HiZ-GUNDAM is a candidate for a Japan Aerospace Exploration Agency satellite mission expected to launch in the 2030s, aiming to detect high-redshift gamma-ray bursts (GRBs) and explore the early universe. The wide-field X-ray monitor EAGLE, onboard the HiZ-GUNDAM satellite and responsible for GRB detection and localization, employs lobster-eye-type micro-pore optics (MPOs) and a pnCCD as the focal-plane detector to focus soft X-rays in the 0.4 to 4.0 keV range. We established an alignment strategy for a modular lobster-eye MPO system, and the required alignment accuracy was derived through Monte Carlo simulations that reproduce the point spread function and localization performance. The optical characteristics of individual MPO segments were then evaluated to select and arrange four segments for a breadboard-level alignment demonstration. Subsequently, alignment tuning was performed by adjusting the angular positions of the MPO segments with actuators under X-ray irradiation in a vacuum environment, followed by an evaluation of the resulting direction-determination accuracy. The resulting angular response measurements show that the estimated incident angles derived from the focal positions achieve systematic uncertainties of less than 3 arcmin over more than 95% of the field of view. This level of performance satisfies the localization requirement for the EAGLE instrument when considering systematic errors intrinsic to the MPO-based detection system. These results demonstrate the feasibility of precise MPO alignment in a segmented lobster-eye optics system and provide practical feedback for the design, alignment strategy, and mechanical tolerance definition of future engineering and flight models of the EAGLE X-ray optics.

HiZ-GUNDAM is a candidate mission for JAXA's competitive M-class program and aims to revolutionize our understanding of the high-redshift universe and to advance multimessenger astronomy. By combining a highly sensitive wide-field X-ray monitor, a near-infrared telescope, and an autonomous spacecraft slewing capability, the mission will provide a powerful platform for detecting X-ray transients and promptly identifying their near-infrared counterparts. The wide-field X-ray monitor, referred to as the Exploration of Ancient GRBs with Lobster Eye (EAGLE), is the primary scientific instrument designed to search for transients in the soft X-ray band (0.4 to 4 keV). EAGLE consists of a lobster-eye-type micro-pore optics (MPO) system and a pnCCD focal-plane sensor. In the baseline design, each MPO has an aperture size of 40 mm & times;40 mm and a radius of curvature of similar to 600 mm and is manufactured by Exosens/Photonis Co., Ltd. An EAGLE X-ray module comprises a 3 & times;3 array of MPOs, providing a field of view of 10.4 deg & times;10.4 deg. The current system configuration adopts 16 X-ray modules, covering a total of similar to 0.53 sr. Each EAGLE X-ray module employs a pnCCD focal-plane pixel sensor with a photon-sensitive area of 55 mm & times;55 mm and a pixel size of approximately 107 mu m in the baseline flight configuration, developed by PNSensor GmbH. The pnCCD is operated with dedicated drive-and-readout electronics developed for EAGLE. The instrument design requires passive cooling of the pnCCD module to below -40 degrees C, and a corresponding thermal design has been established to meet this requirement. In addition, onboard transient detection methods are proposed to suppress background events and efficiently extract X-ray photons from transient sources. We present the design concept, current development status, and future prospects of EAGLE, including the MPO system, the pnCCD with dedicated electronics, the thermal design, and the onboard transient detection methods.

