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The Astrophysical Journal (ApJ)

Resumen/Descripción – provisto por la editorial en inglés
The Astrophysical Journal is an open access journal devoted to recent developments, discoveries, and theories in astronomy and astrophysics. Publications in ApJ constitute significant new research that is directly relevant to astrophysical applications, whether based on observational results or on theoretical insights or modeling.
Palabras clave – provistas por la editorial

astronomy; astrophysics

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Institución detectada Período Navegá Descargá Solicitá
No detectada desde jul. 1995 / hasta dic. 2023 IOPScience

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revistas

ISSN impreso

0004-637X

ISSN electrónico

1538-4357

Editor responsable

American Astronomical Society (AAS)

Idiomas de la publicación

  • inglés

País de edición

Reino Unido

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https://creativecommons.org/licenses/by/4.0/

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Tabla de contenidos

Simulation-based Inference of Reionization Parameters from 3D Tomographic 21 cm Light-cone Images

Xiaosheng ZhaoORCID; Yi MaoORCID; Cheng Cheng; Benjamin D. WandeltORCID

<jats:title>Abstract</jats:title> <jats:p>Tomographic three-dimensional 21 cm images from the epoch of reionization contain a wealth of information about the reionization of the intergalactic medium by astrophysical sources. Conventional power spectrum analysis cannot exploit the full information in the 21 cm data because the 21 cm signal is highly non-Gaussian due to reionization patchiness. We perform a Bayesian inference of the reionization parameters where the likelihood is implicitly defined through forward simulations using density estimation likelihood-free inference (DELFI). We adopt a trained 3D convolutional neural network (CNN) to compress the 3D image data into informative summaries (DELFI-3D CNN). We show that this method recovers accurate posterior distributions for the reionization parameters. Our approach outperforms earlier analysis based on two-dimensional 21 cm images. In contrast, a Monte Carlo Markov Chain analysis of the 3D light-cone-based 21 cm power spectrum alone and using a standard explicit likelihood approximation results in less accurate credible parameter regions than inferred by the DELFI-3D CNN, both in terms of the location and shape of the contours. Our proof-of-concept study implies that the DELFI-3D CNN can effectively exploit more information in the 3D 21 cm images than a 2D CNN or power spectrum analysis. This technique can be readily extended to include realistic effects and is therefore a promising approach for the scientific interpretation of future 21 cm observation data.</jats:p>

Palabras clave: Space and Planetary Science; Astronomy and Astrophysics.

Pp. 151

Relativistic X-Ray Reverberation from Super-Eddington Accretion Flow

Lars Lund ThomsenORCID; Lixin DaiORCID; Erin KaraORCID; Chris ReynoldsORCID

<jats:title>Abstract</jats:title> <jats:p>X-ray reverberation is a powerful technique that uses the echoes of the coronal emission reflected by a black hole (BH) accretion disk to map out the inner disk structure. While the theory of X-ray reverberation has been developed almost exclusively for standard thin disks, reverberation lags have recently been observed from likely super-Eddington accretion sources such as the jetted tidal disruption event Swift J1644+57. In this paper, we extend X-ray reverberation studies into the regime of super-Eddington accretion with a focus on investigating the lags in the fluorescent Fe K<jats:italic>α</jats:italic> line region. We find that the coronal photons are mostly reflected by the fast and optically thick winds launched from the super-Eddington accretion flow, and this funnel-like reflection geometry produces lag–frequency and lag–energy spectra with unique observable characteristics. The lag–frequency spectrum exhibits a step-function-like decline near the first zero-crossing point. As a result, the magnitude of the lag scales linearly with the BH mass for a large parameter space, and the shape of the lag–energy spectrum remains almost independent of the choice of frequency bands. Not only can these features be used to distinguish super-Eddington accretion systems from sub-Eddington systems, but they are also key for constraining the reflection geometry and extracting parameters from the observed lags. When fitting the observed reverberation lag of Swift J1644+57 to our modeling, we find that the super-Eddington disk geometry is slightly preferred over the thin disk geometry, and we obtain a BH mass of 5–6 × 10<jats:sup>6</jats:sup> <jats:italic>M</jats:italic> <jats:sub>☉</jats:sub> and a coronal height around 10 <jats:italic>R<jats:sub>g</jats:sub> </jats:italic>.</jats:p>

Palabras clave: Space and Planetary Science; Astronomy and Astrophysics.

