the-art curve shifting algorithms to these light curves led to measurements of time delays between images, and the three independent delays relative to image D are accurate enough to be used in cosmological studies (uncertainty of about 4%): $\\Delta t_{\\rm{AD}}$ = $-$170.5 $\\pm$ 7.0, $\\Delta t_{\\rm{BD}}$ = $-$170.4 $\\pm$ 6.0, and $\\Delta t_{\\rm{CD}}$ = $-$177.0 $\\pm$ 6.5 d, where image D is trailing all the other images. Our finely sampled light curves and some additional fluxes in the years 2010$-$2013 also demonstrated the presence of significant microlensing variations. From the measured delays relative to image D and typical values of the external convergence, recent lens mass models yielded a Hubble constant that is in clear disagreement with currently accepted values around 70 km s$^{-1}$ Mpc$^{-1}$. We discuss how to account for a standard value of the Hubble constant without invoking the presence of an extraordinary high external convergence.",
  "revisions": [
    {
      "version": "v1",
      "updated": "2023-09-08T12:08:31.000Z"
    }
  ],
  "analyses": {
    "keywords": [
      "hubble constant",
      "time delays",
      "andromedas parachute",
      "state-of-the-art curve shifting algorithms",
      "light curves"
    ],
    "note": {
      "typesetting": "TeX",
      "pages": 10,
      "language": "en",
      "license": "arXiv",
      "status": "editable"
    }
  }
}