adsabs/SciX_UAT_keywords huggingface dataset:
Discovery of Merging Twin Quasars at z = 6.05

We report the discovery of two quasars at a redshift of z = 6.05 in the process of merging. They were serendipitously discovered from the deep multiband imaging data collected by the Hyper Suprime-Cam (HSC) Subaru Strategic Program survey. The quasars, HSC J121503.42‑014858.7 (C1) and HSC J121503.55‑014859.3 (C2), both have luminous (>1043 erg s‑1) Lyα emission with a clear broad component (full width at half maximum >1000 km s‑1). The rest-frame ultraviolet (UV) absolute magnitudes are M 1450 = ‑ 23.106 ± 0.017 (C1) and ‑22.662 ± 0.024 (C2). Our crude estimates of the black hole masses provide $\mathrm{log}({M}_{\mathrm{BH}}/{M}_{\odot })=8.1\pm 0.3$ in both sources. The two quasars are separated by 12 kpc in projected proper distance, bridged by a structure in the rest-UV light suggesting that they are undergoing a merger. This pair is one of the most distant merging quasars reported to date, providing crucial insight into galaxy and black hole build-up in the hierarchical structure formation scenario. A companion paper will present the gas and dust properties captured by Atacama Large Millimeter/submillimeter Array observations, which provide additional evidence for and detailed measurements of the merger, and also demonstrate that the two sources are not gravitationally lensed images of a single quasar.

Keywords: double quasars; quasars; reionization; high-redshift galaxies; active galactic nuclei; galaxy mergers; supermassive black holes
Characterizing the Uncertainty in Cluster Magnetic Fields Derived from Rotation Measures

Magnetic fields play vital roles in intracluster media (ICMs), but estimating their strengths and distributions from observations is a major challenge. Faraday rotation measures (RMs) are widely applied to this task, so it is critical to understand inherent uncertainties in RM analysis. In this paper, we seek to characterize those uncertainties given the types of information available today, independent of the specific technique used. We conduct synthetic RM observations through the ICM of a galaxy cluster drawn from a magnetohydrodynamic cosmological simulation in which the magnetic field is known. We analyze the synthetic RM observations using an analytical formalism based on commonly used model assumptions, allowing us to relate model physical variables to outcome uncertainties. Despite the simplicity of some assumptions, and unknown physical parameters, we are able to extract an approximate magnitude of the central magnetic field within an apparently irreducible uncertain factor of ≈3. Principal, largely irreducible, uncertainties come from the unknown depth along the line of sight of embedded polarized sources, the lack of robust coherence lengths from area-constrained polarization sampling, and the unknown scaling between ICM electron density and magnetic field strength. The RM-estimated central magnetic field strengths span more than an order of magnitude including the full range of synthetic experiments.

Keywords: intracluster medium; galaxy clusters; extragalactic magnetic fields; polarimetry
A CHEOPS Search for Massive, Long-period Companions to the Warm Jupiter K2-139 b

K2-139 b is a warm Jupiter with an orbital period of 28.4 days, but only three transits of this system have previously been observed-in the long-cadence mode of K2-limiting the precision with which the orbital period can be determined and future transits predicted. We report photometric observations of four transits of K2-139 b with ESA's CHaracterising ExOPlanet Satellite (CHEOPS), conducted with the goal of measuring the orbital obliquity via spot-crossing events. We jointly fit these CHEOPS data alongside the three previously-published transits from the K2 mission, considerably increasing the precision of the ephemeris of K2-139 b. The transit times for this system can now be predicted for the next decade with a 1σ precision less than 10 minutes, compared to over one hour previously, allowing the efficient scheduling of observations with Ariel. We detect no significant deviation from a linear ephemeris, allowing us to exclude the presence of a massive outer planet orbiting with a period less than 150 days, or a brown dwarf with a period less than one year. We also determine the scaled semimajor axis, the impact parameter, and the stellar limb darkening with improved precision. This is driven by the shorter cadence of the CHEOPS observations compared to that of K2, and validates the subexposure technique used for analyzing long-cadence photometry. Finally, we note that the stellar spot configuration has changed from the epoch of the K2 observations; unlike the K2 transits, we detect no evidence of spot-crossing events in the CHEOPS data.