Pp. 151

An Infrared Search for Kilonovae with the WINTER Telescope. I. Binary Neutron Star Mergers

Danielle FrostigORCID; Sylvia BiscoveanuORCID; Geoffrey MoORCID; Viraj KarambelkarORCID; Tito Dal CantonORCID; Hsin-Yu ChenORCID; Mansi KasliwalORCID; Erik Katsavounidis; Nathan P. Lourie; Robert A. SimcoeORCID; Salvatore VitaleORCID

<jats:title>Abstract</jats:title> <jats:p>The Wide-Field Infrared Transient Explorer (WINTER) is a new 1 deg<jats:sup>2</jats:sup> seeing-limited time-domain survey instrument designed for dedicated near-infrared follow-up of kilonovae from binary neutron star (BNS) and neutron star–black hole mergers. WINTER will observe in the near-infrared <jats:italic>Y</jats:italic>, <jats:italic>J</jats:italic>, and short-<jats:italic>H</jats:italic> bands (0.9–1.7 <jats:italic>μ</jats:italic>m, to <jats:italic>J</jats:italic> <jats:sub> <jats:italic>AB</jats:italic> </jats:sub> = 21 mag) on a dedicated 1 m telescope at Palomar Observatory. To date, most prompt kilonova follow-up has been in optical wavelengths; however, near-infrared emission fades more slowly and depends less on geometry and viewing angle than optical emission. We present an end-to-end simulation of a follow-up campaign during the fourth observing run (O4) of the LIGO, Virgo, and KAGRA interferometers, including simulating 625 BNS mergers, their detection in gravitational waves, low-latency and full parameter estimation skymaps, and a suite of kilonova lightcurves from two different model grids. We predict up to five new kilonovae independently discovered by WINTER during O4, given a realistic BNS merger rate. Using a larger grid of kilonova parameters, we find that kilonova emission is ≈2 times longer lived and red kilonovae are detected ≈1.5 times further in the infrared than in the optical. For 90% localization areas smaller than 150 (450) deg<jats:sup>2</jats:sup>, WINTER will be sensitive to more than 10% of the kilonova model grid out to 350 (200) Mpc. We develop a generalized toolkit to create an optimal BNS follow-up strategy with any electromagnetic telescope and present WINTER’s observing strategy with this framework. This toolkit, all simulated gravitational-wave events, and skymaps are made available for use by the community.</jats:p>

Palabras clave: Space and Planetary Science; Astronomy and Astrophysics.

Pp. 152

The Second AGILE MCAL Gamma-Ray Burst Catalog: 13 yr of Observations

A. UrsiORCID; M. RomaniORCID; F. VerrecchiaORCID; C. PittoriORCID; M. TavaniORCID; M. Marisaldi; M. Galli; C. LabantiORCID; N. ParmiggianiORCID; A. BulgarelliORCID; A. AddisORCID; L. Baroncelli; M. CardilloORCID; C. CasentiniORCID; P. W. CattaneoORCID; A. ChenORCID; A. Di PianoORCID; F. Fuschino; F. LongoORCID; F. LucarelliORCID; A. MorselliORCID; G. PianoORCID; S. VercelloneORCID

