Abstract Ly α emitters (LAEs) are star-forming galaxies with significant Ly α emission and are often used as tracers of large-scale structure at high redshift. We explore the relationship between the Ly α line profile and environmental density with spectroscopy from the Dark Energy Spectroscopic Instrument (DESI) of LAEs selected with narrowband photometry through the One-hundred-deg 2 DECam Imaging in Narrowbands (ODIN) survey. We use LAE surface density maps in the N419 ( z ∼ 2.45) and N501 ( z ∼ 3.12) narrow bands to probe the relationship between local environmental density and the Ly α line profile. In both narrow bands, we stack the LAE spectra in bins of environmental density and inside and outside of protocluster regions. The N501 data show ∼15% higher Ly α line luminosity for galaxies in protoclusters, suggesting increased star formation in these regions. However, the line luminosity is not appreciably greater in protocluster galaxies in the N419 band, suggesting a potential redshift evolution of this effect. The shape of the line profile itself does not vary with environmental density, suggesting that line shape changes are caused by local effects independent of a galaxy’s environment. These data indicate a potential relationship between LAE local environmental density, ionized gas distribution, and Ly α line luminosity.
Abstract We present the Atacama Large Millimeter/submillimeter Array (ALMA) and the NOrthern Extended Millimeter Array (NOEMA) observations of the molecular outflow from the high-mass young stellar object (HMYSO) G24.33+0.14, which has recently undergone an accretion burst. CO (2–1) and SiO (5–4) reveal a bipolar outflow with pronounced asymmetry and multiple shells, indicating episodic mass ejection. CO reaches projected velocities up to ∼150 km s −1 , placing the outflow in the extremely high-velocity (EHV) regime. Position–velocity (PV) diagrams show distinct Hubble-wedge structures, and high-velocity CO knots cluster into two separate wedges, supporting nonsteady, multiepoch ejection. Crucially, CH 3 CN ( J = 12–11, K = 0–4) emission is detected along the outflow axis and spatially coincides with SiO (5–4). Its velocity gradient aligns with the outflow, rather than the disk, and the derived rotational temperatures have a median value of 135 K, which, together with its spatial and kinematic association with SiO, supports a shock-related origin of the CH 3 CN emission. Comparison of burst-phase (ALMA 2019) and postburst (NOEMA 2020) data shows significant intensity variations in CO and CH 3 OH masers, confirming that accretion bursts modify outflow physical conditions on observable timescales. These results support a possible connection between episodic accretion, shock chemistry, and extreme-velocity mass ejection in a massive protostar.
Abstract Gravitational-wave (GW) signals from compact binary coalescences (CBCs) enable independent measurements of the Hubble constant H 0 via the spectral siren method, which critically depends on an accurate model of the source-frame mass distribution. While the primary-mass function has been extensively studied, the impact of the secondary-mass distribution on cosmological inference has been largely overlooked. Here, we perform a joint inference of population and cosmological parameters using 142 confident CBC detections from GWTC-4.0, adopting a new parametric model that flexibly describes features in both the component-mass spectrum and the pairing function, with particular emphasis on the secondary masses. We find H 0 = 71 . 4 − 13.4 + 13.8 km s − 1 Mpc − 1 (68% CL) from spectral sirens alone, and H 0 = 73 . 5 − 7.2 + 9.2 km s − 1 Mpc − 1 when combined with the bright siren GW170817. Compared to the standard LIGO–Virgo–KAGRA Collaboration Fullpop-4.0 analysis, these constraints represent improvements of ∼29.8% and ∼22.2% in H 0 uncertainty, respectively. The enhanced precision is driven by previously unmodeled features, including peaks near 18 M ⊙ and 65 M ⊙ as well as mass-dependent pairing transitions at 28 M ⊙ and 52 M ⊙ . Our results demonstrate that the secondary-mass function is also a key ingredient for precision standard-siren cosmology.
We investigate the radial evolution of turbulent fluctuations in the inner heliosphere using Parker Solar Probe and Solar Orbiter observations over heliocentric distances of ∼32–90 R _⊙ . We decompose the measured fluctuations of density, velocity, and magnetic field into eight fundamental magnetohydrodynamic modes using the linear mode decomposition technique. The mode-resolved energy results show that the fluctuation energy is highly field-dependent: Velocity fluctuations are primarily Alfvénic, with both forward and backward Alfvén modes exhibiting relatively shallow radial decay, whereas magnetic fluctuations are dominated by transverse nonpropagating incompressible / magnetic island–like components. In particular, the magnetic island mode decreases approximately as δB ^i ∼ r ^−1.90 , followed closely by the forward and backward Alfvénic magnetic modes, δB ^A+ ∼ r ^−1.96 and δB ^A− ∼ r ^−2.17 . In contrast, density fluctuations are mainly governed by fast magnetosonic modes, while entropy and slow magnetosonic contributions remain comparatively weaker and decay more rapidly with heliocentric distance. We find that the variance anisotropy of the transverse incompressible magnetic island mode ( δB ^i ) and the Alfvén modes ( δB ^A± ) increases slightly with heliocentric distance. These results will help identify which magnetohydrodynamic modes are responsible for carrying turbulent energy in the inner heliosphere and how that energy evolves with distance from the Sun.
One of the first high-cadence chromospheric image sequences recorded with the recently commissioned Daniel K. Inouye Solar Telescope (DKIST) has revealed propagating arc-shaped bright fronts of a few hundred kilometers width. These bright fronts maintain their arc shape over up to one minute, travel with apparent horizontal speeds of ∼8 km s ^−1 , and originate from chromospheric bright grains seen at the center of the arc. We identify photospheric G -band bright points underneath the chromospheric bright grains, which are typically the signature of small-scale magnetic flux concentrations. The G -band bright points are found to interact with colocated vortices prior to the appearance of the chromospheric bright fronts. Images synthesized from three-dimensional magnetohydrodynamic simulations show a striking similarity with the discovered phenomenon and reveal that the arc-shaped bright fronts arise from essentially acoustic, weak shock fronts that propagate in the ambient medium, seemingly triggered by the vortex dynamics of the underlying magnetic flux concentration. In this work, we provide the first hints of a hitherto unknown magnetohydrodynamic process by which vortex-driven torsional Alfvén pulses couple to predominantly acoustic waves that steepen into shocks and dissipate their energies. The detected number density and frequency of these events are at least a factor 10 too small to be a major source of solar chromospheric heating but simulations show a seven times higher number density. We therefore expect to discover many more events with tailored narrow band observations.