Keywords: extrasolar gaseous giant planets; exoplanet astronomy; exoplanets
First Detection of the Molecular Cloud Population in the Extended Ultraviolet Disk of M83

We report a CO(J = 3-2) detection of 23 molecular clouds in the extended ultraviolet (XUV) disk of the spiral galaxy M83 with the Atacama Large Millimeter/submillimeter Array. The observed 1 kpc2 region is at about 1.24 times the optical radius (R 25) of the disk, where CO(J = 2-1) was previously not detected. The detection and nondetection, as well as the level of star formation (SF) activity in the region, can be explained consistently if the clouds have the mass distribution common among Galactic clouds, such as Orion A-with star-forming dense clumps embedded in thick layers of bulk molecular gas, but in a low-metallicity regime where their outer layers are CO-deficient and CO-dark. The cloud and clump masses, estimated from CO(3-2), range from 8.2 × 102 to 2.3 × 104 M ⊙ and from 2.7 × 102 to 7.5 × 103 M ⊙, respectively. The most massive clouds appear similar to Orion A in star formation activity as well as in mass, as expected if the cloud mass structure is common. The overall low SF activity in the XUV disk could be due to the relative shortage of gas in the molecular phase. The clouds are distributed like chains up to 600 pc (or longer) in length, suggesting that the trigger of cloud formation is on large scales. The common cloud mass structure also justifies the use of high-J CO transitions to trace the total gas mass of clouds, or galaxies, even in the high-z universe. This study is the first demonstration that CO(3-2) is an efficient tracer of molecular clouds even in low-metallicity environments.

Keywords: interstellar medium; molecular clouds; galaxy evolution; star formation; spiral galaxies
The Carbon-deficient Evolution of TRAPPIST-1c

Transiting planets orbiting M dwarfs provide the best opportunity to study the atmospheres of rocky planets with current facilities. As JWST enters its second year of science operations, an important initial endeavor is to determine whether these rocky planets have atmospheres at all. M dwarfs are thought to pose a major threat to planetary atmospheres due to their high magnetic activity over timescales of several billion years, and might completely strip atmospheres. Several Cycle 1 and 2 General Observers and Guaranteed Time Observations programs are testing this hypothesis, observing a series of rocky planets to determine whether they retained their atmospheres. A key case study is TRAPPIST-1c, which receives almost the same bolometric flux as Venus. We might therefore expect TRAPPIST-1c to possess a thick, CO2-dominated atmosphere. Instead, Zieba et al. show that it has little to no CO2 in its atmosphere. To interpret these results, we run coupled time-dependent simulations of planetary outgassing and atmospheric escape to model the evolution of TRAPPIST-1c's atmosphere. We find that the stellar wind stripping that is expected to occur on TRAPPIST-1c over its lifetime can only remove up to ~16 bar of CO2, less than the modern CO2 inventory of either Earth or Venus. Therefore, we infer that TRAPPIST-1c either formed volatile-poor, as compared to Earth and Venus, or lost a substantial amount of CO2 during an early phase of hydrodynamic hydrogen escape. Finally, we scale our results for the other TRAPPIST-1 planets, finding that the more distant TRAPPIST-1 planets may readily retain atmospheres.

Keywords: exoplanets; exoplanet atmospheres; habitable planets; extrasolar rocky planets
Likely Common Coronal Source of Solar Wind and 3He-enriched Energetic Particles: Uncoupled Transport from the Low Corona to 0.2 au

Parker Solar Probe (PSP) observations of a small dispersive event on 2022 February 27 and 28 indicate scatter-free propagation as the dominant transport mechanism between the low corona and greater than 35 solar radii. The event occurred during unique orbital conditions that prevailed along specific flux tubes that PSP encountered repeatedly between 25 and 35 Rs during outbound orbit 11. This segment of the PSP orbit exhibits almost stationary angular motion relative to the rotating solar surface, such that in the rotating frame, PSP's motion is essentially radial. The time dispersion often observed in impulsive solar energetic particle (SEP) events continues in this case down to velocities including the core solar-wind ion velocities. Especially at the onset of this event, the 3He content is much larger than the usual SEP abundances seen in the energy range from ∼100 keV to several MeV for helium. Later in the event, iron is enhanced. The compositional signatures suggest this to be an example of an acceleration mechanism for generating the seed energetic particles required by shock (or compression) acceleration models in SEP events to account for the enrichment of various species above solar abundances in such events. A preliminary search of similar orbital conditions over the PSP mission has not revealed additional such events, although favorable conditions (isolated impulsive acceleration and well-ordered magnetic field connection with minimal magnetic field fluctuation) that would be required are infrequently realized, given the small fraction of the PSP trajectory that meets these observation conditions.

