adsabs/SciX_UAT_keywords huggingface dataset:
Hot Jupiters Have Giant Companions: Evidence for Coplanar High-eccentricity Migration

This study considers the characteristics of planetary systems with giant planets based on a population-level analysis of the California Legacy Survey planet catalog. We identified three characteristics common to hot Jupiters (HJs). First, while not all HJs have a detected outer giant planet companion ( $M\sin i=0.3\mbox{--}30\,{M}_{\mathrm{Jup}}$ ), such companions are ubiquitous when survey completeness corrections are applied for orbital periods out to 40,000 days. Giant-harboring systems without an HJ also host at least one outer giant planet companion per system. Second, the mass distributions of HJs and other giant planets are indistinguishable. However, within a planetary system that includes an HJ, the outer giant planet companions are at least 3× more massive than the inner HJs. Third, the eccentricity distribution of the outer companions in HJ systems (with an average model eccentricity of <e> = 0.34 ± 0.05) is different from the corresponding outer planets in planetary systems without HJs (<e> = 0.19 ± 0.02). We conclude that the existence of two gas giants, where the outermost planet has an eccentricity ≥0.2 and is 3× more massive, are key factors in the production of an HJ. Our simple model based on these factors predicts that ~10% of warm and cold Jupiter systems will by chance meet these assembly criteria, which is consistent with our measurement of a 16% ± 6% relative occurrence of HJ systems to all giant-harboring systems. We find that these three features favor coplanar high-eccentricity migration as the dominant mechanism for HJ formation.

Keywords: exoplanet formation; exoplanet migration; exoplanets; hot jupiters
Electromagnetic Counterparts of Binary-neutron-star Mergers Leading to a Strongly Magnetized Long-lived Remnant Neutron Star

We explore the electromagnetic counterparts that will associate with binary-neutron-star mergers for the case that remnant massive neutron stars survive for ≳0.5 s after the merger. For this study, we employ the outflow profiles obtained by long-term general-relativistic neutrino-radiation magnetohydrodynamics simulations with a mean-field dynamo effect. We show that a synchrotron afterglow with high luminosity can be associated with the merger event if the magnetic fields of the remnant neutron stars are significantly amplified by the dynamo effect. We also perform a radiative transfer calculation for kilonovae and find that, for the highly amplified magnetic field cases, the kilonovae can be bright in the early epoch (t ≤ 0.5 d), while it shows the optical emission which rapidly declines in a few days and the very bright near-infrared emission which lasts for ~10 days. All these features have not been found in GW170817, indicating that the merger remnant neutron star formed in GW170817 might have collapsed to a black hole within several hundreds milliseconds or magnetic-field amplification might be a minor effect.

Keywords: gravitational wave astronomy; neutron stars; radiative transfer simulations
X-Ray Obscuration around Supermassive Black Holes in Active Galaxies

We investigate obscuration of Active Galactic Nuclei (AGNs), identified as Supermassive Black Holes (BH) in luminous galaxies. In this model, winds of plasma particles launched from the accretion disk are photoionized by hard X-ray continua from the AGN's corona, resulting in obscuration in the X-ray band. Many X-ray spectroscopic observations suggest a majority of AGN are obscured by an intervening gas along our line of sight. Through photoionization calculations for selected wind solutions, we simulate the observed AGN obscuration distribution. We discuss the plausibility of the model by comparing our theoretical obscuration distribution to X-ray data by producing a library of synthetic absorption spectra of X-ray continua. Using our model's obscuration findings, we show how the obscuration distribution is dependent on the model parameters.

Keywords: x-ray active galactic nuclei; radiative magnetohydrodynamics; high energy astrophysics; black hole physics; broad-absorption line quasar
The CO-to-H2 Conversion Factor in the Barred Spiral Galaxy M83

We analyze the CO-to-H2 conversion factor (α CO) in the nearby barred spiral galaxy M83. We present new H I observations from the VLA and single-dish GBT in the disk of the galaxy, and combine them with maps of CO(1-0) integrated intensity and dust surface density from the literature. α CO and the gas-to-dust ratio (δ GDR) are simultaneously derived in annuli of 2 kpc width from R = 1–7 kpc. We find that α CO and δ GDR both increase radially, by a factor of ∼2–3 from the center to the outskirts of the disk. The luminosity-weighted averages over the disk are α CO = 3.14 (2.06, 4.96) and δ GDR = 137 (111, 182) at the 68% (1σ) confidence level. These are consistent with the α CO and δ GDR values measured in the Milky Way. In addition to possible variations of α CO due to the radial metallicity gradient, we test the possibility of variations in α CO due to changes in the underlying cloud populations, as a function of galactic radius. Using a truncated power-law molecular cloud CO luminosity function and an empirical power-law relation for cloud mass and luminosity, we show that the changes in the underlying cloud population may account for a factor of ∼1.5–2.0 radial change in α CO.

