Sazuna/UAT_keywords huggingface dataset:
The Effects of Active Galactic Nuclei Feedback on the Lyα Forest Flux Power Spectrum. We study the effects of active galactic nuclei (AGN) feedback on the Lyα forest 1D flux power spectrum (P1D). Using the SIMBA cosmological-hydrodynamic simulations, we examine the impact that adding different AGN feedback modes has on the predicted P1D. We find that, for SIMBA, the impact of AGN feedback is most dramatic at lower redshifts (z &lt; 1) and that AGN jet feedback plays the most significant role in altering the P1D. The effects of AGN feedback can be seen across a large range of wavenumbers (1.5 × 10‑3 &lt; k &lt; 10‑1 s km‑1) changing the ionization state of hydrogen in the IGM through heating. AGN feedback can also alter the thermal evolution of the IGM and thermally broaden individual Lyα absorbers. For the SIMBA model, these effects become observable at z ≲ 1.0. At higher redshifts (z &gt; 2.0), AGN feedback has a 2% effect on the P1D for k &lt; 5 × 10‑2 s km‑1 and an 8% effect for k &gt; 5 × 10‑2 s km‑1. We show that the small-scale effect is reduced when normalizing the simulation to the observed mean flux. On large scales, the effect of AGN feedback appears via a change in the IGM temperature and is thus unlikely to bias cosmological parameters. The strong AGN jets in the SIMBA simulation can reproduce the z &gt; 2 Lyα forest. We stress that analyses comparing different AGN feedback models to future higher precision data will be necessary to determine the full extent of this effect.

Keywords: Cosmology, Supermassive black holes, Lyman alpha forest, Active galactic nuclei, Intergalactic medium, Extragalactic astronomy
Unraveling the Kinematic and Morphological Evolution of the Small Magellanic Cloud. We model the kinematics of the Small Magellanic Cloud (SMC) by analyzing the proper motions (PMs) from Gaia DR3 of nine different stellar populations, including young main-sequence (MS) stars (&lt;2 Gyr), red giant branch stars, red clump stars, red giants with line-of-sight velocities, and three groups of star clusters. This analysis is carried out using a robust Markov Chain Monte Carlo method, to derive up to seven kinematic parameters. We trace the evolution from a nonrotating flattened elliptical system, as mapped by the old population, to a rotating highly stretched disk structure, as denoted by the young MS stars and clusters (&lt;400 Myr). We estimate that the inclination i (∼58°–82°) decreases and the position angle Θ (∼180°–240°) increases with age. We estimate an asymptotic velocity of ∼49–89 km s‑1 with a scale radius of ∼6–9 kpc for the young MS populations, with velocity dispersion of ∼11 km s‑1, suggesting a rotation-supported disk structure. Our models estimate a line-of-sight extension of ∼30 kpc, in agreement with observations. We identify four regions of the SMC showing anomalies in the residual PM: the East Anomaly, the Southeast Anomaly (SEA), the South Anomaly, and the West Anomaly. The SEA appears like an infalling feature and is identified for the first time. The tidal imprints observed in the residual PM of the SMC suggest that its evolution is considerably shaped by the recent interaction with the Large Magellanic Cloud.

Keywords: Tidal interaction, Dwarf galaxies, Small Magellanic Cloud, Star clusters
The Lyman Continuum Escape Fraction of Star-forming Galaxies at 2.4 ≲ z ≲ 3.0 from UVCANDELS. The UltraViolet Imaging of the Cosmic Assembly Near-infrared Deep Extragalactic Legacy Survey Fields (UVCANDELS) survey is a Hubble Space Telescope (HST) Cycle-26 Treasury Program, allocated in total 164 orbits of primary Wide-Field Camera 3 Ultraviolet and VISible light F275W imaging with coordinated parallel Advanced Camera for Surveys F435W imaging, on four of the five premier extragalactic survey fields: GOODS-N, GOODS-S, EGS, and COSMOS. We introduce this survey by presenting a comprehensive analysis of the absolute escape fraction ( ) of Lyman continuum radiation through stacking the UV images of a population of star-forming galaxies with secure redshifts at 2.4 ≤ z ≤ 3.0. Our stacking benefits from the catalogs of high-quality spectroscopic redshifts compiled from archival ground-based data and HST slitless spectroscopy, carefully vetted by dedicated visual inspection efforts. We develop a robust stacking method to apply to 10 samples of in total 56 galaxies, and perform detailed Monte Carlo simulations of the intergalactic medium (IGM) attenuation, to take into account the sample variance of the mean IGM transmission when measuring  . The full stack at z ≈ 2.44 from 28 galaxies places a stringent 1σ upper limit of  , whereas the full stack at z ≈ 2.72 of an equal number of galaxies gives an upper limit of   at 1σ confidence level. These new F275W and F435W imaging mosaics from UVCANDELS have been made publicly available on the Barbara A. Mikulski Archive for Space Telescopes.

