Sazuna/UAT_keywords huggingface dataset:
Stellar Contamination Correction Using Back-to-back Transits of TRAPPIST-1 b and c. Stellar surface heterogeneities, such as spots and faculae, often contaminate exoplanet transit spectra, hindering precise atmospheric characterization. We demonstrate a novel, epoch-based, model-independent method to mitigate stellar contamination, applicable to multiplanet systems with at least one airless planet. We apply this method using quasi-simultaneous transits of TRAPPIST-1 b and TRAPPIST-1 c observed on 2024 July 9, with JWST/NIRSpec PRISM. These two planets, with nearly identical radii and impact parameters, are likely to either be bare rocks or possess thin, low-pressure atmospheres, making them ideal candidates for this technique, as variations in their transit spectra would be primarily attributed to stellar activity. Our observations reveal their transit spectra exhibit consistent features, indicating similar levels of stellar contamination. We use TRAPPIST-1 b to correct the transit spectrum of TRAPPIST-1 c, achieving a 2.5 × reduction in stellar contamination at shorter wavelengths. At longer wavelengths, lower signal-to-noise ratio prevents clear detection of contamination or full assessment of mitigation. Still, out-of-transit analysis reveals variations across the spectrum, suggesting contamination extends into the longer wavelengths. Based on the success of the correction at shorter wavelengths, we argue that contamination is also reduced at longer wavelengths to a similar extent. This shifts the challenge of detecting atmospheric features to a predominantly white noise issue, which can be addressed by stacking observations. This method enables epoch-specific stellar contamination corrections, allowing coaddition of planetary spectra for reliable searches of secondary atmospheres with signals of 60–250 ppm. Additionally, we identify small-scale cold (∼2000 K) and warm (∼2600 K) regions almost uniformly distributed on TRAPPIST-1, with overall covering fractions varying by ∼0.1% per hour.

Keywords: Starspots, Fundamental parameters of stars, Transmission spectroscopy, Stellar atmospheres, Planet hosting stars, Exoplanet atmospheres
First Mid-infrared Detection and Modeling of a Flare from Sgr A*. The time-variable emission from the accretion flow of Sgr A*, the supermassive black hole at the Galactic center, has long been examined in the radio-to-millimeter, near-infrared (NIR), and X-ray regimes of the electromagnetic spectrum. However, until now, sensitivity and angular resolution have been insufficient in the crucial mid-infrared (MIR) regime. The MIRI instrument on JWST has changed that, and we report the first MIR detection of Sgr A*. The detection was during a flare that lasted about 40 minutes, a duration similar to NIR and X-ray flares, and the source's spectral index steepened as the flare ended. The steepening suggests that synchrotron cooling is an important process for Sgr A*'s variability and implies magnetic fields strengths ~ 40–70 G in the emission zone. Observations at 1.3 mm with the Submillimeter Array revealed a counterpart flare lagging the MIR flare by ≈10 minutes. The observations can be self-consistently explained as synchrotron radiation from a single population of gradually cooling high-energy electrons accelerated through (a combination of) magnetic reconnection and/or magnetized turbulence.

Keywords: Supermassive black holes, Galactic center
A Repeating Fast Radio Burst Source in the Outskirts of a Quiescent Galaxy. We report the discovery of the repeating fast radio burst (FRB) source FRB 20240209A using the Canadian Hydrogen Intensity Mapping Experiment (CHIME)/FRB telescope. We detected 22 bursts from this repeater between 2024 February and July, 6 of which were also recorded at the Outrigger station k'niʔatn k'l⌣stk'masqt (KKO). The multiple very long baseline interferometry localizations using the 66 km long CHIME─KKO baseline, each with a different baseline vector orientation due to the repeater's high decl. of ∼86°, enabled the combined localization region to be constrained to 1″ × 2″. We present deep Gemini optical observations that, combined with the FRB localization, enabled a robust association of FRB 20240209A to the outskirts of a luminous galaxy (P(O∣x) = 0.99; L ≍ 5.3 × 1010 L⊙). FRB 20240209A has a projected physical offset of 40 ± 5 kpc from the center of its host galaxy, making it the FRB with the largest host galaxy offset to date. When normalized by the host galaxy size, the offset of FRB 20240209A (5.1 Reff) is comparable to that of FRB 20200120E (5.7 Reff), the only FRB source known to originate in a globular cluster. We consider several explanations for the large offset, including a progenitor that was kicked from the host galaxy or in situ formation in a low-luminosity satellite galaxy of the putative host, but find the most plausible scenario to be a globular cluster origin. This, coupled with the quiescent, elliptical nature of the host as demonstrated in our companion Letter, provides strong evidence for a delayed formation channel for the progenitor of the FRB source.

