adsabs/SciX_UAT_keywords huggingface dataset:
EXPRES. IV. Two Additional Planets Orbiting ρ Coronae Borealis Reveal Uncommon System Architecture

Thousands of exoplanet detections have been made over the last 25 years using Doppler observations, transit photometry, direct imaging, and astrometry. Each of these methods is sensitive to different ranges of orbital separations and planetary radii (or masses). This makes it difficult to fully characterize exoplanet architectures and to place our solar system in context with the wealth of discoveries that have been made. Here, we use the EXtreme PREcision Spectrograph to reveal planets in previously undetectable regions of the mass-period parameter space for the star ρ Coronae Borealis. We add two new planets to the previously known system with one hot Jupiter in a 39 day orbit and a warm super-Neptune in a 102 day orbit. The new detections include a temperate Neptune planet ( $M\sin i\sim 20$ M ⊕) in a 281.4 day orbit and a hot super-Earth ( $M\sin i=3.7$ M ⊕) in a 12.95 day orbit. This result shows that details of planetary system architectures have been hiding just below our previous detection limits; this signals an exciting era for the next generation of extreme precision spectrographs.

Keywords: planet hosting stars; exoplanets; exoplanet dynamics; radial velocity; solar analogs
TESS Hunt for Young and Maturing Exoplanets (THYME). VI. An 11 Myr Giant Planet Transiting a Very-low-mass Star in Lower Centaurus Crux

Mature super-Earths and sub-Neptunes are predicted to be ≃ Jovian radius when younger than 10 Myr. Thus, we expect to find 5-15 R ⊕ planets around young stars even if their older counterparts harbor none. We report the discovery and validation of TOI 1227b, a 0.85 ± 0.05 R J (9.5 R ⊕) planet transiting a very-low-mass star (0.170 ± 0.015 M ⊙) every 27.4 days. TOI 1227's kinematics and strong lithium absorption confirm that it is a member of a previously discovered subgroup in the Lower Centaurus Crux OB association, which we designate the Musca group. We derive an age of 11 ± 2 Myr for Musca, based on lithium, rotation, and the color-magnitude diagram of Musca members. The TESS data and ground-based follow-up show a deep (2.5%) transit. We use multiwavelength transit observations and radial velocities from the IGRINS spectrograph to validate the signal as planetary in nature, and we obtain an upper limit on the planet mass of ≃0.5 M J. Because such large planets are exceptionally rare around mature low-mass stars, we suggest that TOI 1227b is still contracting and will eventually turn into one of the more common <5 R ⊕ planets.

Keywords: pre-main sequence stars; transits; exoplanet evolution; exoplanet formation; stellar associations; stellar ages; ob associations; time domain astronomy; time series analysis; late-type stars; low mass stars
On the Power to Constrain the Accretion History of Massive Black Holes via Spin Measurements by Upcoming X-Ray Telescopes

The spin distribution of massive black holes (MBHs) contains rich information on their assembly history. However, only limited information can be extracted from currently available spin measurements of MBHs owing to the small sample size and large measurement uncertainties. Upcoming X-ray telescopes with improved spectral resolution and larger effective area are expected to provide new insights into the growth history of MBHs. Here we investigate, at a proof of concept level, how stringent constraints can be placed on the accretion history of MBHs by the spin measurements from future X-ray missions. We assume a toy model consisting of a two-phase accretion history composed of an initial coherent phase with a constant disk orientation, followed by a chaotic phase with random disk orientations in each accretion episode. By utilizing mock spin data generated from such models and performing Bayesian Markov Chain Monte Carlo simulations, we find that most accretion models of MBHs can be reconstructed provided that $\gtrsim 100$ MBH spins are measured with an accuracy of $\lesssim 0.1$ . We also quantify the precision of the reconstructed parameters by adopting various combinations of sample sizes and spin accuracies, and find that the sample size is more crucial to model reconstruction once the spin accuracy reaches ∼0.1. To some extent, a better spin accuracy will compensate for a small sample size and vice versa. Future X-ray missions such as the Advanced Telescope for High Energy Astrophysics and the enhanced X-ray Timing and Polarimetry mission, may provide spin measurements of ≳100 MBHs with an uncertainty of ∼0.04-0.1 and will thus put strong constraints on the MBH growth history.

