Instrumentation and Methods for Astrophysics · Cross-listed from physics.hist-ph
Jodrell Bank and the British Astronomical Association: The Making of a Generation of Scientists
Jeremy Shears
The discovery of radar echoes from meteor trains at Jodrell Bank in 1945 marked the beginning of a new era in meteor astronomy and laid the foundations for the subsequent development of
radio astronomy. This paper examines the close relationship between Bernard Lovell's emerging research group at Jodrell Bank and the British Astronomical Association (BAA) during the formative years, 1946-1951. It explores the contributions of the individuals who connected these two communities. Particular
attention is given to the lives and scientific careers of Michael Ovenden, Gerald Hawkins, John Clegg, John Davies, Victor Hughes and Mary Almond, all of whom were BAA members. Their later achievements demonstrate the remarkable talents of this generation of scientists, whose work extended across
radio astronomy, planetary science, palaeomagnetism, archaeomagnetism and computer science.
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Solar and Stellar Astrophysics
Statistical Analysis of Minifilament Eruptions Using Full-disk H$\alpha$ Blue-wing Observations at Big Bear Solar Observatory
Artin Khaleghi, Qin Li, Nengyi Huang et al. (+2 more)
This paper presents a comprehensive statistical analysis of minifilament eruptions (MFEs) using high-cadence full-disk H$\alpha$ blue-wing observations from Big Bear Solar Observatory. Despite the recognized importance of MFEs for coronal dynamics and solar wind structuring, previous efforts were often limited by small sample sizes or restricted fields of view, leaving open questions about their global occurrence and characteristic properties. We developed an
algorithm incorporating intensity thresholding and temporal tracking to detect sudden enhancements in H$\alpha$ blue-wing images. A total of 1986 such events were identified during a 4 hr period on 2020 June 9. These detections were cross-validated using H$\alpha$ line-center observations to confirm the presence of associated filament structures. The analysis yields an occurrence rate of $\sim$6.6$\times 10^4$ per day, an average length of $\sim$17 Mm, and a typical lifetime of $\sim$21 minutes. A power-law distribution in eruption lengths (with slope $\sim$-4.8) and a sublinear scaling between duration and length suggest that larger eruptions tend to last longer. The length distribution of MFEs was further analyzed relative to active region proximity, revealing that eruptions occurring nearby a sunspot region were, on average, larger than the global mean eruption length. Additionally, an eruption density map was used to analyze the spatial distribution of MFEs relative to coronal hole boundaries. The results indicate a mild suppression of activity inside coronal holes and intermediate eruption frequency in the boundary regions. We briefly discuss their potential role in structuring the small-scale solar wind features such as
magnetic switchbacks and small-scale
magnetic flux ropes.
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All authors Artin Khaleghi, Qin Li, Nengyi Huang, Jeongwoo Lee, Haimin Wang
Astrophysics of Galaxies
Mapping the z>=5 SiIV Column Density Distribution onto the Galaxy Stellar Mass Function Using the Cumulative Absorption Cross Section
Kristian Finlator, Sam Patterson, Nora Nava et al. (+4 more)
Efforts to constrain directly the activity in low-mass
galaxies confront sensitivity limits even in the JWST era. Metal absorbers offer a complementary probe and are easier to detect, but leveraging them requires a known relationship between absorber strength and host mass. To this end, many studies assume a simple monotonic relationship between absorber strength and host mass. This ansatz ignores evidence that
galaxies at fixed luminosity host absorbers spanning a variety of strengths. We address this issue by deriving a six-parameter model for the cumulative absorption cross section from cosmological simulations that combines with the
galaxy stellar mass function to predict the absorber column density distribution (CDD). A maximum-likelihood analysis confirms that this approach reconciles the observed
galaxy stellar mass function with the observed SiIV CDD at z=5-6. The extrapolated CDD grows uncertain outside the observed range and the resulting constraints contain degeneracies, highlighting the need for improved measurements.
