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We present the discovery of NGC253-SNFC-dw1, a new satellite galaxy in the remote stellar halo of the Sculptor Group spiral, NGC 253. The system was revealed using deep, resolved star photometry obtained as part of the Subaru Near-Field Cosmology Survey that uses the Hyper Suprime-Cam on the Subaru Telescope. Although rather luminous ( M _V = −11.7 ± 0.2) and massive ( M _* ∼ 1.25 × 10 ^7 M _⊙ ), the system is one of the most diffuse satellites yet known, with a half-light radius of R _h = 3.37 ± 0.36 kpc and an average surface brightness of ∼30.1 mag arcmin ^−2 within the R _h . The color–magnitude diagram shows a dominant, old (∼10 Gyr), and metal-poor ([M/H] = −1.5 ± 0.1 dex) stellar population, as well as several candidate thermally pulsing asymptotic giant branch stars. The distribution of red giant branch stars is asymmetrical and displays two elongated tidal extensions pointing toward NGC 253, suggestive of a highly disrupted system being observed at apocenter. NGC253-SNFC-dw1 has a size comparable to that of the puzzling Local Group dwarfs Andromeda XIX and Antlia 2 but is 2 magnitudes brighter. While unambiguous evidence of tidal disruption in these systems has not yet been demonstrated, the morphology of NGC253-SNFC-dw1 clearly shows that this is a natural path to produce such diffuse and extended galaxies. The surprising discovery of this system in a previously well-searched region of the sky emphasizes the importance of surface-brightness limiting depth in satellite searches.

The recent gamma-ray burst (GRB) GRB 211211A provides the earliest (∼5 hr) data of a kilonova (KN) event, displaying bright (∼10 ^42 erg s ^−1 ) and blue early emission. Previously, this KN was explained using simplistic multicomponent fitting methods. Here, in order to understand the physical origin of the KN emission in GRB 211211A, we employ an analytic multizone model for r -process-powered KNe. We find that r -process-powered KN models alone cannot explain the fast temporal evolution and the spectral energy distribution (SED) of the observed emission. Specifically, (i) r -process models require high ejecta mass to match early luminosity, which overpredicts late-time emission, while (ii) red KN models that reproduce late emission underpredict early luminosity. We propose an alternative scenario involving early contributions from the GRB central engine via a late low-power jet, consistent with plateau emission in short GRBs and GeV emission detected by Fermi-LAT at ∼10 ^4 s after GRB 211211A. Such late central engine activity, with an energy budget of ∼a few percent of that of the prompt jet, combined with a single red KN ejecta component, can naturally explain the light curve and SED of the observed emission, with the late-jet–ejecta interaction reproducing the early blue emission and r -process heating reproducing the late red emission. This supports claims that late low-power engine activity after prompt emission may be common. We encourage early follow-up observations of future nearby GRBs and compact binary merger events to reveal more about the central engine of GRBs and r -process events.

We report the first observational evidence for magnetic field amplification in the northeast/southwest (NE/SW) shells of supernova remnant SN 1006, one of the most promising sites of cosmic ray acceleration. In previous studies, the strength of magnetic fields in these shells was estimated to be B _SED ≃ 25 μ G from the spectral energy distribution, where the synchrotron emission from relativistic electrons accounted for radio to X-rays, along with the inverse Compton emission extending from the GeV to TeV energy bands. However, the analysis of broadband radio data, ranging from 1.37 to 100 GHz, indicated that the radio spectrum steepened from α _1 = 0.52 ± 0.02 to α _2 = 1.34 ± 0.21 by Δ α = 0.85 ± 0.21. This is naturally interpreted as a cooling break under a strong magnetic field of B _brk ≥ 2 mG. Moreover, the high-resolution MeerKAT image indicated that the width of the radio NE/SW shells was broader than that of the X-ray shell by a factor of only 3−20, as measured by Chandra. Such narrow radio shells can be naturally explained if the magnetic field responsible for the radio emissions is B _R ≥ 2 mG. Assuming that the magnetic field is locally enhanced by a factor of approximately a = 100 along the NE/SW shells, we argue that the filling factor, which is the volume ratio of such a magnetically enhanced region to that of the entire shell, must be as low as approximately k = 2.5 × 10 ^−5 .

Clusters and their progenitors (protoclusters) at z ∼ 2 − 4, the peak epoch of star formation, are ideal laboratories to study the formation process of both the clusters themselves and their member galaxies. However, a complete census of their member galaxies has been challenging due to observational difficulties. Here we present new JWST/NIRCam observations targeting the distant cluster CLJ1001 at z = 2.51 from the COSMOS-Web program, which, in combination with previous narrowband imaging targeting H α emitters and deep millimeter surveys of CO emitters, provide a complete view of massive galaxy assembly in CLJ1001. In particular, JWST reveals a population of massive, extremely red cluster members in the long-wavelength bands that were invisible in previous Hubble Space Telescope (HST)/F160W imaging (HST-dark members). Based on this highly complete spectroscopic sample of member galaxies, we show that the spatial distribution of galaxies in CLJ1001 exhibits a strong central concentration, with the central galaxy density already resembling that of low- z clusters. Moreover, we reveal a “top-heavy” stellar mass function for the star-forming galaxies (SFGs), with an overabundance of massive SFGs piled up in the cluster core. These features strongly suggest that CLJ1001 is caught in a rapid transition, with many of its massive SFGs likely soon becoming quiescent. In the context of cluster formation, these findings suggest that the earliest clusters form from the inside out and top to bottom, with the massive galaxies in the core assembling first, followed by the less massive ones in the outskirts.

The characteristic of inverted singlet-triplet excited states, in which the lowest singlet excited state (S _1 ) is lower than the lowest triplet state (T _1 ) in energy, was observed in a dialkylamine-substituted pentaazaphenalene derivative, 5AP-N(C12) _2 . The transient photoluminescence measurements showed that the reverse intersystem crossing has virtually zero activation energy, whereas the intersystem crossing is proceeded by a thermal activation process. T _1 was located energetically above S _1 with a negative energy gap between S _1 and T _1 (Δ E _ST ) of −37 meV. Fluorescence and phosphorescence spectra also confirmed the negative Δ E _ST of −46 to −32 meV.

