Article, 2024
UNCOVER: JWST Spectroscopy of Three Cold Brown Dwarfs at Kiloparsec-scale Distances
The Astrophysical Journal,
ISSN
0004-637X,
1538-4357,
Volume 962,
2,
Page 177,
10.3847/1538-4357/ad206f
Contributors
Burgasser, Adam J
0000-0002-6523-9536
(Corresponding author)
[1]
Bezanson, Rachel S
0000-0001-5063-8254
[2]
Labbé, I F L
0000-0002-2057-5376
[3]
Brammer, Gabriel B
0000-0003-2680-005X
[4]
Cutler, Sam E
0000-0002-7031-2865
[5]
Furtak, Lukas J
0000-0001-6278-032X
[6]
Greene, Jenny E
0000-0002-5612-3427
[7]
Gerasimov, Roman
0000-0003-0398-639X
[1]
[8]
Leja, Joel
0000-0001-6755-1315
[9]
Pan, Richard
0000-0002-9651-5716
[10]
Price, Sedona H
0000-0002-0108-4176
[2]
Wang, Bingjie
0000-0001-9269-5046
[9]
Weaver, John R
0000-0003-1614-196X
[5]
Whitaker, Katherine E
0000-0001-7160-3632
[4]
[5]
Fujimoto, Seiji
0000-0001-7201-5066
[11]
[12]
Kokorev, Vasily I
0000-0002-5588-9156
[13]
Dayal, Pratika
[13]
Nanayakkara, Themiya
0000-0003-2804-0648
[3]
Williams, Christina C
[14]
Marchesini, Danilo M
0000-0001-9002-3502
[10]
Zitrin, Adi
0000-0002-0350-4488
[6]
van Dokkum, Pieter G
[15]
Affiliations
- [1]
University of California, San Diego
[NORA names:
United States; America, North; OECD];
- [2]
University of Pittsburgh
[NORA names:
United States; America, North; OECD];
- [3]
Swinburne University of Technology
[NORA names:
Australia; Oceania; OECD];
- [4]
University of Copenhagen
[NORA names:
KU University of Copenhagen; University; Denmark; Europe, EU; Nordic; OECD];
- [5]
University of Massachusetts System
[NORA names:
United States; America, North; OECD];
(... more)
- [6]
Ben-Gurion University of the Negev
[NORA names:
Israel; Asia, Middle East; OECD];
- [7]
Princeton University
[NORA names:
United States; America, North; OECD];
- [8]
University of Notre Dame
[NORA names:
United States; America, North; OECD];
- [9]
Pennsylvania State University
[NORA names:
United States; America, North; OECD];
- [10]
Tufts University
[NORA names:
United States; America, North; OECD];
- [11]
Hubble Fellow.
- [12]
The University of Texas at Austin
[NORA names:
United States; America, North; OECD];
- [13]
University of Groningen
[NORA names:
Netherlands; Europe, EU; OECD];
- [14]
NOIRLab
[NORA names:
United States; America, North; OECD];
- [15]
Yale University
[NORA names:
United States; America, North; OECD]
(less)
Abstract
We 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 T eff = 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 T eff = 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.
Keywords
AB mag,
Abel,
CO2,
Galactic midplane,
Galactic thick disk,
JWST,
L dwarfs,
Milky Way,
NIRCam,
NIRCam observations,
NIRSPEC,
PH3,
T dwarf atmospheres,
T dwarfs,
T eff,
T subdwarfs,
T-type brown dwarfs,
T/I,
T6,
T8-T9,
analysis,
atmosphere,
boundaries,
brown dwarfs,
classification,
cold brown dwarfs,
cold source,
comparison,
confirmation,
disk,
disk members,
distance,
dwarf,
epoch,
epoch of reionization,
estimated distance,
evidence,
field,
fitness,
galactic nuclei,
halo membership,
indicators,
lensing field,
mag,
members,
membership,
metal,
midplane,
model fit,
nucleus,
observations,
photometry,
population,
population simulations,
presence,
presence of PH3,
probability,
probability of membership,
region,
reionization,
results,
simulation,
source,
spectra,
spectral standards,
spectroscopic confirmation,
spectroscopy,
standards,
subsolar metallicity,
survey,
thick disk,
ultradeep,
warm sources,
way
Funders
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