Keywords: interstellar medium; gas-to-dust ratio; galactic and extragalactic astronomy; molecular gas; interstellar dust; co line emission
Extremely Red Galaxies at z = 5–9 with MIRI and NIRSpec: Dusty Galaxies or Obscured Active Galactic Nuclei?

We study a new population of extremely red objects (EROs) recently discovered by the James Webb Space Telescope (JWST) based on their NIRCam colors F277W ‑ F444W > 1.5 mag. We find 37 EROs in the Cosmic Evolution Early Release Science Survey (CEERS) field with F444W < 28 mag and photometric redshifts between 5 < z < 7, with median $z={6.9}_{-1.6}^{+1.0}$ . Surprisingly, despite their red long-wavelength colors, these EROs have blue short-wavelength colors (F150W ‑ F200W ∼ 0 mag) indicative of bimodal spectral energy distributions (SEDs) with a red, steep slope in the rest-frame optical, and a blue, flat slope in the rest-frame UV. Moreover, all these EROs are unresolved, point-like sources in all NIRCam bands. We analyze the SEDs of eight of them with MIRI and NIRSpec observations using stellar population models and active galactic nucleus (AGN) templates. We find that dusty galaxies or obscured AGNs provide similarly good SED fits but different stellar properties: massive and dusty, $\mathrm{log}{M}_{\star }/{M}_{\odot }$ ∼ 10 and A V ≳ 3 mag, or low mass and obscured, $\mathrm{log}{M}_{\star }/{M}_{\odot }$ ∼ 7.5 and A V ∼ 0 mag, hosting an obscured quasi-stellar object (QSO). SED modeling does not favor either scenario, but their unresolved sizes are more suggestive of AGNs. If any EROs are confirmed to have $\mathrm{log}{M}_{\star }/{M}_{\odot }$ ≳ 10.5, it would increase the pre-JWST number density at z > 7 by up to a factor ∼60. Similarly, if they are QSOs with luminosities in the L bol > 1045–46 erg s‑1 range, their number would exceed that of bright blue QSOs by more than three orders of magnitude. Additional photometry at mid-infrared wavelengths will reveal the true nature of the red continuum emission in these EROs and will place this puzzling population in the right context of galaxy evolution.

Keywords: galaxy formation; galaxy evolution; high-redshift galaxies; stellar populations; james webb space telescope; galaxy photometry
Solar Orbiter and SDO Observations, and a Bifrost Magnetohydrodynamic Simulation of Small-scale Coronal Jets

We report high-resolution, high-cadence observations of five small-scale coronal jets in an on-disk quiet Sun region observed with Solar Orbiter's EUI/HRIEUV in 174 Å. We combine the HRIEUV images with the EUV images of SDO/AIA and investigate the magnetic setting of the jets using coaligned line-of-sight magnetograms from SDO/HMI. The HRIEUV jets are miniature versions of typical coronal jets as they show narrow collimated spires with a base brightening. Three out of five jets result from a detectable minifilament eruption following flux cancelation at the neutral line under the minifilament, analogous to coronal jets. To better understand the physics of jets, we also analyze five small-scale jets from a high-resolution Bifrost MHD simulation in synthetic Fe IX/Fe X emissions. The jets in the simulation reside above neutral lines and four out of five jets are triggered by magnetic flux cancelation. The temperature maps show evidence of cool gas in the same four jets. Our simulation also shows the signatures of opposite Doppler shifts (of the order of ±10 s of km s-1) in the jet spire, which is evidence of untwisting motion of the magnetic field in the jet spire. The average jet duration, spire length, base width, and speed in our observations (and in synthetic Fe IX/Fe X images) are 6.5 ± 4.0 min (9.0 ± 4.0 minutes), 6050 ± 2900 km (6500 ± 6500 km), 2200 ± 850 km, (3900 ± 2100 km), and 60 ± 8 km s-1 (42 ± 20 km s-1), respectively. Our observation and simulation results provide a unified picture of small-scale solar coronal jets driven by magnetic reconnection accompanying flux cancelation. This picture also aligns well with the most recent reports of the formation and eruption mechanisms of larger coronal jets.

