adsabs/SciX_UAT_keywords huggingface dataset:
Extending the Dynamic Range of Galaxy Outflow Scaling Relations: Massive Compact Galaxies with Extreme Outflows

We investigate galactic winds in the HizEA galaxies, a collection of 46 late-stage galaxy mergers at z = 0.4-0.8, with stellar masses of $\mathrm{log}({M}_{* }/{M}_{\odot })=10.4\mbox{--}11.5$ , star formation rates (SFRs) of 20-500 M ⊙ yr-1, and ultra-compact (a few 100 pc) central star-forming regions. We measure their gas kinematics using the Mg II λ λ 2796,2803 absorption lines in optical spectra from MMT, Magellan, and Keck. We find evidence of outflows in 90% of targets, with maximum outflow velocities of 550-3200 km s-1. We combine these data with ten samples from the literature to construct scaling relations for outflow velocity versus SFR, star formation surface density (ΣSFR), M *, and SFR/M *. The HizEA galaxies extend the dynamic range of the scaling relations by a factor of ~2-4 in outflow velocity and an order of magnitude in SFR and ΣSFR. The ensemble scaling relations exhibit strong correlations between outflow velocity, SFR, SFR/R, and ΣSFR, and weaker correlations with M * and SFR/M *. The HizEA galaxies are mild outliers on the SFR and M * scaling relations, but they connect smoothly with more typical star-forming galaxies on plots of outflow velocity versus SFR/R and ΣSFR. These results provide further evidence that the HizEA galaxies' exceptional outflow velocities are a consequence of their extreme star formation conditions rather than hidden black hole activity, and they strengthen previous claims that ΣSFR is one of the most important properties governing the velocities of galactic winds.

Keywords: compact galaxies; galaxy evolution; starburst galaxies; scaling relations
Limits on the Spin-Orbit Angle and Atmospheric Escape for the 22 Myr Old Planet AU Mic b

We obtained spectra of the pre-main-sequence star AU Microscopii during a transit of its Neptune-sized planet to investigate its orbit and atmosphere. We used the high-dispersion near-infrared spectrograph InfraRed Doppler (IRD) on the Subaru telescope to detect the Doppler "shadow" from the planet and constrain the projected stellar obliquity. Modeling of the observed planetary Doppler shadow suggests a spin-orbit alignment of the system ( $\lambda =-{4.7}_{-6.4}^{+6.8}$ deg), but additional observations are needed to confirm this finding. We use both the IRD data and spectra obtained with NIRSPEC on Keck II to search for absorption in the 1083 nm line of metastable triplet He I by the planet's atmosphere and place an upper limit for the equivalent width of 3.7 mÅ at 99% confidence. With this limit and a Parker wind model we constrain the escape rate from the atmosphere to $\lt 0.15\mbox{--}0.45$ M⊕ Gyr-1, comparable to the rates predicted by an X-ray and ultraviolet energy-limited escape calculation and hydrodynamic models, but refinement of the planet mass is needed for rigorous tests. * Based on data collected at Subaru Telescope, which is operated by the National Astronomical Observatory of Japan, and the W. M. Keck Observatory, which is supported by the W. M. Keck Foundation and operated by the California Institute of Technology, the University of California and the National Aeronautics and Space Administration.

Keywords: high resolution spectroscopy; exoplanet evolution; radial velocity
Model-independent Constraints on Cosmic Curvature: Implication from Updated Hubble Diagram of High-redshift Standard Candles

The cosmic curvature (Ωk) is a fundamental parameter for cosmology. In this paper, we propose an improved model-independent method to constrain the cosmic curvature, which is geometrically related to the Hubble parameter H(z) and luminosity distance DL(z). Using the currently largest H(z) sample from the well-known cosmic chronometers, as well as the luminosity distance DL(z) from the relation between the UV and X-ray luminosities of 1598 quasars and the newly compiled Pantheon sample including 1048 SNe Ia, 31 independent measurements of the cosmic curvature Ωk(z) can be expected covering the redshift range of 0.07 < z < 2. Our estimation of Ωk(z) is fully compatible with flat universe at the current level of observational precision. Meanwhile, we find that, for the Hubble diagram of 1598 quasars as a new type of standard candle, the spatial curvature is constrained to be Ωk = 0.08 ± 0.31. For the latest Pantheon sample of SNe Ia observations, we obtain Ωk = - 0.02 ± 0.14. Compared to other approaches aiming for model-independent estimations of spatial curvature, our analysis also achieves constraints with competitive precision. More interestingly, it is suggested that the reconstructed curvature Ωk is negative in the high-redshift region, which is also consistent with the results from the model-dependent constraints in the literature. Such findings are confirmed by our reconstructed evolution of Ωk(z), in the framework of a model-independent method of Gaussian processes (GP) without assuming a specific form.