The analysis of samples returned from the C-type asteroid Ryugu has drastically advanced our knowledge of the evolution of early solar system materials. However, no consensus has been obtained on the chronological data, which is important for understanding the evolution of the asteroid Ryugu. Here, the aqueous alteration age of Ryugu particles was determined by the Mn–Cr method using bulk samples, yielding an age of 4.13 + 0.62/−0.55 Myr after the formation of Ca–Al-rich inclusions (CAI). The age corresponds to 4563.17 + 0.60/−0.67 Myr ago. The higher ^55 Mn/ ^52 Cr, ε ^54 Cr, and initial ε ^53 Cr values of the Ryugu samples relative to any carbonaceous chondrite samples implies that its progenitor body formed from the least thermally processed precursors in the outermost region of the protoplanetary disk. Despite accreting at different distances from the Sun, the hydrous asteroids (Ryugu and the parent bodies of CI, CM, CR, and ungrouped C2 meteorites) underwent aqueous alteration during a period of limited duration (3.8 ± 1.8 Myr after CAI). These ages are identical to the crystallization age of the carbonaceous achondirtes NWA 6704/6693 within the error. The ε ^54 Cr and initial ε ^53 Cr values of Ryugu and NWA 6704/6693 are also identical, while they show distinct Δ' ^17 O values. This suggests that the precursors that formed the progenitor bodies of Ryugu and NWA 6703/6693 were formed in close proximity and experienced a similar degree of thermal processing in the protosolar nebula. However, the progenitor body of Ryugu was formed by a higher ice/dust ratio, than NWA6703/6693, in the outer region of the protoplanetary disk.

This study investigates the timing margin required to handle fluctuations and variations in superconductor single-flux-quantum gate-level-pipelined adders; a smaller timing margin would improve the clock frequencies of gate-level-pipelined circuits. To evaluate timing margins, we demonstrated three 4 bit adders with 50-, 75-, and 100 GHz target clock frequencies using a 1.0 μ m process. We estimated that the required timing margin of the adders was 2.1 ps. This indicates that previously reported gate-level-pipelined circuits operating at 30–60 GHz could operate at higher clock frequencies by reducing the timing margins.

To address the issue of the high cost of GaN substrates, a recycling process for GaN substrates using a laser slicing technique was investigated. The channel properties of lateral MOSFETs and the reverse characteristics of vertical PN diodes, which represent the main components of vertical power devices, exhibited no degradation either before and after laser slicing or due to the overall GaN substrate recycling process. This result indicates that the proposed recycling process is an effective method for reducing the cost of GaN substrates and has the potential to encourage the popularization of GaN vertical power devices.

We report the characterization and application of mist-CVD-grown rutile-structured Ge _x Sn _1− _x O _2 ( x = ∼ 0.53) films lattice-matched to isostructural TiO _2 (001) substrates. The grown surface was flat throughout the growth owing to the lattice-matching epitaxy. Additionally, the film was single-crystalline without misoriented domains and TEM-detectable threading dislocations due to the coherent heterointerface. Using the Ge _0.49 Sn _0.51 O _2 film with a carrier density of 7.8 × 10 ^18 cm ^−3 and a mobility of 24 cm ^2 V ^−1 s ^−1 , lateral Schottky barrier diodes were fabricated with Pt anodes and Ti/Au cathodes. The diodes exhibited rectifying properties with a rectification ratio of 8.2 × 10 ^4 at ±5 V, showing the potential of Ge _x Sn _1- _x O _2 as a practical semiconductor.

MOS capacitors fabricated on substrates with doping concentrations as high as 10 ^18 cm ^−3 were characterized at 4.2 K. The highly doped substrate exhibited an intrinsic imaginary component of impedance at 4.2 K. The imaginary component is attributed to the time delay induced by hopping phenomena, leading to a decrease in the gate capacitance. Furthermore, we investigated the time constant associated with dopant ionization under depletion conditions and determined it to be 0.35 μ s. An equivalent circuit model of the highly doped substrate at 4.2 K is also shown.

We demonstrate a method for fast and precise Brillouin frequency shift measurement based on searching for the zero-crossing point of a virtually composed spectrum of Brillouin gain and loss obtained by a dual-frequency probe beam. Simulations and experiments show that searching for the zero-crossing point of a virtually synthesized Brillouin gain spectrum can be easily done without a large error compared with peak search of the Brillouin gain spectrum in the conventional method.

A facile method for chemical doping of conducting polymers is demonstrated with an ionic liquid containing FeCl _4 ^− anions as the oxidizing agents. A drop of the ionic liquid on the film of a typical semicrystalline polymer immediately changed the room temperature conductivity to 500 S cm ^−1 . The highly conductive state originated from both the high doping level and the high crystallinity of the doped film, as confirmed by optical absorption and X-ray diffraction measurements, respectively. Furthermore, the doping level was continuously controlled by the gate voltage of the ionic-liquid-gated transistor structure through an electrochemical dedoping process.

For radiation-hardened CMOS image sensors (CIS), 4H-SiC 64 pixel array CIS were developed, and real time imaging with an operation frequency of 30 Hz was demonstrated. Two types of pixel arrays with a 3-transistor active pixel sensor (3T-APS) and a 4-transistor active pixel sensor (4T-APS) were fabricated with SiC MOSFETs, UV photodiodes and 3-layered Al interconnections. The SiC pixel arrays were combined with peripheral circuits and an optical lens, and SiC 64 pixel CIS with 3T-/4T-APS arrays were developed.

We find a candidate for new permanent-magnet materials with the 1–16 stoichiometry on the basis of first-principles calculations utilizing a materials database. An extremely iron-rich NdFe _16 compound shows exceptionally high saturation magnetization with an adequate magnetocrystalline anisotropy energy and Curie temperature. Although it has an excessive formation energy in its binary composition, introducing interstitial light elements into NdFe _16 successfully decreases the formation energy while maintaining its superior magnetic properties. The density of states explains the alteration of magnetization from incorporating light elements.

