Abstract
We present a sample of four emission-line galaxies at
z
= 6.11–6.35 that were serendipitously discovered using the commissioning data for the James Webb Space Telescope (JWST)/NIRCam ...wide-field slitless spectroscopy mode. One of them (at
z
= 6.11) has been reported previously, while the others are new discoveries. These sources are selected by the secure detections of both O
iii
λ
5007 and H
α
lines with other fainter lines, which were tentatively detected in some cases (e.g., O
ii
λ
3727, O
iii
λ
4959). In the O
iii
/H
β
–N
ii
/H
α
Baldwin–Phillips–Terlevich diagram, these galaxies occupy the same parameter space as that of
z
∼ 2 star-forming galaxies, indicating that they have been enriched rapidly to subsolar metallicities (∼0.4
Z
⊙
), similar to galaxies with comparable stellar masses at much lower redshifts. The detection of strong H
α
lines suggests a higher ionizing photon production efficiency within galaxies in the early universe. We find brightening of the O
iii
λ
5007 line-luminosity function (LF) from
z
= 3 to 6, and weak or no redshift evolution of the H
α
line LF from
z
= 2 to 6. Both LFs are underpredicted at
z
∼ 6 by a factor of ∼10 in certain cosmological simulations. This further indicates a global Ly
α
photon escape fraction of 7%–10% at
z
∼ 6, which is slightly lower than previous estimates through the comparison of the UV-derived star formation rate density and Ly
α
luminosity density. Our sample recovers
66
−
44
+
128
% of
z
= 6.0–6.6 galaxies in the survey volume with stellar masses greater than 5 × 10
8
M
⊙
, suggesting the ubiquity of strong H
α
and O
iii
line emitters in the Epoch of Reionization, which will be further uncovered in the era of JWST.
Abstract We present JWST/NIRCam F187N, F200W, F405N, and F410M direct imaging data of the disk surrounding SAO 206462. Previous images show a very structured disk, with a pair of spiral arms thought ...to be launched by one or more external perturbers. The spiral features are visible in three of the four filters, with the nondetection in F410M due to the large detector saturation radius. We detect with a signal-to-noise ratio of 4.4 a companion candidate that, if on a coplanar circular orbit, would orbit SAO 206462 at a separation of ∼300 au, 2.25 σ away from the predicted separation for the driver of the eastern spiral. No other companion candidates were detected. At the location predicted by simulations of both spirals generated by a single massive companion, the NIRCam data exclude objects more massive than ∼2.2 M J assuming the BEX evolutionary models. In terms of temperatures, the data are sensitive to objects with T eff ∼ 650–850 K, when assuming planets emit like blackbodies ( R p between 1 and 3 R J ). From these results, we conclude that if the spirals are driven by gas giants, these must be either cold or embedded in circumplanetary material. In addition, the NIRCam data provide tight constraints on ongoing accretion processes. In the low extinction scenario we are sensitive to mass accretion rates of the order M ̇ ∼ 10 − 9 M J yr −1 . Thanks to the longer wavelengths used to search for emission lines, we reach unprecedented sensitivities to processes with M ̇ ∼ 10 − 7 M J yr −1 even toward highly extincted environments ( A V ≈ 50 mag).
Abstract
The Y-dwarf WISE 1828+2650 is one of the coldest known brown dwarfs with an effective temperature of ∼300 K. Located at a distance of just 10 pc, previous model-based estimates suggest ...WISE1828+2650 has a mass of ∼5–10
M
J
, making it a valuable laboratory for understanding the formation, evolution, and physical characteristics of gas giant planets. However, previous photometry and spectroscopy have presented a puzzle, with the near impossibility of simultaneously fitting both the short- (0.9–2.0
μ
m) and long-wavelength (3–5
μ
m) data. A potential solution to this problem has been the suggestion that WISE 1828+2650 is a binary system whose composite spectrum might provide a better match to the data. Alternatively, new models being developed to fit JWST/NIRSpec, and MIRI spectroscopy might provide new insights. This article describes JWST/NIRCam observations of WISE 1828+2650 in six filters to address the binarity question and to provide new photometry to be used in model fitting. We also report adaptive optics imaging with the Keck I0 m telescope. We find no evidence for multiplicity for a companion beyond 0.5 au with either JWST or Keck. Companion articles will present low- and high-resolution spectra of WISE 1828 obtained with both NIRSpec and MIRI.