Keywords: quasars; cosmological parameters; hubble diagram
Discovery of Kiloparsec-scale Semirelativistic Fe Kα Complex Emission in NGC 5728

We present Chandra ACIS-S imaging spectroscopy results of the extended (1.″5–8″, 300–1600 pc) hard X-ray emission of NGC 5728, the host galaxy of a Compton-thick active galactic nucleus. We find spectrally and spatially resolved features in the Fe Kα complex (5.0–7.5 keV) redward and blueward of the neutral Fe line at 6.4 keV in the extended narrow-line region bicone. A simple phenomenological fit of a power law plus Gaussians gives a significance of 5.4σ and 3.7σ for the red and blue wings, respectively. Fits to a suite of physically consistent models confirm a significance of ≥3σ for the red wing. The significance of the blue wing may be diminished by the presence of rest-frame highly ionized Fe XXV and Fe XXVI lines (1.4σ–3.7σ range). A detailed investigation of the Chandra ACIS-S point-spread function and comparison with the observed morphology demonstrates that these red and blue wings are radially extended (∼5″, ∼1 kpc) along the optical bicone axis. If the wing emission is due solely to redshifted and blueshifted high-velocity neutral Fe Kα, then the implied line-of-sight velocities are +/‑ ∼0.1c, and their fluxes are consistent with being equal. A symmetric high-velocity outflow is then a viable explanation. This outflow has deprojected velocities ∼100 times larger than the outflows detected in optical spectroscopic studies, potentially dominating the kinetic feedback power.

Keywords: agn host galaxies; x-ray active galactic nuclei
Scaling of Turbulent Viscosity and Resistivity: Extracting a Scale-dependent Turbulent Magnetic Prandtl Number

Turbulent viscosity νt and resistivity ηt are perhaps the simplest models for turbulent transport of angular momentum and magnetic fields, respectively. The associated turbulent magnetic Prandtl number Prt ≅ νt/ηt has been well recognized to determine the final magnetic configuration of accretion disks. Here, we present an approach to determining these "effective transport" coefficients acting at different length scales using coarse-graining and recent results on decoupled kinetic and magnetic energy cascades. By analyzing the kinetic and magnetic energy cascades from a suite of high-resolution simulations, we show that our definitions of νt, ηt, and Prt have power-law scalings in the "decoupled range." We observe that Prt ≈ 1-2 at the smallest inertial-inductive scales, increasing to ≈5 at the largest scales. However, based on physical considerations, our analysis suggests that Prt has to become scale independent and of order unity in the decoupled range at sufficiently high Reynolds numbers (or grid resolution) and that the power-law scaling exponents of velocity and magnetic spectra become equal. In addition to implications for astrophysical systems, the scale-dependent turbulent transport coefficients offer a guide for large-eddy simulation modeling.

Keywords: magnetohydrodynamics; magnetic fields; magnetohydrodynamical simulations
Evidence for Ultra-diffuse Galaxy Formation through Tidal Heating of Normal Dwarfs

We have followed up two ultra-diffuse galaxies (UDGs), detected adjacent to stellar streams, with Hubble Space Telescope (HST) imaging and H I mapping with the Jansky Very Large Array in order to investigate the possibility that they might have a tidal origin. With the HST F814W and F555W images we measure the globular cluster (GC) counts for NGC 2708-Dw1 and NGC 5631-Dw1 as ${2}_{-1}^{+1}$ and ${5}_{-2}^{+1}$ , respectively. NGC 2708-Dw1 is undetected in H I down to a 3σ limit of log (MH I/M⊙) = 7.3, and there is no apparent H I associated with the nearby stellar stream. There is a 2σ H I feature coincident with NGC 5631-Dw1. However, this emission is blended with a large gaseous tail emanating from NGC 5631 and is not necessarily associated with the UDG. The presence of any GCs and the lack of clear H I connections between the UDGs and their parent galaxies strongly disfavor a tidal dwarf galaxy origin, but cannot entirely rule it out. The GC counts are consistent with those of normal dwarf galaxies, and the most probable formation mechanism is one where these UDGs were born as normal dwarfs and were later tidally stripped and heated. We also identify an overluminous (MV = -11.1) GC candidate in NGC 2708-Dw1, which may be a nuclear star cluster transitioning to an ultra-compact dwarf as the surrounding dwarf galaxy gets stripped of stars.

