bluuebunny/crossref_metadata_2025_split huggingface dataset:
Seismic Signatures of the 12C(α, γ)16O Reaction Rate in White Dwarf Models with Overshooting
Authors: Chidester Morgan T. , Timmes F. X. , Farag Ebraheem 
Published: August 2023

Abstract
We consider the combined effects that overshooting and the 12C(α, γ)16O reaction rate have on variable white dwarf (WD) stellar models. We find that carbon–oxygen (CO) WD models continue to yield pulsation signatures of the current experimental 12C(α, γ)16O reaction rate probability distribution function when overshooting is included in the evolution. These signatures hold because the resonating mantle region, encompassing ≃0.2 M
⊙ in a typical ≃0.6 M
⊙ WD model, still undergoes radiative helium burning during the evolution to a WD. Our specific models show two potential low-order adiabatic g-modes, g
2 and g
6, that signalize the 12C(α, γ)16O reaction rate probability distribution function. Both g-mode signatures induce average relative period shifts of ΔP/P = 0.44% and ΔP/P = 1.33% for g
2 and g
6, respectively. We find that g
6 is a trapped mode, and the g
2 period signature is inversely proportional to the 12C(α, γ)16O reaction rate. The g
6 period signature generally separates the slower and faster reaction rates, and has a maximum relative period shift of ΔP/P = 3.45%. We conclude that low-order g-mode periods from CO WDs may still serve as viable probes for the 12C(α, γ)16O reaction rate probability distribution function when overshooting is included in the evolution.
Accretion Spin-up and a Strong Magnetic Field in the Slow-spinning Be X-Ray Binary MAXI J0655-013
Authors: Pike Sean N. , Sugizaki Mutsumi , Eijnden Jakob van den , Coughenour Benjamin , Jaodand Amruta D. , Mihara Tatehiro , Motta Sara E. , Negoro Hitoshi , Shaw Aarran W. , Shidatsu Megumi , Tomsick John A. 
Published: August 2023

Abstract
We present Monitor of All-sky X-ray Image (MAXI) and Nuclear Spectroscopic Telescope Array (NuSTAR) observations of the Be X-ray binary, MAXI J0655−013, in outburst. NuSTAR observed the source once early in the outburst, when spectral analysis yields a bolometric (0.1–100 keV), unabsorbed source luminosity of L
bol = 5.6 × 1036 erg s−1, and a second time 54 days later, by which time the luminosity had dropped to L
bol = 4 × 1034 erg s−1 after first undergoing a dramatic increase. Timing analysis of the NuSTAR data reveals a neutron star spin period of 1129.09 ± 0.04 s during the first observation, which decreased to 1085 ± 1 s by the time of the second observation, indicating spin-up due to accretion throughout the outburst. Furthermore, during the first NuSTAR observation, we observed quasi-periodic oscillations (QPOs) with centroid frequency ν
0 = 89 ± 1 mHz, which exhibited a second harmonic feature. By combining the MAXI and NuSTAR data with pulse period measurements reported by Fermi/GBM, we are able to show that apparent flaring behavior in the MAXI light curve is an artifact introduced by uneven sampling of the pulse profile, which has a large pulsed fraction. Finally, we estimate the magnetic field strength at the neutron star surface via three independent methods, invoking a tentative cyclotron resonance scattering feature at 44 keV, QPO production at the inner edge of the accretion disk, and spin-up via interaction of the neutron star magnetic field with accreting material. Each of these result in a significantly different value. We discuss the strengths and weaknesses of each method and infer that MAXI J0655−013 is likely to have a high surface magnetic field strength, B

s
> 1013 G.
Choked Jets in Expanding Envelope as the Origin of the Neutrino Emission Associated with Tidal Disruption Events
Authors: Zheng Jian-He , Liu Ruo-Yu , Wang Xiang-Yu 
Published: August 2023