<jats:title>Abstract</jats:title> <jats:p>We present the results of a systematic search and analysis of GRBs detected by the Astrorivelatore Gamma ad Immagini LEggero (AGILE) MiniCALorimeter (MCAL; 0.4–100 MeV) over a time frame of 13 yr, from 2007 to 2020 November. The MCAL GRB sample consists of 503 bursts triggered by MCAL, 394 of which were fully detected onboard with high time resolution. The sample consists of about 44% short GRBs and 56% long GRBs. In addition, 109 bursts triggered partial MCAL onboard data acquisitions, providing further detections that can be used for joint analyses or triangulations. More than 90% of these GRBs were also detected by the AGILE Scientific RateMeters (RMs), providing simultaneous observations between 20 keV and 100 MeV. We performed spectral analysis of these events in the 0.4–50 MeV energy range. We could fit the time-integrated spectrum of 258 GRBs with a single power-law model, resulting in a mean photon index 〈<jats:italic>β</jats:italic>〉of−2.3. Among them, 43 bursts could also be fitted with a Band model, with peak energy above 400 keV, resulting in a mean low-energy photon index 〈<jats:italic>α</jats:italic>〉 = −0.6, a mean high-energy photon index 〈<jats:italic>β</jats:italic>〉 = −2.5, and a mean peak energy 〈<jats:italic>E</jats:italic> <jats:sub> <jats:italic>p</jats:italic> </jats:sub>〉 = 640 keV. The AGILE MCAL GRB sample mostly consists of hard-spectrum GRBs, with a large fraction of short-duration events. We discuss properties and features of the MCAL bursts, whose detections can be used to perform joint broad-band analysis with other missions, and to provide insights on the high-energy component of the prompt emission in the tens of mega electron volt energy range.</jats:p>

Palabras clave: Space and Planetary Science; Astronomy and Astrophysics.

Pp. 152

Astrophysical Distance Scale. IV. Preliminary Zero-point Calibration of the JAGB Method in the HST/WFC3-IR Broad J-band (F110W) Filter

Barry F. MadoreORCID; Wendy L. FreedmanORCID; Abigail J. LeeORCID

<jats:title>Abstract</jats:title> <jats:p>We present an absolute calibration of the J-region Asymptotic Giant Branch (JAGB) method using published photometry of resolved stars in 20 nearby galaxies observed with the Hubble Space Telescope using the WFC3-IR camera and the F110W (broad <jats:italic>J</jats:italic>-band) filter. True distance moduli for each of the galaxies are based on the Tip of the Red Giant Branch (TRGB) method as uniformly determined by Dalcanton et al. From a composite color–magnitude diagram composed of over 6 million stars, leading to a sample of 453 JAGB stars in these galaxies, we find <jats:inline-formula> <jats:tex-math> <?CDATA ${M}_{{\rm{F}}110{\rm{W}}}^{\mathrm{JAGB}}=-5.77\pm 0.02$?> </jats:tex-math> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:msubsup> <mml:mrow> <mml:mi>M</mml:mi> </mml:mrow> <mml:mrow> <mml:mi mathvariant="normal">F</mml:mi> <mml:mn>110</mml:mn> <mml:mi mathvariant="normal">W</mml:mi> </mml:mrow> <mml:mrow> <mml:mi>JAGB</mml:mi> </mml:mrow> </mml:msubsup> <mml:mo>=</mml:mo> <mml:mo>−</mml:mo> <mml:mn>5.77</mml:mn> <mml:mo>±</mml:mo> <mml:mn>0.02</mml:mn> </mml:math> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="apjac426aieqn1.gif" xlink:type="simple" /> </jats:inline-formula> mag (statistical error on the mean). The external scatter seen in a comparison of the individual TRGB and the JAGB moduli is ±0.081 mag (or 4% in distance). Some of this scatter can be attributed to small number statistics arising from the sparse JAGB populations found in the generally low-luminosity galaxies that comprise the particular sample studied here. However, if this intermethod scatter is shared equitably between the JAGB and TRGB methods, that implies that each is good to ±0.06 mag, or better than 3% in distance.</jats:p>

Palabras clave: Space and Planetary Science; Astronomy and Astrophysics.