Keywords: low surface brightness galaxies; galaxy interactions; dwarf galaxies; galaxy formation; globular star clusters; tidal tails; h i line emission
PSR J2150+3427: A Possible Double Neutron Star System

PSR J2150+3427 is a 0.654 s pulsar discovered by the Commensal Radio Astronomy FAST Survey. From the follow-up observations, we find that the pulsar is in a highly eccentric orbit (e = 0.601) with an orbital period of 10.592 days and a projected semimajor axis of 25.488 lt-s. Using 2.7 yr of timing data, we also measured the rate of periastron advance $\dot{\omega }$ = 0.0115(4) deg yr-1. An estimate for the total mass of the system using the $\dot{\omega }$ gives M tot = 2.59(13)M ⊙, which is consistent with most of the known double neutron star (DNS) systems and one neutron star (NS)-white dwarf (WD) system named B2303+46. Combining $\dot{\omega }$ with the mass function of the system gives the masses of M p < 1.67 and M c > 0.98 M ⊙ for the pulsar and the companion star, respectively. This constraint, along with the spin period and orbital parameters, suggests that it is possibly a DNS system, and we cannot entirely rule out the possibility of an NS-WD system. Future timing observations will vastly improve the uncertainty in $\dot{\omega }$ , and are likely to allow the detection of additional relativistic effects, which can be used to modify the values of M p and M c . With a spin-down luminosity of $\dot{E}$ = 5.07(6) × 1029 erg s-1, PSR J2150+3427 is a very low-luminosity pulsar, with only the binary pulsar J2208+4610 having a smaller $\dot{E}$ .

Keywords: binary pulsars; pulsars; radio pulsars; neutron stars
First Discovery of a Fast Radio Burst at 350 MHz by the GBNCC Survey

We report the first discovery of a fast radio burst (FRB), FRB 20200125A, by the Green Bank Northern Celestial Cap (GBNCC) Pulsar Survey conducted with the Green Bank Telescope at 350 MHz. FRB 20200125A was detected at a Galactic latitude of 58°43 with a dispersion measure of 179 pc cm3, while electron density models predict a maximum Galactic contribution of 25 pc cm3 along this line of sight. Moreover, no apparent Galactic foreground sources of ionized gas that could account for the excess DM are visible in multiwavelength surveys of this region. This argues that the source is extragalactic. The maximum redshift for the host galaxy is zmax = 0.17, corresponding to a maximum comoving distance of approximately 750 Mpc. The measured peak flux density for FRB 20200125A is 0.37 Jy, and we measure a pulse width of 3.7 ms, consistent with the distribution of FRB widths observed at higher frequencies. Based on this detection and assuming a Euclidean flux density distribution of FRBs, we calculate an all-sky rate at 350 MHz of ${3.4}_{-3.3}^{+15.4}\times {10}^{3}$ FRBs sky-1 day-1 above a peak flux density of 0.42 Jy for an unscattered pulse having an intrinsic width of 5 ms, consistent with rates reported at higher frequencies, albeit with large uncertainties. Given the recent improvements in our single-pulse search pipeline, we also revisit the GBNCC survey sensitivity to various burst properties. Finally, we find no evidence of strong interstellar scattering in FRB 20200125A, adding to the growing evidence that some FRBs have circumburst environments where free-free absorption and scattering are not significant.

Keywords: radio transient sources; radio bursts; surveys
Characteristics of Pluto's Haze and Surface from an Analytic Radiative Transfer Model

Observations of Pluto from New Horizons have been combined with previous ground-based observations and fit to a radiative transfer model based on Chandrasekhar's planetary problem and Hapke theory to simultaneously derive the physical properties of the dwarf planet's surface and atmosphere. We derive the macroscopic roughness, single-scattering albedo, and directional scattering properties of the surface, and the single-scattering albedo, optical depth, and single-scattering phase function of Pluto's haze. The haze particles are small, with best-fit sizes in the range of ∼0.41-1.14 μm. We find that Pluto's haze is more similar to that of Titan, rich in organic compounds and highly forward scattering, than that of Triton. With organic compounds and a likely subsurface water ocean, Pluto may harbor sustainable habitable environments. Our model, which includes the coherent backscatter effect, fits the anomalously large opposition surge recently discovered on Pluto.

