adsabs/SciX_UAT_keywords huggingface dataset:
Directly Tracing Cool Filamentary Accretion over >100 kpc into the Interstellar Medium of a Quasar Host at z = 1

We report the discovery of giant (50-100 kpc) [O II] emitting nebulae with MUSE in the field of TXS 0206-048, a luminous quasar at z = 1.13. "Down-the-barrel" UV spectra of the quasar show absorption at velocities coincident with those of the extended nebulae, enabling new insights into inflows and outflows around the quasar host. One nebula exhibits a filamentary morphology extending over 120 kpc from the halo toward the quasar and intersecting with another nebula surrounding the quasar host with a radius of 50 kpc. This is the longest cool filament observed to date and arises at higher redshift and in a less massive system than those in cool-core clusters. The filamentary nebula has line-of-sight velocities >300 km s-1 from nearby galaxies but matches that of the nebula surrounding the quasar host where they intersect, consistent with accretion of cool intergalactic or circumgalactic medium or cooling hot halo gas. The kinematics of the nebulae surrounding the quasar host are unusual and complex, with redshifted and blueshifted spiral-like structures. The emission velocities at 5-10 kpc from the quasar match those of inflowing absorbing gas observed in UV spectra of the quasar. Together, the extended nebulae and associated redshifted absorption represent a compelling case of cool, filamentary gas accretion from halo scales into the extended interstellar medium and toward the nucleus of a massive quasar host. The inflow rate implied by the combined emission and absorption constraints is well below levels required to sustain the quasar's radiative luminosity, suggesting anisotropic or variable accretion.

Keywords: intergalactic filaments; circumgalactic medium; quasars; galaxy groups
How Well Can We Measure Galaxy Dust Attenuation Curves? The Impact of the Assumed Star-dust Geometry Model in Spectral Energy Distribution Fitting

One of the most common methods for inferring galaxy attenuation curves is via spectral energy distribution (SED) modeling, where the dust attenuation properties are modeled simultaneously with other galaxy physical properties. In this paper, we assess the ability of SED modeling to infer these dust attenuation curves from broadband photometry, and suggest a new flexible model that greatly improves the accuracy of attenuation curve derivations. To do this, we fit mock SEDs generated from the SIMBA cosmological simulation with the PROSPECTOR SED fitting code. We consider the impact of the commonly assumed uniform screen model and introduce a new nonuniform screen model parameterized by the fraction of unobscured stellar light. This nonuniform screen model allows for a nonzero fraction of stellar light to remain unattenuated, resulting in a more flexible attenuation curve shape by decoupling the shape of the UV attenuation curve from the optical attenuation curve. The ability to constrain the dust attenuation curve is significantly improved with the use of a nonuniform screen model, with the median offset in UV attenuation decreasing from -0.30 dex with a uniform screen model to -0.17 dex with the nonuniform screen model. With this increase in dust attenuation modeling accuracy, we also improve the star formation rates (SFRs) inferred with the nonuniform screen model, decreasing the SFR offset on average by 0.12 dex. We discuss the efficacy of this new model, focusing on caveats with modeling star-dust geometries and the constraining power of available SED observations.

Keywords: spectral energy distribution; galactic and extragalactic astronomy; hydrodynamical simulations; radiative transfer simulations
4-8 GHz Fourier-domain Searches for Galactic Center Pulsars

The Galactic Center (GC), with its high density of massive stars, is a promising target for radio transient searches. In particular, the discovery and timing of a pulsar orbiting the central supermassive black hole (SMBH) of our galaxy will enable stringent strong-field tests of gravity and accurate measurements of SMBH properties. We performed multiepoch 4-8 GHz observations of the inner ≈15 pc of our galaxy using the Robert C. Byrd Green Bank Telescope in 2019 August-September. Our investigations constitute the most sensitive 4-8 GHz GC pulsar survey conducted to date, reaching down to a 6.1 GHz pseudo-luminosity threshold of ≈1 mJy kpc2 for a pulse duty cycle of 2.5%. We searched our data in the Fourier domain for periodic signals incorporating a constant or linearly changing line-of-sight pulsar acceleration. We report the successful detection of the GC magnetar PSR J1745-2900 in our data. Our pulsar searches yielded a nondetection of novel periodic astrophysical emissions above a 6σ detection threshold in harmonic-summed power spectra. We reconcile our nondetection of GC pulsars with inadequate sensitivity to a likely GC pulsar population dominated by millisecond pulsars. Alternatively, close encounters with compact objects in the dense GC environment may scatter pulsars away from the GC. The dense central interstellar medium may also favorably produce magnetars over pulsars.

