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Research Trends

Latest preprints in space engineering and astrophysics.

astro-ph.GA

A New Window on the Hα Luminosity Function and Star Formation Rate Density from 1.2 < z < 6.6 from JWST Medium-Band Photometry

Nicholas S. Martis, Chris Willott, Gregor Rihtaršič, Vesna Pirc Jevšenak, Roberto Abraham, Yoshihisa Asada, Maruša Bradač, Gabriel Brammer et al.

We present the first self-consistent measurement of the Hα luminosity function over a wide redshift range, covering cosmic noon into the epoch of reionization. Our analysis utilizes a novel method based on James Webb Space Telescope (JWST) NIRCam medium-band imaging. We combine data from the CANUCS, JWST in Technicolor, and JUMPS surveys which offer deep, uniform imaging (29.5-30 AB, 3σ) with extensive NIRCam medium-band coverage, reaching up to 29 total filters (up to 20 JWST) when including an…

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hep-phastro-ph.HE

Probing Memory-Burdened Primordial Black Holes with High-Energy Neutrinos

Arian Moradi Asl, Sandhya Choubey, Andreas Lund

The memory-burden effect can suppress the late-time evaporation of primordial black holes (PBHs), allowing those below the standard Hawking evaporation threshold to survive until the present epoch. These lighter PBHs emit high and ultra-high-energy neutrinos, opening the tentalizing possibility of discovery via neutrino telescopes. We study the constraints on memory-burdened PBHs from current IceCube HESE, MESE, and EHE data; and forecast the sensitivity reach of IceCube-Gen2 radio and GRAND200k…

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physics.space-ph

Skills for forecasting space weather

H. J. Austin, N. P. Savani

Coronal mass ejections (CMEs) from the Sun can have severe impacts on the Earth environment in the form of geomagnetic storms. These storms pose a risk to the global technological infrastructure, making the prediction of these events imperative. In this paper, we have broadened the statistical verification of the Bz4Cast tool, the first empirically-driven model to forecast solar wind magnetic vectors inside a CME prior to their Earth arrival. Twenty five CME events (between 2012 and 2016) have b…

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astro-ph.GAastro-ph.HE

Diagnosing the Fe line complex of the intracluster medium by XRISM high-resolution spectroscopy

K. Fukushima, L. Hirata, N. Y. Yamasaki, P. Chakraborty, S. Dupourqué, Y. Fujita, L. Gu, C. Kilbourne et al.

We aim to test the validity of the CIE framework in the ICM by performing line diagnostics based mainly on resolved Fe-K emission lines. Methods. We analyse Resolve full-array spectra of 17 galaxy clusters. Prominent Fe-K line components (the Fe xxv w, x, y, z, and Fe xxvi Lyα1,2 lines) are removed from plasma emission models and instead fitted with Gaussian profiles, enabling direct measurements of line fluxes without relying on synthetic spectral models. Some cool-core systems show w/z ratios…

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astro-ph.GA

Breathing Fire: Hot Dust in the Big Three Dragons at z = 7.15

Gitanjali Rajulal, Hiddo S. B. Algera, Yuma Sugahara, Tom J. L. C. Bakx, Takuya Hashimoto, Suzuka Arai, Akio K. Inoue, Ikki Mitsuhashi et al.

We present new Atacama Large Millimeter/submillimeter Array (ALMA) Band 9 ($λ_\mathrm{obs} = 0.45\,\mathrm{mm}$) and 4 ($λ_\mathrm{obs} = 2.2\,\mathrm{mm}$) observations towards the Big Three Dragons, a pair of merging Lyman-break galaxies (LBGs) at $z=7.15$. The system was previously detected in ALMA Bands 6, 7 and 8 ($λ_\mathrm{obs} = 0.73 - 1.32\,\mathrm{mm}$), which, combined with our new observations, allows us to robustly constrain its dust temperature and obscured SFR. The unresolved Band…

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astro-ph.GA

First detection of C2H+ in the interstellar medium

Arshia M. Jacob, Karl M. Menten, Sandra Brünken, Arnaud Belloche, Friedrich Wyrowski, Weslley G. D. P. Silva, Oskar Asvany, Sarwar Khan et al.