HiZ-GUNDAM is a candidate for JAXA's competitive medium-class mission program, with its concept approved by ISAS/JAXA in 2018. This proposed satellite aims to play a leading role in time-domain astronomy in the 2030s by pursuing two primary scientific goals: (1) probing the early universe through the detection of high-redshift gamma-ray bursts (GRBs) and (2) enabling the rapid identification of X-ray and optical-near-infrared counterparts of multimessenger sources. To achieve these objectives, HiZ-GUNDAM is equipped with two key instruments. A wide-field X-ray monitor, EAGLE, utilizes a micropore optics array and a focal plane imaging sensor to observe transients across similar to 0.5 sr in the 0.4 to 4 keV energy range. To follow up on this observation, an optical-near-infrared telescope, MONSTER, features a 30 cm aperture and conducts simultaneous five-band photometry over the 0.5 to 2.5 mu m wavelength range. It employs a K & ouml;sters-type prism for multi-band photometry to follow up on transients detected by the EAGLE. A sun-synchronous dawn-dusk orbit has been selected to ensure thermal stability for the MONSTER. We present a comprehensive overview of the HiZ-GUNDAM mission concept. The mission is expected to make a significant contribution to our understanding of cosmic evolution through observations of high-redshift GRBs, as well as to the identification of the multiwavelength properties of multimessenger sources by enhancing the observational capabilities for transient searches. The specifications and concepts discussed herein are subject to refinement as the mission progresses.

We report the Australian Telescope Compact Array and Nobeyama 45 m telescope detection of a remarkably bright (S1.1mm = 44 mJy) submillimeter galaxy MM J154506.4-344318 in emission lines at 48.5 and 97.0 GHz, respectively. We also identify part of an emission line at approximate to 218.3 GHz using the Atacama Large Millimeter/submillimeter Array (ALMA). Together with photometric redshift estimates and the ratio between the line and infrared luminosities, we conclude that the emission lines are most likely to be the J = 2-1, 4-3, and 9-8 transitions of 12CO at redshift z = 3.753 +/- 0.001. ALMA 1.3 mm continuum imaging reveals an arc and a spot separated by an angular distance of 1.'' 6 , indicative of a strongly lensed dusty star-forming galaxy with respective molecular and dust masses of logMmol/M circle dot approximate to 11.5 and logMdust/M circle dot approximate to 9.4 after being corrected for approximate to 6.6x gravitational magnification. The inferred dust-to-gas mass ratio is found to be high (approximate to 0.0083) among coeval dusty star-forming galaxies, implying the presence of a massive, chemically enriched reservoir of cool interstellar medium at z approximate to 4, or 1.6 Gyr after the Big Bang.

The future satellite HiZ-GUNDAM will be equipped with a wide-field X-ray monitor using Lobster Eye Optics (LEO), covering a wide field of view of ∼ 0.6 steradian in the 0.4–4 keV energy range. LEO, an X-ray optics system, achieves both a wide field of view and high sensitivity by focusing soft X-rays through spherically curved SiO 2 plates with heavy-metal-coated micropores. This design significantly enhances sensitivity by reducing cosmic X-ray background events, outperforming conventional non-focusing detectors. As a prototype, we developed a breadboard frame capable of holding nine LEO segments, aligning them on a single spherical surface to achieve a wide field of view. Given LEO's brittleness, there are concerns about potential damage from launch vehicle vibrations. In addition, the system must be structurally robust, avoiding strong resonances at expected vibration frequencies. To address these concerns, we performed vibration tests simulating launch conditions to assess the structural integrity of the combined LEO and breadboard frame. X-ray performance, particularly angular resolution, was evaluated before and after the tests. The results demonstrate that the system is structurally robust and capable of maintaining imaging performance after simulated rocket launch vibrations.

Carbon-rich Wolf–Rayet (WR) binaries are a prominent source of carbonaceous dust that contribute to the dust budget of galaxies. The “textbook” example of an episodic dust-producing WR binary, WR 140 (HD 193793), provides us with an ideal laboratory for investigating the dust physics and kinematics in an extreme environment. This study is among the first to utilize two separate JWST observations, from Cycle 1 ERS (2022 July) and Cycle 2 (2023 September), to measure WR 140’s dust kinematics and confirm its morphology. To measure the proper motions and projected velocities of the dust shells, we performed a novel point-spread function (PSF) subtraction to reduce the effects of the bright diffraction spikes and carefully aligned the Cycle 2 to the Cycle 1 images. At 7.7 μ m, through the bright feature common to 16 dust shells (C1), we find an average dust shell proper motion of 390 ± 29 mas yr ^−1 , which equates to a projected velocity of 2714 ± 188 km s ^−1 at a distance of 1.64 kpc. Our measured speeds are constant across all visible shells and consistent with previously reported dust expansion velocities. Our observations not only prove that these dusty shells are astrophysical (i.e., not associated with any PSF artifact) and originate from WR 140, but also confirm the “clumpy” morphology of the dust shells, in which identifiable substructures within certain shells persist for at least 14 months from one cycle to the next. These results support the hypothesis that clumping in the wind collision region is required for dust production in WR binaries.