Keywords: Radio bursts, Galaxies, Very long baseline interferometry, Radio transient sources
The Massive and Quiescent Elliptical Host Galaxy of the Repeating Fast Radio Burst FRB 20240209A. The discovery and localization of FRB 20240209A by the Canadian Hydrogen Intensity Mapping Fast Radio Burst (CHIME/FRB) experiment marks the first repeating FRB localized with the CHIME/FRB Outriggers and adds to the small sample of repeating FRBs with associated host galaxies. Here we present Keck and Gemini observations of the host that reveal a redshift z = 0.1384 ± 0.0004. We perform stellar population modeling to jointly fit the optical through mid-IR data of the host and infer a median stellar mass log(M*/M⊙) = 11.35 ± 0.01 and a mass-weighted stellar population age ~11 Gyr, corresponding to the most massive and oldest FRB host discovered to date. Coupled with a star formation rate &lt;0.31 M⊙ yr−1, the specific star formation rate &lt;10−11.9 yr−1 classifies the host as quiescent. Through surface brightness profile modeling, we determine an elliptical galaxy morphology, marking the host as the first confirmed elliptical FRB host. The discovery of a quiescent early-type host galaxy within a transient class predominantly characterized by late-type star-forming hosts is reminiscent of short-duration gamma-ray bursts, Type Ia supernovae, and ultraluminous X-ray sources. Based on these shared host demographics, coupled with a large offset as demonstrated in our companion Letter, we conclude that preferred sources for FRB 20240209A include magnetars formed through merging binary neutron stars/white dwarfs or the accretion-induced collapse of a white dwarf, or a luminous X-ray binary. Together with FRB 20200120E localized to a globular cluster in M81, our findings provide strong evidence that some fraction of FRBs may arise from a process distinct from the core collapse of massive stars.

Keywords: Elliptical galaxies, Transient sources, Radio transient sources
Formation of Super-Earths and Mini-Neptunes from Rings of Planetesimals. The solar system's planetary architecture has been proposed to be consistent with the terrestrial and giant planets forming from material rings at ∼1 au and ∼5 au, respectively. Here, we show that super-Earths and mini-Neptunes may share a similar formation pathway. In our simulations conducted with a disk α-viscosity of 4 × 10‑3, super-Earths accrete from rings of rocky material in the inner disk, growing predominantly via planetesimal accretion. Mini-Neptunes primarily originate from rings located beyond the water snowline, forming via pebble accretion. Our simulations broadly match the period-ratio distribution, the intrasystem size uniformity, and the planet multiplicity distribution of exoplanets. The radius valley constrains the typical total mass available for rocky planet formation to be less than 3–6 M⊕. Our results predict that planets at ∼1 au in systems with close-in super-Earths and mini-Neptunes are predominantly water-rich. Though relatively uncommon, at ∼1% level, such systems might also host rocky Earth-sized planets in the habitable zone that underwent late giant impacts, akin to the Moon-forming event.

Keywords: Exoplanets, Exoplanet atmospheres, Super Earths, Planetesimals, Planetary migration, Mini Neptunes, Exoplanet formation, Planet formation
Dual Jet Interaction, Magnetically Arrested Flows, and Flares in Accreting Binary Black Holes. Supermassive binary black holes in galactic centers are potential multimessenger sources in gravitational waves and electromagnetic radiation. To find such objects, isolating unique electromagnetic signatures of their accretion flow is key. With the aid of three-dimensional general-relativistic magnetohydrodynamic simulations that utilize an approximate, semianalytic, superimposed spacetime metric, we identify two such signatures for merging binaries. Both involve magnetic reconnection and are analogous to plasma processes observed in the solar corona. The first, like colliding flux tubes that can cause solar flares, involves colliding jets that form an extended reconnection layer, dissipating magnetic energy and causing the two jets to merge. The second, akin to coronal mass ejection events, involves the accretion of magnetic field lines onto both black holes; these magnetic fields then twist, inflate, and form a trailing current sheet, ultimately reconnecting and driving a hot outflow. We provide estimates for the associated electromagnetic emission for both processes, showing that they likely accelerate electrons to high energies and are promising candidates for continuous, stochastic, and/or quasi-periodic higher-energy electromagnetic emission. We also show that the accretion flows around each black hole can display features associated with the magnetically arrested state. However, simulations with black hole spins misaligned with the orbital plane and simulations with larger Bondi radii saturate at lower values of horizon-penetrating magnetic flux than standard magnetically arrested disks, leading to weaker, intermittent jets owing to feedback from the weak jets or equatorial flux tubes ejected by reconnecting field lines near the horizon.