1550 nm wavelength photonic-crystal surface-emitting lasers (PCSELs) are attractive for optical communication and eye-safe sensing applications. In this study, we present InP-based PCSELs featuring a double-lattice photonic-crystal structure designed for high-power single-mode operation at a wavelength of 1550 nm. These PCSELs demonstrate output powers exceeding 300 mW under continuous-wave conditions at 25 °C. Additionally, highly stable single-mode oscillation with a side-mode suppression ratio of over 60 dB is verified at temperatures from 15 °C to 60 °C. Measurement and simulation of photonic band structures reveal the impacts of the threshold gain margin and optical coupling coefficient on the single-mode stability.

Free electron mobility ( μ _free ) in 4H-SiC(0001) MOSFETs with gate oxides annealed in NO or POCl _3 was calculated in a wide range of effective normal field ( E _eff ) from 0.02 to 2 MV cm ^−1 , taking account of scattering by fixed charges and trapped electrons. The present calculation indicates that the Hall mobility in the high- E _eff region experimentally obtained for NO-annealed MOSFETs (14 cm ^2 V ^−1 s ^−1 at 1.1 MV cm ^−1 ) is much lower than that for POCl _3 -annealed MOSFETs (41 cm ^2 V ^−1 s ^−1 ) due to severe Coulomb scattering by electrons trapped at a very high density of interface states.

We report on the control of carrier density in r-SnO _2 thin films grown on isostructural r-TiO _2 substrates by doping with Sb aiming for power-electronics applications. The carrier density was tuned within a range of 3 × 10 ^16 –2 × 10 ^19 cm ^−3 . Two types of donors with different activation energies, attributed to Sb at Sn sites and oxygen vacancies, are present in the thin films. Both activation energies decrease as the concentration of Sb increases. A vertical Schottky barrier diode employing a Sb:r-SnO _2 /Nb:r-TiO _2 exhibits a clear rectifying property with a rectification ratio of 10 ^3 at ±1 V.

We analyze the outer regions of M33, beyond 15 kpc in projected distance from its center, using Subaru/Hyper Suprime-Cam multicolor imaging. We identify red giant branch (RGB) stars and red clump (RC) stars using the surface-gravity-sensitive NB515 filter for the RGB sample and a multicolor selection for both samples. We construct the radial surface density profiles of these RGB and RC stars and find that M33 has an extended stellar population with a shallow power-law index of α > −3, depending on the intensity of the contamination. This result represents a flatter profile than the stellar halo that was detected by the previous study focusing on the central region, suggesting that M33 may have a double-structured halo component, i.e., inner/outer halos or a very extended disk. Also, the slope of this extended component is shallower than those typically found for halos in large galaxies, implying intermediate-mass galaxies may have different formation mechanisms (e.g., tidal interaction) from large spirals. We also analyze the radial color profiles of RC/RGB stars and detect a radial gradient, consistent with the presence of an old and/or metal-poor population in the outer region of M33, thereby supporting our proposal that the stellar halo extends beyond 15 kpc. Finally, we estimate that the surface brightness of this extended component is μ _V = 35.72 ± 0.08 mag arcsec ^−2 . If our detected component is the stellar halo, this estimated value is consistent with the detection limit of previous observations.

Among multimessenger observations of the next Galactic core-collapse supernova, Super-Kamiokande (SK) plays a critical role in detecting the emitted supernova neutrinos, determining the direction to the supernova (SN), and notifying the astronomical community of these observations in advance of the optical signal. In 2022, SK has increased the gadolinium dissolved in its water target (SK-Gd) and has achieved a Gd concentration of 0.033%, resulting in enhanced neutron detection capability, which in turn enables more accurate determination of the supernova direction. Accordingly, SK-Gd’s real-time supernova monitoring system has been upgraded. SK_SN Notice, a warning system that works together with this monitoring system, was released on 2021 December 13, and is available through GCN Notices. When the monitoring system detects an SN-like burst of events, SK_SN Notice will automatically distribute an alarm with the reconstructed direction to the supernova candidate within a few minutes. In this paper, we present a systematic study of SK-Gd’s response to a simulated Galactic SN. Assuming a supernova situated at 10 kpc, neutrino fluxes from six supernova models are used to characterize SK-Gd’s pointing accuracy using the same tools as the online monitoring system. The pointing accuracy is found to vary from 3° to 7° depending on the models. However, if the supernova is closer than 10 kpc, SK_SN Notice can issue an alarm with three-degree accuracy, which will benefit follow-up observations by optical telescopes with large fields of view.

We report on discovery of a concentration of massive quiescent galaxies located at z = 4. The concentration is first identified using high-quality photometric redshifts based on deep, multiband data in Subaru/XMM-Newton Deep Field. Follow-up near-infrared spectroscopic observations with MOSFIRE on Keck confirm a massive (∼10 ^11 M _⊙ ) quiescent galaxy at z = 3.99. Our spectral energy distribution analyses reveal that the galaxy experienced an episode of starburst about 500 Myr prior to the observed epoch, followed by rapid quenching. Since its spectrum is sufficiently good to measure the stellar velocity dispersion, we infer its dynamical mass and find that it is consistent with its stellar mass. The galaxy is surrounded by four massive (>10 ^10 M _⊙ ) quiescent galaxies on a ∼1 physical Mpc scale, all of which are consistent with being located at the same redshift based on high-accuracy spectrophotometric redshifts. This is likely a (proto)cluster dominated by quiescent galaxies, the first of the kind reported at such a high redshift as z = 4. Interestingly, it is in a large-scale structure revealed by spectroscopic redshifts from VANDELS. Furthermore, it also exhibits a red sequence, adding further support to the physical concentration of the galaxies. We find no such concentration in the Illustris-TNG300 simulation; it may be that the cluster is such a rare system that the simulation box is not sufficiently large to reproduce it. The total halo mass of the quiescent galaxies is ∼10 ^13 M _⊙ , suggesting that they form a group-sized halo once they collapse together. We discuss the implications of our findings for the quenching physics and conclude with future prospects.