Keywords: galactic center; neutron stars; radio pulsars; radio transient sources
Spectral Variability of a Soft-intermediate State QPO from MAXI J1820+070

Black Hole X-ray binaries are known to exhibit variability in their light curves on timescales as short as milliseconds and as long as months. The short-timescale variability can be in the form of quasi-periodic oscillations (QPOs), which may be produced by general relativistic effects. In this work, we looked at low-frequency QPOs from an exciting recent black hole transient, MAXI J1820+070, which first went into outburst in 2018. This source was observed in a multi-wavelength campaign that included the NICER mission, a soft X-ray telescope attached to the International Space Station. In our analysis, we applied X-ray timing and spectral-timing techniques to help place constraints on the QPO emission mechanism in the extreme environment surrounding the black hole. Although the QPO amplitude was too low to carry out phase-resolved spectroscopy, our work indicates that weak QPOs such as this one may be present in the light curves of many sources.

Keywords: high time resolution astrophysics; black holes; low-mass x-ray binary stars
Counterstreaming Strahls and Heat Flux Dropouts as Possible Signatures of Local Particle Acceleration in the Solar Wind

Suprathermal electrons with energies of ∼70 eV and above are observed at 1 au as dispersionless halo electrons and magnetic field-aligned beams of strahls. For a long time, it has been thought that both populations originate only from the solar corona, and that the only active process impacting their properties in the solar wind is scattering. This view has consequently impacted the interpretation of typical patterns of pitch-angle distributions (PADs) of suprathermal electrons. Meanwhile, recent observational studies supported by numerical simulations have shown that there is an unaccounted population of electrons accelerated to suprathermal energies at reconnecting current sheets (RCSs) and 3D dynamical plasmoids (or 2D magnetic islands (MIs)) directly in the heliosphere. We present multispacecraft observations of counterstreaming strahls and heat flux dropouts in PADs within a region filled with plasmoids and RCSs unaffected by interplanetary shocks, comparing observed PAD features with those predicted by particle-in-cell simulations. We show typical PAD patterns determined by local acceleration of thermal-core electrons up to hundreds of electron volts. Resulting PAD views depend on properties and topology of particular RCSs, MIs, and plasma/magnetic field parameters. Our study suggests that solar wind-borne suprathermal electrons coexist with those of solar origin. Therefore, some of heat flux dropout and bidirectional strahl events can be explained by local dynamical processes involving magnetic reconnection. Possible implications of the results for the interpretation of the actively debated decrease in the strahl/halo relative density with heliocentric distance and puzzling features of suprathermal electrons observed at crossings of the heliospheric current sheet and cometary comas are also discussed.

Keywords: interplanetary magnetic fields; solar magnetic reconnection; solar wind; solar energetic particles; interplanetary particle acceleration
First Detection of Interaction between a Magnetic Disk Wind and an Episodic Jet in a Protostellar System

Rotating outflows from protostellar disks might trace extended magnetohydrodynamic (MHD) disk winds (DWs), providing a solution to the angular momentum problem in disk accretion for star formation. In the jet system HH 212, a rotating outflow was detected in SO around an episodic jet detected in SiO. Here we spatially resolve this SO outflow into three components: a collimated jet aligned with the SiO jet, the wide-angle disk outflow, and an evacuated cavity in between created by a large jet-driven bow shock. Although it was theoretically predicted, this is the first time that such a jet-DW interaction has been directly observed and resolved, and it is crucial for the proper interpretation and modeling of non-resolved DW candidates. The resolved kinematics and brightness distribution both support the wide-angle outflow to be an extended MHD DW dominating the local angular momentum extraction out to 40 au, but with an inner launching radius truncated to ≳4 au. Inside 4 au, where the DW may not exist, the magnetorotational instability might be transporting angular momentum outward. The jet-DW interaction in HH 212, potentially present in other similar systems, opens an entirely new avenue to probe the large-scale magnetic field in protostellar disks.