Abstract
Three tidal disruption event (TDE) candidates (AT2019dsg, AT2019fdr, AT2019aalc) have been found to be coincident with high-energy astrophysical neutrinos in multimessenger follow-ups. Recent studies suggest the presence of a quasi-spherical, optically thick envelope around the supermassive black holes in TDEs, resulted from stellar debris after the disruption. The envelope may expand outwardly with a velocity of ∼104 km s−1, as indicated by the emission line widths. We study whether the neutrino signal can be explained by choked relativistic jets inside the expanding envelope. While powerful jets, such as that in Swift J1644+57, can successfully break out from the envelope, those with relatively weak power could be choked by the envelope. Choked jets can still accelerate cosmic rays and produce high-energy neutrinos via interaction with the thermal photons in the envelope. We explore the parameter space of the jets that can produce detectable neutrino flux while being choked in the expanding envelope. We find that the cumulative neutrino numbers of AT2019fdr and AT2019aalc are consistent with the expected range imposed by observations, while the allowed parameter space for AT2019dsg is small. The neutrino time delay relative to the optical peak time of TDEs can be explained as the jet propagation time in the envelope before being choked. The discovery of TDE-associated neutrino events may suggest that jets might have been commonly formed in TDEs, as expected from super-Eddington accretion, but most of them are too weak to break out from the expanding envelopes.
Alfvén Wave Connection between the Chromosphere and the Corona of the Sun: An Analytical Study
Authors: Chae Jongchul , Lee Kyoung-Sun 
Published: August 2023

Abstract
Alfvén waves are closely relevant to the three outstanding problems in the solar corona: coronal heating, solar wind acceleration, and the fractionization of low first ionization potential (FIP) elements. There has been increasing observational evidence for the Alfvén waves, not only in the corona, but also in the chromosphere. Here we investigate the Alfvén wave connection between the chromosphere and the corona based on the analytical solution of Alfvén waves in a layer where Alfvén speed varies along magnetic field lines with a constant gradient. The wave transmission of the layer is determined by two parameters: the Alfvénic cutoff frequency and the dimensionless thickness of the layer. It is shown that the ponderomotive acceleration originating from Alfvén waves is always directed upward in the solar atmosphere with the peak occurring in the chromosphere-corona transition region in association with downward low-frequency waves. We also find that some velocity amplitudes observed in the chromosphere of quiet regions and all the velocity amplitudes observed in active regions fall short of the theoretical estimates obtained with the assumption that the Alfvén waves generated below the chromosphere transport upward the energy required for the corona. We suggest considering the possibility that the Alfvén waves responsible for the coronal heating and the FIP fractionization originate from above the chromosphere.
A Tight Universal Relation between the Shape Eccentricity and the Moment of Inertia for Rotating Neutron Stars
Authors: Gao Yong , Shao Lijing , Steinhoff Jan 
Published: August 2023

Abstract
Universal relations that are insensitive to the equation of state are useful in reducing the parameter space when measuring global quantities of neutron stars (NSs). In this paper, we reveal a new universal relation that connects the eccentricity to the radius and moment of inertia of rotating NSs. We demonstrate that the universality of this relation holds for both conventional NSs and bare quark stars (QSs) in the slow-rotation approximation, albeit with different relations. The maximum relative deviation is approximately 1% for conventional NSs and 0.1% for QSs. Additionally, we show that the universality still exists for fast-rotating NSs if we use the dimensionless spin to characterize their rotation. The new universal relation will be a valuable tool to reduce the number of parameters used to describe the shape and multipoles of rotating NSs, and it may also be used to infer the eccentricity or moment of inertia of NSs in future X-ray observations.
Suprathermal Electron Transport and Electron Beam Formation in the Solar Corona
Authors: Tang Bofeng , Che Haihong , Zank Gary P. , Kolobov Vladimir I. 
Published: August 2023

Abstract
Electron beams that are commonly observed in the corona were discovered to be associated with solar flares. These “coronal” electron beams are found ≥300 Mm above the acceleration region and have velocities ranging from 0.1c up to 0.6c. However, the mechanism for producing these beams remains unclear. In this paper, we use kinetic transport theory to investigate how isotropic suprathermal energetic electrons escaping from the acceleration region of flares are transported upwardly along the magnetic field lines of flares to develop coronal electron beams. We find that magnetic focusing can suppress the diffusion of Coulomb collisions and background turbulence and sharply collimate the suprathermal electron distribution into beams with the observed velocity within the observed distance. A higher bulk velocity is produced if energetic electrons have harder energy spectra or travel along a more rapidly expanding coronal magnetic field. By modeling the observed velocity and location distributions of coronal electron beams, we predict that the temperature of acceleration regions ranges from 5 × 106 to 2 × 107 K. Our model also indicates that the acceleration region may have a boundary where the temperature abruptly decreases so that the electron beam velocity can become more than triple (even up to 10 times) the background thermal velocity and produce the coronal type III radio bursts.
Instabilities Driven by Proton Temperature Anisotropy in the Presence of Alpha Particles: Implications for Proton-temperature-anisotropy Constraint in the Solar Wind
Authors: Xiang L. , Wu D. J. , Chen L. , Li Q. H. , Zhao G. Q. , Feng H. Q. , Yu H. W. 
Published: August 2023

