adsabs/SciX_UAT_keywords huggingface dataset:
The Luminosity-Area Relation of z > 2 Quasars' Lyα Nebulae

Cool (T ~ 104 K) gas is commonly observed around z > 2 quasars as traced by extended Lyα emission. These large-scale nebulae are usually studied using circularly averaged surface-brightness profiles, which suppress information on morphological differences. Here, we revisit the Lyα nebulae around 78 z ~ 2-3 quasars to obtain a novel estimate of their area and asymmetry using a common redshift-corrected surface-brightness threshold. We find a luminosity-area relation of the form $\mathrm{log}({L}_{\mathrm{Ly}\alpha }^{\mathrm{Neb}})={a}_{1}\mathrm{log}({\mathrm{Area}}^{\mathrm{Neb}})+{a}_{0}$ . Most nebulae are symmetric and bright, the most lopsided ones being the faintest and less extended. The enormous Lyα nebulae, asymmetric due to the presence of active companions, are the exceptions to this trend. By using simulations able to reproduce z ~ 6 quasars' nebulae, we show that the observed relation should not vary with redshift. Finally, we discuss possible mechanisms that drive the relation and future work needed to constrain them.

Keywords: quasars; circumgalactic medium; high-redshift galaxies; extended radiation sources
On the Encounter between the GASP Galaxy JO36 and the Radio Plume of GIN 049

We report the serendipitous discovery of an unprecedented interaction between the radio lobe of a radio galaxy and a spiral galaxy. The discovery was made thanks to LOFAR observations at 144 MHz of the galaxy cluster A160 (z = 0.04317) provided by the LOFAR Two-metre Sky Survey. The new low-frequency observations revealed that one of the radio plumes of the central galaxy GIN 049 overlaps the spiral galaxy JO36. Previous studies carried out with MUSE revealed that the warm ionized gas in the disk of JO36, traced by the Hα emission, is severely truncated with respect to the stellar disk. We further explore this unique system by including new uGMRT observations at 675 MHz to map the spectral index. The emerging scenario is that JO36 has interacted with the radio plume in the past 200-500 Myr. The encounter resulted in a positive feedback event for JO36 in the form of a star formation rate burst of ~14 M ⊙ yr-1. In turn, the galaxy passage left a trace in the radio-old plasma by reshaping the old relativistic plasma via magnetic draping.

Keywords: radio astronomy; radio galaxies; galactic and extragalactic astronomy; giant radio galaxies; fanaroff-riley radio galaxies; galaxy evolution
Optical Spectroscopic Observations of Gamma-ray Blazar Candidates. XI. Optical Observations from SOAR, Blanco, NTT and OAN-SPM. The Story So Far

Blazars represent about 62% of the sources in the γ-ray Fermi-LAT catalog, and about 80% of the γ-ray sources associated with a lower-energy counterpart, dominating the γ-ray sky. In particular, about 42% of the γ-ray blazars are classified as Blazars Candidates of Uncertain type (BCUs) for which spectroscopic observations are mandatory to confirm their blazar nature. Here we report the spectra of 64 targets observed as part of our follow-up optical spectroscopic campaign. This sample includes 62 sources classified in Fermi-LAT catalog as BCUs, one source classified as a generic active galactic nucleus, and one source classified as a BL Lac in Fermi-LAT and as blazar of uncertain type in the Roma-BZCAT catalog. We confirm the blazar nature of all BCUs. We classify 33 of them as BL Lacs, 11 as Flat Spectrum Radio Quasars, and 18 as blazars with nonnegligible host-galaxy emission. We also classify the generic active galactic nucleus as a BL Lac. Finally, we confirm the classification of the BL Lac. We also reported a lower limit redshift for 43 sources. For 20 sources, we got redshift measurements consistent with the literature values. For the other 21 sources, we obtained their first spectroscopic redshift measurement; while, for two sources, we provide lower limits on the redshift. With the upcoming release of the sixth edition of the Roma-BZCAT Multifrequency Catalog of Blazars, we take the opportunity in the present work to present the collective results of the first phase of our optical spectroscopic follow-up campaign.