We present the luminosity functions and stellar mass functions of supernova (SN) host galaxies and test if they differ from the functions of normal field galaxies. We utilize homogeneous samples consisting of 273 SNe Ia ( z ≤ 0.3) and 44 core-collapse (CC) SNe ( z ≤ 0.1) from the Sloan Digital Sky Survey II Supernova Survey and the high-signal-to-noise-ratio photometry of galaxies from the Hyper Suprime-Cam Subaru Strategic Program. SN hosts are classified into star-forming and passive galaxy groups based on the spectral energy distribution fitting. We find that the SN host luminosity functions and stellar mass functions deviate from those of normal field galaxies. Star-forming galaxies dominate the low-mass end of the SN Ia host mass function, while passive galaxies dominate the high-mass end. CC SNe are predominantly hosted by star-forming galaxies. In addition, intermediate-mass hosts produce CC SNe with the highest efficiency, while the efficiency of producing SNe Ia monotonically increases as the hosts become more massive. Furthermore, we derive the pseudo mass normalized SN rates (pSNuM) based on the mass functions. We find that the star-forming component of pSNuM _Ia is less sensitive to the changes in stellar mass, in comparison with the total rate. The behavior of pSNuM _CC suggests that the CC rate is proportional to the star-forming rate.

IRAS 00500+6713 is a hypothesized remnant of a Type Iax supernova SN 1181. Multiwavelength observations have revealed its complicated morphology; a dusty infrared ring is sandwiched by the inner and outer X-ray nebulae. We analyze the archival X-ray data taken by XMM-Newton and Chandra X-ray Observatory to constrain the angular radius, mass, and metal abundance of the X-ray nebulae, and construct a theoretical model describing the dynamical evolution of IRAS 00500+6713, including the effects of the interaction between the SN ejecta and the intense wind enriched with carbon-burning ashes from the central white dwarf (WD) J005311. We show that the inner X-ray nebula corresponds to the wind termination shock while the outer X-ray nebula to the shocked interface between the SN ejecta and the interstellar matter. The observed X-ray properties can be explained by our model with an ejecta kinetic energy of E _ej = (0.77–1.1) × 10 ^48 erg, an ejecta mass of M _ej = 0.18–0.53 M _⊙ , if the currently observed wind from WD J005311 started to blow t _w ≳ 810 yr after the explosion, i.e., approximately after 1990 CE. The inferred SN properties are compatible with those of Type Iax SNe and the timing of the wind launch may correspond to the Kelvin–Helmholtz contraction of the oxygen–neon core of WD J005311 that triggered a surface carbon burning. Our analysis supports that IRAS 00500+6713 is the remnant of SN Iax 1181 produced by a double degenerate merger of oxygen–neon and carbon–oxygen WDs, and WD J005311 is the surviving merger product.

We studied the optical variability of 241 BL Lacertae (BL Lacs) and 83 flat-spectrum radio quasars (FSRQs) from the 4LAC catalog using data from the Tomo-e Gozen Northern Sky Transient Survey, with ∼50 epochs per blazar on average. We excluded blazars whose optical variability may be underestimated due to the influence of their host galaxy based on their optical luminosity ( L _O ). FSRQs with γ -ray photon index greater than 2.6 exhibit very low optical variability, and their distribution of standard deviation of repeated photometry is significantly different from that of the other FSRQs (Kolmogorov–Smirnov test p -value equal to 5 × 10 ^−6 ). Among a sample of blazars at any particular cosmological epoch, those with lower γ -ray luminosity ( L _γ ) tend to have lower optical variability, and those FSRQs with a γ -ray photon index greater than 2.6 tend to have low L _γ . We also measured the structure function of optical variability and found that the amplitude of the structure function for FSRQs is higher than previously measured and higher than that of BL Lacs at multiple time lags. Additionally, the amplitude of the structure function of FSRQs with high γ -ray photon index is significantly lower than that of FSRQs with low γ -ray photon index. The structure function of FSRQs of high γ -ray photon index shows a characteristic timescale of more than 10 days, which may be the variability timescale of the accretion disk. In summary, we infer that the optical component of FSRQs with high γ -ray photon index may be dominated by the accretion disk.

We investigate early ( t < 1 day) kilonova from a neutron star merger by deriving atomic opacities for all the elements from La to Ra ( Z = 57–88) ionized to the states V–XI. The opacities at high temperatures for the elements with open f -shells (e.g., lanthanides) are exceptionally high, reaching ${\kappa }_{\exp }\,\sim 3\times {10}^{3}\,{\mathrm{cm}}^{2}\,{{\rm{g}}}^{-1}$ at λ ≤ 1000 Å at T ∼ 70,000 K, whereas the opacities at the same temperature and wavelengths for the elements with open d -, p -, and s -shells reach ${\kappa }_{\exp }\,\sim 1$ , 0.1, and 0.01 cm ^2 g ^−1 , respectively. Using the new opacity data set, we derive early kilonovae for various compositions and density structures expected for neutron star merger ejecta. The bolometric luminosity of the lanthanide-rich ejecta shows distinct signatures and is fainter than that of the lanthanide-free ejecta. Early luminosity is suppressed by the presence of a thin outer layer, agreeing with the results of Kasen et al. and Banerjee et al. The early brightness in the Swift UVOT filters and in the optical g , r , i , and z filters for a source at 100 Mpc are about ∼22–19.5 and ∼21–20 mag, respectively, at t ∼ 0.1 day. Such kilonovae are ideal targets for the upcoming UV satellites, such as ULTRASAT, UVEX, and DORADO, and the upcoming surveys, e.g., the Vera Rubin Observatory. We suggest that the gray opacities that reproduce the bolometric light curves with and without lanthanides are ∼1–10 and ∼0.8 cm ^2 g ^−1 .

We performed linear calculations to determine the Type I planetary migration rate for 3D locally isothermal disks with radial temperature gradients. For 3D disks with radial temperature gradients, the linear wave equation has a divergent term of the third pole, which makes corotation a nonremoval singularity. We suppressed the divergence with the Landau prescription to obtain the wave solutions. Despite the singularity at corotation, we derived a definite torque on the planet because the divergent term amplifies the waves only in the neighborhood of corotation and has little effect on the planetary torque. Consequently, we derived the formulas for the total, Lindblad, and corotation torques for locally isothermal disks. The resulting torque term due to the disk temperature gradient agrees well with the results of previous 3D hydrodynamical simulations for locally isothermal disks. Our linear calculation also provides the 3D horseshoe torque, which is close to the results of previous 3D hydrodynamical simulations.