Abstract
In situ measurements reveal that proton temperature anisotropy is ubiquitous in the solar wind. Various plasma instabilities have been proposed to regulate the distribution of the proton temperature anisotropy in the solar wind; detailed constraint processes are still unclear. In this paper, we study the effects of alpha beams on both the forward and backward proton temperature anisotropy instabilities at parallel and oblique propagation with the Vlasov theory, and compare the theoretical results with the Wind observation. As the alpha-beam drift velocity v

α
/v
A increases, the growth rates of forward Alfvén/ion-cyclotron (FA/IC) and backward magnetosonic/whistler (BM/W) instabilities increase, those of backward Alfvén/ion-cyclotron (BA/IC) and forward magnetosonic/whistler (FM/W) instabilities decrease, and those of the mirror and forward Alfvén wave (FAW) instabilities are nearly constant. In particular, there are different constraining mechanisms on the distribution of proton temperature anisotropy for different values of the alpha-beam drift velocity. The proton temperature anisotropy instability together with the alpha beam can provide a potential explanation for the distribution of the proton temperature anisotropy in the solar wind.
Avalanches and the Distribution of Reconnection Events in Magnetized Circumstellar Disks
Authors: Fatuzzo Marco , Adams Fred C. , Feinstein Adina D. , Seligman Darryl Z. 
Published: August 2023

Abstract
Cosmic rays produced by young stellar objects can potentially alter the ionization structure, heating budget, chemical composition, and accretion activity in circumstellar disks. The inner edges of these disks are truncated by strong magnetic fields, which can reconnect and produce flaring activity that accelerates cosmic radiation. The resulting cosmic rays can provide a source of ionization and produce spallation reactions that alter the composition of planetesimals. These reconnection and particle acceleration processes are analogous to the physical processes that produce flaring in and the heating of stellar coronae. Flaring events on the surface of the Sun exhibit a power-law distribution of energy, reminiscent of those measured for earthquakes and avalanches. Numerical lattice reconnection models are capable of reproducing the observed power-law behavior of solar flares under the paradigm of self-organized criticality. One interpretation of these experiments is that the solar corona maintains a nonlinear attractor—or “critical”—state by balancing energy input via braided magnetic fields and output via reconnection events. Motivated by these results, we generalize the lattice reconnection formalism for applications in the truncation region of magnetized disks. Our numerical experiments demonstrate that these nonlinear dynamical systems are capable of both attaining and maintaining criticality in the presence of Keplerian shear and other complications. The resulting power-law spectrum of flare energies in the equilibrium attractor state is found to be nearly universal in magnetized disks. This finding indicates that magnetic reconnection and flaring in the inner regions of circumstellar disks occur in a manner similar to the activity on stellar surfaces. These results, in turn, have ramifications for the spallation-driven injection of radionuclides in planetesimals, disk ionization, and the subsequent planetary formation process.
Long-term Evolution of Warps in Debris Disks—Application to the Gyr-old System HD 202628
Authors: Brady Madison T. , Faramaz-Gorka Virginie , Bryden Geoffrey , Ertel Steve 
Published: August 2023

Abstract
We present the results of N-body simulations meant to reproduce the long-term effects of mutually inclined exoplanets on debris disks, using the HD 202628 system as a proxy. HD 202628 is a Gyr-old solar-type star that possesses a directly observable, narrow debris ring with a clearly defined inner edge and nonzero eccentricity, hinting at the existence of a sculpting exoplanet. The eccentric nature of the disk leads us to examine the effect on it over Gyr timescales from an eccentric and inclined planet, placed on its orbit through scattering processes. We find that, in systems with dynamical timescales akin to that of HD 202628, a planetary companion is capable of completely tilting the debris disk. This tilt is preserved over the Gyr age of the system. Simulated observations of our models show that an exoplanet around HD 202628 with an inclination misalignment ≳10° would cause the disk to be observably diffuse and broad, which is inconsistent with Atacama Large Millimeter Array (ALMA) observations. With these observations, we conclude that, if there is an exoplanet shaping this disk, it likely had a mutual inclination of less than 5° with the primordial disk. The conclusions of this work can be applied either to debris disks appearing as narrow rings (e.g., Fomalhaut and HR 4796) or to disks that are vertically thick at ALMA wavelengths (e.g., HD 110058).
CoLFI: Cosmological Likelihood-free Inference with Neural Density Estimators
Authors: Wang Guo-Jian , Cheng Cheng , Ma Yin-Zhe , Xia Jun-Qing , Abebe Amare , Beesham Aroonkumar 
Published: August 2023

