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Direct Imaging Explorations for Companions around Mid–Late M Stars from the Subaru/IRD Strategic Program
No full textThe Subaru telescope is currently performing a strategic program (SSP) using the high-precision near-infrared (NIR) spectrometer IRD to search for exoplanets around nearby mid/late M dwarfs via radial velocity (RV) monitoring. As part of the observing strategy for the exoplanet survey, signatures of massive companions such as RV trends are used to reduce the priority of those stars. However, this RV information remains useful for studying the stellar multiplicity of nearby M dwarfs. To search for companions around such "deprioritized" M dwarfs, we observed 14 IRD-SSP targets using Keck/NIRC2 with pyramid wave-front sensing at NIR wavelengths, leading to high sensitivity to substellar-mass companions within a few arcseconds. We detected two new companions (LSPM J1002+1459 B and LSPM J2204+1505 B) and two new candidates that are likely companions (LSPM J0825+6902 B and LSPM J1645+0444 B), as well as one known companion. Including two known companions resolved by the IRD fiber injection module camera, we detected seven (four new) companions at projected separations between ∼2 and 20 au in total. A comparison of the colors with the spectral library suggests that LSPM J2204+1505 B and LSPM J0825+6902 B are located at the boundary between late M and early L spectral types. Our deep high-contrast imaging for targets where no bright companions were resolved did not reveal any additional companion candidates. The NIRC2 detection limits could constrain potential substellar-mass companions (∼10–75 M_(Jup)) at 10 au or further. The failure with Keck/NIRC2 around the IRD-SSP stars having significant RV trends makes these objects promising targets for further RV monitoring or deeper imaging with the James Webb Space Telescope to search for smaller-mass companions below the NIRC2 detection limits
Study of Rotor-Jetpack-Wind Aerodynamic Interaction for Mid-Air Helicopter Delivery on Mars
No full textMid-Air Helicopter Delivery (MAHD) is a new Entry, Descent and Landing (EDL) architecture for enabling future Martian helicopter-only missions (e.g., Mars Science Helicopter (MSH)), that offer much greater in situ mobility compared to traditional rover missions at lower cost. This EDL concept utilizes a delivery jetpack to slow down the rotorcraft free fall after separation from the parachuting backshell, thus avoiding unfavorable rotorcraft descent aerodynamics, and provides suitable aerodynamic conditions for helicopter take-off in mid air. While Martian rotorcraft operation has been successfully demonstrated by the Ingenuity system, the mid-air helicopter take-off from a self-propelled jetpack platform has been identified as one of the critical aspects of this EDL strategy. This paper presents the development of an experimental sub-scale test-bench to assess the aerodynamic interactions between the MSH, a jetpack analogue system, and the wind to evaluate the technical feasibility of MAHD. Aerodynamic measurements and various qualitative and quantitative flow visualizations were performed in a (1 atm / 1 g) environment and compared to computational fluid dynamics (CFD) simulation for validation. We also demonstrate in-flight capabilities of wind sensing as well as active trimming of the rotorcraft under relative crosswinds using an integrated force-torque sensor to be placed between rotorcraft and jetpack
A Monolithic 3D Magnetic Sensor in 65nm CMOS with <10μTrms Noise and 14.8μW Power
No full textMagnetic sensors have become increasingly ubiquitous as they constitute an integral part of several fast-growing sectors such as automotive, navigation, robotics, medical devices and consumer electronics. Due to their compatibility with the standard CMOS process, Hall magnetic sensors are widely used. However, one of the key challenges of CMOS-based Hall sensors is their relatively low sensitivity, which is inevitable given the low Hall coefficient of Si. For better sensitivity, Hall sensors are biased at higher current levels which hinders their widescale use in low-power bioelectronics and other power-constrained applications. Another challenge is the difficulty in implementing high-sensitivity vertical Hall elements in planar CMOS processes for 3D sensing. This is often overcome by using ferromagnetic materials that require additional and expensive steps during fabrication, thus increasing the cost
Early Results from GLASS-JWST. XVIII. A First Morphological Atlas of the 1 < z < 5 Universe in the Rest-frame Optical
No full textWe present a rest-frame optical morphological analysis of galaxies observed with the NIRCam imager on the James Webb Space Telescope (JWST) as part of the GLASS-JWST Early Release Science program. We select 388 sources at redshifts 0.8 1.5, revealed by rest-frame optical imaging. We detect 123 clear disks (58 at z > 1.5) of which 76 have bulges. No evolution of bulge fraction with redshift is evident: 61% at z 10^(9.5) M_⊙ (N = 41) but only 52% at M 1.5, with smoother (i.e., lower Gini) and more symmetrical light distributions
CHEX-MATE: Pressure profiles of six galaxy clusters as seen by SPT and Planck
No full textContext. Pressure profiles are sensitive probes of the thermodynamic conditions and the internal structure of galaxy clusters. The intra-cluster gas resides in hydrostatic equilibrium within the dark-matter gravitational potential. However, this equilibrium may be perturbed; for example, as a consequence of thermal energy losses, feedback, and non-thermal pressure supports. Accurate measures of the gas pressure over cosmic time are crucial for constraining cluster evolution as well as the contributions from astrophysical processes.
