Abstract
Selecting the first galaxies at
z
> 7 − 10 from JWST surveys is complicated by
z
< 6 contaminants with degenerate photometry. For example, strong optical nebular emission lines at
z
< 6 may ...mimic JWST/NIRCam photometry of
z
> 7–10 Lyman-break galaxies (LBGs). Dust-obscured 3 <
z
< 6 galaxies in particular are potentially important contaminants, and their faint rest-optical spectra have been historically difficult to observe. A lack of optical emission line and continuum measures for 3 <
z
< 6 dusty galaxies now makes it difficult to test their expected JWST/NIRCam photometry for degenerate solutions with NIRCam dropouts. Toward this end, we quantify the contribution by strong emission lines to NIRCam photometry in a physically motivated manner by stacking 21 Keck II/NIRES spectra of hot, dust-obscured, massive (
log
M
*
/
M
⊙
≳
10
–
11
) and infrared (IR) luminous galaxies at
z
∼ 1–4. We derive an average spectrum and measure strong narrow (broad) O
iii
5007
and H
α
features with equivalent widths of 130 ± 20 Å (150 ± 50 Å) and 220 ± 30 Å (540 ± 80 Å), respectively. These features can increase broadband NIRCam fluxes by factors of 1.2 − 1.7 (0.2–0.6 mag). Due to significant dust attenuation (
A
V
∼ 6), we find H
α
+N
ii
to be significantly brighter than O
iii
+H
β
and therefore find that emission-line dominated contaminants of high −
z
galaxy searches can only reproduce moderately blue perceived UV continua of
S
λ
∝
λ
β
with
β
> − 1.5 and
z
> 4. While there are some redshifts (
z
∼ 3.75) where our stack is more degenerate with the photometry of
z
> 10 LBGs at
λ
rest
∼ 0.3–0.8
μ
m , redder filter coverage beyond
λ
obs
> 3.5
μ
m and far-IR/submillimeter follow-up may be useful for breaking the degeneracy and making a crucial separation between two fairly unconstrained populations, dust-obscured galaxies at
z
∼ 3–6 and LBGs at
z
> 10.
Abstract
The detection of satellites around extrasolar planets, so called exomoons, remains a largely unexplored territory. In this work, we study the potential of detecting these elusive objects ...from radial velocity monitoring of self-luminous, directly imaged planets. This technique is now possible thanks to the development of dedicated instruments combining the power of high-resolution spectroscopy and high-contrast imaging. First, we demonstrate a sensitivity to satellites with a mass ratio of 1%–4% at separations similar to the Galilean moons from observations of a brown-dwarf companion (HR 7672 B;
K
mag
= 13; 0.″7 separation) with the Keck Planet Imager and Characterizer (
R
∼ 35,000 in the
K
band) at the W. M. Keck Observatory. Current instrumentation is therefore already sensitive to large unresolved satellites that could be forming from gravitational instability akin to binary star formation. Using end-to-end simulations, we then estimate that future instruments such as the Multi-Object Diffraction-limited High-resolution Infrared Spectrograph, planned for the Thirty Meter Telescope, should be sensitive to satellites with mass ratios of ∼10
−4
. Such small moons would likely form in a circumplanetary disk similar to the Jovian satellites in the solar system. Looking for the Rossiter–McLaughlin effect could also be an interesting pathway to detecting the smallest moons on short orbital periods. Future exomoon discoveries will allow precise mass measurements of the substellar companions that they orbit and provide key insight into the formation of exoplanets. They would also help constrain the population of habitable Earth-sized moons orbiting gas giants in the habitable zone of their stars.
Abstract
We present James Webb Space Telescope (JWST) Mid-Infrared Instrument (MIRI) integral-field spectroscopy of the nearby merging, luminous infrared galaxy, NGC 7469. This galaxy hosts a Seyfert ...type-1.5 nucleus, a highly ionized outflow, and a bright, circumnuclear star-forming ring, making it an ideal target to study active galactic nucleus (AGN) feedback in the local universe. We take advantage of the high spatial/spectral resolution of JWST/MIRI to isolate the star-forming regions surrounding the central active nucleus and study the properties of the dust and warm molecular gas on ∼100 pc scales. The starburst ring exhibits prominent polycyclic aromatic hydrocarbon (PAH) emission, with grain sizes and ionization states varying by only ∼30%, and a total star formation rate of 10–30
M
⊙
yr
−1
derived from fine structure and recombination emission lines. Using pure rotational lines of H
2
we detect 1.2 × 10
7
M
⊙
of warm molecular gas at a temperature higher than 200 K in the ring. All PAH bands get significantly weaker toward the central source, where larger and possibly more ionized grains dominate the emission, likely the result of the ionizing radiation and/or the fast wind emerging from the AGN. The small grains and warm molecular gas in the bright regions of the ring however display properties consistent with normal star-forming regions. These observations highlight the power of JWST to probe the inner regions of dusty, rapidly evolving galaxies for signatures of feedback and inform models that seek to explain the coevolution of supermassive black holes and their hosts.