Galaxies of all masses host absorbers of all strengths, but a weak empirical association between massive
galaxies and strong absorbers is indicated. Faint
galaxies (M* < 10^8 Msun) host the majority of weak SiIV absorbers (log N < 13), emphasizing emission/absorber complementarity. The assumption of a power-law relationship between absorbers'
geometric cross sections and host
galaxy masses is empirically disfavored. The model may be applied to any combination of ion and
redshift if the
galaxy stellar mass function is well-constrained. Future observational tests incorporating improved host statistics will extend the model's range.
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All authors Kristian Finlator, Sam Patterson, Nora Nava, Ayanah Cason, Samir Kušmić, Ezra Huscher, Farhanul Hasan
Cosmology and Nongalactic Astrophysics · Cross-listed from gr-qc
Causal Gravitational-Wave Production Does Not Generate Infrared Adiabatic Curvature
Ruth Durrer and Alessandro Melchiorri
Short tensor modes can generate a white noise contribution to the local scalar $K=8\pi G\rho/3-\theta^2/9$, but this does not induce an infrared-enhanced adiabatic
curvature spectrum. For a conserved causal source, analyticity of the longitudinal velocity correlator requires $P_V=\mathcal O(k^2)$, hence $P_{\mathcal R}=\mathcal O(k^0)$ and $\Delta_{\mathcal R}^2=\mathcal O(k^3)$, excluding the $\Delta_{\mathcal R}^2\propto k^{-1}$ relic. We also construct a conserved conversion of radiation into gravitational waves: the white field resides in a compensated
entropy mode, and the fluid response cancels the slowly decaying $a^{-2}$ relic. Adiabatic bounds on such sources are therefore source- and matching-dependent.
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Instrumentation and Methods for Astrophysics · Cross-listed from cs.PL
Portability of Fortran's 'do concurrent' on GPUs II
Ronald M. Caplan, Miko M. Stulajter, Jon A. Linker et al. (+6 more)
There continues to be growing interest in using standard
language constructs for parallel and accelerated HPC computing, avoiding the need for (sometimes vendor-specific) external APIs. For Fortran applications,
language features such as 'do concurrent' loops open the door for compilers to implement multi-threaded, GPU-accelerated, and even distributed multi-node code with only the standard
language. Here, we explore the current status of using 'do concurrent' for GPU-accelerated Fortran applications across three major GPU vendors (NVIDIA, AMD, and Intel). Using a production application, we test their current capabilities, showing where the standard
language alone can be used, and where augmenting the code with a directive-based API (e.g., OpenMP) is still desirable or required. Multi-GPU tests are performed with GPU-aware MPI libraries. We find that the three GPU vendors can now GPU-accelerate pure Fortran (zero directives), but that manual data movement directives can help with performance and compatibility. The results show that there is rapid advancement towards making GPU-accelerated scientific HPC code performance portable using the Fortran standard
language.
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All authors Ronald M. Caplan, Miko M. Stulajter, Jon A. Linker, Jeff Larkin, Nikolaos Tselepidis, Harald Servat, Shiquan Su, Giacomo Capodaglio, Johanna Potyka
Earth and Planetary Astrophysics
JWST Spatial-Spectral Mapping of Green Comet C/2022 E3 (ZTF)
Stefanie N. Milam, Nathan X. Roth, Geronimo L. Villanueva et al. (+9 more)
We report a survey of molecular emission from cometary volatiles using the James Webb Space
Telescope (JWST) toward Oort cloud comet C/2022 E3 (ZTF) carried out on UT 2023 February 28 and March 1 at a heliocentric distance (rH) of 1.33 au. These measurements of H2O, HCN, CH3OH, C2H6, CH4, CO, CO2, 13CO2, and OCS sampled post-perihelion molecular chemistry in C/2022 E3. A suite of near to mid-infrared OH (
prompt emission) transitions were also detected. This work presents
nucleus-centered spectra for all detected species, spatial-spectral maps of column density and rotational temperature as a function of distance from the
nucleus for all except C2H6, HCN, and OH, and maps of co-measured continuum. The spatial distributions of both quantities were anisotropic for all mapped molecules; however, H2O showed distributions distinct from the remaining species. Coma-averaged values of the ortho-to-para ratio (OPR) for H2O and the 12CO2/13CO2 ratio derived from these maps were consistent with the statistical
equilibrium value of 3 and the terrestrial value of 89, respectively. The modeled mass fraction of the sub-micron dust grains is dominated by amorphous carbon (56%) followed by amorphous Mg:Fe pyroxene (28%), crystalline olivine (10%), and amorphous Mg:Fe olivine (5%) with a crystalline mass fraction of 0.2385(0.0008). We compare the volatile and dust composition of C/2022 E3 (ZTF) against comets measured to date, including those surveyed by JWST.