Keywords: optical identification; blazars; bl lacertae objects; flat-spectrum radio quasars
Development of the MICADO Flat-field and Wavelength Calibration Unit: From Design to Prototyping

We describe the evolution and the analysis of the design that led to the development of the Flat-field and wavelength Calibration Unit (FCU) for the Multi-AO Imaging CAmera for Deep Observations (MICADO) instrument. MICADO will be one of the first light instruments of the Extremely Large Telescope. The FCU challenge in terms of calibration is related to the large size of the MICADO entrance and final focal plane, ∼200 mm × 200 mm. Such a focal plane scale and its segmentation in 3 × 3 detectors, require significant design modifications with respect to the calibration units of the current and past generation of instruments. The design analysis and ray tracing calculations are complemented with the test and verification of lab prototypes to assess the reliability of the FCU architecture in terms of flat-field illumination uniformity and signal to noise, spectral calibration line coverage and radial velocity stability of the wavelength solution provided to the instrument.

Keywords: fabry-perot interferometers; flux calibration
The First Robust Evidence Showing a Dark Matter Density Spike Around the Supermassive Black Hole in OJ 287

Black hole dynamics suggests that dark matter would redistribute near a supermassive black hole (SMBH) to form a density spike. However, no direct evidence of a dark matter density spike around an SMBH has been identified. In this Letter, we present the first robust evidence showing a dark matter density spike around an SMBH. We revisit the data of the well-known SMBH binary OJ 287 and show that the inclusion of the dynamical friction due to a dark matter density spike around the SMBH can satisfactorily account for the observed orbital decay rate. The derived spike index ${\gamma }_{\mathrm{sp}}={2.351}_{-0.045}^{+0.032}$ gives an excellent agreement with the value γ sp = 2.333 predicted by the benchmark model assuming an adiabatically growing SMBH. This provides a strong verification of the canonical theory suggested two decades ago modeling the gravitational interaction between collisionless dark matter and SMBHs.

Keywords: dark matter density; dark matter distribution
The Arizona Radio Observatory 1 mm Spectral Survey of the Hypergiant Star NML Cygni (215-285 GHz)

A sensitive (1σ rms ≤ 3 mK; 2 MHz resolution) 1 mm spectral survey (214.5-285.5 GHz) of the envelope of the oxygen-rich supergiant star NML Cygni (NML Cyg) has been conducted using the 10 m Submillimeter Telescope of the Arizona Radio Observatory. These data represent the first spectral line survey of NML Cyg and are complementary to a previous 1 mm survey of the envelope of a similar hypergiant, VY Canis Majoris (VY CMa). The complete NML Cyg data set is presented here. In the survey, 104 emission lines were observed, arising from 17 different molecules and 4 unidentified features. Many of the observed features have complex line profiles, arising from asymmetric outflows characteristic of hypergiant stars. While most of the lines in the survey arise from SiO, SO, SO2, and SiS, CO had the strongest emission. Five other C-bearing species are identified in the survey (HCN, CN, HCO+, CS, and HNC), demonstrating an active carbon chemistry despite the O-rich environment. Moreover, NS was observed, but not NO, although favorable transitions of both molecules lie in the surveyed region. Sulfur chemistry appears to be prominent in NML Cyg and plays an important role in the collimated outflows. The refractory species observed, NaCl and AlO, have narrow emission lines, indicating that these molecules do not reach the terminal expansion velocity. NaCl and AlO likely condense into dust grains at r < 50 R *. From NaCl, the chlorine isotope ratio was determined to be 35Cl/37Cl = 3.85 ± 0.30.

Keywords: circumstellar envelopes; hypergiant stars; millimeter astronomy; molecular spectroscopy; astrochemistry; stellar mass loss; stellar winds; stellar evolution; isotopic abundances
Polar Ice Accumulation from Volcanically Induced Transient Atmospheres on the Moon

