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arXiv · 1701.05283

Evidence for a Dusty Dark Dwarf Galaxy in the Quadruple Lens MG0414+0534

Kaiki Taro Inoue·Satoki Matsushita·Takeo Minezaki·Masashi Chiba
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Abstract

We report the $4 \, \sigma$ detection of a faint object with a flux of ~ 0.3 mJy, in the vicinity of the quadruply lensed QSO MG0414+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 (NIR) or radio (cm) bands. An anomaly in the flux ratio of the lensed images observed in Band 7 and the mid-infrared (MIR) 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 ~ 0.7 at a redshift of $0.5 \lesssim z \lesssim 1$. Using the best-fit lens models with three lenses, we find that the dark matter plus baryon mass associated with the object is $\sim 10^9\, M_{\odot}$, the dust mass is $\sim 10^7\,M_{\odot}$ and the linear size is $\gtrsim 5\,$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.

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Kaiki Taro Inoue, Satoki Matsushita, Takeo Minezaki, Masashi Chiba. 2017-01-19. Evidence for a Dusty Dark Dwarf Galaxy in the Quadruple Lens MG0414+0534. https://doi.org/10.3847/2041-8213/835/2/l23

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