Keywords: Accretion, Supermassive black holes, High energy astrophysics, Active galactic nuclei, General relativity, Magnetohydrodynamical simulations
GRB 241107A: A Giant Flare from a Close-by Extragalactic Magnetar?. We report the results on the short gamma-ray burst GRB 241107A, obtained with the IBIS instrument on board the INTEGRAL satellite. The burst had a duration of about 0.2 s, a fluence of 8 × 10‑7 erg cm‑2 in the 20 keV–10 MeV range, and a hard spectrum, characterized by a peak energy of 680 keV. The position of GRB 241107A has been precisely determined because it fell inside the imaging field of view of the IBIS coded mask instrument. The presence of the nearby galaxy PGC 86046 in the 3' radius error region suggests that GRB 241107A might be a giant flare from a magnetar rather than a canonical short gamma-ray burst. For the 4.1 Mpc distance of PGC 86046, the isotropic energy of 1.6 × 1045 erg is in agreement with this hypothesis, which is also supported by the time-resolved spectral properties similar to those of the few other extragalactic magnetars giant flares detected so far.

Keywords: Magnetars, Gamma-ray bursts
Unusual Space Weathering on a CE-5 Metal Grain Indicates Deceptive Surface Signatures of M-type Asteroids. M-type asteroids are historically thought to be exposed metallic cores of differentiated planets with a composition dominated by pure iron and nickel. However, recent spectral and radar observations reveal an insufficient number of M-type asteroids in the main belt. Here, we report unusual space weathering characteristics associated with a natural metal grain found in Chang'e 5 lunar soil. Microcraters, impact glass, iron whiskers, and unique vesicular rims on the surface of this grain help to explain the unusual properties of some potential M-type asteroids, including low thermal inertia and density. Our findings indicate that space weathering processes, including micrometeorite bombardment and solar wind irradiation, conceal the real surface signatures of M-type asteroids. Furthermore, the presence of He and Ge alloy on the metal grain suggests that M-type asteroids are not only a large metallic Fe and Ni reservoir but also a potential source of noble gases and precious metals.

Keywords: Lunar composition, Asteroids, The Moon, Lunar surface, Asteroid surfaces
Constraining Binary Mergers in Active Galactic Nuclei Disks Using the Nonobservation of Lensed Gravitational Waves. The dense and dynamic environments within active galactic nuclei (AGN) accretion disks may serve as prolific birthplaces for binary black holes (BBHs) and one possible origin for some of the BBHs detected by gravitational-wave (GW) observatories. We show that a considerable fraction of the BBH in AGN disks will be strongly lensed by the central supermassive black hole (SMBH). Thus, the nonobservation of lensed GW signals can be used to constrain the fraction of BBH binaries residing in AGN disks. The nondetection of lensing with current   detections will be sufficient to start placing constraints on the fraction of BBHs living within accretion disks near the SMBH. In the next-generation detectors era, with   BBH observations and no lensed events, we will be able to rule out most migration traps as dominant birthplaces of BBH mergers; moreover, we will be able to constrain the minimum size of the accretion disk. On the other hand, should AGNs constitute a major formation channel, lensed events from AGNs will become prominent in the future.

Keywords: Gravitational wave astronomy, Strong gravitational lensing, Active galactic nuclei, Gravitational waves
Long-term Radio Monitoring of the Fast X-Ray Transient EP 240315a: Evidence for a Relativistic Jet. The recent launch of Einstein Probe (EP) in early 2024 opened up a new window onto the transient X-ray sky, allowing for real-time discovery and follow-up of fast X-ray transients (FXRTs). Multiwavelength observations of FXRTs and their counterparts are key to characterize the properties of their outflows and, ultimately, identify their progenitors. Here, we report our long-term radio monitoring of EP 240315A, a long-lasting (∼1000 s) high-redshift (z = 4.9) FXRT associated to gamma-ray burst (GRB) 240315C. Our campaign, carried out with the Australian Telescope Compact Array, followed the transient's evolution at two different frequencies (5.5 and 9 GHz) for 3 months. In the radio light curves we identify an unusual steep rise at 9 GHz, possibly due to a refreshed reverse shock, and a late-time rapid decay of the radio flux, which we interpret as a jet break due to the outflow collimation. We find that the multiwavelength counterpart of EP 240315A is well described by a model of relativistic jet seen close to its axis, with jet half-opening angle θ  j  ≈ 3° and beaming-corrected total energy E ≃ 4 × 1051 erg, typical of GRBs. These results show that a substantial fraction of FXRTs may be associated to standard GRBs and that sensitive X-ray monitors, such as EP and the proposed HiZ-GUNDAM and Theseus missions, can successfully pinpoint their relativistic outflows up to high redshifts.