We present observations and analysis of the starburst PACS-819 at z = 1.45 ( M _* = 10 ^10.7 M _⊙ ), using high-resolution (0.″1; 0.8 kpc) Atacama Large Millimeter/submillimeter Array (ALMA) and multiwavelength JWST images from the COSMOS-Web program. Dissimilar to Hubble Space Telescope (HST) ACS images in the rest-frame UV, the redder NIRCam and MIRI images reveal a smooth central mass concentration and spiral-like features, atypical for such an intense starburst. Through dynamical modeling of the CO ( J = 5–4) emission with ALMA, PACS-819 is rotation dominated and thus consistent with having a disk-like nature. However, kinematic anomalies in CO and asymmetric features in the bluer JWST bands (e.g., F150W) support a more disturbed nature likely due to interactions. The JWST imaging further enables us to map the distribution of stellar mass and dust attenuation, thus clarifying the relationships between different structural components not discernible in the previous HST images. The CO ( J = 5–4) and far-infrared dust continuum emission are cospatial with a heavily obscured starbursting core (

Massive protostars launch accretion-powered, magnetically collimated outflows, which play crucial roles in the dynamics and diagnostics of the star formation process. Here we calculate the shock heating and resulting free–free radio emission in numerical models of outflows of massive star formation within the framework of the Turbulent Core Accretion model. We postprocess 3D magnetohydrodynamic simulation snapshots of a protostellar disk wind interacting with an infalling core envelope, and calculate shock temperatures, ionization fractions, and radio free–free emission. We find heating up to ∼10 ^7 K and near-complete ionization in shocks at the interface between the outflow cavity and infalling envelope. However, line-of-sight averaged ionization fractions peak around ∼10%, in agreement with values reported from observations of massive protostar G35.20-0.74N. By calculating radio-continuum fluxes and spectra, we compare our models with observed samples of massive protostars. We find our fiducial models produce radio luminosities similar to those seen from low- and intermediate-mass protostars that are thought to be powered by shock ionization. Comparing to more massive protostars, we find our model radio luminosities are ∼10–100 times less luminous. We discuss how this apparent discrepancy either reflects aspects of our modeling related to the treatment of cooling of the post-shock gas or a dominant contribution in the observed systems from photoionization. Finally, our models exhibit 10 yr radio flux variability of ∼5%, especially in the inner 1000 au region, comparable to observed levels in some hypercompact H ii regions.

HESS J1641−463 is an unidentified gamma-ray source with a hard TeV gamma-ray spectrum, and thus it has been proposed to be a possible candidate for a cosmic-ray (CR) accelerator up to PeV energies (a PeVatron candidate). The source spatially coincides with the radio supernova remnant G338.5+0.1 but has not yet been fully explored in the X-ray band. We analyzed newly taken NuSTAR data, pointing at HESS J1641−463, with 82 ks effective exposure time. There is no apparent X-ray counterpart of HESS J1641−463, while nearby stellar cluster, Mercer 81, and stray-light X-rays are detected. Combined with the archival Chandra data, partially covering the source, we derived an upper limit of ∼6 × 10 ^−13 erg cm ^−2 s ^−1 in 2–10 keV (∼3 × 10 ^−13 erg cm ^−2 s ^−1 in 10–20 keV). If the gamma-ray emission is originated from the decay of π ^0 mesons produced in interactions between CR protons and ambient materials, secondary electrons in the proton–proton interactions can potentially emit synchrotron photons in the X-ray band, which can be tested by our X-ray observations. Although the obtained X-ray upper limits cannot place a constraint on the primary proton spectrum, it will be possible with a future hard X-ray mission.

Filamentary structures are ubiquitously found in high-mass star-forming clouds. To investigate the relationship between filaments and star formation, we carry out the INFANT (Investigations of Massive Filaments and Sar Formation) survey, a multiscale, multiwavelength survey of massive filamentary clouds with Atacama Large Millimeter/submillimeter Array (ALMA) band 3/band 6 and Very Large Array K band. In this first paper, we present the ALMA band 6 continuum observations toward a sample of eight high-mass star-forming filaments. We covered each target with an approximately rectangular mosaic field of view with two 12 m array configurations, achieving an angular resolution of ∼0.″6 (2700 au at 4.5 kpc) and a continuum rms of ∼0.1 mJy beam ^−1 (∼0.06 M _⊙ in gas mass assuming 15 K). We identify cores using the getsf and astrodendro and find the former is more robust in terms of both identification and measuring flux densities. We identify in total 183 dense cores (15–36 cores in each cloud) and classify their star formation states via outflow and warm gas tracers. The protostellar cores are statistically more massive than the prestellar cores, possibly indicating further accretion onto cores after the formation of protostars. For the high-mass end ( ${M}_{\mathrm{core}}$ > 1.5 M _⊙ ) of the core mass function (CMF) we derive a power-law index of −1.15 ± 0.12 for the whole sample and −1.70 ± 0.25 for the prestellar population. We also find a steepening trend in CMF with cloud evolution (−0.89 ± 0.15 for the young group versus. −1.44 ± 0.25 for the evolved group) and discuss its implications for cluster formation.

H-poor Type I superluminous supernovae (SLSNe I) are characterized by O ii lines around 4000–4500 Å in pre-/near-maximum spectra, the so-called W-shaped O ii lines. As these lines are from relatively high excitation levels, they have been considered a sign of nonthermal processes, which may provide a hint of the power sources of SLSNe I. However, the conditions for these lines to appear have not been well understood. In this work, we systematically calculate synthetic spectra to reproduce the observed spectra of eight SLSNe I, parameterizing departure coefficients from the nebular approximation in the supernova ejecta (expressed as b _neb ). We find that most of the observed spectra can be well reproduced with b _neb ≲ 10, which means that no strong departure is necessary for the formation of the W-shaped O ii lines. We also show that the appearance of the W-shaped O ii lines is sensitive to temperature; only spectra with temperatures in the range of T ∼ 14,000–16,000 K can produce the W-shaped O ii lines without large departures. Based on this, we constrain the nonthermal ionization rate near the photosphere. Our results suggest that spectral features of SLSNe I can give independent constraints on the power source through the nonthermal ionization rates.

