Sazuna/UAT_keywords huggingface dataset:
The Rise of Faint, Red Active Galactic Nuclei at z &gt; 4: A Sample of Little Red Dots in the JWST Extragalactic Legacy Fields. We present a sample of 341 "little red dots" (LRDs) spanning the redshift range z ∼ 2─11 using data from the CEERS, PRIMER, JADES, UNCOVER, and NGDEEP surveys. Unlike past use of color indices to identify LRDs, we employ continuum slope fitting using shifting bandpasses to sample the same rest-frame emission blueward and redward of the Balmer break. This enables the detection of LRDs over a wider redshift range and with less contamination from galaxies with strong breaks that otherwise lack a rising red continuum. The redshift distribution of our sample increases at z &lt; 8 and then undergoes a rapid decline at z ∼ 4.5, which may tie the emergence of these sources to the inside-out growth that galaxies experience during this epoch. We find that LRDs are ∼1 dex more numerous than X-ray- and UV-selected active galactic nuclei (AGN) at z ∼ 5─7. Within our sample, we have identified the first two X-ray-detected LRDs. An X-ray spectral analysis confirms that these AGN are moderately obscured with  log(NH/cm2 ) of  23.3−1.3+0.4  and  22.72−0.16+0.13 . Our analysis reveals that reddened AGN emission dominates their rest-optical light, while the rest-UV originates from their host galaxies. We also present NIRSpec observations from the RUBIES survey of 17 LRDs that show broad emission lines consistent with AGN activity. The confirmed AGN fraction of our sample is 71% for sources with F444W &lt; 26.5. In addition, we find three LRDs with blueshifted Balmer absorption features in their spectra, suggesting an outflow of high-density, low-ionization gas from near the central engine of these faint, red AGN.

Keywords: Supermassive black holes, Active galactic nuclei
COZMIC. I. Cosmological Zoom-in Simulations with Initial Conditions Beyond Cold Dark Matter. We present 72 cosmological dark-matter--only N-body zoom-in simulations with initial conditions beyond cold, collisionless dark matter (CDM), as the first installment of the COZMIC suite. We simulate Milky Way (MW) analogs with linear matter power spectra P(k) for (i) thermal-relic warm dark matter (WDM) with masses mWDM ∈ [3, 4, 5, 6, 6.5, 10]keV, (ii) fuzzy dark matter (FDM) with masses mFDM ∈ [25.9,69.4, 113, 151, 185, 490] × 10−22eV, and (iii) interacting dark matter (IDM) with a velocity-dependent elastic proton scattering cross section σ = σ0vn, relative particle velocity scaling n ∈ [2, 4], and dark matter mass mIDM ∈ [10−4, 10−2, 1] GeV. Subhalo mass function (SHMF) suppression is significantly steeper in FDM versus WDM, while dark acoustic oscillations in P(k) can reduce SHMF suppression for IDM. We fit SHMF models to our simulation results and derive new bounds on WDM and FDM from the MW satellite population, obtaining mWDM &gt; 5.9 keV and mFDM &gt; 1.4 × 10−20 eV at 95% confidence; these limits are ≍10% weaker and 5× stronger than previous constraints owing to the updated transfer functions and SHMF models, respectively. We estimate IDM bounds for n = 2 (n = 4) and obtain σ0 &lt; 1.0 × 10−27 cm2, 1.3 × 10−24 cm2, and 3.1 × 10−23 cm2 (σ0 &lt; 9.9 × 10−27 cm2, 9.8 × 10−21 cm2, and 2.1 × 10−17 cm2) for mIDM = 10−4, 10−2, and 1 GeV, respectively. Thus, future development of IDM SHMF models can improve IDM cross section bounds by up to a factor of ∼20 with current data. COZMIC presents an important step toward accurate small-scale structure modeling in beyond-CDM cosmologies, critical to upcoming observational searches for dark matter physics.