Keywords: Gamma-ray bursts
Timescales of Solar System Formation Based on Al–Ti Isotope Correlation by Supernova Ejecta. The radioactive decay of short-lived 26Al–26Mg has been used to estimate the timescales over which 26Al was produced in a nearby star and the protosolar disk evolved. The chronology commonly assumes that 26Al was uniformly distributed in the protosolar disk; however, this assumption is challenged by the discordance between the timescales defined by the Al–Mg and assumption-free Pb–Pb chronometers. We find that the 26Al heterogeneity is correlated with the nucleosynthetic stable Ti isotope variation, which can be ascribed to the nonuniform distribution of ejecta from a core-collapse supernova in the disk. We use the Al–Ti isotope correlation to calibrate variable 26Al abundances in Al–Mg dating of early solar system processes. The calibrated Al–Mg chronometer indicates a ≥1 Myr gap between parent body accretion ages of carbonaceous and noncarbonaceous chondrites. We further use the Al–Ti isotope correlation to constrain the timing and location of the supernova explosion, indicating that the explosion occurred at 20–30 pc from the protosolar cloud, 0.94 +0.25/–0.21 Myr before the formation of the oldest solar system solids. Our results imply that the Sun was born in association with a ∼25 Mʘ star.

Keywords: Solar system formation, Core-collapse supernovae, Isotope shifts, Protoplanetary disks, Meteorites, Stellar nucleosynthesis
Characterization of a Peculiar Einstein Probe Transient EP240408a: An Exotic Gamma-Ray Burst or an Abnormal Jetted Tidal Disruption Event?. We present the results of our multiwavelength (X-ray to radio) follow-up campaign of the Einstein Probe transient EP240408a. The initial 10 s trigger displayed bright soft X-ray (0.5─4 keV) radiation with peak luminosity LX ≳ 1049 (1050) erg s−1 for an assumed redshift z ≳ 0.5 (2.0). The Neil Gehrels Swift Observatory and Neutron star Interior Composition ExploreR discovered a fading X-ray counterpart lasting for ∼5 days (observer frame), which showed a long-lived (∼4 days) plateau-like emission (t−0.5) before a sharp power-law decline (t−7). The plateau emission was in excess of LX ≳ 1046 (1047) erg s−1 at z ≳ 0.5 (2.0). Deep optical and radio observations resulted in nondetections of the transient. Our observations with Gemini South revealed a faint potential host galaxy (r ≍ 24 AB mag) near the edge of the X-ray localization. The faint candidate host, and lack of other potential hosts (r ≳ 26 AB mag; J ≳ 23 AB mag), imply a higher redshift origin (z ≳ 0.5), which produces extreme X-ray properties that are inconsistent with many known extragalactic transient classes. In particular, the lack of a bright gamma-ray counterpart, with the isotropic-equivalent energy (10─10,000 keV) constrained by GECam and Konus-Wind to Eγ,iso ≲ 4 × 1050 (6 × 1051) erg at z ≍ 0.5 (2.0), conflicts with known gamma-ray bursts of similar X-ray luminosities. We therefore favor a jetted tidal disruption event as the progenitor of EP240408a at z ≳ 1.0, possibly caused by the disruption of a white dwarf by an intermediate-mass black hole. The alternative is that EP240408a may represent a new, previously unknown class of transient.

Keywords: X-ray astronomy, Gamma-ray bursts, Black holes, Relativistic jets, X-ray transient sources
Hot Jupiters Are Asynchronous Rotators. Hot Jupiters are typically assumed to be synchronously rotating, from tidal locking. Their thermally driven atmospheric winds experience Lorentz drag on the planetary magnetic field anchored at depth. We find that the magnetic torque does not integrate to zero over the entire atmosphere. The resulting angular momentum feedback on the bulk interior can thus drive the planet away from synchronous rotation. Using a toy tidal–ohmic model and atmospheric general circulation model outputs for HD189733b, HD209458b, and Kepler7b, we establish that off-synchronous rotation can be substantial at tidal–ohmic equilibrium for sufficiently hot and/or magnetized hot Jupiters. Potential consequences of asynchronous rotation for hot Jupiter phenomenology motivate follow-up work on the tidal–ohmic scenario with approaches that go beyond our toy model.