Despite the detection of nearly 350 molecules in the interstellar medium, almost half of which are carbon chains, the pathways that build molecular complexity remain poorly understood. Observed abundances of carbon-chain and aromatic species are difficult to reconcile with existing top-down or bottom-up formation scenarios, due in part to limited observational constraints and incomplete theoretical understanding. In particular, small intermediary ions, key drivers of ion-molecule reactions capab…

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astro-ph.SRastro-ph.GA

JWST Reveals a Galaxy-Wide Association of Red Supergiants with OB Stars in NGC 5584

Min Dai, Shu Wang, Biwei Jiang

The spatial relationship between young and evolved massive-star tracers offers a means of probing recent star formation across galactic disks. We combine JWST/NIRCam, $Swift$/UVOT UVW2, and GALEX FUV/NUV images to investigate the spatial association between red-supergiant (RSG) candidates and UV-selected star-forming complexes (SFCs) in the spiral galaxy NGC 5584. We identify 5,310 RSG candidates using colour--magnitude criteria and define 106 UV-selected SFCs from the UVOT/UVW2 morphology, with…

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astro-ph.GAastro-ph.IM

A Two-level Radial-velocity Zero-point Calibration for LAMOST MRS with Gaia and APOGEE and a Value-added RV Catalogue

Jinming Zhang, Haibo Yuan

The LAMOST Medium-Resolution Survey (MRS) provides a large stellar spectroscopic data set for Galactic kinematics and time-domain radial-velocity (RV) studies. However, the multi-spectrograph, multi-exposure, multi-fiber observing strategy can imprint RV zero-point (RVZP) systematics that vary across instrumental and temporal hierarchies. We construct a two-level empirical RVZP correction to LAMOST DR12 MRS using Gaia DR3 magnitude-colour-corrected RVs and APOGEE DR17 RVs as external references:…

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gr-qcastro-ph.HEhep-th

Gravitational radiation from binary systems with time varying masses

Teodora M. Matei, Cristian A. Croitoru, Tiberiu Harko

We consider the properties of the gravitational radiation emitted by massive stars in binary systems with time varying mass, orbiting around each other in Keplerian orbits under the influence of the gravitational force. When this effect is combined to the quadrupole expression of the gravitational radiation, some supplementary terms in the standard formulae describing radiative effects do appear. By using the generalized quadrupole formalism, with time dependent masses, we obtain the expressions…

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astro-ph.IM

Spec-S5: A Next-Generation All-Sky Spectroscopic Facility Enabling Large-Scale Surveys for Cosmology and Astrophysics

Claire Poppett, David J. Schlegel, Arjun Dey, Klaus Honscheid, Paul Martini, Alex Drlica-Wagner, Pat Jelinsky, Chang-Jin Oh et al.

The Stage-5 Spectroscopic Experiment (Spec-S5) is a next-generation, all-sky spectroscopic facility designed to address fundamental questions in cosmology and astrophysics. Building on the legacy of the Dark Energy Spectroscopic Instrument (DESI), Spec-S5 will upgrade two existing 4-m telescopes into 6-m, wide-field observatories, each equipped with a highly multiplexed spectrograph capable of measuring 13,000 spectra simultaneously. This overview paper summarizes the science motivation, system…

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astro-ph.HE

Anisotropic Particle Transport from a Pulsar Wind Nebula Revealed by Einstein Probe and LHAASO

Zhen Cao, F. Aharonian, Y. X. Bai, Y. W. Bao, D. Bastieri, X. J. Bi, Y. J. Bi, W. Bian et al.

Pulsar wind nebulae (PWNe) are major cosmic ray accelerators, yet the mechanisms transporting high-energy particles into the interstellar medium remain elusive. Building on the LHAASO discovery of an ultra-high-energy (UHE) $γ$-ray source near the bow-shock PWN powered by the pulsar PSR J1740+1000, we present a joint Einstein Probe (EP) and LHAASO study of this system. EP observations reveal an extended X-ray tail far exceeding the structure previously seen by XMM-Newton. Updated LHAASO observat…

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astro-ph.SRastro-ph.GA

NATA: a chemical-picture equation of state for stellar merger hydrodynamics

Natalia Ivanova

We present NATA (Nearly Always Truthful Approximations), a self-contained chemical-picture equation of state for hydrogen-helium-carbon-oxygen mixtures, developed for hydrodynamics calculations of stellar mergers and common envelope evolution. NATA carries bound species explicitly in ionisation and dissociation equilibrium and evaluates pressure, internal energy, and entropy from one continuous, single-physics chemical-picture solve built on analytic and semi-analytic component physics, rather t…