Pp. 153

Now You See It, Now You Don’t: Star Formation Truncation Precedes the Loss of Molecular Gas by ∼100 Myr in Massive Poststarburst Galaxies at z ∼ 0.6

Rachel BezansonORCID; Justin S. SpilkerORCID; Katherine A. SuessORCID; David J. SettonORCID; Robert FeldmannORCID; Jenny E. GreeneORCID; Mariska KriekORCID; Desika NarayananORCID; Margaret VerricoORCID

<jats:title>Abstract</jats:title> <jats:p>We use ALMA observations of CO(2–1) in 13 massive (<jats:italic>M</jats:italic> <jats:sub>*</jats:sub> ≳ 10<jats:sup>11</jats:sup> <jats:italic>M</jats:italic> <jats:sub>⊙</jats:sub>) poststarburst galaxies at <jats:italic>z</jats:italic> ∼ 0.6 to constrain the molecular gas content in galaxies shortly after they quench their major star-forming episode. The poststarburst galaxies in this study are selected from the Sloan Digital Sky Survey spectroscopic samples (Data Release 14) based on their spectral shapes, as part of the Studying QUenching at Intermediate-z Galaxies: Gas, angu<jats:inline-formula> <jats:tex-math> <?CDATA $\overrightarrow{L}\mathrm{ar}$?> </jats:tex-math> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="block" overflow="scroll"> <mml:mover accent="true"> <mml:mi>L</mml:mi> <mml:mo stretchy="true">→</mml:mo> </mml:mover> <mml:mi>ar</mml:mi> </mml:math> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="apjac3dfaieqn1.gif" xlink:type="simple" /> </jats:inline-formula> momentum, and Evolution (<jats:inline-formula> <jats:tex-math> <?CDATA ${SQuIGG}\vec{L}E$?> </jats:tex-math> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mi mathvariant="italic">SQuIGG</mml:mi> <mml:mover accent="true"> <mml:mrow> <mml:mi>L</mml:mi> </mml:mrow> <mml:mrow> <mml:mo>⃗</mml:mo> </mml:mrow> </mml:mover> <mml:mi>E</mml:mi> </mml:math> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="apjac3dfaieqn2.gif" xlink:type="simple" /> </jats:inline-formula>) program. Early results showed that two poststarburst galaxies host large H<jats:sub>2</jats:sub> reservoirs despite their low inferred star formation rates (SFRs). Here we expand this analysis to a larger statistical sample of 13 galaxies. Six of the primary targets (45%) are detected, with <jats:inline-formula> <jats:tex-math> <?CDATA ${M}_{{{\rm{H}}}_{2}}\gtrsim {10}^{9}$?> </jats:tex-math> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:msub> <mml:mrow> <mml:mi>M</mml:mi> </mml:mrow> <mml:mrow> <mml:msub> <mml:mrow> <mml:mi mathvariant="normal">H</mml:mi> </mml:mrow> <mml:mrow> <mml:mn>2</mml:mn> </mml:mrow> </mml:msub> </mml:mrow> </mml:msub> <mml:mo>≳</mml:mo> <mml:msup> <mml:mrow> <mml:mn>10</mml:mn> </mml:mrow> <mml:mrow> <mml:mn>9</mml:mn> </mml:mrow> </mml:msup> </mml:math> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="apjac3dfaieqn3.gif" xlink:type="simple" /> </jats:inline-formula> <jats:italic>M</jats:italic> <jats:sub>⊙</jats:sub>. Given their high stellar masses, this mass limit corresponds to an average gas fraction of <jats:inline-formula> <jats:tex-math> <?CDATA $\langle {f}_{{{\rm{H}}}_{2}}\equiv {M}_{{{\rm{H}}}_{2}}/{M}_{* }\rangle \sim 7 \% $?> </jats:tex-math> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mo stretchy="false">〈</mml:mo> <mml:msub> <mml:mrow> <mml:mi>f</mml:mi> </mml:mrow> <mml:mrow> <mml:msub> <mml:mrow> <mml:mi mathvariant="normal">H</mml:mi> </mml:mrow> <mml:mrow> <mml:mn>2</mml:mn> </mml:mrow> </mml:msub> </mml:mrow> </mml:msub> <mml:mo>≡</mml:mo> <mml:msub> <mml:mrow> <mml:mi>M</mml:mi> </mml:mrow> <mml:mrow> <mml:msub> <mml:mrow> <mml:mi mathvariant="normal">H</mml:mi> </mml:mrow> <mml:mrow> <mml:mn>2</mml:mn> </mml:mrow> </mml:msub> </mml:mrow> </mml:msub> <mml:mrow> <mml:mo stretchy="true">/</mml:mo> </mml:mrow> <mml:msub> <mml:mrow> <mml:mi>M</mml:mi> </mml:mrow> <mml:mrow> <mml:mo>*</mml:mo> </mml:mrow> </mml:msub> <mml:mo stretchy="false">〉</mml:mo> <mml:mo>∼</mml:mo> <mml:mn>7</mml:mn> <mml:mo>%</mml:mo> </mml:math> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="apjac3dfaieqn4.gif" xlink:type="simple" /> </jats:inline-formula> or ∼14% using lower stellar masses estimates derived from analytic, exponentially declining star formation histories. The gas fraction correlates with the <jats:italic>D</jats:italic> <jats:sub> <jats:italic>n</jats:italic> </jats:sub>4000 spectral index, suggesting that the cold gas reservoirs decrease with time since burst, as found in local K+A galaxies. Star formation histories derived from flexible stellar population synthesis modeling support this empirical finding: galaxies that quenched ≲150 Myr prior to observation host detectable CO(2–1) emission, while older poststarburst galaxies are undetected. The large H<jats:sub>2</jats:sub> reservoirs and low SFRs in the sample imply that the quenching of star formation precedes the disappearance of the cold gas reservoirs. However, within the following 100–200 Myr, the <jats:inline-formula> <jats:tex-math> <?CDATA ${SQuIGG}\vec{L}E$?> </jats:tex-math> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mi mathvariant="italic">SQuIGG</mml:mi> <mml:mover accent="true"> <mml:mrow> <mml:mi>L</mml:mi> </mml:mrow> <mml:mrow> <mml:mo>⃗</mml:mo> </mml:mrow> </mml:mover> <mml:mi>E</mml:mi> </mml:math> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="apjac3dfaieqn5.gif" xlink:type="simple" /> </jats:inline-formula> galaxies require the additional and efficient heating or removal of cold gas to bring their low SFRs in line with standard H<jats:sub>2</jats:sub> scaling relations.</jats:p>