Keywords: Warm dark matter, Milky Way dark matter halo, Galaxy dark matter halos, Galaxy abundances, N-body simulations, Dark matter
COZMIC. II. Cosmological Zoom-in Simulations with Fractional non-CDM Initial Conditions. We present 24 cosmological dark matter (DM)-only zoom-in simulations of a Milky Way analog with initial conditions appropriate for scenarios where non-cold dark matter (NCDM) is a fraction of the total DM abundance (f-NCDM models) as the second installment of the COZMIC suite. We initialize our simulations using transfer functions,  Tf‑NCDM(k)≡Pf‑NCDM(k)/PCDM(k)  (where P(k) is the linear matter power spectrum), with an initial suppression similar to thermal-relic warm dark matter (WDM) followed by a constant-amplitude plateau. We simulate suppression wavenumbers [22.8, 32.1, 41.8, 52.0, 57.1, 95.3] Mpc‑1, corresponding to thermal-relic WDM masses mWDM ∈ [3, 4, 5, 6, 6.5, 10] keV, and plateau amplitudes δ ∈ [0.2, 0.4, 0.6, 0.8]. We model the subhalo mass function in terms of the suppression wave number and δ. Integrating these models into a forward model of the MW satellite galaxy population yields new limits on f-NCDM scenarios, with suppression wavenumbers greater than 46 and 40 Mpc‑1 for δ = 0.2 and 0.4, respectively, at 95% confidence. The current data do not constrain δ &gt; 0.4. We map these limits to scenarios where a fraction fWDM of DM behaves as a thermal relic, which yields the following bounds on cosmologies with a mixture of WDM and CDM: mWDM &gt; 3.6, 4.1, 4.6, 4.9, 5.4 keV for fWDM = 0.5, 0.6, 0.7, 0.8, 0.9, respectively, at 95% confidence. The current data do not constrain WDM fractions fWDM &lt; 0.5. Our results affirm that low-mass halo abundances are sensitive to partial suppression in P(k), indicating the possibility of using galactic substructure to reconstruct P(k) on small scales.

Keywords: Warm dark matter, Milky Way dark matter halo, Galaxy dark matter halos, N-body simulations
COZMIC. III. Cosmological Zoom-in Simulations of Self-interacting Dark Matter with Suppressed Initial Conditions. We present eight cosmological dark matter (DM)-only zoom-in simulations of a Milky Way─like system that include suppression of the linear matter power spectrum P(k), and/or velocity-dependent DM self-interactions, as the third installment of the COZMIC suite. We consider a model featuring a massive dark photon that mediates DM self-interactions and decays into massless dark fermions. The dark photon and dark fermions suppress linear matter perturbations, resulting in dark acoustic oscillations in P(k), which ultimately affect dwarf galaxy scales. The model also features a velocity-dependent elastic self-interaction between DM particles (SIDM), with a cross section that can alleviate small-scale structure anomalies. For the first time, our simulations test the impact of P(k) suppression on gravothermal evolution in an SIDM scenario that leads to core collapse in (sub)halos with present-day virial masses below ≍109 M⊙. In simulations with P(k) suppression and self-interactions, the lack of low-mass (sub)halos and the delayed growth of structure reduce the fraction of core-collapsed systems relative to SIDM simulations without P(k) suppression. In particular, P(k) suppression that saturates current warm DM constraints almost entirely erases core collapse in isolated halos. Models with less extreme P(k) suppression produce core collapse in ≍20% of subhalos and ≍5% of isolated halos above 108 M⊙, and also increase the abundance of extremely low-concentration isolated low-mass halos relative to SIDM. These results reveal a complex interplay between early and late-Universe DM physics, revealing new discovery scenarios in the context of upcoming small-scale structure measurements.

Keywords: Galaxy dark matter halos, Dark matter, N-body simulations
Another Piece to the Puzzle: Radio Detection of a JWST-detected Active Galactic Nucleus Candidate. Radio observations can provide crucial insight into the nature of a new abundant and mysterious population of dust-reddened active galactic nuclei (AGN) candidates discovered by the James Webb Space Telescope (JWST), including "Little Red Dots." In this study, we search for radio bright sources in a large sample of ∼700 JWST-discovered AGN candidates (z ∼ 2–11) in the 0.144–3 GHz frequency range, utilizing deep radio imaging in the Cosmic Evolution Survey and Great Observatories Origins Deep Survey North and South. Only one source, PRIMER-COS 3866 at z = 4.66, is significantly detected in our radio surveys, which has been previously identified as an X-ray AGN. Its radio properties are consistent with both an AGN and star formation origin with a spectral index of  α=‑0.76‑0.09+0.11 , radio-loudness of R ≈ 0.5, and brightness temperature limit of Tb ≳ 103 K. Our stacking results of both spectroscopically and photometrically selected AGN candidates yield nondetections in all fields, with 3σ limits of L1.4 GHz &lt; 8.6 × 1039 erg s‑1 (spectroscopic sample) and L1.3 GHz &lt; 1.3 × 1039 erg s‑1 (photometric sample). We demonstrate that these results are still consistent with expectations from the empirical LX–LHα and LX–LR correlations established for local AGN. We argue that current radio observations in these studied fields have insufficient depth to claim JWST-discovered AGN candidates are radio weak. We project that future surveys carried out by the Square Kilometer Array and Next Generation Very Large Array should be able to obtain significant detections within a few hours, providing crucial measurements of their brightness temperature, which would allow for distinguishing between AGN and starburst-driven origins of this new abundant population.