Abstract We present the first on-sky segmented primary mirror closed-loop piston control using a Zernike wavefront sensor (ZWFS) installed on the Keck II telescope. Segment cophasing errors are a ...primary contributor to contrast limits on Keck and will be necessary to correct for the next generation of space missions and ground-based extremely large telescopes, which will all have segmented primary mirrors. The goal of the ZWFS installed on Keck is to monitor and correct primary mirror cophasing errors in parallel with science observations. The ZWFS is ideal for measuring phase discontinuities such as segment cophasing errors and is one of the most sensitive WFSs, but has limited dynamic range. The vector-ZWFS at Keck works on the adaptive-optics-corrected wavefront and consists of a metasurface focal plane mask that imposes two different phase shifts on the core of the point-spread function to two orthogonal light polarizations, producing two pupil images. This design extends the dynamic range compared with the scalar ZWFS. The primary mirror segment pistons were controlled in closed loop using the ZWFS, improving the Strehl ratio on the NIRC2 science camera by up to 10 percentage points. We analyze the performance of the closed-loop tests, the impact on NIRC2 science data, and discuss the ZWFS measurements.
Abstract
The formation and evolution pathway for the directly imaged multiplanetary system HR 8799 remains mysterious. Accurate constraints on the chemical composition of the planetary atmosphere(s) ...are key to solving the mystery. We perform a detailed atmospheric retrieval on HR 8799 c to infer the chemical abundances and abundance ratios using a combination of photometric data along with low- and high-resolution spectroscopic data (
R
∼ 20–35,000). We specifically retrieve C/H, O/H, and C/O and find them to be
0.55
−
0.39
+
0.36
,
0.47
−
0.32
+
0.31
, and
0.67
−
0.15
+
0.12
at 68% confidence. The superstellar C and O abundances, yet a stellar C/O ratio, reveal a potential formation pathway for HR 8799 c. Planet c, and likely the other gas giant planets in the system, formed early on (likely within ∼1 Myr), followed by further atmospheric enrichment in C and O through the accretion of solids beyond the CO ice line. The enrichment either preceded or took place during the early phase of the inward migration to the current planet locations.
Abstract
We present Keck Planet Imager and Characterizer (KPIC) high-resolution (
R
∼35,000)
K
-band thermal emission spectroscopy of the ultrahot Jupiter WASP-33b. The use of KPIC’s single-mode ...fibers greatly improves both blaze and line-spread stabilities relative to slit spectrographs, enhancing the cross-correlation detection strength. We retrieve the dayside emission spectrum with a nested-sampling pipeline, which fits for orbital parameters, the atmospheric pressure–temperature profile, and the molecular abundances. We strongly detect the thermally inverted dayside and measure mass-mixing ratios for CO (
logCO
MMR
=
−
1.1
−
0.6
+
0.4
), H
2
O (
logH
2
O
MMR
=
−
4.1
−
0.9
+
0.7
), and OH (
logOH
MMR
=
−
2.1
−
1.1
+
0.5
), suggesting near-complete dayside photodissociation of H
2
O. The retrieved abundances suggest a carbon- and possibly metal-enriched atmosphere, with a gas-phase C/O ratio of
0.8
−
0.2
+
0.1
, consistent with the accretion of high-metallicity gas near the CO
2
snow line and post-disk migration or with accretion between the soot and H
2
O snow lines. We also find tentative evidence for
12
CO/
13
CO ∼ 50, consistent with values expected in protoplanetary disks, as well as tentative evidence for a metal-enriched atmosphere (2–15 × solar). These observations demonstrate KPIC’s ability to characterize close-in planets and the utility of KPIC’s improved instrumental stability for cross-correlation techniques.
Abstract
We present high-resolution
K
-band emission spectra of the quintessential hot Jupiter HD 189733 b from the Keck Planet Imager and Characterizer. Using a Bayesian retrieval framework, we fit ...the dayside pressure–temperature profile, orbital kinematics, mass-mixing ratios of H
2
O, CO, CH
4
, NH
3
, HCN, and H
2
S, and the
13
CO/
12
CO ratio. We measure mass fractions of
logH
2
O
=
−
2.0
−
0.4
+
0.4
and
logCO
=
−
2.2
−
0.5
+
0.5
, and place upper limits on the remaining species. Notably, we find logCH
4
< −4.5 at 99% confidence, despite its anticipated presence at the equilibrium temperature of HD 189733 b assuming local thermal equilibrium. We make a tentative (∼3
σ
) detection of
13
CO, and the retrieved posteriors suggest a
12
C/
13
C ratio similar to or substantially less than the local interstellar value. The possible
13
C enrichment would be consistent with accretion of fractionated material in ices or in the protoplanetary disk midplane. The retrieved abundances correspond to a substantially substellar atmospheric C/O = 0.3 ± 0.1, while the carbon and oxygen abundances are stellar to slightly superstellar, consistent with core-accretion models which predict an inverse correlation between C/O and metallicity. The specific combination of low C/O and high metallicity suggests significant accretion of solid material may have occurred late in the formation process of HD 189733 b.
