adsabs/SciX_UAT_keywords huggingface dataset:
Dying of the Light: An X-Ray Fading Cold Quasar at z ∼ 0.405

Cold quasars are a rare subpopulation observed to host unobscured, X-ray luminous active galactic nuclei (AGN) while also retaining a cold gas supply fueling high star formation rates. These objects are interpreted as AGN early in their evolution. We present new SOFIA HAWC+ far-infrared observations, far-ultraviolet to far-infrared (FUV-FIR) photometry, and optical spectroscopy to characterize the accretion and star formation behavior in a cold quasar at z ∼ 0.405 (CQ 4479). CQ 4479 is a starburst galaxy with a predominantly young stellar population and a high gas mass fraction of ∼50%-70%. The AGN component has yet to become the dominant component of the FIR emission. We also find AGN bolometric luminosity that varies as a function of observation method and AGN region probed. Finally, we identify a candidate outflow feature corroborating the hypothesis that cold quasars have energetic feedback. This object presents an intriguing look into the early stages of AGN feedback and probes the rare phase where an AGN and cold gaseous component coexist.

Keywords: active galactic nuclei; infrared excess galaxies; galaxy evolution; galaxy quenching; x-ray quasars
Probing Multiple Populations of Compact Binaries with Third-generation Gravitational-wave Detectors

Third-generation (3G) gravitational-wave detectors will be able to observe binary black hole mergers (BBHs) up to a redshift of ∼30. This gives unprecedented access to the formation and evolution of BBHs throughout cosmic history. In this paper, we consider three subpopulations of BBHs originating from the different evolutionary channels: isolated formation in galactic fields, dynamical formation in globular clusters, and mergers of black holes formed from Population III (Pop III) stars at very high redshift. Using input from population synthesis analyses, we create 2 months of simulated data of a network of 3G detectors made of two Cosmic Explorers and one Einstein Telescope consisting of ∼16,000 field and cluster BBHs, as well as ∼400 Pop III BBHs. First, we show how one can use a nonparametric model to infer the existence and characteristics of a primary and secondary peak in the merger rate distribution as a function of redshift. In particular, the location and height of the secondary peak around z ≈ 12, arising from the merger of Pop III remnants, can be constrained at the ${ \mathcal O }(10 \% )$ level (95% credible interval). Then we perform a modeled analysis using phenomenological templates for the merger rates of the three subpopulations and extract the branching ratios and characteristic parameters of the merger rate densities of the individual formation channels. With this modeled method, the uncertainty on the measurement of the fraction of Pop III BBHs can be improved to ≲10%, while the ratio between field and cluster BBHs can be measured with an uncertainty of ∼100%.

Keywords: gravitational waves; gravitational wave sources; gravitational wave astronomy
NEID Reveals That the Young Warm Neptune TOI-2076 b Has a Low Obliquity

TOI-2076 b is a sub-Neptune-sized planet (R = 2.39 ± 0.10 R ⊕) that transits a young (204 ± 50 MYr) bright (V = 9.2) K-dwarf hosting a system of three transiting planets. Using spectroscopic observations obtained with the NEID spectrograph on the WIYN 3.5 m Telescope, we model the Rossiter-McLaughlin effect of TOI-2076 b, and derive a sky-projected obliquity of $\lambda =-{3}_{-15}^{+16^\circ }$ . Using the size of the star (R = 0.775 ± 0.015 R ⊙), and the stellar rotation period (P rot = 7.27 ± 0.23 days), we estimate an obliquity of $\psi ={18}_{-9}^{+10^\circ }$ (ψ < 34° at 95% confidence), demonstrating that TOI-2076 b is in a well-aligned orbit. Simultaneous diffuser-assisted photometry from the 3.5 m telescope at Apache Point Observatory rules out flares during the transit. TOI-2076 b joins a small but growing sample of young planets in compact multi-planet systems with well-aligned orbits, and is the fourth planet with an age ≲300 Myr in a multi-transiting system with an obliquity measurement. The low obliquity of TOI-2076 b and the presence of transit timing variations in the system suggest the TOI-2076 system likely formed via convergent disk migration in an initially well-aligned disk.