Keywords: Ultraviolet surveys, Galaxy evolution, Intergalactic medium, Reionization, High-redshift galaxies
Spatial and Temporal Distribution of Nanoflare Heating during Active Region Evolution. Nanoflares are believed to be key contributors to heating solar nonflaring active regions, though their individual detection remains challenging. This study uses a data-driven field-aligned hydrodynamic model to examine nanoflare properties throughout the lifecycle of active region (AR) 12758. We simulate coronal loop emissions, where each loop is heated by random nanoflares depending on the loop parameters derived from photospheric magnetograms observed by the Solar Dynamics Observatory/Helioseismic and Magnetic Imager. Simulated X-ray flux and temperature can reproduce the temporal variations observed by the Chandrayaan-2/Solar X-ray Monitor. Our findings show that high-frequency nanoflares contribute to cool emissions across the AR, while low- and intermediate-frequency primarily contribute to hot emissions. During the emerging phase, energy deposition is dominated by low-frequency events. Post-emergence, energy is deposited by both low- and intermediate-frequency nanoflares, while as the AR ages, the contribution from intermediate- and high-frequency nanoflares increases. The spatial distribution of heating frequencies across the AR reveals a clear pattern: the core of the active region spends most of its time in a low-frequency heating state, the periphery is dominated by high-frequency heating, and the region between the core and periphery experiences intermediate-frequency heating.

Keywords: Solar active regions, Solar coronal heating, Solar x-ray emission
Tidal Reconstruction of Neutron Star Mergers from Their Late Inspiral. We investigate the measurement correlation between the effective spin and the effective tidal deformability in gravitational-wave signals from binary neutron star mergers. To efficiently measure the effective tidal deformability parameter, we exploit the fact that the tidal effects in a binary system are prominent when the components are closer, during the late inspiral. Thus, we indicate a computationally efficient strategy of extracting the tidal information compressed within the seconds before the merger. We report our observations for GW170817 and explore the suitability of our approach for the upcoming observation scenarios of the current and future ground-based observatories. Fast and accurate measurements of the tidal deformability parameters can be used to inform astronomers when prioritizing the electromagnetic follow-up efforts for such sources.

Keywords: Neutron stars, Gravitational wave sources, Compact objects
Uncovering Deterministic Behavior of Black Hole IGR J17091–3624: A Twin of GRS 1915+105. Understanding the nonlinear properties in accreting systems, particularly for black holes, from observation is illuminating as they are expected to be general relativistic magnetohydrodynamic flows that are nonlinear. Two commonly used features associated with nonlinear systems are chaos, which is deterministic, and randomness, which is stochastic. The differentiation between chaotic and stochastic systems is often considered to quantify the nonlinear properties of an astrophysical system. Particular emphasis is given to the fact that data are often noise contaminated and finite. We examine the dual nature of the black hole X-ray binary IGR J17091–3624, whose behavior has been closely studied in parallel to GRS 1915+105. Certain similarities in the temporal classes of these two objects have been explored in the literature. However, this has not been the case with their nonlinear dynamics: GRS 1915+105 shows signs of both determinism and stochasticity, while IGR J17091–3624 was found to be predominantly stochastic. Here, we confront the inherent challenge of noise contamination faced by previous studies, particularly Poisson noise, which adversely impacts the reliability of nonlinear results. We employ several denoising techniques to mitigate noise effects, and employ methods like principal component analysis, singular value decomposition, and correlation integrals to isolate the deterministic signatures. We find signs of determinism in IGR J17091–3624, thus supporting the hypothesis of it being similar to GRS 1915+105, even as a dynamical system. Our findings not only shed light on the complex nature of IGR J17091–3624 but also pave the way for future research employing noise-reduction techniques to analyze nonlinearity in observed dynamical systems.