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All authors Stefanie N. Milam, Nathan X. Roth, Geronimo L. Villanueva, Dominique Bockelee-Morvan, Jacques Crovisier, David E. Harker, Michael S.P. Kelley, Kiernan D. Foster, Ian Wong, Davide Farnocchia, Marco Micheli, Heidi B. Hammel
Earth and Planetary Astrophysics
Effects of Outer Giant Planets on In Situ Formation of Inner Super-Earths
Phoebe Sandhaus, Rebekah I. Dawson, Mariah G. MacDonald et al. (+2 more)
Recent studies have found an observational correlation between the presence of outer giant
planets and inner super-Earths, which implies that outer giants do not suppress the formation of super-Earths. We simulate late-stage in situ
planet formation in the presence of outer giant
planets using $N$-body simulations. We investigate the effects of two sets of outer giants: the four Solar System giant
planets and three dynamically active giant
planets. Compared to systems without outer giants, we find that systems with the Solar System giants tend to form inner super-Earths that are more compact, coplanar, and circular, while the systems with the dynamically active giants form inner super-Earths that are more eccentric, inclined, and widely spaced, with lower intrinsic multiplicity. Including a contribution from systems that form with dynamically active giant
planets allows us to match observable quantities of super-Earths, including their two component eccentricity distribution. However, matching the observed population requires different formation conditions prior to the giant impact stage for systems with vs. without giant
planets. In our model, observed super-Earths that form in the presence of dynamically active outer giants emerge from disks with lower solid surface densities and without a depleted gas stage, suggesting that the giant
planets may have reduced, but not prevented, delivery and/or
accretion of solids in the inner disk. With a large enough sample of inner and outer systems, we could break down occurrence rates of inner super-Earths based on the properties of outer giants, and vice versa, and then compare these conditional probabilities with simulations.
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All authors Phoebe Sandhaus, Rebekah I. Dawson, Mariah G. MacDonald, Cody J. Shakespeare, Sarah Morrison
High Energy Astrophysical Phenomena
AT 2016blu: Accretion-Powered Outbursts in a Luminous Blue Variable and Compact Object Binary
Mojgan Aghakhanloo, Núria Torres-Albà, Nathan Smith et al. (+33 more)
We present the first X-ray detection of the
supernova (SN) impostor AT 2016blu in NGC 4559. AT 2016blu exhibited 27 detected quasiperiodic (~113 day) outbursts between 2012 and June 2026, presumably triggered by periastron passages in an eccentric binary system in which the primary is a $\gtrsim 33~M_{\odot}$ luminous blue variable (LBV). AT 2016blu was serendipitously observed by Chandra in 2001-2002, prior to its first documented outburst in 2012, but the stacked archival data show no X-ray detection. We monitored the source's visual-wavelength variability around its predicted outburst time and triggered a Chandra Target of Opportunity program in March 2026, obtaining observations with detections over five closely spaced epochs. These data indicate an X-ray luminosity of $\log L_{\rm X} \approx 38.64 \pm 0.11$~erg~s$^{-1}$ and an
accretion rate of $\dot{M} \gtrsim 8\times10^{-8}~M_{\odot}~\mathrm{yr^{-1}}$, consistent with the presence of a compact companion. We therefore conclude that AT 2016blu is the first known case of an LBV SN impostor whose outbursts are driven by intermittent
accretion onto a compact object. Given that the system consists of a massive
star and a compact companion, AT 2016blu is a high-mass X-ray binary, similar to SN 2010da, although the donor
star in SN 2010da is a red supergiant.