Water ice exists at the lunar poles, but its origin, abundance, and distribution are not well understood. One potential source of water to the poles is the volcanic outgassing of volatiles from the lunar interior and subsequent condensation of erupted water vapor as surface ice. We investigate whether volcanic outgassing is a viable source for the accumulation of lunar polar water ice. We construct a model that accounts for volcanic outgassing, atmospheric escape to space, and surface ice accumulation over the period of peak lunar volcanic activity (4-2 Ga) and map the resulting water ice distribution and abundance using current surface temperature data from the Lunar Reconnaissance Orbiter. Our model suggests that ~41% of the total H2O mass erupted over this period could have condensed as ice in the polar regions, with thicknesses up to several hundreds of meters. The south pole accumulates roughly twice the ice mass of the north, and the southern deposits are thicker. Typical modeled eruptions generate collisional atmospheres with lifetimes of ~2500 yr. However, these atmospheres are episodic and generally do not persist between eruptions. Roughly 15% of an atmosphere's water vapor mass forms a frost on the lunar nightside, while the transient atmosphere persists. Our work suggests that the volcanically active period of the early Moon would have been punctuated by short-lived, collisional atmospheres that enabled the efficient sequestration of large quantities (8.2 × 1015 kg) of water ice at the poles and the temporary diurnal availability of water ice and vapor at all latitudes.

Keywords: lunar science; lunar atmosphere; polar caps; planetary polar regions; volcanoes
To Be or Not to Be: Alicante-8, a Cluster or Not?

Recent surveys have uncovered new young massive clusters that host dozens of red supergiants (RSGs) near the inner Galaxy. However, many of them have still not been fully studied. Using Very Large Telescope/X-shooter near-infrared spectra, we present the first radial velocity analysis for the putative members of the candidate RSG cluster Alicante-8. Our results show a large dispersion of radial velocities among the candidate member stars, indicating that Alicante-8 does not seem to be a real cluster, unlike Alicante-7 and Alicante-10, which are confirmed by the distribution of the radial velocities of their RSG members. Measuring the spectral indices reveals that the assumption that the candidate stars are RSGs was incorrect, leading to the misclassification of Alicante-8 as a candidate RSG cluster. Our results imply that spectral classification based on the widely used CO band at 2.3 μm alone is not a sufficient criterion, because both red giants and RSGs can attain similar CO equivalent widths, and that spectroscopic radial velocities are needed in order to confirm unambiguously the cluster membership.

Keywords: b supergiant stars; young massive clusters; radial velocity; galactic center
Probing Orbital Parameters of Gamma-Ray Binaries with TeV Light Curves

Gamma-ray binaries are binary systems in which the energy flux peaks in the gamma-ray energy band. They harbor a compact object (a neutron star or a black hole) orbiting around a massive star, which provides a strong radiation field. It is believed that the gamma-ray emission from such objects can be strongly attenuated through the electron-positron pair production in gamma-gamma interactions. The importance of gamma-gamma absorption depends on the orbital phase and on the geometry of the system. In this work, we propose a method showing how the orbital parameters of gamma-ray binaries could be probed with TeV light curves that have imprinted features of gamma-gamma absorption.

Keywords: gamma-ray sources; pulsars; non-thermal radiation sources; binary stars; companion stars
A Catalog of M-dwarf Flares with ASAS-SN

We analyzed the light curves of 1376 early-to-late, nearby M dwarfs to search for white-light flares using photometry from the All-Sky Automated Survey for Supernovae. We identified 480 M dwarfs with at least one potential flare employing a simple statistical algorithm that searches for sudden increases in V-band flux. After more detailed evaluation, we identified 62 individual flares on 62 stars. The event amplitudes range from 0.12 lt; Δ V < 2.04 mag. Using classical flare models, we place lower limits on the flare energies and obtain V-band energies spanning 2.0× 1030 ≲ EV ≲ 6.9× 1035 erg. The fraction of flaring stars increases with spectral type, and most flaring stars show moderate to strong Hα emission. Additionally, we find that 14 of the 62 flaring stars are rotational variables, and they have shorter rotation periods and stronger Hα emission than nonflaring rotational variable M dwarfs.