Keywords: exoplanet dynamics; exoplanet astronomy; radial velocity; transit photometry; exoplanets; mini neptunes; exoplanet evolution
Negative Cosmic Evolution of BL Lac Objects from the Sloan Digital Sky Survey

BL Lacertae (BL Lac) objects are a type of active galactic nucleus (AGN) characterized by featureless optical spectra, where a relativistic jet is oriented toward the observer. By studying BL Lacs objects, we improve our understanding of accretion processes, high-energy particle acceleration, magnetic field structures in extreme environments, and galaxy formation and evolution. Generally, luminous AGNs (i.e., quasars) exhibit "positive" evolution. This means that, on average, quasars are more numerous and/or more luminous in the early Universe, at higher redshifts, than they are today. However, the evolution of BL Lacs has been long disputed, in part due to selection biases and small sample sizes. Here we perform the luminosity–volume test of BL Lac evolution on a uniformly selected sample and find that BL Lacs instead exhibit mild negative evolution. We conclude by putting our results into context with previous studies on BL Lac evolution.

Keywords: blazars; bl lacertae objects; cosmological evolution
Rubin Observatory's Survey Strategy Performance for Tidal Disruption Events

Tidal disruption events (TDEs) are rare transients, which are considered as promising tools for probing supermassive black holes in quiescent galaxies. The majority of the ≈60 known TDEs have been discovered with time-domain surveys in the last two decades. Currently, ≈10 TDEs are discovered per year, and this number will increase with the Legacy Survey of Space and Time (LSST) at the Rubin Observatory. This work evaluates LSST survey strategies in view of their performance in identifying TDEs. We assume that TDEs can be identified photometrically based on their colors, particularly in the u band, and will be scientifically useful if we can detect the light-curve peak to derive physical quantities. We define the requirements for the Rubin light curves that are needed to achieve this (detections prepeak, postpeak, and in different bands to measure color). We then inject model light curves into the Operations Simulator and calculate the fractions of TDEs passing our requirements for several strategies. We find that under the baseline strategy, ≈1.5% of simulated TDEs fulfill our detection criteria, while this number increases when more time is devoted to u-band observations. An ideal observing strategy for the photometric identification of TDEs would have longer u-band exposures, which should not come at the expense of fewer u-band visits. A filter distribution weighted toward more observing time in bluer bands, intranight visits in different filters, and strategies with frequent sampling leading to higher-quality light curves are preferred. We find that these strategies benefiting TDE science do not impact significantly other science cases.

Keywords: tidal disruption; surveys; black holes
Compton Scattering of Electrons in the Intergalactic Medium

This paper investigates the distribution and implications of cosmic-ray electrons within the intergalactic medium (IGM). Utilizing a synthesis model of the extragalactic background, we evolve the spectrum of Compton-included cosmic rays. The energy density distribution of cosmic-ray electrons peaks at redshift z ≈ 2, and peaks in the ∼MeV range. The fractional contribution of cosmic-ray pressure to the general IGM pressure progressively increases toward lower redshift. At mean density, the ratio of cosmic-ray electron to thermal pressure in the IGM ${P}_{\mathrm{CRe}}/{P}_{\mathrm{th}}$ is 0.3% at z = 2, rising to 1.0% at z = 1, and 1.8% at z = 0.1 (considering only the cosmic rays produced locally by Compton scattering). We compute the linear Landau damping rate of plasma oscillations in the IGM caused by the ∼MeV cosmic-ray electrons, and find it to be of order ∼10‑6 s‑1 for wavenumbers 1.2 ≲ ck/ω p ≲ 5 at z = 2 and mean density (where ω p is the plasma frequency). This strongly affects the fate of TeV e + e ‑ pair beams produced by blazars, which are potentially unstable to oblique instabilities involving plasma oscillations with wavenumber ${ck}/{\omega }_{{\rm{p}}}\approx \sec \theta $ (θ being the angle between the beam and wavevector). Linear Landau damping is at least thousands of times faster than either pair beam instability growth or collisional effects; it thus turns off the pair beam instability except for modes with very small θ (ck/ω p → 1, where linear Landau damping is kinematically suppressed). This leaves open the question of whether the pair beam instability is turned off entirely, or can still proceed via the small-θ modes.