Keywords: Radio continuum emission, Active galactic nuclei, High-redshift galaxies, James Webb Space Telescope
Origins of Persistence in Energetic Neutral Atom Time Series from IBEX. Recently, we studied the persistence of energetic neutral atom (ENA) fluxes recorded by the Interstellar Boundary Explorer (IBEX) from the north and south polar regions by examining the correct time order for the 14 yr of IBEX data. Here, we further explore the origins of this persistence by comparing the time series of the ENA fluxes obtained from the near-Earth with the time series of the solar wind flow pressure at 1 au. To this end, we employ the detrended fluctuation analysis (DFA), a modern technique for characterizing the persistence of a time series. We show that even when removing all periodic trends from the flux time series, the remaining fluctuations exhibit DFA exponents compatible with those found for the solar wind pressure time series, indicating a causal relation between the two time series. The analysis was performed separately for the north and south poles, characterizing their anisotropy. Finally, we apply the DFA technique to the ENA time series of the polar spectral indices, an exponent related to the thermodynamic kappa and the stationary state of the source protons. This reveals that the plasma proton thermodynamics in both north and south polar regions share the same DFA persistence, despite the hemispheric asymmetry between the generated ENAs.

Keywords: Solar cycle, Heliosphere, Solar wind, Interstellar magnetic fields, Pickup ions, Interstellar medium, Solar activity, Heliosheath, Interdisciplinary astronomy, Time series analysis
Truncated Star Formation and Ram Pressure Stripping in the Coma Cluster. We use 45 galaxies from the Mapping Nearby Galaxies at Apache Point Observatory survey to study the physical drivers of star formation quenching in the Coma Cluster. We measure specific star formation rate (sSFR) radial profiles for the Coma sample as well as a control sample of noncluster field galaxies. We find that compared to the control sample, galaxies within the Coma Cluster have sSFR profiles that fall off more steeply with galactocentric radius. We then apply a toy model based on slow-then-rapid quenching via ram pressure stripping. We find that this model is able to reproduce the difference in sSFR profiles between field and Coma galaxies. These results demonstrate that ram pressure stripping plays a significant role in quenching star formation in the nearest massive galaxy cluster.

Keywords: Ram pressure stripped tails, Coma Cluster, Galaxy disks, Star formation, Galaxy quenching
Cosmology with One Galaxy: Autoencoding the Galaxy Properties Manifold. Cosmological simulations like CAMELS and IllustrisTNG characterize hundreds of thousands of galaxies using various internal properties. Previous studies have demonstrated that machine learning can be used to infer the cosmological parameter Ωm from the internal properties of even a single randomly selected simulated galaxy. This ability was hypothesized to originate from galaxies occupying a low-dimensional manifold within a higher-dimensional galaxy property space, which shifts with variations in Ωm. In this work, we investigate how galaxies occupy the high-dimensional galaxy property space, particularly the effect of Ωm and other cosmological and astrophysical parameters on the putative manifold. We achieve this by using an autoencoder with an information-ordered bottleneck, a neural layer with adaptive compression, to perform dimensionality reduction on individual galaxy properties from CAMELS simulations, which are run with various combinations of cosmological and astrophysical parameters. We find that for an autoencoder trained on the fiducial set of parameters, the reconstruction error increases significantly when the test set deviates from fiducial values of Ωm and ASN1, indicating that these parameters shift galaxies off the fiducial manifold. In contrast, variations in other parameters such as σ8 cause negligible error changes, suggesting galaxies shift along the manifold. These findings provide direct evidence that the ability to infer Ωm from individual galaxies is tied to the way Ωm shifts the manifold. Physically, this implies that parameters like σ8 produce galaxy property changes resembling natural scatter, while parameters like Ωm and ASN1 create unsampled properties, extending beyond the natural scatter in the fiducial model.