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All authors Mojgan Aghakhanloo, Núria Torres-Albà, Nathan Smith, Raphael Baer-Way, Shazrene Mohamed, Alexei V. Filippenko, WeiKang Zheng, Thomas G. Brink, D. Andrew Howell, Brian Hsu, Moira Andrews, Joseph R. Farah, Curtis McCully, Kathryn Wynn, Réka Könyves-Tóth, Conor L. Ransome, Enrique Rathmann, Tamás Tordai, Sjoerd Dufoer, Charles Cynamon, Franz-Josef Hambsch, Thomas Rutherford, Simone Leonini, Franky Dubois, Ivo Peretto, Donald F. Collins, Lorenzo Betti, Lara Fossi, Irene Parenti, Vincenzo Pettina, Giulio Giordano Chiti, Maria Hofheinz, André Steenkamp, Sauro Gaudenzi, Nikola Antonov, Giuseppe Pappaa
High Energy Astrophysical Phenomena
Investigating the Multiwavelength Emission of Binary SMBH Candidate SDSS J095036.75+512838.1
Cassandra Daniele, Adi Foord, Jessie Runnoe et al. (+2 more)
We present results from a multiwavelength study of the binary AGN candidate SDSS J095036.75+512838.1, which was identified as a candidate binary SMBH system due to its significant and variable broad H$\beta$ line shifts. We use available infrared-to-X-ray data to investigate the system's
accretion properties. Analyzing recent Chandra observations, we characterize the X-ray emission and test the binary SMBH hypothesis. We find that the X-ray spectrum is well-modeled as a single AGN, with a 2–10 keV luminosity of $1.3 \times10^{43}$ erg s$^{-1}$. By assembling a comprehensive multiwavelength spectral energy distribution, we further examine the possibility of circumbinary
accretion. The infrared-optical emission matches that expected from a single AGN, though we observe an excess in emission between $\sim 9500-19000 \r{A}$ and a deficit near $\sim 2600 \r{A}$. Archival optical spectra also suggest a deficit near $\sim 8500 \r{A}$. We investigate whether these SED anomalies can be explained by long-term variability or interstellar reddening. We find no evidence of dimming, while reddening can account for the deficit in UV emission. However, the origin of the near-infrared excess remains unclear. Ultimately, the SED of SDSS J095036 is well described by emission from a single, reddened AGN. Future high-resolution infrared and X-ray spectral observations will be crucial for disentangling the origin of the infrared excess and testing the binary SMBH scenario in SDSS J095036.
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All authors Cassandra Daniele, Adi Foord, Jessie Runnoe, Michael Eracleous, Niana N. Mohammed
High Energy Astrophysical Phenomena · Cross-listed from nucl-th
Trace Anomaly and Effective Topological Sources in Neutron Stars
Federico Nola
This work investigates whether the trace anomaly can diagnose the stellar response to a topological scalar field in tensor multi-scalar
gravity. Eleven cold tabulated equations of state (EoSs) were examined, with six selected after conservative GR stability and speed of sound checks over the tabulated density range. Their fiducial topological configurations were compared with the corresponding GR models under complementary matching prescriptions. After controlling for stellar mass and EoS dependence, the GR trace source strength $S_T$ remained strongly correlated with the topological mass response, with a partial Spearman coefficient $\rho = 0.975$ within the sampled fiducial sequences. Near $1.4\,M_\odot$, the topological configurations were systematically more compact, with reductions in the Jordan frame radius of $6.7$–$8.7\%$ at fixed baryonic mass and $0.87$–$1.29\,\mathrm{km}$ at fixed gravitational mass. These shifts are comparable to current uncertainties from the
Neutron Star Interior Composition Explorer (NICER) and their observational impact depends on the source. Despite the global deformation, the interior effective source remained dominated by matter, with a median topological contribution of about $0.8\%$. The GR matter trace therefore emerges as a useful diagnostic of the fiducial topological stellar response.