Keywords: accretion; active galaxies; black hole physics; galaxy nuclei; supermassive black holes; x-ray detectors
Galaxy Flows within 8000 km s-1 from Numerical Action Methods

The trajectories since z = 4 of systems of galaxies ("halos") with cz < 8000 km s-1 are found through numerical action reconstructions. A set of 9719 halos from a Two Micron All Sky Survey group catalog and Cosmicflows-3 catalogs are given attention. Present distances are adjusted to minimize departures from observed redshifts. For those with the most precisely determined distances, compromises are made between distance and redshift agreement. H 0 is varied from 69 to 77 km s-1 Mpc-1, with Ω m set by the baryon acoustic oscillation constraint from the Planck satellite. A best-fitting amplitude of the mass-to-light relation is found. A uniform density associated with the interhalo medium accounts for the matter not in halos. The solution paths provide the histories of the formation of the nearby large structures and depict how the voids emptied. Assuming no local over/underdensity, the best model has H 0 = 73 km s-1 Mpc-1, with nearly the same density arising from interhalo matter (IHM) as from halos. We examine local over/underdensities by varying the IHM density and find a valley of best-fit models along H 0 = 73.0(1 + 0.165δ) km s-1 Mpc-1. Friedmann models with distinct densities internal and external to the study region give a similar relationship. The fraction of matter in the IHM seen in n-body simulations roughly matches that in our H 0 = 72 scenario. Videos have been created to visualize the complexities of formation of large-scale structures. Standard n-body calculations, starting from the first time steps as tests of the numerical action method solutions and continuing until cosmic scale factor a = 2, provide glimpses into the future.

Keywords: cosmological parameters from large-scale structure; cosmological parameters; hubble constant; dark matter density; mass-to-light ratio; large-scale structure of the universe; superclusters
Long-term Monitoring of Didymos with the LCOGT Network and MRO after the DART Impact

The world's first planetary defense test mission was carried out in late 2022 by NASA's Double Asteroid Redirection Test (DART) mission. The main DART spacecraft, which was accompanied by the ASI-provided LICIACube cubesat, intentionally impacted Dimorphos, the smaller secondary of the near-Earth object binary system (65803) Didymos, on 2022 September 26. The impact released a large amount of ejecta, which, combined with the spacecraft's momentum, produced the observed 33 ± 1 minute period change that was subsequently observed from ground-based telescopes. The DART mission, in addition to having successfully changed the orbital period of Dimorphos, also activated the asteroid as a result of the impact but under known conditions, unlike other impacts on asteroids. We have conducted long-term monitoring over 5 months following the impact with the Las Cumbres Observatory Global Telescope (LCOGT) network and Magdalena Ridge Observatory (MRO). This was supplemented by almost 3 months of more sparsely sampled data, primarily from educational users of the LCOGT network during the period from 2022 July 5 to 2022 September 25, prior to the impact date of 2022 September 26. Here we report the observations of the Didymos system and DART impact ejecta with the telescopes of the LCOGT network from T+1.93 days to T+151.3 days after impact, and we study the evolving morphology of the ejecta cloud and evolving tail over the entire length of the data set. In addition, we combined these intensive data sets with the earlier sparse observations over the ∼90 days prior to impact to derive a new disk-integrated phase function model using the H, G 1, G 2 parameterization.

Keywords: asteroids; near-earth objects; optical astronomy; ejecta; photometry
CHANG-ES. XXX. 10 kpc Radio Lobes in the Sombrero Galaxy

We report the discovery of the 10 kpc scale radio lobes in the Sombrero galaxy (NGC 4594), using data from the Continuum Halos in Nearby Galaxies—an Expanded Very Large Array Survey project. We further examine the balance between the magnetic pressure inside the lobes and the thermal pressure of the ambient hot gas. At the radii r of ∼(1–10) kpc, the magnetic pressure inside the lobes and the thermal pressure of the ambient hot gas are generally in balance. This implies that the jets could expand into the surroundings to at least r ∼ 10 kpc. The feedback from the active galactic nucleus jet responsible for the large-scale lobes may help to explain the unusually high X-ray luminosity of this massive quiescent isolated disk galaxy, although more theoretical work is needed to further examine this possibility.