Keywords: Hydrodynamical simulations, Galaxy formation, Cosmological parameters, Cosmological models
Forming Prominences Accounting for Partial Ionization Effects. One of the most striking structures in the solar atmosphere are prominences, predominantly coronal structures, with thermodynamic conditions that vary from chromospheric internally to the corona that surrounds them. These structures play an important role in the energy transfer between all layers of the atmosphere. Although mostly studied as a fully ionized plasma, prominences are, in fact, composed of partially ionized plasma. We do not yet fully understand the extent to which the two-fluid plasma-neutral properties play a role in the evolution of these coronal structures. In this work, we explore for the very first time how prominence formation and growth in a coronal loop evolve in a two-fluid setting. We used MPI-AMRVAC to study the evaporation–condensation process, where we consider radiative cooling, thermal conduction, and localized heating in a coronal loop in a fully stratified atmosphere. We report on the differences the two-fluid plasma brings into the prominence evolution and more specifically in the period after the dynamic formation process finishes. Furthermore, we highlight the role it plays during the linear and the nonlinear phases of the evolution. We find pronounced two-fluid effects in shocks that appear with the first complete condensation and confirm decoupling effects in the prominence–corona transition region on the order of 100 m s‑1, consistent with observations.

Keywords: Plasma physics, Solar prominences, Magnetohydrodynamical simulations
Detection Prospects of Electromagnetic Signatures from OGLE-2011-BLG-0462. Stellar-mass isolated black holes wandering in the interstellar medium are expected to be abundant in our Galaxy. Recently, an isolated free floating black hole (IsoBH), OGLE-2011-BLG-0462, was unambiguously discovered using astrometric microlensing. We examine prospects for detecting electromagnetic signatures from an accretion flow surrounding the IsoBH. The accretion rate onto the IsoBH should be highly sub-Eddington, which leads to formation of a hot accretion flow. In this paper, we evaluate the detectability of electromagnetic signals from the hot accretion flows in two accretion states: magnetically arrested disk (MAD) and classical radiatively inefficient accretion flows (RIAFs). For the MAD scenario, we find that the optical, infrared, and X-ray signals can be detectable by the current best facilities, such as the Hubble Space Telescope, JWST, and Chandra, if the IsoBH is in a warm neutral medium. In contrast, for the classical RIAF scenario, the optical and X-ray emissions are weaker than the MAD scenario, leading to unobservable signals for a typical parameter set. Future follow-up observations of OGLE-2011-BLG-0462 will provide a good test for theories of accretion processes.

Keywords: Accretion, Black holes, Bondi accretion, Non-thermal radiation sources, Astrophysical black holes
Submillimeterwave Spectroscopy of and Interstellar Search for Nitrosomethane: CH<SUB>3</SUB>NO. New measurements of nitrosomethane (CH3NO), a formamide isomer, were done up to 660 GHz. The molecule exhibits internal rotation motion from the CH3 group, and therefore the analysis with a dedicated rho-axis method code, RAM36, was used. A total of 2035 lines for vt = 0 and 1 states of A and E symmetries were fitted with an rms deviation of 41.1 kHz, with the maximum quantum numbers values J = 30 and Ka = 15. Using these new data, CH3NO was searched in the cold dark cloud Taurus Molecular Cloud 1 as well as the high mass star-forming regions Sgr B2(N) and NGC 6334I. CH3NO was not observed in any of the sources, 3σ column density upper limits were determined, and we discuss the implications for the chemistry of CH3NO in the interstellar medium. The accurate spectroscopic prediction of its spectra provided in this work will allow astronomers to continue the search of CH3NO in other interstellar sources.

Keywords: Astrochemistry
Unprecedented Continuum Time Delay Variation Phenomenon in an Active Supermassive Black Hole. Resolving the accretion disks and broad-line regions of active galactic nuclei (AGNs) can probe the physics behind supermassive black hole (SMBH) fueling and weigh SMBHs. With time-domain observations, the reverberation mapping (RM) technique measures time delays between different light curves, probing the AGN inner structures that are otherwise often too compact to resolve spatially with current facilities. Theoretically, the SMBH accretion disk structure does not evolve over decades. Here we report the significant variations in the continuum time delays of NGC 4151. In the high-flux state, our high-cadence (∼2 days) spectroscopy reveals that continuum time delays are  3.8‑1.0+1.8  times larger than those in the low-flux state and 14.9 ± 2.0 times longer than the classical standard thin-disk prediction. Notably, the continuum time delays can be comparable to the time delay between Hβ and the 5100 Å continuum, and the latter is commonly used to calculate the BLR sizes. Hence, the BLR sizes are underestimated if the continuum time delays are not considered, which introduces ∼0.3 dex systematic uncertainties on RM SMBH masses. Our findings underscore that simultaneous continuum and BLR RMs are vital for better deciphering the SMBH accretion and mass function.