Keywords: accretion; star formation; jets; herbig-haro objects; young stellar objects; stellar jets
Spectral Lags of 90 Swift Gamma-Ray Bursts and the Constraint on the Lorentz Invariance Violation

The arrival times of photons with different energy could be different, even when they are emitted from the same source simultaneously. Such a spectral lag is a common property among high-energy astrophysics phenomena like gamma-ray bursts (GRBs). The potential violation of the Lorentz invariance caused by quantum fluctuations in background spacetime metrics could cause the spectral lag. In this paper, we try to make a constraint on Lorentz invariance violation (LIV) with multiple energy bands light curves of GRBs. With a sample of 90 Swift GRBs with redshifts, we calculate their spectral offsets from four fixed energy bands within their source frame. With help from the cross-correlation function and kernel smooth procedure, we extract improved spectral shifts. By using these more general spectral lags, we obtain an upper limit on LIV, equivalent to a lower limit on the quantum-gravitational energy scale of E QG ≥ 2.2 × 1014GeV.

Keywords: gamma-ray bursts; gravitation; quantum gravity; astronomical methods; time domain astronomy; time series analysis
Photometric Calibrations of M-dwarf Metallicity with Markov Chain Monte Carlo and Bayesian Inference

Knowledge of stellar atmospheric parameters (T eff, $\mathrm{log}g$ , [Fe/H]) of M dwarfs can be used to constrain both theoretical stellar models and Galactic chemical evolutionary models, and guide exoplanet searches, but their determination is difficult due to the complexity of the spectra of their cool atmospheres. In our ongoing effort to characterize M dwarfs, and in particular their chemical composition, we carried out multiband photometric calibrations of metallicity for early- and intermediate-type M dwarfs. The third Gaia data release provides high-precision astrometry and three-band photometry. This information, combined with the 2MASS and CatWISE2020 infrared photometric surveys and a sample of 4919 M dwarfs with metallicity values determined with high-resolution spectroscopy by The Cannon and APOGEE spectra, allowed us to study the effect of the metallicity in color-color and color-magnitude diagrams. We divided this sample into two subsamples: we used 1000 stars to train the calibrations with Bayesian statistics and Markov Chain Monte Carlo techniques, and the remaining 3919 stars to check the accuracy of the estimations. We derived several photometric calibrations of metallicity applicable to M dwarfs in the range of -0.45 ≤ [Fe/H] ≤ + 0.45 dex and spectral types down to M5.0 V that yield uncertainties down to the 0.10 dex level. Lastly, we compared our results with other photometric estimations published in the literature for an additional sample of 46 M dwarfs in wide binary systems with FGK-type primary stars and found a great predictive performance.

Keywords: hertzsprung russell diagram; metallicity; fundamental parameters of stars; low mass stars
An Analysis of the North Polar Spur Using HaloSat

We present HaloSat X-ray observations of the entirety of the bright X-ray emitting feature known as the North Polar Spur (NPS). The large field of view of HaloSat enabled coverage of the entire bright NPS in only 14 fields, which were each observed for ≈30,000 s. We find that the NPS fields are distinct in both brightness and spectral shape from the surrounding halo fields. We fit the NPS as two thermal components in ionization equilibrium with temperatures ${\text{}}{{kT}}_{\mathrm{cool}}\approx 0.087\,{keV}$ and ${\text{}}{{kT}}_{\mathrm{hot}}\approx 0.28\,{keV}$ . We note a temperature gradient in the NPS hot component with an inner arc temperature warmer than the outer arc. The emission measures we find for the cool component of the NPS is a factor of 3-5 greater than that of the hot component, which suggests that the bulk of the NPS material is in the ≈0.1 keV component. We evaluate distance estimates of 0.4 and 8.0 kpc for the NPS. Our findings suggest a preference for a distant NPS with an energy of ≈ 6 × 1054 erg, an age of ≈ 10 Myr, and pressures consistent with a 10μG magnetic field associated with the Fermi bubbles. The electron density ≈10 × 10-3 cm-3 is consistent with estimates for the shock region surrounding a Galactic-scale event.

