Sangam: A Confluence of Knowledge Streams

New Horizons Observations of the Cosmic Optical Background

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dc.contributor Massachusetts Institute of Technology. Department of Earth, Atmospheric, and Planetary Sciences
dc.creator Binzel, Richard P
dc.date 2022-09-16T19:01:34Z
dc.date 2021-10-27T19:56:33Z
dc.date 2022-09-16T19:01:34Z
dc.date 2021
dc.date 2021-09-14T14:12:07Z
dc.date.accessioned 2023-02-17T20:22:06Z
dc.date.available 2023-02-17T20:22:06Z
dc.identifier https://hdl.handle.net/1721.1/133770.2
dc.identifier.uri http://localhost:8080/xmlui/handle/CUHPOERS/242541
dc.description © 2021. The American Astronomical Society. All rights reserved. We used existing data from the New Horizons Long-range Reconnaissance Imager (LORRI) to measure the optical-band (0.4 ≲ λ ≲ 0.9 μm) sky brightness within seven high-Galactic latitude fields. The average raw level measured while New Horizons was 42-45 au from the Sun is 33.2 ± 0.5 nW m−2 sr−1. This is ∼10× as dark as the darkest sky accessible to the Hubble Space Telescope, highlighting the utility of New Horizons for detecting the cosmic optical background (COB). Isolating the COB contribution to the raw total required subtracting scattered light from bright stars and galaxies, faint stars below the photometric detection limit within the fields, and diffuse Milky Way light scattered by infrared cirrus. We removed newly identified residual zodiacal light from the IRIS 100 μm all-sky maps to generate two different estimates for the diffuse Galactic light. Using these yielded a highly significant detection of the COB in the range 15.9 ± 4.2 (1.8 stat., 3.7 sys.) nW m−2 sr−1 to 18.7 ± 3.8 (1.8 stat., 3.3 sys.) nW m−2 sr−1 at the LORRI pivot wavelength of 0.608 μm. Subtraction of the integrated light of galaxies fainter than the photometric detection limit from the total COB level left a diffuse flux component of unknown origin in the range 8.8 ± 4.9 (1.8 stat., 4.5 sys.) nW m−2 sr−1 to 11.9 ± 4.6 (1.8 stat., 4.2 sys.) nW m−2 sr−1. Explaining it with undetected galaxies requires the assumption that the galaxy count faint-end slope steepens markedly at V > 24 or that existing surveys are missing half the galaxies with V < 30.
dc.format application/octet-stream
dc.language en
dc.publisher American Astronomical Society
dc.relation 10.3847/1538-4357/ABC881
dc.relation Astrophysical Journal
dc.rights Article is made available in accordance with the publisher's policy and may be subject to US copyright law. Please refer to the publisher's site for terms of use.
dc.source The American Astronomical Society
dc.title New Horizons Observations of the Cosmic Optical Background
dc.type Article
dc.type http://purl.org/eprint/type/JournalArticle


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