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astro-ph.EP

What can Planetary Ice Shells Teach Us about Ocean Mixing and Life, and Why Salt Matters

Nicole Shibley

Past and present climates, both on Earth and in planetary systems, maintain ice covers with underlying oceans. This can range from sea ice in the Arctic Ocean to global ice shells on ice-covered moons in the Solar System to ice sheets in past episodes of Earth's history. When an ice shell overlies an ocean, it becomes challenging to infer what ocean processes could be going on below as in-situ ocean measurements are often lacking. This means that what we learn about ocean mixing must often be in…

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astro-ph.HEastro-ph.IM

Insights into the Pulsar Timing Array hypothesis space

El Mehdi Zahraoui, Patricio Maturana-Russel, Willem van Straten, Renate Meyer, Sergei Gulyaev

We present novel insights into the pulsar-noise model space in pulsar timing array (PTA) experiments. Through a comparative analysis of the same Parkes PTA second data release observations processed with the 2020 and 2023 pipelines, we show that data processing materially changes the distribution of posterior support across competing noise hypotheses and increases sensitivity to weak contributions such as the solar wind. A solar-wind component appears in the highest-posterior hypothesis for ten…

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astro-ph.IM

Overview and status of BICEP Array's BA4-90/150 CMB polarimeter

M. A. Petroff, P. A. R. Ade, Z. Ahmed, M. Amiri, D. Barkats, R. Basu Thakur, C. A. Bischoff, D. Beck et al.

The inflation paradigm postulates a period of rapid expansion in the early Universe, which would generate gravitational waves. These tensor perturbations would produce a faint B-mode signature in the polarization of the cosmic microwave background (CMB), but this signal is orders of magnitude weaker than that from the CMB's other anisotropy and that from astrophysical foregrounds. Placing more-stringent upper limits on this signal or making a definitive detection thus requires exceptional contro…

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astro-ph.SR

The $δ$ Scuti pulsator occurrence as a function of age, $T_{\rm eff}$, rotation, and metallicity

Ian Berry, Daniel Huber, Yaguang Li, Daniel Hey, Timothy R. Bedding, Simon J. Murphy

Many A- and F- type stars do not display $δ$ Scuti pulsations, despite being located within the instability strip. We use photometry from the TESS Mission to discover and study $δ$ Scuti pulsators in open clusters within 500 pc and with ages between ~20 and 900 Myr, which provide a unique opportunity to study $δ$ Scuti pulsators in coeval populations with uniform chemical composition. We measure pulsator occurrence, which corrects the pulsator fraction for incompleteness, across all clusters. We…

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astro-ph.HE

A Systematic Study of Type Ia Supernova Remnants: Using Nucleosynthesis to Probe their Supernova Progenitors

Cole Treyturik, Samar Safi-Harb, Gilles Ferrand

We present the first systematic, spatially resolved X-ray spectroscopic study of a largely thermonuclear (Type Ia) sample of supernova remnants (SNRs), aimed at probing the explosion properties and progenitors through a comparison to a suite of nucleosynthesis models available in the literature. Our sample focuses on Galactic and LMC ejecta-dominated SNRs believed to be, or otherwise assumed to be, of thermonuclear origin. Using archival XMM-Newton observations (and Chandra for G1.9+0.3), we ext…

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astro-ph.HEhep-ph

Neutrino quantum kinetics for fast flavor conversion in a time-dependent environment

Zewei Xiong, Meng-Ru Wu

Fast flavor conversions (FFCs) of neutrinos, driven by the fast flavor instability (FFI), can reshape the neutrino flavor content in dense astrophysical environments such as core-collapse supernovae and neutron star mergers. Most studies of FFCs adopt a two-step approach, in which a flavor-unstable state containing deep electron-minus-heavy-flavor lepton number (E-XLN) angular crossings is first constructed and subsequently evolved. Because realistic crossings should instead develop gradually th…

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astro-ph.IM

On-sky capabilities and performance of the Keck All Sky Precision Adaptive Optics system

Avinash Surendran, Maxwell Service, Jacques R. Delorme, Carlos M. Correia, Marcos A. Van Dam, Eduardo Marin, Antonin Bouchez, Peter Wizinowich et al.