Abstract MWC 758 is a young star hosting a spiral protoplanetary disk. The spirals are likely companion-driven, and two previously identified candidate companions have been identified—one at the end ...the Southern spiral arm at ∼0.″6, and one interior to the gap at ∼0.″1. With JWST/NIRCam, we provide new images of the disk and constraints on planets exterior to ∼1″. We detect the two-armed spiral disk, a known background star, and a spatially resolved background galaxy, but no clear companions. The candidates that have been reported are at separations that are not probed by our data with sensitivity sufficient to detect them−nevertheless, these observations place new limits on companions down to ∼2 M Jup at ∼150 au and ∼0.5 M Jup at ≳600 au. Owing to the unprecedented sensitivity of JWST and youth of the target, these are among the deepest mass-detection limits yet obtained through direct imaging observations, and provide new insights into the system’s dynamical nature.
Abstract
We observed HD 19467 B with JWST’s NIRCam in six filters spanning 2.5–4.6
μ
m with the long-wavelength bar coronagraph. The brown dwarf HD 19467 B was initially identified through a ...long-period trend in the radial velocity of the G3V star HD 19467. HD 19467 B was subsequently detected via coronagraphic imaging and spectroscopy, and characterized as a late-T type brown dwarf with an approximate temperature ∼1000 K. We observed HD 19467 B as a part of the NIRCam GTO science program, demonstrating the first use of the NIRCam Long Wavelength Bar coronagraphic mask. The object was detected in all six filters (contrast levels of 2 × 10
−4
to 2 × 10
−5
) at a separation of 1.″6 using angular differential imaging and synthetic reference differential imaging. Due to a guide star failure during the acquisition of a preselected reference star, no reference star data were available for post-processing. However, reference differential imaging was successfully applied using synthetic point-spread functions developed from contemporaneous maps of the telescope’s optical configuration. Additional radial velocity data (from Keck/HIRES) are used to constrain the orbit of HD 19467 B. Photometric data from TESS are used to constrain the properties of the host star, particularly its age. NIRCam photometry, spectra, and photometry from the literature, and improved stellar parameters are used in conjunction with recent spectral and evolutionary substellar models to derive the physical properties of HD 19467 B. Using an age of 9.4 ± 0.9 Gyr inferred from spectroscopy, Gaia astrometry, and TESS asteroseismology, we obtain a model-derived mass of 62 ± 1
M
J
, which is consistent within 2
σ
with the dynamically derived mass of
81
−
12
+
14
M
J
.
Abstract
We report the serendipitous discovery of an O
iii
λ
λ
4959/5007 and H
α
line emitter in the Epoch of Reionization (EoR) with the James Webb Space Telescope (JWST) commissioning data taken ...in the NIRCam wide-field slitless spectroscopy (WFSS) mode. Located ∼55″ away from the flux calibrator P330-E, this galaxy exhibits bright O
iii
λ
λ
4959/5007 and H
α
lines detected at 3.7
σ
, 9.9
σ
, and 5.7
σ
, respectively, with a spectroscopic redshift of
z
= 6.112 ± 0.001. The total H
β
+O
iii
equivalent width is 664 ± 98 Å (454 ± 78 Å from the O
iii
λ
5007 line). This provides direct spectroscopic evidence for the presence of strong rest-frame optical lines (H
β
+O
iii
and H
α
) in EoR galaxies as inferred previously from the analyses of the Spitzer/IRAC spectral energy distributions (SEDs). Two spatial and velocity components are identified in this source, possibly indicating that this system is undergoing a major merger, which might have triggered the ongoing starburst with strong nebular emission lines over a timescale of ∼2 Myr, as our SED modeling suggests. The tentative detection of He
ii
λ
4686 line (1.9
σ
), if real, may indicate the existence of very young and metal-poor star-forming regions with a hard UV radiation field. Finally, this discovery demonstrates the power and readiness of the JWST/NIRCam WFSS mode, and marks the beginning of a new era for extragalactic astronomy, in which EoR galaxies can be routinely discovered via blind slitless spectroscopy through the detection of rest-frame optical emission lines.
![First Sample of Hα+[O iii]λ...](http://api.summon.serialssolutions.com/2.0.0/image/issn/XR4PS5YY4K/0004-637X/small "First Sample of Hα+[O iii]λ5007 Line Emitters at z > 6 Through JWST/NIRCam Slitless Spectroscopy: Physical Properties and Line-luminosity Functions")
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