Palabras clave: Space and Planetary Science; Astronomy and Astrophysics.

Pp. 153

Exploring the S-process History in the Galactic Disk: Cerium Abundances and Gradients in Open Clusters from the OCCAM/APOGEE Sample

J. V. Sales-SilvaORCID; S. Daflon; K. CunhaORCID; D. Souto; V. V. Smith; C. Chiappini; J. Donor; P. M. FrinchaboyORCID; D. A. García-HernándezORCID; C. Hayes; S. R. MajewskiORCID; T. MasseronORCID; R. P. SchiavonORCID; D. H. WeinbergORCID; R. L. BeatonORCID; J. G. Fernández-Trincado; H. JönssonORCID; R. R. LaneORCID; D. Minniti; A. ManchadoORCID; C. Moni Bidin; C. NitschelmORCID; J. O’Connell; S. VillanovaORCID

<jats:title>Abstract</jats:title> <jats:p>The APOGEE Open Cluster Chemical Abundances and Mapping survey is used to probe the chemical evolution of the s-process element cerium in the Galactic disk. Cerium abundances were derived from measurements of Ce <jats:sc>ii</jats:sc> lines in the APOGEE spectra using the Brussels Automatic Code for Characterizing High Accuracy Spectra in 218 stars belonging to 42 open clusters. Our results indicate that, in general, for ages &lt; 4 Gyr, younger open clusters have higher [Ce/Fe] and [Ce/<jats:italic>α</jats:italic>-element] ratios than older clusters. In addition, metallicity segregates open clusters in the [Ce/X]–age plane (where X can be H, Fe, or the <jats:italic>α</jats:italic>-elements O, Mg, Si, or Ca). These metallicity-dependent relations result in [Ce/Fe] and [Ce/<jats:italic>α</jats:italic>] ratios with ages that are not universal clocks. Radial gradients of [Ce/H] and [Ce/Fe] ratios in open clusters, binned by age, were derived for the first time, with <jats:italic>d</jats:italic>[Ce/H]/<jats:italic>d</jats:italic> <jats:italic>R</jats:italic> <jats:sub>GC</jats:sub> being negative, while <jats:italic>d</jats:italic>[Ce/Fe]/<jats:italic>d</jats:italic> <jats:italic>R</jats:italic> <jats:sub>GC</jats:sub> is positive. [Ce/H] and [Ce/Fe] gradients are approximately constant over time, with the [Ce/Fe] gradient becoming slightly steeper, changing by ∼+0.009 dex kpc<jats:sup>−1</jats:sup> Gyr<jats:sup>−1</jats:sup>. Both the [Ce/H] and [Ce/Fe] gradients are shifted to lower values of [Ce/H] and [Ce/Fe] for older open clusters. The chemical pattern of Ce in open clusters across the Galactic disk is discussed within the context of s-process yields from asymptotic giant branch (AGB) stars, gigayear time delays in Ce enrichment of the interstellar medium, and the strong dependence of Ce nucleosynthesis on the metallicity of its AGB stellar sources.</jats:p>