Keywords: pluto
A Direct Connection between the Wake and the Former Host Galaxy of a Proposed Runaway Supermassive Black Hole

This Research Note presents VLT B-band imaging of a candidate runaway supermassive black hole that was recently discovered in HST/ACS F606W+F814W imaging. The ACS data show an extremely thin, linear feature at z = 0.964 that points toward a compact galaxy at the same redshift. There is a gap between the feature and the compact galaxy, which means that the proposed causal connection between the two objects is not definitive. We show here that the linear feature extends all the way to the compact galaxy in the B-band, with no gap. The B-band morphology is difficult to reconcile with models where the compact galaxy and the linear feature are independent objects, and in particular with the proposal of Sanchez Almeida et al. that the linear feature is an edge-on disk galaxy.

Keywords: supermassive black holes
Discovered the Long-term Variation of the Variable Star CzeV818

In this study we describe the reclassification of the variable star CzeV818, discovered in 2015 by Pavel Cagas (Skarka et al. 2017), which was cataloged as a delta Scuti variable. From the photometric study performed with the telescopes of the SSV-UAI-GRAV (Unione Astrofili Italiani, Variable Star Section), All-Sky Automated Survey for Supernovae (Kochanek et al. 2017) (ASAS-SN) and Zwicky Transient Facility (Masci et al. 2019) (ZTF) surveys and the G-spectrum obtained from Gaia DR3 (Gaia Collaboration et al. 2023) (Astrophysical parameters inference system, Apsis) data, it was possible to understand that the luminous variation was not due to pulsations but due to spots (as discussed in Roxburgh 1964), present in the photosphere with a cycle of 0.402533 day (9.66 hr). Analyzing the long-term data present in the ASAS-SN and ZTF surveys, it was possible to determine a cycle of 2900 days (7.95 yr), which is similar to the solar cycle.

Keywords: variable stars; starspots
Orbital- and Spin-phase Variability in the X-Ray Emission from the Accreting Pulsar Centaurus X-3

We present a time-resolved analysis using 39 ks NuSTAR observation data of the X-ray pulsar Centaurus X-3, covering an orbital-phase interval of Φ = 0.199-0.414. The orbital- and spin-phase variabilities are investigated through time-resolved spectra, light curves, and pulse profiles. The orbital-phase variability was due to the mixture of two comparable effects: intrinsic flux variability of ~10% and obscuration by the clumpy stellar wind. The typical size and number density of the clumps are ~9 × 1010 cm and ~3 × 1012 cm-3, respectively. In the spin-phase-resolved analysis, we detected variations in the spectral features of the continuum, the Fe line, and the cyclotron resonance scattering feature (CRSF). The photon index ranged from 0.72 to 1.06, corresponding to the difference in the Comptonization optical depth by a factor of ~1.6. The equivalent width and intensity of the Fe line had negative correlations with the continuum flux. The central energy and the strength of the CRSF increased at the pulse maximum. The former ranged from 26.0 to 28.7 keV, while the latter varied by a factor of ~1.9. The pulse profile was double-peaked in the low-energy band, and it gradually shifted to being single-peaked with energy, indicating the existence of two distinct emission patterns, corresponding to the pencil and fan beams. Finally, we found that the pulse profiles were highly stable along the orbital phase, within a variation degree of ~20%, which provides evidence of the highly stable accretion stream of the binary system.

Keywords: accretion; neutron stars
The Mass and Age Distribution of Halo White Dwarfs in the Canada-France Imaging Survey

We present optical spectroscopy for 18 halo white dwarfs identified using photometry from the Canada-France Imaging Survey and Pan-STARRS1 DR1 3π survey combined with astrometry from Gaia DR2. The sample contains 13 DA, 1 DZ, 2 DC, and 2 potentially exotic types of white dwarf. We fit both the spectrum and the spectral energy distribution in order to obtain the temperature and surface gravity, which we then convert into mass and then age using stellar isochrones and the initial-to-final mass relation. We find a large spread in ages that is not consistent with expected formation scenarios for the Galactic halo. We find a mean age of ${9.03}_{-2.03}^{+2.13}$ Gyr and a dispersion of ${4.21}_{-1.58}^{+2.33}$ Gyr for the inner halo using a maximum-likelihood method. This result suggests an extended star formation history within the local halo population.