Keywords: solar magnetic fields; solar magnetic reconnection; jets; solar corona; solar chromosphere
Recovering Data of an Observation of the Leonids in 1869 from the Lisbon Geophysical Observatory (Portugal)

The Leonid meteor shower is renowned for its scientific and public interest. In a search for meteorological data from Portuguese stations, records on an observation of the Leonids in 1869 from the Lisbon Geophysical Observatory "Infante Dom Luiz" were found. Given their potential value, a digital version with metadata is provided in the present note (the recovered data are available on doi:10.5281/zenodo.11221019). The observation took place from 9 PM on 1869 November 13 to 6 AM on November 14, local time in Lisbon, with mostly clear skies and 4–5 observers covering completely the sky. They recorded 1980 meteors, noting Zodiacal Light visibility and detailing meteor counts every five minutes.

Keywords: meteors
The Critical Role of Collisionless Plasma Energization on the Structure of Relativistic Magnetic Reconnection

During magnetically dominated relativistic reconnection, inflowing plasma depletes the initial relativistic pressure at the X-line and collisionless plasma heating inside the diffusion region is insufficient to overcome this pressure loss. The resulting significant pressure drop causes a collapse at the X-line, essentially a localization mechanism of the diffusion region necessary for fast reconnection. The extension of this low-pressure region (into the outflow) further explains the bursty nature of antiparallel reconnection because a once opened outflow exhaust can also collapse, which repeatedly triggers secondary tearing islands. However, a stable single X-line reconnection can be achieved when an external guide field exists, since the reconnecting magnetic field component rotates out of the reconnection plane at outflows, providing additional magnetic pressure to keep the exhaust open.

Keywords: plasma astrophysics; plasma physics
Discovery of Carbon Monoxide in Distant Comet C/2017 K2 (PANSTARRS)

Optical observations of the Oort cloud comet C/2017 K2 (PANSTARRS) show that its activity began at large heliocentric distances (up to 35 au), which cannot be explained by either the sublimation or the crystallization of water ice. Supervolatile sublimation, most likely of carbon monoxide (CO), has been proposed as a plausible driver of the observed mass loss. Here, we present the detection of the J = 2-1 rotational transition in outgassed CO from C/2017 K2 when at heliocentric distance rH = 6.72 au, using the James Clerk Maxwell Telescope. The CO line is blueshifted by 0.20 ± 0.03 km s-1 with an area and width of 8.3 ± 2.3 mK km s-1 and 0.28 ± 0.08 km s-1, respectively. The CO production rate is QCO = (1.6 ± 0.5) × 1027 s-1. These are the first observations of a gaseous species in C/2017 K2 and provide observational confirmation of the role of supervolatile sublimation in this comet.

Keywords: small solar system bodies
Testing a Data-driven Active Region Evolution Model with Boundary Data at Different Heights from a Solar Magnetic Flux Emergence Simulation

A data-driven active region evolution (DARE) model has been developed to study the complex structures and dynamics of solar coronal magnetic fields. The model is configured with a typical coronal environment of tenuous gas governed by strong magnetic field, and thus its lower boundary is set at the base of the corona, but driven by magnetic fields observed in the photosphere. A previous assessment of the model using data from a flux emergence simulation (FES) showed that the DARE failed to reproduce the coronal magnetic field in the FES, which is attributed to the fact that the photospheric data in the FES has a very strong Lorentz force and therefore spurious flows are generated in the DARE model. Here we further test the DARE by using three sets of data from the FES sliced at incremental heights, which correspond to the photosphere, the chromosphere, and the base of the corona. It is found that the key difference in the three sets of data is the extent of the Lorentz force, which makes the data-driven model perform very differently. At the two higher levels above the photosphere, the Lorentz force decreases substantially, and the DARE model attains results in much better agreement with the FES, confirming that the Lorentz force in the boundary data is a key issue affecting the results of the DARE model. However, unlike the FES data, the photospheric field from SDO/HMI observations has recently been found to be very close to force-free. Therefore, we suggest that it is still reasonable to use the photospheric magnetic field as an approximation of the field at the coronal base to drive the DARE model.

