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

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.

8 pages, 4 figures, accepted in ApJL

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Cited by in corpus (4)

• SHARP -- VII. New constraints on the dark matter free-streaming properties and substructure abundance from gravitationally lensed quasars
• A flux-ratio anomaly in the CO spectral line emission from gravitationally-lensed quasar MG J0414+0534
• ALMA 50-parsec resolution imaging of jet-ISM interaction in the lensed quasar MGJ0414+0534
• ALMA Measurement of 10 kpc-scale Lensing Power Spectra towards the Lensed Quasar MG J0414+0534