To test theoretical models of massive star formation it is important to compare their predictions with observed systems. To this end, we conduct CO molecular line radiative transfer post-processing of 3D magnetohydrodynamic simulations of various stages in the evolutionary sequence of a massive protostellar core, including its infall envelope and disk wind outflow. Synthetic position–position–velocity cubes of various transitions of ^12 CO, ^13 CO, and C ^18 O emission are generated. We also carry out simulated Atacama Large Millimeter/submillimeter Array (ALMA) observations of this emission. We compare the mass, momentum, and kinetic energy estimates obtained from molecular lines to the true values, finding that the mass and momentum estimates can have uncertainties of up to a factor of 4. However, the kinetic energy estimated from molecular lines is more significantly underestimated. Additionally, we compare the mass outflow rate and momentum outflow rate obtained from the synthetic spectra with the true values. Finally, we compare the synthetic spectra with real examples of ALMA-observed protostars and determine the best-fitting protostellar masses and outflow inclination angles. We then calculate the mass outflow rate and momentum outflow rate for these sources, finding that both rates agree with theoretical protostellar evolutionary tracks.

Each run of an integrated assessment models produces a single mitigation pathway consistent with stated objectives (e.g. maximum temperature) and optimizing some objective function (e.g. minimizing total discounted costs of mitigation). Even though models can be run thousands of times, it is unclear how built-in assumptions constrain the final set of pathways. Here we aim at broadly exploring the space of possible mitigation scenarios for a given mitigation target, and at characterizing the sets of pathways that are (near-)optimal, taking uncertainties into account. We produce an extensive set of CO _2 emission pathways that stay below 2 °C of warming using a reduced-form climate-carbon model with a 1000 different physical states. We then identify 18 sets of quasi ‘least-cost’ mitigation pathways, under six assumptions about cost functions and three different cost minimization functions embarking different visions of intergenerational cost distribution. A first key outcome is that the absence or presence of inertia in the cost function plays a pivotal role in the resulting set of least-cost pathways. Second, despite inherent structural differences, we find common pathways across the 18 combinations in 96% of the physical states studied. Interpreting these common pathways as robust economically and in terms of intergenerational distribution, we shed light on some of their characteristics, even though these robust pathways differ for each physical state.

We present the results of a systematic study of the rest-frame optical morphology of quiescent galaxies at z ≥ 3 using the Near-Infrared Camera (NIRCam) on board the James Webb Space Telescope (JWST). Based on a sample selected by UVJ color or NUVUVJ color, we focus on 26 quiescent galaxies with $9.8\lt \mathrm{log}({M}_{\star }/{M}_{\odot })\lt 11.4$ at 2.8 < z _phot < 4.6 with publicly available JWST data. Their sizes are constrained by fitting the Sérsic profile to all available NIRCam images. We see a negative correlation between the observed wavelength and the size and derive their size at the rest frame 0.5 μ m using size measurements in multiple bands. Our quiescent galaxies show a significant correlation between the rest-frame 0.5 μ m size and the stellar mass at z ≥ 3. The analytical fit for them at $\mathrm{log}({M}_{\star }/{M}_{\odot })\gt 10.3$ implies that our size–stellar mass relations are below those at lower redshifts, with the amplitude of ∼0.6 kpc at M _⋆ = 5 × 10 ^10 M _⊙ . This value agrees with the extrapolation of the size evolution of quiescent galaxies at z < 3 in the literature, implying that the size of quiescent galaxies increases monotonically from z ∼ 3–5. Our sample mainly comprises galaxies with bulge-like structures according to their median Sérsic index and axis ratio of n ∼ 3–4 and q ∼ 0.6–0.8, respectively. On the other hand, there is a trend of increasing fraction of galaxies with low Sérsic index at higher redshift, suggesting 3 < z < 5 might be the epoch of onset of morphological transformation with a fraction of very notable disky quenched galaxies.

Element substitutions with magnetic or non-magnetic atoms are known to significantly impact the magnetic structure and related transport properties of magnets. To clarify the change of magnetic structure of B20-type magnets with element doping, we conduct real-space observations of spin textures and their temperature ( T )-magnetic field ( H ) phase diagrams of a helimagnet FeGe with partially substituting Fe and Ge with Co and Si, respectively. The helical period ( λ ) changes dramatically by the element doping: λ increases by 147% to 103 nm in 30% Co-doped FeGe, whereas it decreases by around 70% to 49 nm in 30% Si-doped FeGe, compared to the λ = 70 nm in FeGe. Upon applying the magnetic field normally to (001), (110), and (111) thin plates of both FeSi _0.3 Ge _0.7 and Fe _0.7 Co _0.3 Ge, the hexagonal skyrmion crystal (SkX) state emerges. The magnetic phase diagrams observed through the real-space imaging reveal that (1) the SkX can extend to a larger T-H window by reducing the sample thickness or by cooling the sample under specific magnetic fields from temperatures above the transition temperature ( T _C ); (2) the stability of the SkX phase differs between Si-doped and Co-doped FeGe: the SkX phase is most unstable in the (111) FeSi _0.3 Ge _0.7 , while it remains robust in the (111) Fe _0.7 Co _0.3 Ge. These differences indicate distinct anisotropic behavior in FeGe with magnetic (Co) and non-magnetic-element (Si) dopants.