We have analyzed the aromatic infrared bands (AIBs) in the 6–11.2 μ m range around the Wolf–Rayet (WR) binary WR 140 ( d = 1.64 kpc) obtained with the James Webb Space Telescope Mid-Infrared Instrument Medium-Resolution Spectrometer (MRS). In WR 140’s circumstellar environment, we have detected AIBs at 6 and 7.7 μ m, which are attributed to C–C stretching modes. These features have been detected in the innermost dust shell (Shell 1; ∼2100 au from WR 140), the subsequent dust shell (Shell 2; ∼5200 au), and “off-shell” regions in the MRS coverage. The 11.2 μ m AIB, which is associated with the C–H out-of-plane bending mode, has been tentatively detected in Shell 2 and the surrounding off-shell positions around Shell 2. We compared the AIB features from WR 140 to spectra of established AIB feature classes A, B, C, and D. The detected features around WR 140 do not agree with these established classes. The peak wavelengths and full width half maxima of the 6 and 7.7 μ m features are, however, consistent with those of R Coronae Borealis stars with hydrogen-poor conditions. We discuss a possible structure of carbonaceous compounds and environments where they form around WR 140. It is proposed that hydrogen-poor carbonaceous compounds initially originate from the carbon-rich WR wind, and the hydrogen-rich stellar wind from the companion O star may provide hydrogen to these carbonaceous compounds.

We are promoting a design of high-dispersion immersion grating for the high-resolution mid-infrared spectrometer (HRS, resolving power R equivalent to lambda/Delta lambda approximate to 30,000 at lambda = 10 to 18 mu m), which will be mounted onboard the next-generation infrared space telescope, Galaxy Reionization EXplorer and PLanetary Universe Spectrometer (GREX-PLUS). Compared with conventional diffraction gratings, immersion gratings reduce optical path length and the collimated mean diameter by a factor of 1/n, where n is the refractive index of the immersion material. Achieving such high spectral dispersion requires the use of highly transparent optical materials characterized by low absorption coefficients (alpha <= 0.01 cm(-1)) at the instrument's operating temperature (T approximate to 20 K), to reduce instrumental background radiation. Cadmium Zinc Telluride (CdZnTe) has been identified as a promising candidate material, not only due to its low absorption coefficient but also due to its machinability. Recent transmittance measurements conducted by Maeshima et al. at cryogenic temperatures indicated that high-resistivity CdZnTe exhibits superior optical properties suitable for immersion gratings, in contrast to low-resistivity CdZnTe. To precisely determine the absorption coefficient of high-resistivity CdZnTe, we developed a cryogenic common-path double-beam transmittance measurement system with an original design. Utilizing a filament lamp placed within the vacuum chamber, combined with three bandpass filters, we achieved transmittance measurement precision better than 0.06% across a continuous temperature range from room temperature to 5.7 K. Employing recently published refractive index data, we derived absorption coefficients (alpha) at T approximate to 20 K of 0.00049, 0.00333, and 0.00251 cm(-1) for wavelengths of 10.6, 15.1, and 19.0 mu m, respectively. Notably, the absorption coefficient for high-resistivity CdZnTe exhibited minimal temperature dependence and remained consistently below 0.01 cm(-1), satisfying the stringent optical requirements for GREX-PLUS HRS. (c) The Authors. Published by SPIE under a Creative Commons Attribution 4.0 International License. Distribution or reproduction of this work in whole or in part requires full attribution of the original publication, including its DOI.