Keywords: extragalactic magnetic fields; low-luminosity active galactic nuclei; radio jets; radio continuum emission
Automatic Search for Low-surface-brightness Galaxies from Sloan Digital Sky Survey Images Using Deep Learning

Low-surface-brightness (LSB) galaxies play a crucial role in our understanding of galaxy evolution and dark matter cosmology. However, efficiently detecting them in large-scale surveys is challenging, due to their dim appearance. In this study, we propose a two-step detection method based on deep learning to address this issue. First, an object detection model called GalCenterNet was designed to detect LSB galaxy candidates in astronomical images. The model was trained using a data set of 665 Sloan Digital Sky Survey (SDSS) images, which contained 667 LSB galaxies. On the test set, the model achieved an accuracy of 95.05% and a recall of 96.00%. Next, an anomaly detection technique known as Deep Support Vector Data Description was applied to identify abnormal sources, thus refining the LSB candidates. By applying the two-step detection method to SDSS images, we have obtained a sample of 37,536 LSB galaxy candidates. This wide-area sample contains diverse and abundant LSB galaxies, which are valuable for studying the properties of LSB galaxies and the role that the environment plays in their evolution. The proposed detection method enables end-to-end detection from the SDSS images to the final detection results. This approach will be further employed to efficiently identify objects in the upcoming Chinese Survey Space Telescope sky survey.

Keywords: low surface brightness galaxies; astronomy data analysis
Could SNAD160 be a Pair-instability Supernova?

The SNAD team reports the discovery of SNAD160 (AT2018lzi) within the Zwicky Transient Facility third data release. The transient has been found using the active anomaly detection algorithm, an adaptive learning strategy aimed at incorporating expert knowledge into machine learning models. Our preliminary analysis shows that SNAD160 could be a superluminous supernova powered by a pair-instability mechanism-its light curve behavior is consistent with the observed slow rise and slow decay expected from these events.

Keywords: supernovae; transient detection; transient sources; light curve classification; time series analysis; astronomical object identification
The SUPERCOLD-CGM Survey. I. Probing the Extended CO(4-3) Emission of the Circumgalactic Medium in a Sample of 10 Enormous Lyα Nebulae at z ∼ 2

To understand how massive galaxies at high z coevolve with enormous reservoirs of halo gas, it is essential to study the coldest phase of the circumgalactic medium (CGM), which directly relates to stellar growth. The SUPERCOLD-CGM survey is the first statistical survey of cold molecular gas on CGM scales. We present Atacama Large Millimeter Array and Atacama Compact Array observations of CO(4-3) and continuum emission from 10 enormous Lyα nebulae (ELANe) around ultraluminous type I quasi-stellar objects (QSOs) at z ~ 2. We detect CO(4-3) in 100% of our targets, with 60% showing extended CO on scales of 15-100 kpc. Q1228+3128 reveals the most extended CO(4-3) reservoir of ~100 kpc and is the only radio-loud target in our sample. The CO reservoir is located along the radio axis, which could indicate a link between the inner radio jet and cold halo gas. For the other five radio-quiet ELANe, four of them show extended CO(4-3) predominantly in the direction of their companions. These extended CO(4-3) reservoirs identify enrichment of the CGM and may potentially contribute to widespread star formation. However, there is no evidence from CO(4-3) for diffuse molecular gas spread across the full extent of the Lyα nebulae. One target in our sample (Q0107) shows significant evidence for a massive CO disk associated with the QSO. Moreover, 70% of our QSO fields contain at least one CO companion, two of which reveal extended CO emission outside the ELANe. Our results provide insight into roles of both the cold CGM and companions in driving the early evolution of massive galaxies.

Keywords: circumgalactic medium; galaxy evolution; radio astronomy
Investigating Pre-eruptive Magnetic Properties at the Footprints of Erupting Magnetic Flux Ropes

It is well established that solar eruptions are powered by free magnetic energy stored in the current-carrying magnetic field in the corona. It has also been generally accepted that magnetic flux ropes (MFRs) are a critical component of many coronal mass ejections. What remains controversial is whether MFRs are present well before the eruption. Our aim is to identify progenitors of MFRs, and investigate pre-eruptive magnetic properties associated with these progenitors. Here we analyze 28 MFRs erupting within 45° from the disk center from 2010 to 2015. All MFRs' feet are well identified by conjugate coronal dimmings. We then calculate the magnetic properties at the feet of the MFRs, prior to their eruptions, using Helioseismic and Magnetic Imager vector magnetograms. Our results show that only 8 erupting MFRs are associated with significant nonneutralized electric currents, 4 of which also exhibit pre-eruptive dimmings at the footprints. Twist and current distributions are asymmetric at the two feet of these MFRs. The presence of pre-eruption dimmings associated with nonneutralized currents suggests the preexisting MFRs. Furthermore, the evolution of conjugate dimmings and electric currents within the footprints can provide clues about the internal structure of MFRs and their formation mechanism.