Palabras clave: Space and Planetary Science; Astronomy and Astrophysics.

Pp. 154

Predictions for Gravity-mode Periods and Surface Abundances in Intermediate-mass Dwarfs from Shear Mixing and Radiative Levitation

Joey S. G. MombargORCID; Aaron DotterORCID; Michel RieutordORCID; Mathias MichielsenORCID; Timothy Van ReethORCID; Conny AertsORCID

<jats:title>Abstract</jats:title> <jats:p>The treatment of chemical mixing in the radiative envelopes of intermediate-mass stars has hardly been calibrated so far. Recent asteroseismic studies demonstrated that a constant diffusion coefficient in the radiative envelope is not able to explain the periods of trapped gravity modes in the oscillation spectra of <jats:italic>γ</jats:italic> Doradus pulsators. We present a new generation of <jats:monospace>MESA</jats:monospace> stellar models with two major improvements. First, we present a new implementation for computing radiative accelerations and Rosseland mean opacities that requires significantly less CPU time. Second, the inclusion of shear mixing based on rotation profiles computed with the 2D stellar structure code <jats:monospace>ESTER</jats:monospace> is considered. We show predictions for the mode periods of these models covering stellar masses from 1.4 to 3.0 <jats:italic>M</jats:italic> <jats:sub>⊙</jats:sub> across the main sequence, computed for different metallicities. The morphology of the chemical mixing profile resulting from shear mixing in combination with atomic diffusion and radiative levitation does allow for mode trapping, while the diffusion coefficient in the outer envelope is large (&gt;10<jats:sup>6</jats:sup> cm<jats:sup>2</jats:sup> s<jats:sup>−1</jats:sup>). Furthermore, we make predictions for the evolution of surface abundances for which radiative accelerations can be computed. We find that the N/C and C/O abundance ratios correlate with stellar age. We predict that these correlations are observable with precisions ≲ 0.1 dex on these ratios, given that a precise age estimate can be made.</jats:p>

Palabras clave: Space and Planetary Science; Astronomy and Astrophysics.

Pp. 154

A Census of Optically Dark Massive Galaxies in the Early Universe from Magnification by Lensing Galaxy Clusters

Xinwen ShuORCID; Lei Yang; Daizhong LiuORCID; Wei-Hao WangORCID; Tao WangORCID; Yunkun HanORCID; Xingxing HuangORCID; Chen-Fatt LimORCID; Yu-Yen ChangORCID; Wei Zheng; XianZhong ZhengORCID; Junxian WangORCID; Xu KongORCID