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Cosmology and Nongalactic Astrophysics
One-point matter PDFs beyond TopHat filters
Anton Chudaykin, Alexander M. Kayssi and Sergey Sibiryakov
We study the one-point probability distribution function (PDF) for matter densities averaged with an arbitrary spherically symmetric window function. The PDF is analytically modeled within the path integral framework, enabling a non-perturbative description of large-scale structure. It contains a leading order contribution controlled by the spherically symmetric gravitational collapse dynamics, as well as an order-one factor arising from aspherical fluctuations. We develop a numerical pipeline to compute the leading spherical-collapse part of the PDF and apply it to a family of window functions interpolating between the TopHat and Gaussian filters in coordinate space, as well as to a window function with non-monotonic radial dependence. We find that the PDF weakly depends on the choice of the filter, provided the width of the filter is normalized to yield a fixed linear averaged density variance. For each filter and each value of the averaged density, our pipeline gives the most probable density profile. We find that these profiles vastly differ for different filters in the case of overdensities, but closely follow a universal curve at underdensities. We obtain a perturbative expression for the aspherical part of the PDF valid at small density contrasts. We find from it that all PDFs are equally sensitive to the effective field theory (EFT) corrections accounting for short-scale clustering, regardless of how smooth the filter's boundary is. We test our PDF model against the results of high-resolution N-body simulations. The agreement is excellent for filters with widths larger than 10 Mpc/h. Small discrepancies at a few percent level arise for narrower filters and are interpreted as higher-order perturbative corrections.
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Instrumentation and Methods for Astrophysics
High-contrast aperture masking interferometry: detecting companions within the diffraction limit
Benjamin Calvin, Michael Fitzgerald and Jessica Castellanos
The pursuit of the direct discovery and characterization of Earth-like
exoplanets has motivated high contrast imaging surveys using coronagraphs with narrow inner working angles. Traditional imaging methods, however, are limited by the size of the on-axis PSF and typically only detect companions at angular separations of > 2$\lambda$/D. Meanwhile, non-redundant masking (NRM) techniques have been used with single-aperture
telescopes to interferometrically resolve astrophysical features at angular scales within the diffraction limit, but NRM interferometry faces sensitivity issues for high-contrast objects. In this project, we investigate utilizing high contrast coronagraphy in conjunction with NRM interferometry. We conduct a preliminary investigation of this combined architecture with the goal of determining the potential bounds of performance and discovery space for high-contrast targets within the inner working angle of traditional high-contrast imaging. We predict an improvement in the achievable contrast for
photon-limited observations by combining the techniques, and we also develop estimates for wavefront stability requirements for the system.
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Cosmology and Nongalactic Astrophysics
On what scales does strong lensing robustly constrain the mass profile of low-mass perturbers?
Maryam Tajalli and Simona Vegetti
Galaxy-
galaxy strong gravitational
lensing is an established method to detect and characterise low-mass
haloes, which are otherwise too faint to be directly observed. Recent analyses have shown empirically that there exists a characteristic radius within which the projected enclosed mass of these
haloes can be robustly measured. Here we provide a physically and mathematically motivated definition of this robust radius based on the Fisher information
matrix. We show that for any spherically symmetric smooth profile with at least two free parameters, there exists a pivot radius at which estimates of the projected mass become decorrelated from the local logarithmic slope and have minimum relative uncertainty. As a result, the projected mass within this radius can be recovered consistently by any profile that fits the data well enough. This robust radius coincides, to leading order, with the weighted
geometric mean of the arc pixel distances from the
halo, where the weights depend on the perturber deflection angle, the macro-model magnification, and the source surface brightness gradient. Beyond leading order, corrections are of order the weighted log-width of the arc. The data constraining power on the local properties of the
halo profile beyond amplitude is shown to depend on the radial leverage of the arc around the perturber, and on the imprint of the perturber deflection angle on high signal-to-noise-ratio pixels. Our definition generalises to both subhaloes and line-of-sight
haloes and naturally captures the important physical aspects of the problem and the effect of the data resolution and signal-to-noise ratio.