Keywords: solar flares; solar coronal mass ejections; solar photosphere; solar magnetic fields
Study of Time Evolution of Thermal and Nonthermal Emission from an M-class Solar Flare

We conduct a wide-band X-ray spectral analysis in the energy range of 1.5-100 keV to study the time evolution of the M7.6-class flare of 2016 July 23, with the Miniature X-ray Solar Spectrometer (MinXSS) CubeSat and the Reuven Ramaty High Energy Solar Spectroscopic Imager (RHESSI) spacecraft. With the combination of MinXSS for soft X-rays and RHESSI for hard X-rays, a nonthermal component and three-temperature multithermal component-"cool" (T ≈ 3 MK), "hot" (T ≈ 15 MK), and "superhot" (T ≈ 30 MK)-were measured simultaneously. In addition, we successfully obtained the spectral evolution of the multithermal and nonthermal components with a 10 s cadence, which corresponds to the Alfvén timescale in the solar corona. We find that the emission measures of the cool and hot thermal components are drastically increasing more than hundreds of times and the superhot thermal component is gradually appearing after the peak of the nonthermal emission. We also study the microwave spectra obtained by the Nobeyama Radio Polarimeters, and we find that there is continuous gyrosynchrotron emission from mildly relativistic nonthermal electrons. In addition, we conducted a differential emission measure (DEM) analysis by using Atmospheric Imaging Assembly on board the Solar Dynamics Observatory and determined that the DEM of cool plasma increases within the flaring loop. We find that the cool and hot plasma components are associated with chromospheric evaporation. The superhot plasma component could be explained by the thermalization of the nonthermal electrons trapped in the flaring loop.

Keywords: non-thermal radiation sources; solar flares
Ambipolar Diffusion in the Lower Solar Atmosphere: Magnetohydrodynamic Simulations of a Sunspot

Magnetohydrodynamic (MHD) simulations of the solar atmosphere are often performed under the assumption that the plasma is fully ionized. However, in the lower solar atmosphere a reduced temperature often results in only the partial ionization of the plasma. The interaction between the decoupled neutral and ionized components of such a partially ionized plasma produces ambipolar diffusion. To investigate the role of ambipolar diffusion in propagating wave characteristics in the photosphere and chromosphere, we employ the MANCHA3D numerical code to model magnetoacoustic waves propagating through the atmosphere immediately above the umbra of a sunspot. We solve the nonideal MHD equations for data-driven perturbations to the magnetostatic equilibrium and the effect of ambipolar diffusion is investigated by varying the simulation to include additional terms in the MHD equations that account for this process. Analyzing the energy spectral densities for simulations with/without ambipolar diffusion, we find evidence to suggest that ambipolar diffusion plays a pivotal role in wave characteristics in the weakly ionized low density regions, hence maximizing the local ambipolar diffusion coefficient. As a result, we propose that ambipolar diffusion is an important mechanism that requires careful consideration into whether it should be included in simulations, and whether it should be utilized in the analysis and interpretation of particular observations of the lower solar atmosphere.

Keywords: solar physics; solar oscillations; sunspots; solar atmosphere; solar chromosphere; active solar chromosphere; magnetohydrodynamics; magnetohydrodynamical simulations; fast fourier transform
Seeds of Life in Space (SOLIS). IX. Chemical Segregation of SO2 and SO toward the Low-mass Protostellar Shocked Region of L1157