Aims. In this work we present a novel algorithm for deriving the pressure profiles of galaxy clusters from the Sunyaev-Zeldovich (SZ) signal measured on a combination of Planck and South Pole Telescope (SPT) observations. The synergy of the two instruments makes it possible to track the profiles on a wide range of spatial scales. We exploited the sensitivity of the Planck High-Frequency Instrument to the larger scales in order to observe the faint peripheries, and took advantage of the higher spatial resolution of SPT to solve the innermost regions.
Methods. We developed a two-step pipeline to take advantage of the specifications of each instrument. We first performed a component separation on the two data sets separately in order to remove the background (CMB) and foreground (Galactic emission) contaminants. We then jointly fitted a parametric pressure profile model on a combination of Planck and SPT data.
Results. We validated our technique on a sample of six CHEX-MATE clusters detected by SPT. We compare the results of the SZ analysis with profiles derived from X-ray observations with XMM-Newton. We find excellent agreement between these two independent probes of the gas pressure structure
A superluminous supernova lightened by collisions with pulsational pair-instability shells
No full textSuperluminous supernovae are among the most energetic stellar explosions in the Universe, but their energy sources remain an open question. Here we present long-term observations of one of the closest examples of the hydrogen-poor superluminous supernovae subclass SLSNe-I, supernova SN 2017egm, revealing the most complicated known luminosity evolution of SLSNe-I. Three distinct post-peak bumps were recorded in its light curve collected at about 100–350 days after maximum brightness, challenging current popular power models such as magnetar, fallback accretion, and interaction between ejecta and a circumstellar shell. However, the complex light curve can be well modelled by successive interactions with multiple circumstellar shells with a total mass of about 6.8–7.7 M⊙. In this scenario, large energy deposition from interaction-induced reverse shocks results in ionization of neutral oxygen in the supernova ejecta and hence a much lower nebular-phase line ratio of [O I] λ6,300/([Ca II] + [O II]) λ7,300 (~0.2) compared with that derived for other superluminous and normal stripped-envelope supernovae. The pre-existing multiple shells indicate that the progenitor of SN 2017egm experienced pulsational mass ejections triggered by pair instability within 2 years before explosion, in robust agreement with theoretical predictions for a pre-pulsation helium-core mass of 48–51 M⊙
Flexible biomimetic block copolymer composite for temperature and long-wave infrared sensing
No full textBiological compounds often provide clues to advance material designs. Replicating their molecular structure and functional motifs in artificial materials offers a blueprint for unprecedented functionalities. Here, we report a flexible biomimetic thermal sensing (BTS) polymer that is designed to emulate the ion transport dynamics of a plant cell wall component, pectin. Using a simple yet versatile synthetic procedure, we engineer the physicochemical properties of the polymer by inserting elastic fragments in a block copolymer architecture, making it flexible and stretchable. The thermal response of our flexible polymer outperforms current state-of-the-art temperature sensing materials, including vanadium oxide, by up to two orders of magnitude. Thermal sensors fabricated from these composites exhibit a sensitivity that exceeds 10 mK and operate stably between 15° and 55°C, even under repeated mechanical deformations. We demonstrate the use of our flexible BTS polymer in two-dimensional arrays for spatiotemporal temperature mapping and broadband infrared photodetection
Extreme Weather Risk in a Changing Climate: Enhancing prediction and protecting communities
No full textExtreme weather has devastating impacts on the American people, our communities, and our economy. All of us have seen the damage wrought by catastrophic wildfires in western states, by floods, and tropical cyclones on the Gulf Coast, and by recent severe tornados in southern and eastern states. Extreme weather also reduces property values, raises the costs of insurance, and poses national and global economic risks from supply chain disruptions and forced migrations. Today, climate change is changing the patterns and risks of extreme weather, including the frequency and severity of many hazards.
The challenge of hurricanes and other severe storms, floods, and wildfires is gaining significant attention and the annual cost of climate and weather disasters has been rising. The National Oceanic and Atmospheric Administration (NOAA) has catalogued over 2 trillion per year from climate change at the end of the century, along with additional expenditures of 128 billion on selected insurance and disaster relief programs. In addition, there are deeper costs from loss of life, negative health impacts, and the destruction of communities. The Census Bureau recently estimated that in 2022 alone, 3.4 million Americans were displaced from their homes by extreme weather disasters. Moreover, lower-income households are often those at greatest risk from floods, storms, and wildfires. These households have fewer resources to take actions that will offset a rising risk of extreme weather.