Keywords: Light curve classification , High energy astrophysics, Astrophysical black holes, Astronomy data analysis, X-ray transient sources, Time series analysis
Magnetic Field Strengths in the Vicinity of Sgr A* via 18 cm Zeeman Observations. Very Large Array (VLA) observations of 18 cm OH absorption lines were used to determine the strength of the line-of-sight magnetic field in the Galactic center region. This study is an extension of the VLA OH Zeeman observations of Killeen et al. with fourfold the on-source integration time and twice the sensitivity to the Zeeman effect. The new data fail to confirm the 7σ Zeeman detections of 2 mG fields reported in the earlier work. Also, we cannot reproduce these reported detections from our own analysis of archival data of the earlier work. We find no certain detections of the OH Zeeman effect in the Galactic center region. Our results suggest magnetic fields of no more than about a milligauss in the sampled regions.

Keywords: Galaxy magnetic fields, Galactic center
MAGICS. II. Seed Black Holes Stripped of Their Surrounding Stars Do Not Sink. Massive black hole (MBH) seed mergers are expected to be among the loudest sources of gravitational waves detected by the Laser Interferometer Space Antenna, providing a unique window into the birth and early growth of MBHs. We present the MAGICS-II simulation suite, which consists of six galaxy mergers that result in MBH seed mergers identified in the cosmological simulation ASTRID. With the enhanced resolution (mass resolution: 500 M⊙; softening length: 5 pc), improved subgrid models for the MBH dynamics and accretion, and the accurate regularized gravity integrator included in KETJU, we trace MBH seed dynamics down to 0.1 pc. After evolving all the systems for ≈1.2 Gyr in three stages (MAGICS-2000, MAGICS-500, and MAGICS-K), we find in four of the six systems that the MBHs stall at separations Δr ≳ 200 pc. Only in two systems, the MBHs manage to sink further, and only in one of them a bound binary forms. In the sinking systems, the MBH retains a population of bound stars. The final separation between the MBH is related to the surrounding unstripped stellar (and/or dark matter) mass: if more than 90% of the surrounding stellar system is stripped away, the MBHs stall. Besides the unstripped stars from the original host galaxy, we find that newly formed stars bound to the MBH significantly contribute to its sinking. Resolving the stellar system around MBH seeds, and its induced tidal interactions and dynamical friction is key for accurately capturing MBH dynamics. For this, high-resolution simulations are required. In a companion paper (MAGICS-III), we resimulate the central regions of these systems with an increased resolution to model directly the effects of actual star clusters around MBHs.

Keywords: AGN host galaxies, Supermassive black holes, Hydrodynamical simulations, Galaxy mergers, Dynamical friction
Associations between Scattering Screens and Interstellar Medium Filaments. Pulsar scintillation can be used to measure small-scale structure in the Galaxy, but little is known about the specific interstellar medium (ISM) features that cause scintillation. We searched for ISM counterparts to all scintillation screens for which absolute distances and scattering orientations have been measured—a sample of 12 pulsars and 22 screens. For one pulsar, PSR J0737–3039A, we reanalyze its scintillation screen and find evidence for a highly anisotropic screen. Comparisons with tracers of ionized media did not find any new associations. Instead, for seven of the pulsars analyzed, aligned H I filaments are seen for at least one of their screens, for a total of 12 out of 22 screens. This result seems unlikely to be due to chance: Comparing with random trials, we estimate a likelihood of finding 12 or more screens with aligned emission by chance of only 0.004%. Estimating the significance of the amount of aligned emission (in standard deviations over the mean), the probability of finding as much observed aligned emission by chance is larger, at 1.7%, but still indicative of a real correlation. Since H I filaments are preferentially associated with cold neutral gas, and thus unlikely to cause scintillation, this may indicate that both the filaments and the screens are aligned preferentially by the same mechanisms, such as magnetic fields or shocks.