Keywords: cosmic rays; intergalactic gas; cosmic magnetic fields theory
Lunar Orbit Measurement of the Cosmic Dawn's 21 cm Global Spectrum

A redshifted 21 cm line absorption signature is commonly expected from the cosmic dawn era, when the first stars and galaxies formed. The detailed traits of this signal can provide important insight on the cosmic history. However, high-precision measurement of this signal is hampered by ionosphere refraction and absorption, as well as radio frequency interference (RFI). Space observation can solve the problem of the ionosphere, and the Moon can shield the RFI from Earth. In this paper, we present simulations of the global spectrum measurement in the 30-120 MHz frequency band on the lunar orbit from the proposed Discovering the Sky at the Longest wavelength project. In particular, we consider how the measured signal varies as the satellite moves along the orbit and take into account the blockage of different parts of the sky by the Moon and the antenna response. We estimate the sensitivity for such a 21 cm global spectrum experiment. An rms noise level of ≤0.05 K is expected at 75 MHz after 10 orbits (~1 day) observation, for a frequency channel width of 0.4 MHz. We also study the influence of a frequency-dependent beam, which may generate complex structures in the spectrum. Estimates of the uncertainties in the foreground and 21 cm model parameters are obtained.

Keywords: observational cosmology; h i line emission; reionization; radio telescopes; space telescopes
Gravitational Instability, Spiral Substructure, and Modest Grain Growth in a Typical Protostellar Disk: Modeling Multiwavelength Dust Continuum Observations of TMC1A

Embedded class 0/I protostellar disks represent the initial condition for planet formation. This calls for a better understanding of their bulk properties and the dust grains within them. We model multiwavelength dust continuum observations of the disk surrounding the class I protostar TMC1A to provide insight on these properties. The observations can be well fit by a gravitationally self-regulated (i.e., marginally gravitationally unstable and internally heated) disk model with surface density Σ ~ 1720(R/10 au)-1.96 g cm-2 and midplane temperature T mid ~ 185(R/10 au)-1.27 K. The observed disk contains an m = 1 spiral substructure; we use our model to predict the spiral's pitch angle, and the prediction is consistent with the observations. This agreement serves as both a test of our model and strong evidence of the gravitational nature of the spiral. Our model estimates a maximum grain size ${a}_{\max }\sim 196{(R/10\,\mathrm{au})}^{-2.45}\mu {\rm{m}}$ , which is consistent with grain growth being capped by a fragmentation barrier with a threshold velocity of ~1 m s-1. We further demonstrate that the observational properties of TMC1A are typical among the observed population of class 0/I disks, which hints that traditional methods of disk data analysis based on Gaussian fitting and the assumption of optically thin dust emission could have systematically underestimated the disk size and mass and overestimated the grain size.

Keywords: protoplanetary disks; gravitational instability; dust continuum emission; astronomy data modeling; planet formation
The Aligned Orbit of a Hot Jupiter around the M Dwarf TOI-4201

Measuring the obliquities of stars hosting giant planets may shed light on the dynamical history of planetary systems. Significant efforts have been made to measure the obliquities of FGK stars with hot Jupiters, mainly based on observations of the Rossiter–McLaughlin effect. In contrast, M dwarfs with hot Jupiters have hardly been explored because such systems are rare and often not favorable for such precise observations. Here, we report the first detection of the Rossiter–McLaughlin effect for an M dwarf with a hot Jupiter, TOI-4201, using the Gemini-North/MAROON-X spectrograph. We find TOI-4201 to be well aligned with its giant planet, with a sky-projected obliquity of and a true obliquity of with an upper limit of 40◦ at a 95% confidence level. The result agrees with dynamically quiet formation or tidal obliquity damping that realigned the system. As the first hot Jupiter around an M dwarf with its obliquity measured, TOI-4201b joins the group of aligned giant planets around cool stars (T eff < 6250 K), as well as the small but growing sample of planets with relatively high planet-to-star mass ratio (M p /M * ≳ 3 × 10‑3) that also appear to be mostly aligned.