This PCAST report investigates how recent scientific and technical advances could be used to provide more accurate and actionable information to guide decision-making and policy at all levels. PCAST recommends federal actions to better quantify and disseminate current and future risks of extreme weather, including risks of human and financial losses caused by flood, fire, storms, and drought. PCAST also recommends actions to bolster the emerging private ecosystem providing climate risk information. Finally, PCAST recommends the development of a national adaptation plan to assist communities in preparing for and adapting to changing risks from extreme weather events.
This report builds on the October 2021 White House report, A Roadmap to Build a Climate-Resilient Economy, outlining a multi-agency plan to implement Executive Order 14030 on climate-related financial risk. That plan addresses both the rising physical risks from extreme weather, and transition risks in moving toward a low-carbon economy. PCAST’s recommendations focus on how climate science and computing can provide significantly better information about the physical risks from extreme weather to empower households, communities, and companies and enable smart policy
The Direct-method Oxygen Abundance of Typical Dwarf Galaxies at Cosmic High Noon
No full textWe present a Keck/MOSFIRE rest-optical composite spectrum of 16 typical gravitationally lensed star-forming dwarf galaxies at 1.7 ≲ z ≲ 2.6 (z_(mean) = 2.30), all chosen independent of emission-line strength. These galaxies have a median stellar mass of log(M_*/M_⊙)_(med) = 8.29^(+0.51)_(-0.43) and a median star formation rate of SFR^(med)_(Hα) = 2.25^(+2.15)_(-1.26) M_⊙ yr⁻¹. We measure the faint electron-temperature-sensitive [O III] λ4363 emission line at 2.5σ (4.1σ) significance when considering a bootstrapped (statistical-only) uncertainty spectrum. This yields a direct-method oxygen abundance of
12 + log(O/H)_(direct) = 7.88^(+0.25)_(-0.22) (0.15^(+0.12)_(-0.06) Z_⊙). We investigate the applicability at high z of locally calibrated oxygen-based strong-line metallicity relations, finding that the local reference calibrations of Bian et al. best reproduce (≲0.12 dex) our composite metallicity at fixed strong-line ratio. At fixed M_*, our composite is well represented by the z ∼ 2.3 direct-method stellar mass—gas-phase metallicity relation (MZR) of Sanders et al. When comparing to predicted MZRs from the IllustrisTNG and FIRE simulations, having recalculated our stellar masses with more realistic nonparametric star formation histories
(log(M_*/M_⊙)_(med) = 8.92^(+0.31)_(-0.22), we find excellent agreement with the FIRE MZR. Our composite is consistent with no metallicity evolution, at fixed M_* and SFR, of the locally defined fundamental metallicity relation. We measure the doublet ratio [O II] λ3729/[O II] λ3726 = 1.56 ± 0.32 (1.51 ± 0.12) and a corresponding electron density of nₑ = 1⁺²¹⁵₋₀ cm⁻³ (nₑ = 1⁺⁷⁴₋₀ cm⁻³) when considering the bootstrapped (statistical-only) error spectrum. This result suggests that lower-mass galaxies have lower densities than higher-mass galaxies at z ∼ 2
Lower Bound for the T Count Via Unitary Stabilizer Nullity
No full textWe introduce magic measures to quantify the nonstabilizerness of multiqubit quantum gates and establish lower bounds on the T count for fault-tolerant quantum computation. First, we introduce the stabilizer nullity of multiqubit unitary, which is based on the subgroup of the quotient Pauli group associated with the unitary. This unitary stabilizer nullity extends the state-stabilizer nullity by Beverland et al. [Quantum Sci. Technol. 5, 035009 (2020)] to a dynamic version. In particular, we show this nonstabilizerness measure has desirable properties, such as subadditivity under composition and additivity under tensor product. Second, we prove that a given unitary’s stabilizer nullity is a lower bound for the T count, utilizing the above properties in gate synthesis. Third, we compare the state and the unitary stabilizer nullity, proving that the lower bounds for the T count obtained by the unitary stabilizer nullity are never less than the state-stabilizer nullity. Moreover, we show an explicit n-qubit unitary family of unitary stabilizer nullity 2n, which implies that its T count is at least 2n. This gives an example where the bounds derived by the unitary stabilizer nullity strictly outperform the state-stabilizer nullity by a factor of 2. We finally showcase the advantages of unitary stabilizer nullity in estimating the T count of quantum gates with interests