<jats:title>Abstract</jats:title> <jats:p>We present ALMA 870 <jats:italic>μ</jats:italic>m and JCMT/SCUBA2 850 <jats:italic>μ</jats:italic>m dust continuum observations of a sample of optically dark and strongly lensed galaxies in cluster fields. The ALMA and SCUBA2 observations reach a median rms of ∼0.11 mJy and 0.44 mJy, respectively, with the latter close to the confusion limit of the data at 850 <jats:italic>μ</jats:italic>m. This represents one of the most sensitive searches for dust emission in optically dark galaxies. We detect the dust emission in 12 out of 15 galaxies at &gt;3.8<jats:italic>σ</jats:italic>, corresponding to a detection rate of 80%. Thanks to the gravitational lensing, we reach a deeper limiting flux than previous surveys in blank fields by a factor of ∼3. We estimate delensed infrared luminosities in the range 2.9 × 10<jats:sup>11</jats:sup>–4.9 × 10<jats:sup>12</jats:sup> <jats:italic>L</jats:italic> <jats:sub>⊙</jats:sub>, which correspond to dust-obscured star formation rates of ∼30–520 <jats:italic>M</jats:italic> <jats:sub>⊙</jats:sub> yr<jats:sup>−1</jats:sup>. Stellar population fits to the optical-to-NIR photometric data yield a median redshift <jats:italic>z</jats:italic> = 4.26 and delensed stellar mass 6.0 × 10<jats:sup>10</jats:sup> <jats:italic>M</jats:italic> <jats:sub>⊙</jats:sub>. They contribute a lensing-corrected star formation rate density at least an order of magnitude higher than that of equivalently massive UV-selected galaxies at <jats:italic>z</jats:italic> &gt; 3. The results suggest that there is a missing population of massive star-forming galaxies in the early Universe, which may dominate the SFR density at the massive end (<jats:italic>M</jats:italic> <jats:sub>⋆</jats:sub> &gt; 10<jats:sup>10.3</jats:sup> <jats:italic>M</jats:italic> <jats:sub>⊙</jats:sub>). Five optically dark galaxies are located within <jats:italic>r</jats:italic> &lt; 50″ in one cluster field, representing a potential overdensity structure that has a physical origin at a confidence level &gt;99.974% from Poisson statistics. Follow-up spectroscopic observations with ALMA and/or JWST are crucial to confirm whether it is associated with a protocluster at similar redshifts.</jats:p>

Palabras clave: Space and Planetary Science; Astronomy and Astrophysics.

Pp. 155

High-resolution Near-infrared Spectroscopy of a Flare around the Ultracool Dwarf vB 10

Shubham KanodiaORCID; Lawrence W. RamseyORCID; Marissa ManeyORCID; Suvrath MahadevanORCID; Caleb I. CañasORCID; Joe P. NinanORCID; Andrew MonsonORCID; Adam F. KowalskiORCID; Maximos C. Goumas; Gudmundur StefanssonORCID; Chad F. BenderORCID; William D. CochranORCID; Scott A. DiddamsORCID; Connor FredrickORCID; Samuel HalversonORCID; Fred HeartyORCID; Steven JanowieckiORCID; Andrew J. MetcalfORCID; Stephen C. Odewahn; Paul RobertsonORCID; Arpita RoyORCID; Christian SchwabORCID; Ryan C. TerrienORCID

<jats:title>Abstract</jats:title> <jats:p>We present high-resolution observations of a flaring event in the M8 dwarf vB 10 using the near-infrared Habitable-zone Planet Finder (HPF) spectrograph on the Hobby-Eberly Telescope. The high stability of HPF enables us to accurately subtract a vB 10 quiescent spectrum from the flare spectrum to isolate the flare contributions and study the changes in the relative energy of the Ca <jats:sc>ii</jats:sc> infrared triplet, several Paschen lines, the He <jats:italic>λ</jats:italic>10830 triplet lines, and to select iron and magnesium lines in HPF's bandpass. Our analysis reveals the presence of a red asymmetry in the He <jats:italic>λ</jats:italic>10830 triplet, which is similar to signatures of coronal rain in the Sun. Photometry of the flare derived from an acquisition camera before spectroscopic observations and the ability to extract spectra from up-the-ramp observations with the HPF infrared detector enable us to perform time-series analysis of part of the flare and provide coarse constraints on the energy and frequency of such flares. We compare this flare with historical observations of flares around vB 10 and other ultracool M dwarfs and attempt to place limits on flare-induced atmospheric mass loss for hypothetical planets around vB 10.</jats:p>

Palabras clave: Space and Planetary Science; Astronomy and Astrophysics.

Pp. 155