Keywords: planetary alignment; exoplanet dynamics; star-planet interactions; exoplanets; m dwarf stars; hot jupiters
The Tidal Clock Effects of the Lunisolar Gravitational Field and the Earth's Tidal Deformation

State-of-the-art atomic and optical clocks have the great potential to precisely test fundamental physical assumptions and enhance our understanding of nature. Their widespread applications require us to rigorously deduce the relativistic frequency shift in the framework of general relativity. One interesting question for clocks is tidal field effect which contains variously periodic variations. By introducing tidally deformed Earth, the general algorithms for clock and frequency comparisons are derived. We investigate the effects of external gravitational bodies and Earth's tidal deformation on the ground- and space-based clocks. The orbital elements of satellite and locations of laboratory are introduced for corresponding clocks, in which the secular and long-period terms and short-period terms are subsequently presented. These effects called tidal clock effects produce the non-negligible contributions in the modern clock experiments and can be directly evaluated from our parameterized formulas. In addition, we also demonstrate for tidal clock effects the position and distance dependences, as well as periodicity. These tidal effects and dependences can provide valuable information for the clock comparison experiments.

Keywords: tidal interaction; earth-moon system; the sun; solar system; artificial satellites
Updated Transfer Coefficients for Magnetized Plasmas

Accurate radiative transfer coefficients (emissivities, absorptivities, and rotativities) are needed for modeling radiation from relativistically hot, magnetized plasmas such as those found in Event Horizon Telescope sources. Here we review, update, and correct earlier work on radiative transfer coefficients. We also describe an improved method for numerically evaluating rotativities and provide convenient fitting formulae for the relativistic κ distribution of electron energies.

Keywords: radiative transfer; polarimetry; plasma astrophysics; radiative processes; relativistic disks
The Influence of β-decay Rates on r-process Observables

The rapid neutron capture process (r-process) is one of the main mechanisms whereby elements heavier than iron are synthesized, and is entirely responsible for the natural production of the actinides. Kilonova emissions are modeled as being largely powered by the radioactive decay of species synthesized via the r-process. Given that the r-process occurs far from nuclear stability, unmeasured beta-decay rates play an essential role in setting the timescale for the r-process. In an effort to better understand the sensitivity of kilonova modeling to different theoretical global beta-decay descriptions, we incorporate these into nucleosynthesis calculations. We compare the results of these calculations and highlight differences in kilonova nuclear energy generation and light-curve predictions, as well as final abundances and their implications for nuclear cosmochronometry. We investigate scenarios where differences in beta-decay rates are responsible for increased nuclear heating on timescales of days that propagates into a significantly increased average bolometric luminosity between 1 and 10 days post-merger. We identify key nuclei, both measured and unmeasured, whose decay rates directly impact nuclear heating generation on timescales responsible for light-curve evolution. We also find that uncertainties in beta-decay rates significantly impact age estimates from cosmochronometry.

Keywords: r-process; nucleosynthesis; neutron stars; compact objects; nuclear astrophysics
Plasma β Dependence of Density, Temperatures, and Magnetic-field Correlations of Mirror Structures: Observation and Theory

The mirror structures identified by the depressed or enhanced magnetic field associated with the enhanced or depressed plasma density are widely observed in the solar system plasma. These structures are generated by the mirror instability as a result of sufficiently large temperature anisotropy of T⊥ > T∥. Here, T⊥ and T∥ are, respectively, to be the temperatures perpendicular and parallel to the magnetic field and β = p/(B2/2μ0). Two important observed characteristics are the uneven density-magnetic field compressibility, defined as ${C}_{\rho ,B}=(\delta \rho /\rho)/(\delta B/B)$ , among the various mirror events, and the anticorrelation between the temperatures and magnetic field. This study first shows two mirror structures observed in the magnetosheath with distinct β and ${C}_{\rho ,B}$ . Specifically, β ∼ 6.67, ${C}_{\rho ,B}\sim -0.23$ and β ∼ 1.44, ${C}_{\rho ,B}\sim -0.67$ . The linear kinetic theory is adopted to derive the phase relations for the mirror instability which show an inverse relation between ${C}_{\rho ,B}$ and ${C}_{{T}_{\perp },B}=(\delta {T}_{\perp }/{T}_{\perp })/(\delta B/B)$ , which are negative for various parameter values, and β. While the correlation ${C}_{{T}_{\parallel },B}=(\delta {T}_{\parallel }/{T}_{\parallel })/(\delta B/B)$ may be negative or positive for the mirror unstable and stable parameter regimes, respectively. The theoretical analyses are consistent with the observational results that δT⊥δB < 0 for both events and δT∥δB < 0 is more pronounced for the high β case. The statistical analysis results are summarized by the relationships between ${C}_{\rho ,B}$ , ${C}_{{T}_{\perp },B}$ , ${C}_{{T}_{\parallel },B}$ , and β for six mirror wave events that show high agreements between the observations and theory.