Keywords: solar active region magnetic fields; magnetohydrodynamics; magnetohydrodynamical simulations; solar corona; solar magnetic flux emergence
The Minimum Variation Timescales of X-Ray Bursts from SGR J1935+2154

The minimum variation timescale (MVT) of soft gamma-ray repeaters can be an important probe to estimate the emission region in pulsar-like models, as well as the Lorentz factor and radius of the possible relativistic jet in gamma-ray burst (GRB)-like models, thus revealing their progenitors and physical mechanisms. In this work, we systematically study the MVTs of hundreds of X-ray bursts (XRBs) from SGR J1935+2154 observed by Insight-HXMT, GECAM, and Fermi/Gamma-ray Burst Monitor from 2014 July to 2022 January through the Bayesian block algorithm. We find that the MVTs peak at ~2 ms, corresponding to a light-travel time size of about 600 km, which supports the magnetospheric origin in pulsar-like models. The shock radius and the Lorentz factor of the jet are also constrained in GRB-like models. Interestingly, the MVT of the XRB associated with FRB 200428 is ~70 ms, which is longer than that of most bursts and implies its special radiation mechanism. In addition, the median of MVTs is 7 ms, shorter than the median MVTs of 40 ms and 480 ms for short GRBs or long GRBs, respectively. However, the MVT is independent of duration, similar to GRBs. Finally, we investigate the energy dependence of MVT and suggest that there is a marginal evidence for a power-law relationship like GRBs, but the rate of variation is at least about an order of magnitude smaller. These features may provide an approach to identify bursts with a magnetar origin.

Keywords: magnetars
Investigating the Mini and Giant Radio Flare Episodes of Cygnus X-3

The microquasar Cygnus X-3 underwent a giant radio flare in 2017 April, reaching a maximum flux of ∼16.5 Jy at 8.5 GHz. We present results from a long monitoring campaign carried out with Medicina at 8.5, 18.6, and 24.1 GHz, parallel to the Metsähovi radio telescope at 37 GHz, from 2017 April 4 to 11. We observe a spectral steepening from $\alpha =0.2$ to 0.5 (with ${S}_{\nu }\propto {\nu }^{-\alpha }$ ) within 6 hr of the epoch of the flare's peak maximum, and rapid changes in the spectral slope in the following days during brief enhanced emission episodes while the general trend of the radio flux density indicated the decay of the giant flare. We further study the radio orbital modulation of Cyg X-3 emission associated with the 2017 giant flare and with six mini-flares observed in 1983, 1985, 1994, 1995, 2002, and 2016. The enhanced emission episodes observed during the decline of the giant flare at 8.5 GHz coincide with the orbital phase $\phi \sim 0.5$ (orbital inferior conjunction). On the other hand, the light curves of the mini-flares observed at 15-22 GHz peak at $\phi \sim 0$, except for the 2016 light curve, which is shifted 0.5 w.r.t. the other ones. We attribute the apparent phase shift to the variable location of the emitting region along the bent jet. This might be explained by the different accretion states of the flaring episodes (the 2016 mini-flare occurred in the hypersoft X-ray state).

Keywords: high mass x-ray binary stars; radio jets
The First 3D Coronal Loop Model Heated by MHD Waves against Radiative Losses

In the quest to solve the long-standing coronal heating problem, it was suggested half a century ago that coronal loops could be heated by waves. Despite the accumulating observational evidence of the possible importance of coronal waves, still no 3D MHD simulations exist that show significant heating by MHD waves. Here we report on the first 3D coronal loop model that heats the plasma against radiative cooling. The coronal loop is driven at the footpoint by transverse oscillations, and subsequently the induced Kelvin-Helmholtz instability deforms the loop cross section and generates small-scale structures. Wave energy is transferred to smaller scales where it is dissipated, overcoming the internal energy losses by radiation. These results open up a new avenue to address the coronal heating problem.

Keywords: magnetohydrodynamics; magnetohydrodynamical simulations; solar coronal heating; solar coronal waves
What Can We Learn about the Unstable Equation-of-state Branch from Neutron Star Mergers?

The equation of state (EOS) of dense strongly interacting matter can be probed by astrophysical observations of neutron stars (NS), such as X-ray detections of pulsars or the measurement of the tidal deformability of NSs during the inspiral stage of NS mergers. These observations constrain the EOS at most up to the density of the maximum-mass configuration, n TOV, which is the highest density that can be explored by stable NSs for a given EOS. However, under the right circumstances, binary neutron star (BNS) mergers can create a postmerger remnant that explores densities above n TOV. In this work, we explore whether the EOS above n TOV can be measured from gravitational-wave or electromagnetic observations of the postmerger remnant. We perform a total of 25 numerical-relativity simulations of BNS mergers for a range of EOSs and find no case in which different descriptions of the matter above n TOV have a detectable impact on postmerger observables. Hence, we conclude that the EOS above n TOV can likely not be probed through BNS merger observations for the current and next generation of detectors.

