The innermost mass distribution of the gravitational lens SDP.81 from ALMA observations
- Institute of Astronomy and Astrophysics, Academia Sinica (ASIAA), P.O. Box 23-141, Taipei 10617, Taiwan (China)
The central image of a strongly lensed background source places constraints on the foreground lens galaxy’s inner mass profile slope, core radius, and mass of its nuclear supermassive black hole. Using high-resolution long-baseline Atacama Large Millimeter/submillimeter Array (ALMA) observations and archival Hubble Space Telescope (HST) imaging, we model the gravitational lens H-ATLAS J090311.6+003906 (also known as SDP.81) and search for the demagnified central image. There is central continuum emission from the lens galaxy’s active galactic nucleus (AGN) but no evidence of the central lensed image in any molecular line. We use the CO maps to determine the flux limit of the central image excluding the AGN continuum. We predict the flux density of the central image and use the limits from the ALMA data to constrain the innermost mass distribution of the lens. For a power-law profile with a core radius of 0.″15 measured from HST photometry of the lens galaxy assuming that the central flux is attributed to the AGN, we find that a black hole mass of log(M{sub BH}/M{sub ⊙})≳8.5 is preferred. Deeper observations with a detection of the central image will significantly improve the constraints of the innermost mass distribution of the lens galaxy.
- OSTI ID:
- 22882531
- Journal Information:
- Astrophysical Journal, Vol. 811, Issue 2; Other Information: Country of input: International Atomic Energy Agency (IAEA); Since 2009, the country of publication for this journal is the UK.; ISSN 0004-637X
- Country of Publication:
- United Kingdom
- Language:
- English
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