The Keck All Sky Precision Adaptive optics (KAPA) project upgrades the Keck I adaptive optics system to enable laser tomography using a four laser guide star (LGS) asterism. KAPA is now in operation in both narrow field and wide field modes to optimize correction on-axis or over the science field of view of the camera. The use of four LGSs, in conjunction with a tomographic reconstructor and pseudo open-loop control, leads to a significant reduction in wavefront error. We describe the overall ar…

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astro-ph.HEastro-ph.SR

Do Accretion Disks Get Bent Out of Shape? Investigating the Origin of Rapid Fluctuations in the Tails of Long Thermonuclear X-ray Bursts

D. R. Ballantyne, N. Degenaar

Thermonuclear X-ray bursts from the surfaces of neutron stars affect the surrounding accretion flow, revealing details of the underlying physical processes influencing accretion physics. In this context, we perform a spectral analysis of 5 long X-ray bursts that exhibit temporary rapid flux variations during the tails of their light curves. In all cases, spectra extracted from before, during and after the time of fluctuations show evidence for relativistic, ionized reflection with the blackbody…

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astro-ph.GA

The Circumgalactic Medium of Present-Epoch Luminous Galaxies as Probed by CIV Absorption

Mark A. Croom, Christopher W. Churchill, Bart Wakker, Glenn G. Kacprzak, Nikole M. Nielsen

We studied CIV 1548,1550 absorption in the circumgalactic medium (CGM) of 88 isolated, bright (L_B > 0.2L*_B) galaxies at z 0.1 angstroms, we found absorption in the CGM of 9/88 of the galaxies within projected separation R_perp -10.75]. To a confidence level of 99.998% (4.3-sigma), we can rule out that these absorbers are drawn from a random distribution of galaxy-quasar azimuthal angles. These findings suggest strong evidence for biconical polar winds related to the moderately elevated star fo…

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astro-ph.GA

Circumgalactic CIV Absorption Found Only Within 30 Degrees of the Minor Axis of Present-Epoch Galaxies

Mark A. Croom, Christopher W. Churchill, Bart Wakker, Glenn G. Kacprzak, Nikole M. Nielsen

We studied CIV 1548,1550 absorption in the circumgalactic medium (CGM) of 88 isolated, bright (L_B > 0.2L*_B) galaxies at z 0.1 angstroms, we found absorption in the CGM of 9/88 of the galaxies within projected separation R_perp -10.75]. To a confidence level of 99.998% (4.3-sigma), we can rule out that these absorbers are drawn from a random distribution of galaxy-quasar azimuthal angles. These findings suggest strong evidence for biconical polar winds related to the moderately elevated star fo…

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astro-ph.IMastro-ph.EP

Spectrally dispersed non-redundant aperture-masking interferometry in the thermal infrared with LBTI/ALES

T. A. Stuber, J. M. Stone, J. W. Isbell, T. De Prins, J. P. Scott, J. A. Eisner, J. Carlson, S. Ertel et al.

Non-redundant aperture-masking interferometry maximizes the angular resolution of a telescope by turning it into an interferometric array using pupil plane masks. If the interference pattern on the detector is spectrally dispersed, deeper contrasts of the astrophysical scenery and an improved coverage of its spatial Fourier modes is achieved. We combined a non-redundant aperture mask with the integral field spectrograph ALES of LMIRcam at the Large Binocular Telescope Interferometer (LBTI). With…

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astro-ph.GAastro-ph.HE

Mapping gas accretion and stellar kinematics to sub-kiloparsec scales in NGC 4696 with JWST/NIRSpec

Mathieu Marquis, Julie Hlavacek-Larrondo, Olivia Pereira, Michael Reefe, Hyunseop Choi, Jorge Barrera-Ballesteros, Benjamin Vigneron, Ming Sun et al.