Keywords: binary stars; high energy astrophysics
Coronal-jet-producing Minifilament Eruptions as a Possible Source of Parker Solar Probe Switchbacks

The Parker Solar Probe (PSP) has observed copious rapid magnetic field direction changes in the near-Sun solar wind. These features have been called "switchbacks," and their origin is a mystery. But their widespread nature suggests that they may be generated by a frequently occurring process in the Sun's atmosphere. We examine the possibility that the switchbacks originate from coronal jets. Recent work suggests that many coronal jets result when photospheric magnetic flux cancels, and forms a small-scale "minifilament" flux rope that erupts and reconnects with coronal field. We argue that the reconnected erupting-minifilament flux rope can manifest as an outward propagating Alfvénic fluctuation that steepens into an increasingly compact disturbance as it moves through the solar wind. Using previous observed properties of coronal jets that connect to coronagraph-observed white-light jets (a.k.a. "narrow CMEs"), along with typical solar wind speed values, we expect the coronal-jet-produced disturbances to traverse near-perihelion PSP in ≲25 minutes, with a velocity of ∼400 km s-1. To consider further the plausibility of this idea, we show that a previously studied series of equatorial latitude coronal jets, originating from the periphery of an active region, generate white-light jets in the outer corona (seen in STEREO/COR2 coronagraph images; 2.5-15 R⊙), and into the inner heliosphere (seen in Solar-Terrestrial Relations Observatory (STEREO)/Hi1 heliospheric imager images; 15-84 R⊙). Thus it is tenable that disturbances put onto open coronal magnetic field lines by coronal-jet-producing erupting-minifilament flux ropes can propagate out to PSP space and appear as switchbacks.

Keywords: solar filament eruptions; solar magnetic fields; solar magnetic reconnection; solar wind
Halfway to the Peak: Spatially Resolved Star Formation and Kinematics in a z = 0.54 Dusty Galaxy with JWST/MIRI

We present JWST Mid-InfraRed Instrument/Medium-Resolution Spectrometer (MIRI/MRS) observations of an infrared luminous disk galaxy, FLS1, at z ~ 0.54. With a lookback time of 5 Gyr, FLS1 is chronologically at the midpoint between the peak epoch of star formation and the present day. The MRS data provide maps of the atomic fine structure lines [Ar II]6.99, [Ar III]8.99, [Ne II]12.81, and [Ne III]15.55 μm, polycyclic aromatic hydrocarbon (PAH) features at 3.3, 6.2, and 11.3 μm, and the warm molecular gas indicators H2S(5) and H2S(3); all these emission features are spatially resolved. We find that the PAH emission is more extended along the northern side of the galaxy when compared to the well-studied star formation tracer [Ne II]. The H2 rotational lines, which are shock indicators, are strongest and most extended on the southern side of the galaxy. [Ar II] is the second brightest fine structure line detected in FLS1 and we show that it is a useful kinematic probe that can be detected with JWST out to z ~ 3. Velocity maps of [Ar II] show a rotating disk with signs of turbulence. Our results provide an example of how spatially resolved mid-infrared spectroscopy can allow us to better understand the star formation and interstellar medium conditions in a galaxy halfway back to the peak epoch of galaxy evolution.

Keywords: luminous infrared galaxies; agn host galaxies
The Behavior of HgMn Stars in the Far UV-Paper 21: HD 29589

The analysis of two spectra of the Mn Hg star HD 29589 recorded by the SWP camera on board the International Ultraviolet Explorer does not reveal variations of the far-ultraviolet flux over a thirteen years time interval. The TESS lightcurve of HD 29589 shows a complex pattern of oscillations with variable amplitudes and probably several periods. A very strong resonance line of Ga II is present at 1414.40 Å and confirms the Hg Mn status of HD 29589. A P Cygni profile at 1793.20 Å on SWP04948 could correspond to the resonance line of Sr II at 1793.09 Å and indicate transient mass loss.

Keywords: chemically peculiar stars; mercury-manganese stars