Molecular lines are powerful diagnostics of the physical and chemical properties of the interstellar medium (ISM). These ISM properties, which affect future star formation, are expected to differ in starburst galaxies from those of more quiescent galaxies. We investigate the ISM properties in the central molecular zone of the nearby starburst galaxy NGC 253 using the ultrawide millimeter spectral scan survey from the Atacama Large Millimeter/submillimeter Array Large Program ALCHEMI. We present an atlas of velocity-integrated images at a 1.″6 resolution of 148 unblended transitions from 44 species, including the first extragalactic detection of HCNH ^+ and the first interferometric images of C _3 H ^+ , NO, and HCS ^+ . We conduct a principal component analysis (PCA) on these images to extract correlated chemical species and to identify key groups of diagnostic transitions. To the best of our knowledge, our data set is currently the largest astronomical set of molecular lines to which PCA has been applied. The PCA can categorize transitions coming from different physical components in NGC 253 such as (i) young starburst tracers characterized by high-excitation transitions of HC _3 N and complex organic molecules versus tracers of on-going star formation (radio recombination lines) and high-excitation transitions of CCH and CN tracing photodissociation regions, (ii) tracers of cloud-collision-induced shocks (low-excitation transitions of CH _3 OH, HNCO, HOCO ^+ , and OCS) versus shocks from star formation-induced outflows (high-excitation transitions of SiO), as well as (iii) outflows showing emission from HOC ^+ , CCH, H _3 O ^+ , CO isotopologues, HCN, HCO ^+ , CS, and CN. Our findings show these intensities vary with galactic dynamics, star formation activities, and stellar feedback.

The presence of water condensation in the lunar polar region has been reported. However, the origin and amount of water remain unknown, and information on the migration mechanism of water is key for understanding the delivery of water to the Earth–Moon system. We herein report the first identification of the migration process observed as localized and condensed plumes of water ice/gas mixtures ejected from the lunar surface to space in the polar region based on spectral data derived by SELENE/Kaguya. We identified water and other volatile absorption in 10,200 spectra at the nonpermanent shadowed region during the nighttime when no illumination reached the lunar surface, while nearly horizontal solar light at these regions could illuminate the sky. Ray-tracing analyses suggested that the majority of the observed volatile signal did not come from the lunar surface but from the sky (space). The majority of the identified plumes were observed at or near the hydrogen distribution reported previously. Volatile materials were repeatedly identified in some locations and most of the plume events did not coincide with the major meteoroid streams. Rather, more signals were identified during the winter season in each pole. The timing, duration, location, and temperature simulations all suggest that impact events cannot be their main origin, but rather the volatile sublimation from the subsurface (∼10 cm depth). Overall, it was revealed that the lunar polar region is active in terms of volatile migration, which is significant for understanding water delivery to the Earth–Moon system.

Follow-up observations of short gamma-ray bursts (sGRBs) have continuously unveiled late extended/plateau emissions, attributed to jet launch due to late engine activity, the nature of which remains enigmatic. Observations of GW170817 have confirmed that sGRBs are linked to neutron star (NS) mergers, and discovered a kilonova (KN) transient. Nevertheless, the origin of the early blue KN in GW170817 remains unclear. Here, we investigate the propagation of late jets in the merger ejecta. By analytically modeling jet dynamics, we determine the properties of the jet-heated cocoon, and estimate its cooling emission. Our results reveal that late jets generate significantly brighter cocoons compared to prompt jets, primarily due to reduced energy loss by adiabatic cooling. Notably, with typical late jets, emission from the cocoon trapped inside the ejecta can reproduce the blue KN emission. We estimate that the forthcoming Einstein Probe mission will detect the early cocoon emission at a rate of $\sim {2.1}_{-1.6}^{+3.2}$ yr ^−1 , and that optical/UV follow-ups in the LIGO-Virgo-KAGRA O5 run will be able to detect $\sim {1.0}_{-0.7}^{+1.5}$ cocoon emission events. As an electromagnetic counterpart, this emission provides an independent tool to probe NS mergers in the Universe, complementing insights from sGRBs and gravitational waves.

We report on the spectroscopic confirmation of a massive quiescent galaxy at z _spec = 4.53 in the COSMOS field. The object was first identified as a galaxy with suppressed star formation at z _phot ∼ 4.65 from the COSMOS2020 catalog. The follow-up spectroscopy with Keck/MOSFIRE in the K band reveals faint [O ii ] emission and the Balmer break, indicative of evolved stellar populations. We fit the spectral energy distribution using photometry and a spectrum to infer physical properties. The obtained stellar mass is high ( M _* ∼ 10 ^10.8 M _⊙ ) and the current star formation rate is more than 1 dex below that of main-sequence galaxies at z = 4.5. Its star formation history suggests that this galaxy experienced rapid quenching from z ∼ 5. The galaxy is among the youngest quiescent galaxies confirmed so far at z _spec > 3 with z _form ∼ 5.2 (200 Myr ago), which is the epoch when 50% of the total stellar mass was formed. A unique aspect of the galaxy is that it is in an extremely dense region; there are four massive star-forming galaxies at 4.4 < z _phot < 4.7 located within 150 physical kpc from the galaxy. Interestingly, three of them have virial radii that strongly overlap with that of the central quiescent galaxy (∼70 kpc), suggesting that the overdensity region is likely the highest-redshift candidate of a dense group with a spectroscopically confirmed quiescent galaxy at the center. The group provides us with a unique opportunity to gain insights into the role of the group environment in quenching at z ∼ 5, which corresponds to the formation epoch of massive elliptical galaxies in the local Universe.

While various methods have been proposed to disentangle the progenitor system for Type Ia supernovae, their origin is still unclear. A circumstellar environment is key to distinguishing between the double-degenerate and single-degenerate (SD) scenarios since a dense wind cavity is expected only in the case of the SD system. We perform spatially resolved X-ray spectroscopy of Tycho’s supernova remnant (SNR) with XMM-Newton and reveal the three-dimensional velocity structure of the expanding shock-heated ejecta measured from Doppler-broadened lines of intermediate-mass elements. Obtained velocity profiles are fairly consistent with those expected from a uniformly expanding ejecta model near the center, whereas we discover a rapid deceleration (∼4000 to ∼1000 km s ^−1 ) near the edge of the remnant in almost every direction. The result strongly supports the presence of a dense wall entirely surrounding the remnant, which is confirmed also by our hydrodynamical simulation. We thus conclude that Tycho’s SNR is likely of SD origin. Our new method will be useful for understanding progenitor systems of Type Ia SNRs in the era of high-angular/energy-resolution X-ray astronomy with microcalorimeters.