Keywords: solar energetic particles; solar physics; solar abundances; solar wind; solar activity
HST Strong-lensing Model for the First JWST Galaxy Cluster SMACS J0723.3-7327

On 2022 July 8, NASA shared (https://www.nasa.gov/feature/goddard/2022/nasa-shares-list-of-cosmic-targets-for-webb-telescope-s-first-images) the list of five public showcase targets that have been observed with the new James Webb Space Telescope (JWST) and whose data-at the time of writing-are expected to be released to the public around Tuesday, July 12. One of these targets is the galaxy cluster SMACS J0723.3-7327 (z = 0.39), which acts as a gravitational lens and was recently imaged with the Hubble Space Telescope (HST) in the framework of the Reionization Lensing Cluster Survey (RELICS). To facilitate studies by the community with the upcoming JWST data, we publish here a strong-lensing model for SMACS J0723.3-7327-including mass density and magnification maps. We identify five multiple-image families in the HST imaging. For three of them, system membership and redshift are secured by public spectroscopic data. For the remaining two systems, we rely on robust photometric redshift estimates. We use the Light-Traces-Mass lens modeling method, which complements the parametric models already available in the RELICS repository and elsewhere and thus helps span a representative range of solutions. The new model published here can be accessed on the RELICS website at MAST. It will be interesting to examine which properties of the mass models change and improve, and by how much, when the JWST data are incorporated.

Keywords: strong gravitational lensing; galaxy clusters; high-redshift galaxies; dark matter
Measuring the Virial Factor in SDSS DR5 Quasars with Redshifted Hβ and Fe II Broad Emission Lines

Under the hypothesis of gravitational redshift induced by a central supermassive black hole, and based on line widths and shifts of redward-shifted Hβ and Fe II broad emission lines for a sample of 1973 z < 0.8 Sloan Digital Sky Survey DR5 quasars, we measured the virial factor in determining supermassive black hole masses, usually estimated by the reverberation mapping method or the relevant secondary methods. The virial factor had been believed to be from the geometric effect of the broad-line region. The measured virial factor of Fe II is larger than that of Hβ for 98% of these quasars. The virial factor is very different from object to object and for different emission lines. For most of these quasars, the virial factor of Hβ is larger than these averages that were usually used in determining the masses of black holes. There are three positive correlations among the measured virial factor of Hβ, dimensionless accretion rate, and Fe II/Hβ line ratio. A positive three-dimensional correlation is found among these three quantities, and this correlation indicates that the virial factor is likely dominated by the dimensionless accretion rate and metallicity. A negative correlation is found between the redward shift of Hβ and the scaled size of the broad-line region radius in units of the gravitational radius of the black hole. This negative correlation will be expected naturally if the redward shift of Hβ is mainly from the gravity of the black hole. Radiation pressure from the accretion disk may be a significant contributor to the virial factor.

Keywords: black hole physics; active galactic nuclei; emission line galaxies; quasars; supermassive black holes
Tidally Heated Exomoons around Gas Giants

Thousands of exoplanets have been discovered; however, the detection of exomoons remains elusive. Tidally heated exomoons have been proposed as candidate targets for observation; vigorous tidal dissipation can raise the moon's surface temperature, making direct imaging possible, and cause widespread volcanism that can have a signature in transits. We assess whether the required amounts of tidal dissipation can be attained and how long it can be sustained. In a first step, we look at the thermal state of a super-Io for different orbital configurations. We show that close-in exomoons with moderate $(e\sim {e}_{\mathrm{Io}}$ ) to high ( $e\sim 0.1$ ) orbital eccentricities can feature surface heat fluxes 1-3 orders of magnitude higher than that of Io if heat transfer is dominated by heat piping or the moon has a magma ocean. In a second step, we investigate the longevity of a super-Io. The free eccentricity of an isolated close-in exomoon is quickly dampened due to tides; high orbital eccentricities can be maintained if the moon is in a mean-motion resonance with another moon and the planet is highly dissipative. However, this scenario leads to fast orbital migration. For a Mars-sized exomoon, we find that tides alone can raise the surface temperatures to more than 400 K for 10 million yr, and surface heat fluxes higher than that of Io can be maintained for billions of years. Such tidally active bodies are expected to feature more vigorous volcanic activity than Io. The material outgassed via volcanism might be detected in transits.