Keywords: x-ray astronomy; interstellar medium; diffuse x-ray background; superbubbles
Multispacecraft Observations of a Widespread Solar Energetic Particle Event on 2022 February 15–16

On 2022 February 15–16, multiple spacecraft measured one of the most intense solar energetic particle (SEP) events observed so far in Solar Cycle 25. This study provides an overview of interesting observations made by multiple spacecraft during this event. Parker Solar Probe (PSP) and BepiColombo were close to each other at 0.34–0.37 au (a radial separation of ∼0.03 au) as they were impacted by the flank of the associated coronal mass ejection (CME). At about 100° in the retrograde direction and 1.5 au away from the Sun, the radiation detector on board the Curiosity surface rover observed the largest ground-level enhancement on Mars since surface measurements began. At intermediate distances (0.7–1.0 au), the presence of stream interaction regions (SIRs) during the SEP arrival time provides additional complexities regarding the analysis of the distinct contributions of CME-driven versus SIR-driven events in observations by spacecraft such as Solar Orbiter and STEREO-A, and by near-Earth spacecraft like ACE, SOHO, and WIND. The proximity of PSP and BepiColombo also enables us to directly compare their measurements and perform cross-calibration for the energetic particle instruments on board the two spacecraft. Our analysis indicates that energetic proton measurements from BepiColombo and PSP are in reasonable agreement with each other to within a factor of ∼1.35. Finally, this study introduces the various ongoing efforts that will collectively improve our understanding of this impactful, widespread SEP event.

Keywords: solar energetic particles; heliosphere; solar coronal mass ejections
PIC Simulation of Double Plasma Resonance and Zebra Pattern of Solar Radio Bursts

The latest study has reported that plasma emission can be generated by energetic electrons of Dory-Guest-Harris distribution via the electron cyclotron maser instability (ECMI) in plasmas characterized by a large ratio of plasma oscillation frequency to electron gyro-frequency (ωpe/Ωce). In our study, on the basis of the ECMI-plasma emission mechanism, we examine the double plasma resonance (DPR) effect and the corresponding plasma emission at both harmonic (H) and fundamental (F) bands using particle-in-cell simulations with various ωpe/Ωce. This allows us to directly simulate the feature of the zebra pattern (ZP) observed in solar radio bursts for the first time. We find that (1) the simulations reproduce the DPR effect nicely for the upper hybrid and Z modes, as seen from their variation of intensity and linear growth rate with ωpe/Ωce, (2) the intensity of the H emission is stronger than that of the F emission by ∼2 orders of magnitude and varies periodically with increasing ωpe/Ωce, while the F emission is too weak to be significant (therefore, we suggest that it is the H emission accounting for solar ZPs), (3) the peak-valley contrast of the total intensity of H is ∼4, and the peak lies around integer values of ωpe/Ωce (=10 and 11) for the present parameter setup. We also evaluate the effect of energy of energetic electrons on the characteristics of ECMI-excited waves and plasma radiation. The study provides novel insight on the physical origin of ZPs of solar radio bursts.

Keywords: plasma astrophysics; radio bursts; solar corona; solar activity; solar coronal radio emission
Magnetic Cloud and Sheath in the Ground-level Enhancement Event of 2000 July 14. I. Effects on the Solar Energetic Particles

Ground-level enhancements generally accompany fast interplanetary coronal mass ejections (ICMEs), and ICME-driven shocks are sources of solar energetic particles (SEPs). Observations of the GLE event of 2000 July 14 show that a very fast and strong magnetic cloud (MC) is behind the ICME shock and the proton intensity-time profiles observed at 1 au had a rapid two-step decrease near the sheath and MC. Therefore, we study the effect of sheath and MC on SEPs accelerated by an ICME shock by numerically solving the focused transport equation. The shock is regarded as a moving source of SEPs with an assumed particle distribution function. The sheath and MC are set to thick spherical caps with enhanced magnetic field, and the turbulence levels in the sheath and MC are set to be higher and lower than those of the ambient solar wind, respectively. The simulation results of proton intensity-time profiles agree well with the observations in energies ranging from ∼1 to ∼100 MeV, and the two-step decrease is reproduced when the sheath and MC arrived at the Earth. The simulation results show that the sheath-MC structure reduced the proton intensities for about 2 days after the shock passed through the Earth. It is found that the sheath contributed most of the decrease while the MC facilitated the formation of the second step decrease. The simulation also infers that the coordination of magnetic field and turbulence in sheath-MC structure can produce a stronger reduction of SEP intensities.

