Publication:
UNCOVER: JWST Spectroscopy of Three Cold Brown Dwarfs at Kiloparsec-scale Distances

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dc.contributoret. al.
dc.contributor.authorCutler, Sam E.
dc.date2024-03-27T16:17:53.000
dc.date.accessioned2024-04-26T08:26:33Z
dc.date.available2024-03-27T00:00:00Z
dc.date.issued2024-01-01
dc.description.abstractWe report JWST/NIRSpec spectra of three distant T-type brown dwarfs identified in the Ultradeep NIRSpec and NIRCam ObserVations before the Epoch of Reionization (UNCOVER) survey of the Abell 2744 lensing field. One source was previously reported as a candidate T dwarf on the basis of NIRCam photometry, while two sources were initially identified as candidate active galactic nuclei. Low-resolution 1–5 μm spectra confirm the presence of molecular features consistent with T dwarf atmospheres, and comparison to spectral standards infers classifications of sdT1, T6, and T8–T9. The warmest source, UNCOVER-BD-1, shows evidence of subsolar metallicity, and atmosphere model fits indicate Teff = 1300 K and [M/H] ∼ −1.0, making this one of the few spectroscopically confirmed T subdwarfs known. The coldest source, UNCOVER-BD-3, is near the T/Y dwarf boundary with Teff = 550 K, and our analysis indicates the presence of PH3 in the 3–5 μm region, favored over CO2 and a possible indicator of subsolar metallicity. We estimate distances of 0.9–4.5 kpc from the Galactic midplane, making these the most distant brown dwarfs with spectroscopic confirmation. Population simulations indicate high probabilities of membership in the Galactic thick disk for two of these brown dwarfs, and potential halo membership for UNCOVER-BD-1. Our simulations indicate that there are approximately 5 T dwarfs and 1–2 L dwarfs in the Abell 2744 field down to F444W = 30 AB mag, roughly one-third of which are thick disk members. These results highlight the utility of deep JWST/NIRSpec spectroscopy for identifying and characterizing the oldest metal-poor brown dwarfs in the Milky Way.
dc.identifier.doihttps://doi.org/10.3847/1538-4357/ad206f
dc.identifier.urihttps://hdl.handle.net/20.500.14394/2812
dc.relation.ispartofThe Astrophysical Journal
dc.relation.urlhttps://scholarworks.umass.edu/cgi/viewcontent.cgi?article=2183&context=astro_faculty_pubs&unstamped=1
dc.rightsUMass Amherst Open Access Policy
dc.rights.urihttp://creativecommons.org/licenses/by/4.0/
dc.source.issue2
dc.source.issue962
dc.source.statuspublished
dc.subjectAstrophysics and Astronomy
dc.titleUNCOVER: JWST Spectroscopy of Three Cold Brown Dwarfs at Kiloparsec-scale Distances
dc.typearticle
dc.typearticle
digcom.contributor.authorCutler, Sam E.
digcom.date.embargo2024-03-27T00:00:00-07:00
digcom.identifierastro_faculty_pubs/1182
digcom.identifier.contextkey36834282
digcom.identifier.submissionpathastro_faculty_pubs/1182
dspace.entity.typePublication
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