Keywords: space plasmas; planetary magnetospheres; solar wind; alfven waves; plasma physics
The Mid-infrared Instrument for JWST and Its In-flight Performance

The Mid-Infrared Instrument (MIRI) extends the reach of the James Webb Space Telescope (JWST) to 28.5 μm. It provides subarcsecond-resolution imaging, high sensitivity coronagraphy, and spectroscopy at resolutions of λ/Δλ ~ 100-3500, with the high-resolution mode employing an integral field unit to provide spatial data cubes. The resulting broad suite of capabilities will enable huge advances in studies over this wavelength range. This overview describes the history of acquiring this capability for JWST. It discusses the basic attributes of the instrument optics, the detector arrays, and the cryocooler that keeps everything at approximately 7 K. It gives a short description of the data pipeline and of the instrument performance demonstrated during JWST commissioning. The bottom line is that the telescope and MIRI are both operating to the standards set by pre-launch predictions, and all of the MIRI capabilities are operating at, or even a bit better than, the level that had been expected. The paper is also designed to act as a roadmap to more detailed papers on different aspects of MIRI.

Keywords: space vehicle instruments; astronomical instrumentation
Fermi-bubble Bulk and Edge Analysis Reveals Dust, Cooling Breaks, and Cosmic-Ray Diffusion, Facilitating a Self-consistent Model

The full, radio to γ-ray spectrum of the Fermi bubbles is shown to be consistent with standard strong-shock electron acceleration at the bubble edge, without the unnatural energy cutoffs and unrealistic electron cooling of previous studies, if the ambient interstellar radiation is strong; the γ-ray cooling break should then have a microwave counterpart, undetected until now. Indeed, a broadband bubble-edge analysis uncovers a pronounced downstream dust component, which masked the anticipated ∼35 GHz spectral break, and the same overall radio softening consistent with Kraichnan diffusion previously reported in γ-rays. A self-consistent bulk and edge model implies a few Myr old bubbles, with fairly uniform radiation fields and enhanced magnetization near the edge.

Keywords: galactic cosmic rays; milky way magnetic fields; spectral index; infrared astronomy; radio continuum emission; dust continuum emission; gamma-ray astronomy
New Chondritic Bodies Identified in Eight Oxygen-bearing White Dwarfs

We present observations and analyses of eight white dwarf stars (WDs) that have accreted rocky material from their surrounding planetary systems. The spectra of these helium-atmosphere WDs contain detectable optical lines of all four major rock-forming elements (O, Mg, Si, and Fe). This work increases the sample of oxygen-bearing WDs with parent body composition analyses by roughly 33%. To first order, the parent bodies that have been accreted by the eight WDs are similar to those of chondritic meteorites in relative elemental abundances and oxidation states. Seventy-five percent of the WDs in this study have observed oxygen excesses implying volatiles in the parent bodies with abundances similar to those of chondritic meteorites. Three WDs have oxidation states that imply more reduced material than found in CI chondrites, indicating the possible detection of Mercury-like parent bodies, but are less constrained. These results contribute to the recurring conclusion that extrasolar rocky bodies closely resemble those in our solar system, and do not, as a whole, yield unusual or unique compositions.

Keywords: exoplanet astronomy; db stars; white dwarf stars; exoplanets