### Abstract

We report on the spectroscopic identification and the long-awaited redshift measurement of the heavily obscured, gravitationally lensed radio source PKS 1830-211, which was first observed as a radio Einstein ring. The northeast component of the doubly imaged core is identified, in our infrared spectrum covering the wavelength range 1.5-2.5 μm, as an impressively reddened quasar at z = 2.507 ± 0.002. The mass contained within the Einstein ring radius is M(r < 2.1 h^{-1} kpc) = 6.3 × 10^{10} h^{-1} M⊙ for Ω_{M} = 1 or M(r < 2.4 h^{-1} kpc) = 7.4 × 10^{10} h^{-1} M⊙ for Ω_{M} = 0.3. Our redshift measurement, together with the recently measured time delay (Lovell et al.), means that we are a step closer to determining H_{0} from this lens. Converting the time delay into H_{0} by using existing models leads to high values of the Hubble parameter, H_{0} = 65^{+15}_{-9} for Ω_{M} = 1 and H_{0} = 76^{18}_{-10}, for Ω_{M} = 0.3. Since the lensing galaxy lies very close to the center of the lensed ring, improving the error bars on H_{0} will require not only a more precise time delay measurement but also very precise astrometry of the whole system.

Original language | English (US) |
---|---|

Journal | Astrophysical Journal |

Volume | 514 |

Issue number | 2 PART 2 |

State | Published - Apr 1 1999 |

Externally published | Yes |

### Fingerprint

### Keywords

- Cosmology: observations
- Gravitational lensing
- Quasars: individual (PKS 1830-211)

### ASJC Scopus subject areas

- Space and Planetary Science

### Cite this

*Astrophysical Journal*,

*514*(2 PART 2).

**The redshift of the gravitationally lensed radio source PKS 1830-211.** / Lidman, C.; Courbin, F.; Meylan, G.; Broadhurst, T.; Frye, Brenda Louise; Welch, W. J W.

Research output: Contribution to journal › Article

*Astrophysical Journal*, vol. 514, no. 2 PART 2.

}

TY - JOUR

T1 - The redshift of the gravitationally lensed radio source PKS 1830-211

AU - Lidman, C.

AU - Courbin, F.

AU - Meylan, G.

AU - Broadhurst, T.

AU - Frye, Brenda Louise

AU - Welch, W. J W

PY - 1999/4/1

Y1 - 1999/4/1

N2 - We report on the spectroscopic identification and the long-awaited redshift measurement of the heavily obscured, gravitationally lensed radio source PKS 1830-211, which was first observed as a radio Einstein ring. The northeast component of the doubly imaged core is identified, in our infrared spectrum covering the wavelength range 1.5-2.5 μm, as an impressively reddened quasar at z = 2.507 ± 0.002. The mass contained within the Einstein ring radius is M(r < 2.1 h-1 kpc) = 6.3 × 1010 h-1 M⊙ for ΩM = 1 or M(r < 2.4 h-1 kpc) = 7.4 × 1010 h-1 M⊙ for ΩM = 0.3. Our redshift measurement, together with the recently measured time delay (Lovell et al.), means that we are a step closer to determining H0 from this lens. Converting the time delay into H0 by using existing models leads to high values of the Hubble parameter, H0 = 65+15-9 for ΩM = 1 and H0 = 7618-10, for ΩM = 0.3. Since the lensing galaxy lies very close to the center of the lensed ring, improving the error bars on H0 will require not only a more precise time delay measurement but also very precise astrometry of the whole system.

AB - We report on the spectroscopic identification and the long-awaited redshift measurement of the heavily obscured, gravitationally lensed radio source PKS 1830-211, which was first observed as a radio Einstein ring. The northeast component of the doubly imaged core is identified, in our infrared spectrum covering the wavelength range 1.5-2.5 μm, as an impressively reddened quasar at z = 2.507 ± 0.002. The mass contained within the Einstein ring radius is M(r < 2.1 h-1 kpc) = 6.3 × 1010 h-1 M⊙ for ΩM = 1 or M(r < 2.4 h-1 kpc) = 7.4 × 1010 h-1 M⊙ for ΩM = 0.3. Our redshift measurement, together with the recently measured time delay (Lovell et al.), means that we are a step closer to determining H0 from this lens. Converting the time delay into H0 by using existing models leads to high values of the Hubble parameter, H0 = 65+15-9 for ΩM = 1 and H0 = 7618-10, for ΩM = 0.3. Since the lensing galaxy lies very close to the center of the lensed ring, improving the error bars on H0 will require not only a more precise time delay measurement but also very precise astrometry of the whole system.

KW - Cosmology: observations

KW - Gravitational lensing

KW - Quasars: individual (PKS 1830-211)

UR - http://www.scopus.com/inward/record.url?scp=0033110601&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=0033110601&partnerID=8YFLogxK

M3 - Article

AN - SCOPUS:0033110601

VL - 514

JO - Astrophysical Journal

JF - Astrophysical Journal

SN - 0004-637X

IS - 2 PART 2

ER -