Keywords: Accretion, Supermassive black holes, Reverberation mapping, Active galactic nuclei
A MARVEL-ous Study of How Well Galaxy Shapes Reflect Dark Matter Halo Shapes in Cold Dark Matter Simulations. We present a 3D shape analysis of both dark matter (DM) and stellar matter (SM) in simulated dwarf galaxies to determine whether stellar shape traces DM shape. Using 80 central and satellite dwarf galaxies from three simulation suites ("Marvelous Massive Dwarfs," "Marvelous Dwarfs," and the "DC Justice League") spanning stellar masses of 106–1010 M⊙, we measure 3D shapes through the moment of inertia tensor at twice the effective radius to derive axis ratios (C/A and B/A) and triaxiality. We find that stellar shape does follow DM halo shape for our dwarf galaxies. However, the presence of a stellar disk in more massive dwarfs (M* ≳ 107.5 M⊙) pulls the distribution of stellar C/A ratios to lower values, while in lower-mass galaxies the gravitational potential remains predominantly shaped by DM. Similarly, stellar triaxiality generally tracks DM triaxiality, with this relationship being particularly strong for nondisky galaxies and weaker in disky systems. These correlations are reinforced by strong alignment between the SM and DM axes, particularly in disk galaxies. Further, we find no detectable difference in either SM or DM shapes when comparing two different supernova feedback implementations, demonstrating that shape measurements are robust to different implementations of baryonic feedback in dwarf galaxies. We also observe that a dwarf galaxy's shape is largely unperturbed by recent mergers. This comprehensive study demonstrates that stellar shape measurements can serve as a reliable tool for inferring DM shapes in dwarf galaxies.

Keywords: Hydrodynamical simulations, Galaxy dark matter halos, Cold dark matter, Dwarf galaxies, Dark matter, Galaxy structure, Baryonic dark matter, N-body simulations
Cracking the Relation Between Mass and 1P-star Fraction of Globular Clusters. III. Initial Distributions of In Situ and Ex Situ Clusters. Galactic globular clusters consist of two main stellar populations, the pristine (1P) and polluted (2P) stars. The fraction of 1P stars in clusters, F1P, is a decreasing function of the present-day cluster mass, mprst. The information about cluster formation it contains has yet to be unlocked. Paper I demonstrated that the observed distribution (mprst, F1P) of Galactic globular clusters can result from a pristine-star fraction that is inversely proportional to their birth mass, mecl. This relation was then calibrated with a fixed stellar mass threshold for 2P-star formation, mth, i.e., F1P = mth/mecl. We now estimate the masses minit of Galactic globular clusters as they start their long-term gas-free evolution in the Galaxy and we map their behavior in the (minit, F1P) space. Several dissolution timescales are tested (with and without primordial mass segregation), each yielding its own initial cluster distribution (minit, F1P). The (minit, F1P) distributions are mapped according to cluster origin, with the emphasis on the Disk, Low-Energy and Gaia-Enceladus cluster groups of D. Massari et al. All three initial distributions (minit, F1P) are more compact than their present-day counterparts since dynamical evolution scatters clusters in the F1P versus cluster-mass space. The Disk initial distribution is the tightest one and potential reasons for this are discussed. Its power-law representation allows us to generalize the initial mass threshold of Paper I and prompts us to represent the cluster (mass, F1P) distribution in a log–log space. No evidence is found suggesting that, initially, the pristine-star fraction of globular clusters depends on their metallicity on top of their mass.

Keywords: Globular star clusters, Stellar populations, Stellar dynamics, Chemical abundances, Chemical enrichment, Population II stars, Magellanic Clouds, Milky Way Galaxy
Martian Dynamo Change at ∼4.1 Ga: Evidence from the Magnetic Measurements of the Iota Crater. The Martian dynamo evolution is critical for understanding Mars's interior structure, thermal evolution, and climate change. It has been inferred to shut down at ∼4.1–4.0 Ga based on the magnetic signatures of large impact craters, but be present at ∼3.9 Ga and ∼3.7 Ga from the paleomagnetic studies and magnetic fields above volcanic units. Here, we investigate the magnetic signatures of the Iota crater, located inside the CT3-G area with a centrally strong magnetic anomaly. The Iota crater shows a weak central magnetic field with an inside-outside strength ratio of 0.39. Forward modeling is established to explore the relationship between the magnetic field signatures of craters and the magnetization caused by impact. The results show that the average magnetization of the retained materials beneath the Iota crater is about 20% of the maximum of the surroundings, indicating that the dynamo strength at that time became weak. The magnetic signatures of Iota and CT3-G reveal that the Martian dynamo decayed at ∼4.1 Ga, but did not stop completely.

Keywords: Magnetic anomalies, Mars, Impact phenomena