Keywords: Tidal disruption, Magnetic fields, Hot Jupiters
MUSEQuBES: Unveiling Cosmic Web Filaments at z ≍ 3.6 through Dual Absorption and Emission Line Analysis. According to modern cosmological models, galaxies are embedded within cosmic filaments, which supply a continuous flow of pristine gas, fueling star formation and driving their evolution. However, due to their low density, the direct detection of diffuse gas in cosmic filaments remains elusive. Here, we report the discovery of an extremely metal-poor ([X/H] ≍ −3.7), low-density (  −4, corresponding to an overdensity of ≍5) partial Lyman limit system (pLLS) at z ≍ 3.577 along the quasar sightline Q1317─0507, probing cosmic filaments. Additionally, two other low-metallicity ([X/H] ≲ −2) absorption systems are detected at similar redshifts, one of which is also a pLLS. Very Large Telescope (VLT) MUSE observations reveal a significant overdensity of Lyα emitters (LAEs) associated with these absorbers. The spatial distribution of the LAEs strongly suggests the presence of an underlying filamentary structure. This is further supported by the detection of a large Lyα-emitting nebula with a surface brightness of  , with a maximum projected linear size of ≍260 pkpc extending along the LAEs. This is the first detection of giant Lyα emission tracing cosmic filaments, linked to normal galaxies and likely powered by in situ recombination.

Keywords: Lyman-alpha galaxies, Galaxy evolution, Quasar absorption line spectroscopy
Two Channels of Metal-rich Compact Stellar System Formation: Starbursts under High Ram Pressure versus Tidal Stripping. Most galaxies follow a well-defined scaling relation between metallicity and stellar mass; however, some outliers at the low-mass end of the observed galaxy population exhibit unusually high metallicity for their mass. Understanding how these objects get to be so metal-rich is vital for understanding the role of feedback in galaxy formation. Using the TNG50 simulation, we explore the origins of this phenomenon. We identify 227 metal-rich, compact stellar systems (CSSs) that deviate significantly from this scaling relation. These CSSs are satellites located in the vicinity of massive host galaxies, with stellar masses ranging from 108 to 1010 M⊙ (including six systems that are close analogs of the M31–M32 system). Contrary to the previously assumed scenario that such objects are predominantly products of tidal stripping, we find that more often ram pressure plays a major role in their formation. Indeed, 76% (173) of these CSSs are formed through a burst of star formation occurring around the time of the first pericentric passage, typically at redshifts z ≲ 1, aided by strong ram pressure and tidal forces. The high ram pressure, resulting from the CSSs' rapid motion near the host halo center, facilitates metal enrichment, producing high-metallicity CSSs by confining the metal-rich gas from bursty star formation, which leads to distinct stellar populations characterized by enhanced metallicity and high α-abundance. The other 24% (54) of metal-rich CSSs are generated through the tidal stripping of massive progenitors. Our results further indicate that M32 is more likely to have formed through intense star formation events rather than through gradual tidal stripping.

Keywords: Stellar populations, Galaxy formation, Compact dwarf galaxies, Compact galaxies
Uncorrelated Estimations of H<SUB>0</SUB> Redshift Evolution from DESI Baryon Acoustic Oscillation Observations. The Dark Energy Spectroscopic Instrument (DESI) collaboration recently released the first-year data of baryon acoustic oscillations (BAOs). Based on the five different tracers, the cosmological constraint shows a hint of deviation from the standard ΛCDM model. In this Letter, we combine the DESI BAOs with other cosmic probes to constrain the evolution of the Hubble constant as a function of redshift in the flat ΛCDM model. The nonparametric method is used to estimate the value of the Hubble constant at different redshift bins. The correlations among different bins are removed by diagonalizing the covariance matrix. The joint data sample demonstrates a decreasing trend of the Hubble constant with a significance of 6.4σ, which can naturally resolve the Hubble tension. To avoid statistical effects caused by the binning methods, we tested three other different binning methods and also found a decreasing trend. It may be due to dynamical dark energy or modified gravity.

Keywords: Hubble constant, Type Ia supernovae, Baryon acoustic oscillations, Cosmological parameters