Abstract
The nearby, luminous infrared galaxy NGC 7469 hosts a Seyfert nucleus with a circumnuclear star-forming ring and is thus the ideal local laboratory for investigating the starburst–AGN ...(active galactic nucleus) connection in detail. We present integral-field observations of the central 1.3 kpc region in NGC 7469 obtained with the JWST Mid-InfraRed Instrument. Molecular and ionized gas distributions and kinematics at a resolution of ∼100 pc over the 4.9–7.6
μ
m region are examined to study the gas dynamics influenced by the central AGN. The low-ionization Fe
ii
λ
5.34
μ
m and Ar
ii
λ
6.99
μ
m lines are bright on the nucleus and in the starburst ring, as opposed to H
2
S(5)
λ
6.91
μ
m, which is strongly peaked at the center and surrounding ISM. The high-ionization Mg
v
line is resolved and shows a broad, blueshifted component associated with the outflow. It has a nearly face-on geometry that is strongly peaked on the nucleus, where it reaches a maximum velocity of −650 km s
−1
, and extends about 400 pc to the east. Regions of enhanced velocity dispersion in H
2
and Fe
ii
∼ 180 pc from the AGN that also show high
L
(H
2
)/
L
(PAH) and
L
(Fe
ii
)/
L
(Pf
α
) ratios to the W and N of the nucleus pinpoint regions where the ionized outflow is depositing energy, via shocks, into the dense interstellar medium between the nucleus and the starburst ring. These resolved mid-infrared observations of the nuclear gas dynamics demonstrate the power of JWST and its high-sensitivity integral-field spectroscopic capability to resolve feedback processes around supermassive black holes in the dusty cores of nearby luminous infrared galaxies.
Abstract We present new JWST NIRSpec integral field spectroscopy (IFS) data for the luminous infrared galaxy NGC 7469, a nearby (70.6 Mpc) active galaxy with a Seyfert 1.5 nucleus that drives a ...highly ionized gas outflow and a prominent nuclear star-forming ring. Using the superb sensitivity and high spatial resolution of the JWST instrument NIRSpec IFS, we investigate the role of the Seyfert nucleus in the excitation and dynamics of the circumnuclear gas. Our analysis focuses on the Fe ii , H 2 , and hydrogen recombination lines that trace the radiation/shocked-excited molecular and ionized interstellar medium around the active galactic nucleus (AGN). We investigate gas excitation through H 2 /Br γ and Fe ii /Pa β emission line ratios and find that photoionization by the AGN dominates within the central 300 pc of the galaxy except in a small region that shows signatures of shock-heated gas; these shock-heated regions are likely associated with a compact radio jet. In addition, the velocity field and velocity dispersion maps reveal complex gas kinematics. Rotation is the dominant feature, but we also identify noncircular motions consistent with gas inflows as traced by the velocity residuals and the spiral pattern in the Pa α velocity dispersion map. The inflow is 2 orders of magnitude higher than the AGN accretion rate. The compact nuclear radio jet has enough power to drive the highly ionized outflow. This scenario suggests that the inflow and outflow are in a self-regulating feeding–feedback process, with a contribution from the radio jet helping to drive the outflow.
Abstract The 1RXS J034231.8+121622 system consists of an M dwarf primary and a directly imaged low-mass stellar companion. We use high-resolution spectroscopic data from Keck/KPIC to estimate the ...objects' atmospheric parameters and radial velocities (RVs). Using PHOENIX stellar models, we find that the primary has a temperature of 3460 ± 50 K and a metallicity of 0.16 ± 0.04, while the secondary has a temperature of 2510 ± 50 K and a metallicity of 0.13 − 0.11 + 0.12 . Recent work suggests this system is associated with the Hyades, giving it an older age than previous estimates. Both metallicities agree with current Hyades Fe/H measurements (0.11–0.21). Using stellar evolutionary models, we obtain significantly higher masses for the objects, 0.30 ± 0.15 M ⊙ and 0.08 ± 0.01 M ⊙ (84 ± 11 M Jup ), respectively. Using the RVs and a new astrometry point from Keck/NIRC2, we find that the system is likely an edge-on, moderately eccentric ( 0.41 − 0.08 + 0.27 ) configuration. We also estimate the C/O ratio of both objects using custom grid models, obtaining 0.42 ± 0.10 (primary) and 0.55 ± 0.10 (companion). From these results, we confirm that this system most likely went through a binary star formation process in the Hyades. The significant changes in this system's parameters since its discovery highlight the importance of high-resolution spectroscopy for both orbital and atmospheric characterization of directly imaged companions.