Keywords: natural satellites (extrasolar); natural satellites (solar system); galilean satellites; tides; tidal friction; orbital resonances; volcanoes; infrared astronomy; planetary interior
A Gamma-Ray Periodic Modulation in Globular Cluster 47 Tucanae

The globular cluster 47 Tucanae was first detected in gamma rays by the Large Area Telescope (LAT) on board the Fermi Gamma-ray Space Telescope, and the gamma-ray emission has been widely attributed to the millisecond pulsars. In this work, we analyze the Fermi-LAT pass 8 data ranging from 2008 August to 2017 May and report the detection of a modulation with a period of 18.416 ± 0.008 hr at a significance level of ∼4.8σ. This is the first time detecting a significant modulation with a period much longer than that of millisecond pulsars in gamma rays from globular clusters. The periodic modulation signal appears in the Swift Burst Alert Telescope (BAT) data as well. The phase-folded Chandra X-ray light curve of a point source may have provided an additional clue.

Keywords: globular star clusters; gamma-rays; binary pulsars; periodic orbit
The Obliquity of HIP 67522 b: A 17 Myr Old Transiting Hot, Jupiter-sized Planet

HIP 67522 b is a 17 Myr old, close-in (Porb = 6.96 days), Jupiter-sized (R = 10 R⊕) transiting planet orbiting a Sun-like star in the Sco-Cen OB association. We present our measurement of the system's projected orbital obliquity via two spectroscopic transit observations using the CHIRON spectroscopic facility. We present a global model that accounts for large surface brightness features typical of such young stars during spectroscopic transit observations. With a value of $| \lambda | ={5.8}_{-5.7}^{{+2.8}^\circ} $ it is unlikely that this well-aligned system is the result of a high-eccentricity-driven migration history. By being the youngest planet with a known obliquity, HIP 67522 b holds a special place in contributing to our understanding of giant planet formation and evolution. Our analysis shows the feasibility of such measurements for young and very active stars.

Keywords: exoplanet astronomy; exoplanet systems; planetary alignment; planet formation; radial velocity; transit photometry
A Rogue Planet Helps to Populate the Distant Kuiper Belt

The orbital distribution of trans-Neptunian objects (TNOs) in the distant Kuiper Belt (with semimajor axes beyond the 2:1 resonance, roughly a = 50-100 au) provides constraints on the dynamical history of the outer solar system. Recent studies show two striking features of this region: (1) a very large population of objects in distant mean-motion resonances with Neptune, and (2) the existence of a substantial detached population (nonresonant objects largely decoupled from Neptune). Neptune migration models are able to implant some resonant and detached objects during the planet migration era, but many fail to match a variety of aspects of the orbital distribution. In this work, we report simulations carried out using an improved version of the GPU-based code GLISSE, following 100,000 test particles per simulation in parallel while handling their planetary close encounters. We demonstrate for the first time that a 2 Earth-mass rogue planet temporarily present during planet formation can abundantly populate both the distant resonances and the detached populations, surprisingly even without planetary migration. We show how weak encounters with the rogue planet greatly increase the efficiency of filling the resonances, while also dislodging TNOs out of resonance once they reach high perihelia. The rogue's secular gravitational influence simultaneously generates numerous detached objects observed at all semimajor axes. These results suggest that the early presence of additional planet(s) reproduces the observed TNO orbital structure in the distant Kuiper Belt.