Abstract
In previous works, we proposed to estimate cosmological parameters with an artificial neural network (ANN) and a mixture density network (MDN). In this work, we propose an improved method called a mixture neural network (MNN) to achieve parameter estimation by combining ANN and MDN, which can overcome shortcomings of the ANN and MDN methods. Besides, we propose sampling parameters in a hyperellipsoid for the generation of the training set, which makes the parameter estimation more efficient. A high-fidelity posterior distribution can be obtained using


(

10

2

)

forward simulation samples. In addition, we develop a code named CoLFI for parameter estimation, which incorporates the advantages of MNN, ANN, and MDN, and is suitable for any parameter estimation of complicated models in a wide range of scientific fields. CoLFI provides a more efficient way for parameter estimation, especially for cases where the likelihood function is intractable or cosmological models are complex and resource-consuming. It can learn the conditional probability density p(
θ
∣
d
) using samples generated by models, and the posterior distribution p(
θ
∣
d

0) can be obtained for a given observational data
d

0. We tested the MNN using power spectra of the cosmic microwave background and Type Ia supernovae and obtained almost the same result as the Markov Chain Monte Carlo method. The numerical difference only exists at the level of


(

10

−
2

σ
)

. The method can be extended to higher-dimensional data.
General Physical Properties of Fermi Blazars
Authors: Chen 陈 Yongyun 永云 , Gu 顾 Qiusheng 秋生 , Fan 樊 Junhui 军辉 , Yu 俞 Xiaoling 效龄 , Zhong 钟 Xiaogu 晓谷 , Liu 刘 Hongyu 红宇 , Ding 丁 Nan 楠 , Xiong 熊 Dingrong 定荣 , Guo 郭 Xiaotong 晓通 
Published: August 2023

Abstract
We study the general physical properties of Fermi blazars using the Fermi fourth source catalog data (4FGL-DR2). The quasi-simultaneous multiwavelength data of Fermi blazars are fitted by using the one-zone leptonic model to obtain some physical parameters, such as jet power, magnetic field, and Doppler factor. We study the distributions of the derived physical parameters as a function of black hole mass and accretion disk luminosity. The main results are as follows. (1) For a standard thin accretion disk, the jet kinetic power of most flat-spectrum radio quasars can be explained by the Blandford–Payne (BP) mechanism. However, the jet kinetic power of most BL Lacertae objects (BL Lacs) cannot be explained by either the Blandford–Znajek mechanism or the BP mechanism. The BL Lacs may have advection-dominated accretion flows surrounding their massive black holes. (2) After excluding the redshift, there is a moderately strong correlation between the jet kinetic power and jet radiation power and the accretion disk luminosity for Fermi blazars. These results confirm a close connection between jet and accretion. The jet kinetic power is slightly larger than the accretion disk luminosity for Fermi blazars. (3) There is a significant correlation between jet kinetic power and gamma-ray luminosity and radio luminosity for Fermi blazars, which suggests that gamma-ray luminosity and radio luminosity can be used to indicate the jet kinetic power.
cGAS–STING Pathway Activation during Trypanosoma cruzi Infection Leads to Tissue-Dependent Parasite Control
Authors: Perumal Natasha , White Brooke , Sanchez-Valdez Fernando , Tarleton Rick L 
Published: August 2023

Abstract
Host cell invasion by Trypanosoma cruzi is a markedly silent process, with limited host transcriptional changes indicative of innate immune recognition, except for a modest type I IFN (IFN-I) response. In this study, we show that T. cruzi–induced IFN-β production was nearly abolished in primary murine cGAS−/− or stimulator of IFN genes (STING)-deficient (STINGGt) macrophages and fibroblasts. T. cruzi infection did not impact the ability of IFN-regulatory factor reporter macrophages to respond to classical cGAS–STING agonists, indicating that the limited IFN-β induction is not due to active parasite suppression. cGAS−/−, STINGGt, and IFN-α/β receptor−/− (IFNAR−/−) macrophages infected with T. cruzi yielded significantly higher numbers of amastigotes compared with wild-type macrophages; however, the impact of the STING pathway during infection in vivo is more complex. Despite an initial increase in parasite growth, STINGGt and IFNAR−/− mice ultimately had lower parasite burden in footpads as compared with wild-type mice, demonstrating a role for IFN-I expression in potentiating parasite growth at the infection site. STING pathway activation had little impact on parasite levels in the skeletal muscle; however, in the heart, cGAS−/− and STINGGt mice, but not IFNAR−/− mice, accumulated higher acute parasite loads, suggesting a protective role of STING sensing of T. cruzi in this organ that was independent of IFN-I. Together, these results demonstrate that host cGAS–STING senses T. cruzi infection, enhancing parasite growth at the site of entry, and contributes to acute-phase parasite restriction in the heart, a major site of tissue damage in chronic T. cruzi infection.
Early Post-Stroke Seizures in Acute Ischemic Stroke
Authors: Agarwal Ayush , Sharma Jyoti , Padma Srivastava M.V. , Bhatia Rohit , Singh Mamta Bhushan , Gupta Anu , Pandit Awadh K. , Singh Rajesh , Rajan Roopa , Dwivedi Sadanand , Upadhyay Ashish , Garg Ajay , Vishnu Venugopalan Y. 
Published: August 2023

