Evidence for a Dusty Dark Dwarf Galaxy in the Quadruple Lens MG 0414+0534

Kaiki Taro Inoue, Satoki Matsushita, Takeo Minezaki, Masashi Chiba

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5 Citations (Scopus)


We report the 4s detection of a faint object with a flux of ∼0.3 mJy, in the vicinity of the quadruply lensed QSO MG 0414+0534 using the Atacama Large Millimeter/submillimeter array (ALMA) Band 7. The object is most probably a dusty dark dwarf galaxy, which has not been detected in either the optical, near-infrared, or radio (centimeter) bands. An anomaly in the flux ratio of the lensed images observed in Band 7 and the mid-infrared band and the reddening of the QSO light color can be simultaneously explained if we consider the object as a lensing substructure with an ellipticity of ∼0.7 at a redshift of 0.5 ≲ z ≲ 1. Using the best-fit lens models with three lenses, we find that the dark matter plus baryon mass associated with the object is ∼109 Mo, the dust mass is ∼107 Mo, and the linear size is ≳5 kpc. Thus, our findings suggest that the object is a dusty dark dwarf galaxy. A substantial portion of faint submillimeter galaxies (SMGs) in the universe may be attributed to such dark objects.

Original languageEnglish
Article numberL23
JournalAstrophysical Journal Letters
Issue number2
Publication statusPublished - 2017 Feb 1


  • galaxies: dwarf
  • gravitational lensing: strong


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