Keywords: Pulsars, Interstellar scintillation
Fermi Unassociated Sources in the MeerKAT Absorption Line Survey. Over 2000 γ-ray sources identified by the Large Area Telescope on NASA's Fermi Gamma-ray Space Telescope are considered unassociated, meaning that they have no known counterparts in any other frequency regime. We have carried out an image-based search for steep spectrum radio sources, with in-band spectral index &lt; ‑1.4, within the error regions of Fermi unassociated sources using 1–1.4 GHz radio data from the MeerKAT Absorption Line Survey (MALS) data release. The first MALS data release with a median rms noise of 22–25 μJy and 735,649 sources is a significant advance over past image-based searches with improvements in sensitivity, resolution, and bandwidth. Steep spectrum candidates were identified using a combination of in-band spectral indices from MALS and existing radio surveys. We developed an optical and infrared source classification scheme in order to distinguish between Galactic pulsars and radio galaxies. In total, we identify nine pulsar candidates toward six Fermi sources that are worthy of follow-up for pulsation searches. We also report 41 steep spectrum radio galaxy candidates that may be of interest in searches for high-redshift radio galaxies. We show that MALS, due to its excellent continuum sensitivity, can detect 80% of the known pulsar population. This exhibits the promise of identifying exotic pulsar candidates with future image-based surveys with the Square Kilometre Array and its precursors.

Keywords: Millisecond pulsars, Gamma-ray sources, Radio astrometry, Pulsars, Radio galaxies, Discrete radio sources
Late-time Optical and X-Ray Emission Evolution of the Oxygen-rich SN 1996cr. When the ejecta of a supernova (SN) interact with the progenitor star's circumstellar environment, a strong shock is driven back into the ejecta, causing the material to become bright optically and in X-rays. Most notably, as the shock traverses the H-rich envelope, it begins to interact with metal-rich material. Thus, continued monitoring of bright and nearby SNe provides valuable clues about both the progenitor structure and its pre-SN evolution. Here we present late-time, multiepoch optical and Chandra X-ray spectra of the core-collapse SN, SN 1996cr. Magellan IMACS optical spectra taken in 2017 July and 2021 August show a very different spectrum from that seen in 2006 with broad, double-peaked optical emission lines of oxygen, argon, and sulfur with expansion velocities of ±4500 km s‑1. Redshifted emission components are considerably fainter compared to the blueshifted components, presumably due to internal extinction from dust in the SN ejecta. Broad ±2400 km s‑1 Hα is also seen, which we infer is shocked progenitor pre-SN, mass-loss, H-rich material. Chandra data indicate a slow but steady decline in the overall X-ray luminosity, suggesting that the forward shock has broken through any circumstellar shell or torus, which is inferred from prior deep Chandra ACIS-S/HETG observations. The X-ray properties are consistent with what is expected from a shock breaking out into a lower-density environment. Though originally identified as a Type IIn SN, based upon late-time optical emission-line spectra, we argue that the SN 1996cr progenitor was partially or highly stripped, suggesting a Type IIb/Ib SN.

Keywords: Type II supernovae, Type Ib supernovae, Core-collapse supernovae
Chasing the Beginning of Reionization in the JWST Era. Recent JWST observations at z &gt; 6 may imply galactic ionizing photon production above prior expectations. Under observationally motivated assumptions about escape fractions, these suggest a z ~ 8–9 end to reionization, in tension with the z &lt; 6 end required by the Lyα forest. In this work, we use radiative transfer simulations to understand what different observations tell us about when reionization ended and when it started. We consider a model that ends too early (zend ≈ 8) alongside two more realistic scenarios with zend ≈ 5: one starting late (z ~ 9) and another early (z ~ 13). We find that the latter requires up to an order-of-magnitude evolution in galaxy ionizing properties at 6 &lt; z &lt; 12, perhaps in tension with measurements of ξion by JWST, which indicate little evolution. We study how these models compare to recent measurements of the Lyα forest opacity, mean free path, intergalactic medium thermal history, visibility of z &gt; 8 Lyα emitters, and the patchy kSZ signal from the cosmic microwave background (CMB). We find that neither of the late-ending scenarios is strongly disfavored by any single data set. However, a majority of observables, spanning several distinct types of observations, prefer a late start. Not all probes agree with this conclusion, hinting at a possible lack of concordance arising from deficiencies in observations and/or theoretical modeling. Observations by multiple experiments (including JWST, Roman, and CMB-S4) in the coming years will establish a concordance picture of reionization's beginning or uncover such deficiencies.