Keywords: space weather; solar coronal mass ejections; solar energetic particles; solar coronal mass ejection shocks; solar storm; solar particle emission
New Determination of Fundamental Properties of Palomar 5 Using Deep DESI Imaging Data

The legacy imaging surveys for the Dark Energy Spectroscopic Instrument project provides multiple-color photometric data, which are about 2 mag deeper than those from the SDSS. In this study, we redetermine the fundamental properties for an old halo globular cluster of Palomar 5 based on these new imaging data, including structure parameters, stellar population parameters, and luminosity and mass functions. These characteristics, together with its tidal tails, are key for dynamical studies of the cluster and constraining the mass model of the Milky Way. By fitting the King model to the radial surface density profile of Palomar 5, we derive the core radius of ${r}_{c}=2\buildrel{\,\prime}\over{.} 96\pm 0\buildrel{\,\prime}\over{.} 11$ , tidal radius of ${r}_{t}=17\buildrel{\,\prime}\over{.} 99\pm 1\buildrel{\,\prime}\over{.} 49$ , and concentration parameter of c = 0.78 ± 0.04. We apply a Bayesian analysis method to derive the stellar population properties and get an age of 11.508 ± 0.027 Gyr, metallicity of [Fe/H] = -1.798 ± 0.014, reddening of E(B - V) = 0.0552 ± 0.0005, and distance modulus of ${\left(m-M\right)}_{0}\,=\,16.835\pm 0.006$ . The main-sequence luminosity and mass functions for both the cluster center and tidal tails are investigated. The luminosity and mass functions at different distances from the cluster center suggest that there is obvious spatial mass segregation. Many faint low-mass stars have been evaporated at the cluster center, and the tidal tails are enhanced by low-mass stars. Both the concentration and relaxation times suggest that Palomar 5 is a totally relaxed system.

Keywords: globular star clusters; ccd photometry; stellar populations; stellar mass functions
Exploring the Recycling Model of Phobos Formation: Rubble-pile Satellites

Phobos is the target of the return sample mission Martian Moons eXploration by JAXA that will analyze in great detail the physical and compositional properties of the satellite from orbit, from the surface, and in terrestrial laboratories, giving clues about its formation. Some models propose that Phobos and Deimos were formed after a giant impact giving rise to an extended debris disk. Assuming that Phobos formed from a cascade of disruptions and reaccretions of several parent bodies in this disk, and that they are all characterized by a low material cohesion, Hesselbrock & Minton showed that a recycling process may happen during the assembling of Phobos, by which Phobos's parents are destroyed into a Roche-interior ring and reaccreted several times. In this paper, we explore the recycling model in detail and pay particular attention to the characteristics of the disk using 1D models of disk/satellite interactions. In agreement with previous studies, we confirm that, if Phobos's parent bodies are gravitational aggregates (rubble piles), then the recycling process does occur. However, Phobos should be accompanied today by a Roche-interior ring. Furthermore, the characteristics of the ring are not reconcilable with today's observations of Mars' environment, which put stringent constraints on the existence of a ring around Mars. The recycling mechanism may or may not have occurred at the Roche limit for an old moon population, depending on the internal cohesion. However, the Phobos we see today cannot be the outcome of such a recycling process. * Released on 2023 February 27.

Keywords: natural satellite formation
Exclusion of Cosmic Rays from Molecular Clouds by Self-generated Electric Fields

It was recently discovered that in some regions of the Galaxy, the cosmic-ray (CR) abundance is several orders of magnitude higher than previously thought. Additionally, there is evidence that in molecular cloud envelopes, the CR ionization may be dominated by electrons. We show that for regions with high, electron-dominated ionization, the penetration of CR electrons into molecular clouds is modulated by the electric field that develops as a result of the charge they deposit. We evaluate the significance of this novel mechanism of self-modulation and show that the CR penetration can be reduced by a factor of a few to a few hundred in high-ionization environments, such as those found near the Galactic center.

Keywords: galactic cosmic rays; interstellar plasma; interstellar medium