GRAPES-3 is a mid-altitude (2200 m) and near-equatorial (11.°4N) air shower array, overlapping in its field of view for cosmic-ray observations with experiments that are located in the Northern and Southern Hemispheres. We analyze a sample of 3.7 × 10 ^9 cosmic-ray events collected by the GRAPES-3 experiment between 2013 January 1 and 2016 December 31 with a median energy of ∼16 TeV for study of small-scale (

We present a spatially resolved excitation analysis for the central molecular zone (CMZ) of the starburst galaxy NGC 253 using the data from the Atacama Large Millimeter/submillimeter Array Comprehensive High-resolution Extragalactic Molecular Inventory, whereby we explore parameters distinguishing NGC 253 from the quiescent Milky Way’s Galactic center (GC). Non-LTE analyses employing a hierarchical Bayesian framework are applied to Band 3–7 transitions from nine molecular species to delineate the position–position–velocity distributions of column density ( ${N}_{{{\rm{H}}}_{2}}$ ), volume density ( ${n}_{{{\rm{H}}}_{2}}$ ), and temperature ( T _kin ) at 27 pc resolution. Two distinct components are detected: a low-density component with $({n}_{{{\rm{H}}}_{2}},{T}_{\mathrm{kin}})\sim ({10}^{3.3}\ {\mathrm{cm}}^{-3},85\ {\rm{K}})$ and a high-density component with $({n}_{{{\rm{H}}}_{2}},{T}_{\mathrm{kin}})\,\sim ({10}^{4.4}\ {\mathrm{cm}}^{-3},110\ {\rm{K}})$ , separated at ${n}_{{{\rm{H}}}_{2}}\sim {10}^{3.8}\ {\mathrm{cm}}^{-3}$ . NGC 253 has ∼10 times the high-density gas mass and ∼3 times the dense-gas mass fraction of the GC. These properties are consistent with their HCN/CO ratio but cannot alone explain the factor of ∼30 difference in their star formation efficiencies (SFEs), contradicting the dense-gas mass to star formation rate scaling law. The ${n}_{{{\rm{H}}}_{2}}$ histogram toward NGC 253 exhibits a shallow declining slope up to ${n}_{{{\rm{H}}}_{2}}\sim {10}^{6}\ {\mathrm{cm}}^{-3}$ , while that of the GC steeply drops in ${n}_{{{\rm{H}}}_{2}}\gtrsim {10}^{4.5}\ {\mathrm{cm}}^{-3}$ and vanishes at 10 ^5 cm ^−3 . Their dense-gas mass fraction ratio becomes consistent with their SFEs when the threshold ${n}_{{{\rm{H}}}_{2}}$ for the dense gas is taken at ∼10 ^4.2−4.6 cm ^−3 . The rich abundance of gas above this density range in the NGC 253 CMZ, or its scarcity in the GC, is likely to be the critical difference characterizing the contrasting star formation in the centers of the two galaxies.

Among Type Ia supernova remnants (SNRs), Tycho’s SNR has been considered as a typical object from the viewpoints of its spectroscopic, morphological, and environmental properties. A recent reanalysis of Chandra data showed that its forward shock is experiencing a substantial deceleration since around 2007, which suggests recent shock interactions with a dense medium as a consequence of a cavity-wall environment inside a molecular cloud. Such a nonuniform environment can be linked back to the nature and activities of its progenitor. In this study, we perform hydrodynamic simulations to characterize Tycho’s cavity-wall environment using the latest multiepoch proper motion measurements of the forward shock. A range of parameters for the environment is explored in the hydrodynamic models to fit with the observational data for each azimuthal region. Our results show that a wind-like cavity with ρ ( r ) ∝ r ^−2 reconciles with the latest data better than a uniform medium with a constant density. In addition, our best-fit model favors an anisotropic wind with an azimuthally varying wind parameter. The overall result indicates a mass-loss rate which is unusually high for the conventional single-degenerate explosion scenario.

We study the astrochemical diagnostics of the isolated massive protostar G28.20-0.05. We analyze data from Atacama Large Millimeter/submillimeter Array 1.3 mm observations with a resolution of 0.″2 (∼1000 au). We detect emission from a wealth of species, including oxygen-bearing (e.g., H _2 CO, CH _3 OH, CH _3 OCH _3 ), sulfur-bearing (SO _2 , H _2 S), and nitrogen-bearing (e.g., HNCO, NH _2 CHO, C _2 H _3 CN, C _2 H _5 CN) molecules. We discuss their spatial distributions, physical conditions, correlation between different species, and possible chemical origins. In the central region near the protostar, we identify three hot molecular cores (HMCs). HMC1 is part of a millimeter continuum ring-like structure, is closest in projection to the protostar, has the highest temperature of ∼300 K, and shows the most line-rich spectra. HMC2 is on the other side of the ring, has a temperature of ∼250 K, and is of intermediate chemical complexity. HMC3 is further away, ∼3000 au in projection, cooler (∼70 K), and is the least line-rich. The three HMCs have similar mass surface densities (∼10 g cm ^−2 ), number densities ( n _H ∼ 10 ^9 cm ^−3 ), and masses of a few solar masses. The total gas mass in the cores and in the region out to 3000 au is ∼25 M _⊙ , which is comparable to that of the central protostar. Based on spatial distributions of peak line intensities as a function of excitation energy, we infer that the HMCs are externally heated by the protostar. We estimate column densities and abundances of the detected species and discuss the implications for hot core astrochemistry.

We report the first search result for the flux of astrophysical electron antineutrinos for energies ${ \mathcal O }(10)\,\mathrm{MeV}$ in the gadolinium-loaded Super-Kamiokande (SK) detector. In 2020 June, gadolinium was introduced to the ultrapure water of the SK detector in order to detect neutrons more efficiently. In this new experimental phase, SK-Gd, we can search for electron antineutrinos via inverse beta decay with efficient background rejection thanks to the high efficiency of the neutron tagging technique. In this paper, we report the result for the initial stage of SK-Gd, during 2020 August 26, and 2022 June 1 with a 22.5 × 552 kton · day exposure at 0.01% Gd mass concentration. No significant excess over the expected background in the observed events is found for the neutrino energies below 31.3 MeV. Thus, the flux upper limits are placed at the 90% confidence level. The limits and sensitivities are already comparable with the previous SK result with pure water (22.5 × 2970 kton · day) owing to the enhanced neutron tagging. Operation with Gd increased to 0.03% started in 2022 June.