Keywords: white dwarf stars; da stars; dz stars
V1507 CYGNI (HD187399): A Highly Evolved, Enigmatic Interacting Binary System with an Eccentric Orbit

The properties of the interacting, eccentric orbit binary V1507 Cyg (HD187399) are examined with spectra that cover wavelengths from 0.63-0.68 μm. The spectrum of the brightest star is similar to that of the B8 I star β Ori, although with absorption lines that show substructure possibly related to a varying tidal field. The bulk of the Hα emission in the spectrum appears to be associated with this star. Evidence is presented that the period of the system has been stable over timescales of many decades, arguing against large-scale mass transfer at the current epoch. Absorption and emission lines are identified that originate in an expanding asymmetric envelope around the companion, and component masses of 6.4 ± 0.9 and 14.0 ± 0.9 M ⊙ are found, where the former applies to the brighter star and an inclination of 46° has been assumed. Mass transfer has thus progressed to the point where the mass ratio has reversed. It is argued that the brighter star is an α Cyg variable, and that it is those light variations that dominate the system light curve. V1507 Cyg is observed at or near the center of a diffuse H I bubble that is detected at 408 and 1420 MHz. It is suggested that the eccentric orbit is the result of evolution in a hierarchical system, in which a now-defunct massive third body recently disturbed the orbit of the stars in V1507 Cyg, thereby disrupting mass transfer.

Keywords: binary stars; interacting binary stars; close binary stars
Hydrodynamic Response of the Intergalactic Medium to Reionization

The intergalactic medium is expected to clump on scales down to ${10}^{4}\mbox{--}{10}^{8}$ M⊙ before the onset of reionization. The impact of these small-scale structures on reionization is poorly understood despite the modern understanding that gas clumpiness limits the growth of ${\rm{H}}\,{\rm{II}}$ regions. We use a suite of radiation-hydrodynamics simulations that capture the $\sim {10}^{4}{M}_{\odot }$ Jeans mass of unheated gas to study density fluctuations during reionization. Our simulations track the complex ionization and hydrodynamical response of gas in the wake of ionization fronts. The clumping factor of ionized gas (proportional to the recombination rate) rises to a peak value of 5-20 approximately Δt = 10 Myr after ionization front passage, depending on the incident intensity, redshift, and degree to which the gas had been preheated by the first X-ray sources. The clumping factor reaches its relaxed value of ≈3 by Δt = 300 Myr. The mean free path of Lyman-limit photons evolves in unison, being up to several times shorter in unrelaxed, recently reionized regions compared to those that were reionized much earlier. Assessing the impact of this response on the global reionization process, we find that unrelaxed gaseous structures boost the total number of recombinations by ≈50% and lead to spatial fluctuations in the mean free path that persist appreciably for several hundred million years after the completion of reionization.

Keywords: reionization; intergalactic medium; radiative transfer simulations; hydrodynamical simulations; cosmic web
Radial Profile of the Polytropic Index of Solar Wind Plasma in the Heliosphere

We combine different measurements of the polytropic index of the proton plasma in the heliosphere: (i) near-adiabatic index in the inner heliosphere ∼1 au, (ii) subadiabatic indices in the outer heliosphere ∼20-40 au, and (iii) near-zero indices in the inner heliosheath. These observations are unified by a single theoretical model of the polytropic index throughout its radial extent in the heliosphere; the corresponding fitting reveals the decreasing trend of the polytropic index with increasing heliocentric distance R. We anticipate that with increasing R, (i) the Debye length and mean-free-path decreases; (ii) the Landau damping is less effective, transferring thus less wave energy to particles; and (iii) the collisionality degree increases, indicating that the proton plasma in the inner heliosheath might be collisionless.

Keywords: astronomy data analysis; space plasmas; plasma astrophysics; solar wind; slow solar wind; heliosphere
Coronal Mass Ejection Deformation at 0.1 au Observed by WISPR

Although coronal mass ejections (CMEs) resembling flux ropes generally expand self-similarly, deformations along their fronts have been reported in observations and simulations. We present evidence of one CME becoming deformed after a period of self-similar expansion in the corona. The event was observed by multiple white-light imagers on 2021 January 20-22. The change in shape is evident in observations from the heliospheric imagers from the Wide-Field Imager for Solar Probe Plus (WISPR), which observed this CME for ~44 hr. We reconstruct the CME using forward-fitting models. In the first hours, observations are consistent with a self-similar expansion, but later on the front flattens, forming a dimple. Our interpretation is that the CME becomes deformed at ~0.1 au owing to differences in the background solar wind speeds. The CME expands more at higher latitudes, where the background solar wind is faster. We consider other possible causes for deformations, such as loss of coherence and slow-mode shocks. The CME deformation seems to cause a time-of-arrival error of 16 hr at ~0.5 au. The deformation is clear only in the WISPR observations; thus, it would have been missed by 1 au coronagraphs. Such deformations may help explain the time-of-arrival errors in events where only coronagraph observations are available.

Keywords: solar coronal mass ejections