Keywords: Quasar absorption line spectroscopy, Lyman alpha forest, Hubble Space Telescope, Cosmic microwave background radiation, James Webb Space Telescope, Galaxy evolution, Radiative transfer, Intergalactic medium, Reionization, High-redshift galaxies
Assessing the Dark Matter Content of Two Quasar Host Galaxies at z ∼ 6 through Gas Kinematics. We conduct a study of the gas kinematics of two quasar host galaxies at z ≳ 6 traced by the [C II] emission line using the Atacama Large Millimeter/submillimeter Array. By combining deep observations at both low and high resolution, we recover the diffuse emission, resolve its structure, and measure the rotation curves from the inner region of the galaxy to its outskirts using DysmalPy and 3DBarolo. Assuming that both galaxies exhibit disk rotation driven by the gravitational potential of the galaxy, we find that the best-fit disk models have a Vrot/σ ≍ 2 and inferred circular velocities out to ∼6─8 kpc scales, well beyond the likely stellar distribution. We then determine the mass profiles of each component (stars, gas, dark matter) with priors on the baryon and dark matter properties. We find relatively large dark matter fractions within their effective radii (fDM(R &lt; Re) =   and  , respectively), which are significantly larger than those extrapolated from lower redshift studies and remain robust under different input parameters verified by Monte Carlo simulations. The large fDM(R &lt; Re) corresponds to halo masses of ∼1012.5−1012.8 M⊙, thus representative of the most massive halos at these redshifts. Notably, while the masses of these supermassive black holes (SMBHs) are approximately 1 dex higher than the low-redshift relationship with stellar mass, the closer alignment of SMBH and halo masses with a local relationship may indicate that the early formation of these SMBHs is linked to their dark matter halos, providing insights into the coevolution of galaxies and black holes in the early Universe.

Keywords: Galaxy dark matter halos, High-redshift galaxies, Galaxy kinematics, Quasars
Striking a Chord with Spectral Sirens: Multiple Features in the Compact Binary Population Correlate with H<SUB>0</SUB>. Spectral siren measurements of the Hubble constant (H0) rely on correlations between observed detector-frame masses and luminosity distances. Features in the source-frame mass distribution can induce these correlations. It is crucial, then, to understand (i) which features in the source-frame mass distribution are robust against model (re)parameterization, (ii) which features carry the most information about H0, and (iii) whether distinct features independently correlate with cosmological parameters. We study these questions using real gravitational-wave observations from the LIGO-Virgo-KAGRA Collaborations' third observing run. Although constraints on H0 are weak, we find that current data reveals several prominent features in the mass distribution, including peaks in the binary black hole source-frame mass distribution near ∼9M⊙ and ∼32M⊙ and a roll-off at masses above ∼46M⊙. For the first time using real data, we show that all of these features carry cosmological information and that the peak near ∼32M⊙ consistently correlates with H0 most strongly. Introducing model-independent summary statistics, we show that these statistics independently correlate with H0, exactly what is required to limit systematics within future spectral siren measurements from the (expected) astrophysical evolution of the mass distribution.

Keywords: Neutron stars, Black holes, Gravitational wave astronomy, Gravitational waves, Compact objects
Insights into the Properties of Type Ibn/Icn Supernovae and Their Progenitor Channels through X-Ray Emission. Type Ibn/Icn supernovae (SNe Ibn/Icn), which are characterized by narrow helium or carbon lines that originated in hydrogen-poor dense circumstellar medium (CSM), provide new insights into the final evolution of massive stars. While SNe Ibn/Icn are expected to emit strong X-rays through the strong supernova (SN)-CSM interaction, the X-ray emission modeling effort has been limited so far. In the present study, we provide broad-band X-ray light curve (LC) predictions for SNe Ibn/Icn. We find that the soft X-ray LC provides information about the CSM compositions, while the hard X-ray LC is a robust measure of the CSM density, the explosion energy, and the ejecta mass. In addition, considering the evolution of the ionization state in the unshocked CSM, a bright soft X-ray is expected in the first few days since the explosion, which encourages rapid X-ray follow-up observations as a tool to study the nature of SNe Ibn/Icn. Applying our model to the soft X-ray LCs of SNe Ibn 2006jc and 2022ablq, we derive that the CSM potentially contains a larger fraction of carbon and oxygen for SN 2006jc than 2022ablq, highlighting the power of the soft X-ray modeling to address the nature of the CSM. We also discuss detectability and observational strategy, with which the currently operating telescopes such as NuSTAR and Swift can offer an irreplaceable opportunity to explore the nature of these enigmatic rapid transients and their still-unclarified progenitor channel(s).

Keywords: Circumstellar matter, X-ray transient sources, Stellar evolution