Keywords: red dwarf flare stars; low mass stars; stellar activity; stellar rotation
Correlating Changes in Spot Filling Factors with Stellar Rotation: The Case of LkCa 4

We present a multi-epoch spectroscopic study of LkCa 4, a heavily spotted non-accreting T Tauri star. Using SpeX at NASA's Infrared Telescope Facility (IRTF), 12 spectra were collected over five consecutive nights, spanning ≈1.5 stellar rotations. Using the IRTF SpeX Spectral Library, we constructed empirical composite models of spotted stars by combining a warmer (photosphere) standard star spectrum with a cooler (spot) standard weighted by the spot filling factor, f spot. The best-fit models spanned two photospheric component temperatures, T phot = 4100 K (K7V) and 4400 K (K5V), and one spot component temperature, T spot = 3060 K (M5V) with an A V of 0.3. We find values of f spot to vary between 0.77 and 0.94 with an average uncertainty of ~0.04. The variability of f spot is periodic and correlates with its 3.374 day rotational period. Using a mean value for f mean spot to represent the total spot coverage, we calculated spot corrected values for T eff and L ⋆. Placing these values alongside evolutionary models developed for heavily spotted young stars, we infer mass and age ranges of 0.45-0.6 M ⊙ and 0.50-1.25 Myr, respectively. These inferred values represent a twofold increase in the mass and a twofold decrease in the age as compared to standard evolutionary models. Such a result highlights the need for constraining the contributions of cool and warm regions of young stellar atmospheres when estimating T eff and L ⋆ to infer masses and ages as well as the necessity for models to account for the effects of these regions on the early evolution of low-mass stars.

Keywords: t tauri stars; star formation; early stellar evolution; starspots; pre-main sequence stars; stellar evolutionary tracks
Time Delay between Outer Heliosheath Crossing and Observation of Interstellar Neutral Atoms

In situ measurements of the heliospheric particle populations by the Voyager spacecraft can only be put in an appropriate context with remote-sensing observations of energetic and interstellar neutral atoms (ENAs and ISN, respectively) at 1 au when the time delay between the production and the observation times is taken into account. ENA times of flight from the production regions in the heliosheath are relatively easy to estimate because these atoms follow almost constant speed, force-free trajectories. For the ISN populations, dynamical and ballistic selection effects are important, and times of flight are much longer. We estimate these times for ISN He and H atoms observed by IBEX and in the future by IMAP using the WTPM model with synthesis method. We show that for the primary population atoms, the times of flight are on the order of three solar cycle periods, with a spread equivalent to one solar cycle. For the secondary populations, the times of flight are on the order of ten solar cycle periods, and during the past ten years of observations, IBEX has been collecting secondary He atoms produced in the outer heliosheath during almost the entire 19th century. ISN atoms penetrating the heliopause at the time of Voyager crossing will become gradually visible about 2027, during the planned IMAP observations. Hypothetical variations in the ISN flow in the Local Interstellar Medium are currently not detectable. Nevertheless, we expect steady-state heliosphere models used with appropriately averaged solar wind parameters to be suitable for understanding the ISN observations.

Keywords: heliosphere; heliosheath; astrosphere interstellar medium interactions; heliopause; stellar wind bubbles
Accretion of Meteoric Organic Matter at the Surface of Mars and Potential Production of Methane by Ultraviolet Radiation

In this study, a comprehensive model of the meteoric organic cycle on Mars for the current geological period is developed, which characterizes the ablation of exogenous organic matter in the upper atmosphere, the accretion of intact carbon at the surface, and the potential production of methane by UV photolysis from the surface reservoir. The model accounts for both the latitudinal and seasonal variation of the meteoroids' input from the most relevant populations in the inner solar system. A recent version of the University of Leeds Chemical Ablation Model, which includes a semiempirical model to describe the pyrolysis kinetics of the meteoric organic matter, is then combined with this meteoroid input function and a semiempirical model that quantifies the UV production of methane. The minimum and maximum accretion rates of organics are between 18 and 90 kg sol‑1 at aphelion and 45–134 kg sol‑1 at the first crossing of the ecliptic plane. The resulting mixing ratios of carbon, in the top 200 μm of the surface layer, range from 0.09–0.43 ppm at 20°N to 4.8–8.9 ppm around the south pole. To be consistent with the methane upper limit of 0.02 ppbv measured by the NOMAD instrument on the ExoMars Trace Gas Orbiter, the UV photolysis yields for methane production need to be around 3% assuming a meteoric carbon content in comets of 25.6 wt% and an atmospheric lifetime of methane of 329 Earth yr. Alternatively, a laboratory estimate of 20% for the methane production yield would require a lifetime of 60 Earth yr.