Keywords: trans-neptunian objects; kuiper belt; celestial mechanics
Early Planet Formation in Embedded Disks (eDisk). IX. High-resolution ALMA Observations of the Class 0 Protostar R CrA IRS5N and Its Surroundings

We present high-resolution high-sensitivity observations of the Class 0 protostar RCrA IRS5N as part of the Atacama Large Milimeter/submilimeter Array large program Early Planet Formation in Embedded Disks. The 1.3 mm continuum emission reveals a flattened continuum structure around IRS5N, consistent with a protostellar disk in the early phases of evolution. The continuum emission appears smooth and shows no substructures. However, a brightness asymmetry is observed along the minor axis of the disk, suggesting that the disk is optically and geometrically thick. We estimate the disk mass to be between 0.007 and 0.02 M ⊙. Furthermore, molecular emission has been detected from various species, including C18O (2-1), 12CO (2-1), 13CO (2-1), and H2CO (30,3 - 20,2, 32,1 - 22,0, and 32,2 - 22,1). By conducting a position-velocity analysis of the C18O (2-1) emission, we find that the disk of IRS5N exhibits characteristics consistent with Keplerian rotation around a central protostar with a mass of approximately 0.3 M ⊙. Additionally, we observe dust continuum emission from the nearby binary source IRS5a/b. The emission in 12CO toward IRS5a/b seems to emanate from IRS5b and flow into IRS5a, suggesting material transport between their mutual orbits. The lack of a detected outflow and large-scale negatives in 12CO observed toward IRS5N suggests that much of the flux from IRS5N is being resolved out. Using a 1D radiative transfer model, we infer the mass of the envelope surrounding IRS5N to be ~1.2 M ⊙. Due to this substantial surrounding envelope, the central IRS5N protostar is expected to be significantly more massive in the future.

Keywords: protostars; young stellar objects; protoplanetary disks; interstellar medium
Intermediate-mass Stars Become Magnetic White Dwarfs

When a star exhausts its nuclear fuel, it either explodes as a supernova or more quiescently becomes a white dwarf, an object about half the mass of our Sun with a radius of about that of the Earth. About one-fifth of white dwarfs exhibit the presence of magnetic fields, whose origin has long been debated as either the product of previous stages of evolution or of binary interactions. We here report the discovery of two massive and magnetic white-dwarf members of young star clusters in the Gaia second data release (DR2) database, while a third massive and magnetic cluster white dwarf was already reported in a previous paper. These stars are most likely the product of single-star evolution and therefore challenge the merger scenario as the only way to produce magnetic white dwarfs. The progenitor masses of these stars are all above 5 solar masses, and there are only two other cluster white dwarfs whose distances have been unambiguously measured with Gaia and whose progenitors' masses fall in this range. This high incidence of magnetic white dwarfs indicates that intermediate-mass progenitors are more likely to produce magnetic remnants and that a fraction of magnetic white dwarfs forms from intermediate-mass stars.

Keywords: young star clusters; open star clusters; white dwarf stars; da stars; db stars; magnetic stars; magnetic fields; stellar evolution; stellar magnetic fields
The Sloan Digital Sky Survey Reverberation Mapping Project: the XMM-Newton X-Ray Source Catalog and Multiband Counterparts

The XMM-RM project was designed to provide X-ray coverage of the Sloan Digital Sky Survey Reverberation Mapping (SDSS-RM) field. Forty-one XMM-Newton exposures, placed surrounding the Chandra AEGIS field, were taken, covering an area of 6.13 deg2 and reaching a nominal exposure depth of ∼15 ks. We present an X-ray catalog of 3553 sources detected in these data, using a PSF-fitting algorithm and a sample selection threshold that produces a ∼5% fraction of spurious sources. In addition to the PSF-fitting likelihood, we calculate a second source reliability measure based on Poisson theory using source and background counts within an aperture. Using the Poissonian likelihood, we select a subsample with a high purity and find that it has number count profiles similar to previous X-ray surveys. The Bayesian method "NWAY" was employed to identify counterparts of the X-ray sources from the optical Legacy and the IR unWISE catalogs, using a two-dimensional unWISE magnitude-color prior created from optical/IR counterparts of Chandra X-ray sources. A significant number of the optical/IR counterparts correspond to sources with low detection likelihoods, proving the value of retaining the low-likelihood detections in the catalog. A total of 932 of the XMM-RM sources are covered by SDSS spectroscopic observations, where 89% of them are classified as active galactic nuclei, and 71% of these active galactic nuclei are in the SDSS-RM quasar catalog. Among the SDSS-RM quasars, 80% are detectable at the depth of the XMM observations.

Keywords: astronomy data analysis; supermassive black holes; active galactic nuclei; x-ray active galactic nuclei; quasars; x-ray point sources