We present JWST/NIRSpec IFU spectroscopy of the central $618\times618$ pc$^2$ ($\sim3''\times3''$) of NGC 4696, the BCG in the Centaurus cluster. Leveraging the $\sim0.1''$ ($20.6$ pc) pixel size of JWST, we resolve a compact circumnuclear rotating disk (radius of $\sim120$ pc) traced by Pa$α$ and H$_2$ 1$-$0 S(1) emission, which allows a reassessment of the AGN position based on the kinematic centre of this disk. A central Pa$α$ velocity dispersion reaching $σ\sim449$ km s$^{-1}$ implies a SMBH…

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astro-ph.HEgr-qc

Capture Driven Evolution of Asymmetric Dark Matter in Non-rotating Neutron Stars

Peiran Liu, Wenrong Sun

We develop a self-consistent framework that connects dark matter capture to the long term accumulation and structural evolution of neutron stars, allowing us to quantify the impact of capture driven asymmetric dark matter on gravitational wave observables over astrophysical timescales. We model cold, non-rotating neutron stars using a three layer polytropic EoS coupled to a dark matter component through the two fluid Tolman Oppenheimer Volkoff equations, and reconstruct the long term evolution u…

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astro-ph.HEgr-qcnucl-th

Fast and Accurate Prediction of Neutron Star Structure with Deep Neural Networks

Kaushikk V N, Bhaskar Biswas, Stephan Rosswog

Solving the Tolman--Oppenheimer--Volkoff (TOV) equations, together with the tidal perturbation equations, for large numbers of equation-of-state (EOS) samples is a major computational bottleneck in Bayesian inference of the dense-matter EOS, and this will become increasingly limiting as next-generation observatories deliver far larger and more precise datasets. We develop neural-network surrogates for the forward TOV mapping that predict neutron star mass, radius, and tidal deformability simulta…

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astro-ph.HE

X-Ray Observation of Type II Supernova 2024ggi

Elisa J. Gao, Vikram V. Dwarkadas

We investigate the Chandra and XMM-Newton X-ray emission from the core-collapse SN 2024ggi. Spectral fitting is carried out using the vapec model. We find X-ray temperatures between 5-7 keV, lower than the value assumed by previous authors by about a factor of 4-6. However the unabsorbed flux is consistent with published values within the error bars. The X-ray luminosity evolution is somewhat steeper than expected for a steady wind, although it could be consistent with a steady wind within the e…

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astro-ph.GAastro-ph.COastro-ph.HE

The large-scale ordered magnetic field in the Galactic halo and the Local Bubble

Elena Orlando

All-sky synchrotron polarization observations are the primary probe of the Galactic large-scale ordered magnetic field, which includes both coherent and ordered random components. However, magnetic-field strength estimates from synchrotron observations depend on the assumed cosmic-ray electron model, which itself depends on the magnetic-field configuration and strength throughout the Galaxy. We aim to constrain the strength of the large-scale ordered magnetic field in the Galactic halo through a…

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astro-ph.GA

Radial Stellar Age Gradients in 42 Local Volume Dwarf Galaxies

Roger E. Cohen, Kristen B. W. McQuinn, O. Grace Telford, Liese Van Zee, Laura Congreve Hunter, Andrew E. Dolphin, Suchindram Dasgupta

We present radial stellar age gradients measured from star formation histories (SFHs) fit to resolved color-magnitude diagrams (CMDs) of 42 Local Volume dwarfs (6$\lesssim$Log M$_{\star}$/M$_{\odot}$$\lesssim$9), spatially divided into elliptical annuli. Ages in each annulus are quantified using $τ_{90}$ and $τ_{50}$, the lookback times to form 90% and 50% of the cumulative stellar mass. We find that radial age gradients are uncorrelated with environment, but gradients in $τ_{90}$ are significan…

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astro-ph.GA

Scattering from Dusty Outflows in Hot Dust-Obscured Galaxies with Blue Excess Emission

R. J. Assef, M. Stalevski, F. E. Bauer, A. Blain, T. Diaz-Santos, P. R. M. Eisenhardt, R. Fernandez-Aranda, H. D. Jun et al.

(Context) Hot Dust-Obscured Galaxies (Hot DOGs) are a population of hyper-luminous quasars heavily obscured by dust and gas. While most have rest UV/optical SEDs dominated by their host galaxy emission, a small fraction shows blue emission in excess of what is expected for star-formation. Detailed multi-wavelength studies from X-rays to the far-IR of these Blue Excess Hot DOGs (BHDs) have concluded the most likely origin of this blue excess is scattered light from the central engine. This scenar…

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