We present observations of SO and SO2 lines toward the shocked regions along the L1157 chemically rich outflow, taken in the context of the Seeds of Life in Space IRAM Northern Extended Millimeter Array Large Program, and supported by data from the Submillimeter Array and IRAM-30 m telescope at 1.1-3.6 mm wavelengths. We simultaneously analyze, for the first time, all of the brightest shocks in the blueshifted lobe, namely, B0, B1, and B2. We found the following. (1) SO and SO2 may trace different gas, given that the large(-scale) velocity gradient analysis indicates for SO2 a volume density ( ${10}^{5}\mbox{--}{10}^{6}\,{\mathrm{cm}}^{-3}$ ) denser than that of the gas emitting in SO by a factor up to an order of magnitude. (2) Investigating the 0.1 pc scale field of view, we note a tentative gradient along the path of the precessing jet. More specifically, $\chi (\mathrm{SO}/{\mathrm{SO}}_{2})$ decreases from the B0-B1 shocks to the older B2. (3) At a linear resolution of 500-1400 au, a tentative spatial displacement between the two emitting molecules is detected, with the SO peak closer (with respect to SO2) to the position where the recent jet is impinging on the B1 cavity wall. Our astrochemical modeling shows that the SO and SO2 abundances evolve on timescales less than about 1000 years. Furthermore, the modeling requires high abundances (2 × 10-6) of both ${{\rm{H}}}_{2}{\rm{S}}/{\rm{H}}$ and S/H injected in the gas phase due to the shock occurrence, so prefrozen OCS only is not enough to reproduce our new observations.

Keywords: star formation; low mass stars; interstellar medium
Ionized Gas Outflows in Low-excitation Radio Galaxies Are Radiation Driven

Low-excitation radio galaxies (LERGs) are weakly accreting active galactic nuclei (AGNs) believed to be fueled by radiatively inefficient accretion processes. Despite this, recent works have shown evidence for ionized and neutral hydrogen gas outflows in these galaxies. To investigate the potential drivers of such outflows, we select a sample of 802 LERGs using the Best & Heckman (2012) catalog of radio galaxies. By modeling the [O III] λ5007 profile in Sloan Digital Sky Survey spectra of a sample of 802 LERGs, we determine that the ionized outflows are present in ~1.5% of the population. Using 1.4 GHz imaging from the Faint Images of the Radio Sky at Twenty Centimeters survey we analyze the radio morphology of LERGs with outflows and find these to be consistent with the parent LERG population. However, we note that unlike the majority of the LERG population, those LERGs showing outflows have Eddington-scaled accretion rates close to 1%. This is indicative that ionized outflows in LERGs are driven by the radiation pressure from the accretion disk of the AGN rather than the radio jets. We report specific star formation rates in the range of 10-12 < sSFR < 10-9 yr-1. Moreover, we observe higher mass outflow rates, 7-150 M⊙ yr-1, for these LERGs than luminous quasars for a given bolometric luminosity, which could possibly be due to the radio source in LERGs boosting the mass loading. This scenario could indicate that these outflows could potentially drive feedback in LERGs.

Keywords: active galactic nuclei; radio active galactic nuclei; radio jets; galaxy accretion disks; agn host galaxies
Chronicling the Host Galaxy Properties of the Remarkable Repeating FRB 20201124A

We present the Australian Square Kilometre Array Pathfinder localization and follow-up observations of the host galaxy of the repeating fast radio burst (FRB) source, FRB 20201124A, the fifth such extragalactic repeating FRB with an identified host. From spectroscopic observations using the 6.5 m MMT Observatory, we derive a redshift z = 0.0979 ± 0.0001, a star formation rate inferred from Hα emission SFR(Hα) ≈ 2.1 M⊙ yr-1, and a gas-phase metallicity of 12+log(O/H) ≈ 9.0. By jointly modeling the 12 filter optical-mid-infrared (MIR) photometry and spectroscopy of the host, we infer a median stellar mass of ~2 × 1010 M⊙, internal dust extinction AV ≈ 1-1.5 mag, and a mass-weighted stellar population age of ~5-6 Gyr. Connecting these data to the radio and X-ray observations, we cannot reconcile the broadband behavior with strong active galactic nucleus activity and instead attribute the dominant source of persistent radio emission to star formation, likely originating from the circumnuclear region of the host. The modeling also indicates a hot dust component contributing to the MIR luminosity at a level of ~10%-30%. We model the host galaxy's star formation and mass assembly histories, finding that the host assembled >90% of its mass by 1 Gyr ago and exhibited a fairly constant SFR for most of its existence, with no clear evidence of past starburst activity.

Keywords: radio transient sources; radio bursts; star formation; stellar populations; neutron stars