Keywords: mars; meteoroids; meteors; meteorites; meteorite composition; comets; asteroid belt; long period comets; methane; complex organic molecules; zodiacal cloud; short period comets
Kepler K2 and TESS Observations of Two Magnetic Cataclysmic Variables: The New Asynchronous Polar SDSS J084617.11+245344.1 and Paloma

There have been relatively few published long-duration, uninterrupted light curves of magnetic cataclysmic variable stars in which the accreting white dwarf's rotational frequency is slightly desynchronized from the binary orbital frequency. We report Kepler K2 and TESS observations of two such systems. The first, SDSS J084617.11+245344.1, was observed by the Kepler spacecraft for 80 days during Campaign 16 of the K2 mission, and we identify it as a new asynchronous polar with a likely 4.64 hr orbital period. This is significantly longer than any other asynchronous polar, as well as all but several synchronous polars. Its spin and orbital periods beat against each other to produce a conspicuous 6.77-day beat period, across which the system's accretion geometry gradually changes. The second system in this study, Paloma, was observed by TESS for one sector and was already known to be asynchronous. Until now, there had been an ambiguity in its spin period, but the TESS power spectrum pinpoints a spin period of 2.27 hr. During the resulting 0.7-day spin-orbit beat period, the light curve phased on the spin modulation alternates between being single and double humped. We explore two possible explanations for this behavior: the accretion flow being diverted from one of the poles for part of the beat cycle, or an eclipse of the emitting region responsible for the second hump.

Keywords: dq herculis stars; am herculis stars; cataclysmic variable stars; white dwarf stars
Absolute Properties of the Eclipsing γ Dor Star V404 Lyrae

We present the first high-resolution spectra for the eclipsing binary V404 Lyr showing γ Dor pulsations, which we use to study its absolute properties. By fitting models to the disentangling spectrum of the primary star, we found that it has an effective temperature of T eff,1 = 7330 ± 150 K and a rotational velocity of v 1 sin i = 148 ± 18 km s-1. The simultaneous analysis of our double-lined radial velocities and the pulsation-subtracted Kepler data gives us accurate stellar and system parameters of V404 Lyr. The masses, radii, and luminosities are M 1 = 2.17 ± 0.06 M ⊙, R 1 = 1.91 ± 0.02 R ⊙, and L 1 = 9.4 ± 0.8 L ⊙ for the primary, and M 2 = 1.42 ± 0.04 M ⊙, R 2 = 1.79 ± 0.02 R ⊙, and L 2 = 2.9 ± 0.2 L ⊙ for the secondary. The tertiary component orbiting the eclipsing pair has a mass of M 3b = 0.71 ± 0.15 M ⊙ in an orbit of P 3b = 642 ± 3 days, e 3b = 0.21 ± 0.04, and a 3b = 509 ± 2 R ⊙. The third light of l 3 = 4.1% ± 0.2% could be partly attributable to the K-type circumbinary object. By applying a multiple frequency analysis to the eclipse-subtracted light residuals, we detected 45 frequencies with signal-to-noise amplitude ratios larger than 4.0. Identified as independent pulsation modes, seven frequencies (f 1 - f 6, f 9), their new pulsation constants, and the location in the Hertzsprung-Russell diagram indicate that the pulsating primary is a γ Dor-type variable star.

Keywords: eclipsing binary stars; fundamental parameters of stars; stellar oscillations; spectroscopy; multi-periodic pulsation; asteroseismology
The Flat Galactic Rotation Curves from First Principles: A Novel Logarithmic Potential Originating in Laplace's Equation

This note reports flat galactic rotation curves coinciding with observation and originating in Laplace's classical field equation. Dark matter, identified with a primordial fluid populating the entire universe, is represented by the homogeneous Klein-Gordon equation (KGE). The key element is the novel solution for the KGE discovered by the leading author in 1994, expressed as a permanent background ${ \mathcal B }$ -potential plus an entangled ${ \mathcal E }$ -potential where time and distance appear as a ratio. The ${ \mathcal B }$ -potential may be viewed as solution to a non-homogeneous Laplace equation, for which the general solution contains in addition to Newton's 1/r potential a new logarithmic Zwicky potential overlooked thus far. The ensuing 1/r-Zwicky force predicts the observed flat galatic rotation curves exhibiting the observed limiting speed at long distance.

Keywords: galaxy rotation curves; newtonian gravitation