{
  "id": "1810.12302",
  "version": "v1",
  "published": "2018-10-29T18:00:01.000Z",
  "updated": "2018-10-29T18:00:01.000Z",
  "title": "Most Lensed Quasars at $z>6$ are Missed by Current Surveys",
  "authors": [
    "Fabio Pacucci",
    "Abraham Loeb"
  ],
  "comment": "Theoretical follow-up of the discovery paper Fan et al. (2018). Submitted to ApJ Letters. Comments welcome",
  "categories": [
    "astro-ph.GA",
    "astro-ph.CO",
    "astro-ph.HE"
  ],
  "abstract": "The discovery of the first strongly lensed $(\\mu \\approx 50)$ quasar at $z>6$ (J0439+1634, Fan et al. 2018) represents a breakthrough in our understanding of the early Universe. We derive the theoretical consequences of the new discovery. We predict that the observed population of $z > 6$ quasars should contain many mildly magnified $(\\mu \\lesssim 10)$ sources, with image separations below the resolution threshold. Additionally, current selection criteria should have missed a substantial population of lensed $z > 6$ quasars, due to the contamination of the drop-out photometric bands by lens galaxies. We quantify the fraction of undetected quasars as a function of the slope of the bright end of the quasar luminosity function, $\\beta$. For $\\beta \\lesssim 3.6$, we predict that the undetected lensed quasars could reach half of the population, whereas for $\\beta \\gtrsim 4.5$ the vast majority of the $z > 6$ quasar population is lensed and still undetected. We argue that this predicted population of lensed $z>6$ quasars would be misclassified and mixed up with low-$z$ galaxies. This would significantly affect the $z > 6$ quasar luminosity function and inferred black hole mass distributions, with profound implications for the UV, X-ray and infrared cosmic backgrounds and the growth of early quasars.",
  "revisions": [
    {
      "version": "v1",
      "updated": "2018-10-29T18:00:01.000Z"
    }
  ],
  "analyses": {
    "keywords": [
      "lensed quasars",
      "current surveys",
      "quasar luminosity function",
      "population",
      "inferred black hole mass distributions"
    ],
    "note": {
      "typesetting": "TeX",
      "pages": 0,
      "language": "en",
      "license": "arXiv",
      "status": "editable"
    }
  }
}