Introduction:
Stroke is the most common cause of epilepsy in the adult population. Post-stroke seizures (PSSs) are classified into early-onset seizures (ES) and late-onset (LS). ES can significantly affect the clinical outcome and occurrence of LS.

Methods:
We analyzed data from a prospective cohort of acute ischemic stroke patients between June 2018 and May 2020 in a neurology unit at a tertiary hospital. We screened all acute stroke patients and included consecutive patients older than 18 years of age, presenting with acute, first-ever neuroimaging-confirmed ischemic stroke. We excluded patients with a previous stroke, transient ischemic attacks, hemorrhagic stroke, cerebral venous thrombosis, prior history of seizures, or any other epileptogenic comorbidity. ES were classified as spontaneous seizures occurring within 1 week of the stroke. The main outcome assessed was the occurrence of ES. The secondary outcome was to determine predictors of ES and create an ES prediction score.

Results:
We screened 432 patients; of them, 291 were enrolled. ES occurred in 37 patients (12.7%). Cortical location (OR: 4.2), large artery disease subtype (OR: 2.9), mRS at presentation (OR: 1.4), use of anticoagulants (OR: 2.6), and hypertension (OR: 0.3) were significantly associated with the occurrence of ES. Patients with ES had a statistically significant worse clinical outcome at 3 months follow-up (P = 0.0072).

Conclusion:
We could formulate an ES prediction tool using the following components: (a) cortical location, (b) large vessel stroke, (c) mRS at admission, (d) anticoagulant use, and (e) presence of hypertension. This tool might help in treating patients at high risk for ES with prophylactic ASD, thereby preventing seizures and their complications.
Neuropsychiatric Features, Health-Related Quality of Life, and Caregiver Burden in Parkinson's Disease
Authors: Goel Atul , Narayan Sunil K. , Sugumaran Ramkumar 
Published: August 2023

Aim:
Parkinson's disease (PD) is a progressive neurodegenerative disease and significantly impacts patients and their caregivers. The current study aims at recognizing its neuropsychiatric symptoms, its impact on the health-related quality of life (HRQOL) of the patients, and the caregiver burden in a middle- to-low-income country.

Methods:
We conducted a cross-sectional survey of 73 idiopathic Parkinson's disease (IPD) patients and their caregivers from January 2021 to June 2021. Neuropsychiatric Inventory (NPI-12) and Parkinson's disease questionnaire (PDQ-39) were used to assess patients' symptoms and HRQOL, respectively. We used the Zarit caregiver burden interview (ZBI) and Hamilton depression scale (Ham-D) for the caregiver's burden assessment.

Results:
Of the 73 patients, 43 (59%) were men, and 30 (41%) were women. Their mean age was 60.25 years (± 11.1), and the mean duration of PD was 6.4 years (± 3.4). Eighty-six percent of the patients reported having one or more neuropsychiatric symptoms. HRQOL, as indicated by PDQ-39, correlated most significantly with H and Y staging (r = 0.680, P < 0.001) of the disease. Sixty-eight percent of the caregivers felt a disease burden, and 55% had depression. On regression analysis, NPI total score on caregiver burden (beta = 0.883, P < 0.001, confidence interval [CI] of 1.087 to 1.400,) and H and Y staging on depression (beta = 0.772, P < 0.001, [CI of 0.629 to 0.934) were having the most decisive impact.

Conclusion:
Our study showed the presence of frequent neuropsychiatric symptoms in PD patients. It has a detrimental effect on the quality of life of patients and results in a significant increase in caregiver burden and depression among them.