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Cosmology and Nongalactic Astrophysics · Cross-listed from hep-ph
Tunneling from a Slowly Rolling Multifield Background Using Tadpole Subtraction
Masaki Yamada
We study semiclassical tunneling in scalar field theories with slowly evolving homogeneous backgrounds. We formulate the problem by combining tadpole subtraction with an adiabatic expansion: the former maps the rolling system to an instantaneous multi-field tunneling problem, while the latter systematically tracks the slow
evolution of the background. This formulation is particularly useful for tunneling during slow-roll inflation, where the tunneling direction may be transverse to the rolling inflaton direction. For a time-reflection-symmetric bounce on a fixed on-shell geometry, we show that the real tunneling exponent receives no direct correction linear in the rolling velocity. The tunneling rate nevertheless drifts along the rolling trajectory because the frozen tadpole-subtracted potential evolves. We also find that the exponent approaches a finite but nonanalytic limit as the tangential
curvature vanishes, suggesting that a weakly tachyonic tangential direction can yield an exponent of the same order.
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Earth and Planetary Astrophysics
Leveraging Impact Parameter to Mitigate the Transit Light Source Effect: Early Insights from TRAPPIST-1
Ana Glidden, Alexander I. Shapiro, Sara Seager et al. (+19 more)
Stellar activity complicates
exoplanet transmission spectra, particularly for smaller
planets around M dwarfs with JWST. The transit light source (TLS) effect, the imprinting of spectral differences between the average stellar disk and the occulted transit chord onto the transmission spectrum, makes it challenging to directly use the out-of-transit spectrum to correct for stellar contamination. Theory and observations suggest that spots may concentrate towards higher latitudes when the Coriolis force is substantial relative to buoyancy, leaving the equatorial region relatively quiet. Here, we evaluate how the latitudinal distribution of active regions shapes the strength of the TLS effect for
planets spanning a range of impact parameters ($b$), using TRAPPIST-1 as a testbed. We first construct a fiducial model to illustrate two distribution regimes. With our model, the moderate-$b$ outer TRAPPIST-1
planets (f, g, h) occult a more typical region of the stellar disk than the inner
planets and are thereby less affected by the TLS effect, though their bias may vary more from visit-to-visit as these active regions evolve with time. More generally, our results imply an impact parameter "sweet spot" for atmospheric characterization, independent of the sign of the active region temperature contrast, whose location depends on the distribution of active regions. The distribution may be revealed by transit residuals as multiple
planets probe different latitudes, while longitudes are sampled in time, such that the variance and frequency of the correlated scatter could constrain active-region filling factors, sizes, and separations.
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All authors Ana Glidden, Alexander I. Shapiro, Sara Seager, Nadiia Kostogryz, Valeriy Vasilyev, Roeland P. van der Marel, Julien de Wit, Benjamin V. Rackham, Prajwal Niraula, Natalie H. Allen, Jingcheng Huang, Nikole K. Lewis, Zifan Lin, Jacob Lustig-Yaeger, Ryan J. MacDonald, Brett M. Morris, Elijah Mullens, Kevin B. Stevenson, Jeff A. Valenti, Daniel Valentine, Hannah R. Wakeford, C. Matt Mountain
Instrumentation and Methods for Astrophysics
A Multi-instrument Generalized Lomb-Scargle Periodogram Implementation
Giulia Martos, Néstor Espinoza and Jorge Meléndez
We present an implementation of the well-known and broadly used Generalized Lomb-Scargle Periodogram (GLS) which simultaneously takes into account individual offsets introduced in the data by different instruments: a "multi-instrument" GLS periodogram. While the
algorithm itself is not new, the simple closed form implementation we provide, to our knowledge, is. We showcase an application of our multi-instrument GLS on radial-velocity data of the hot Jupiter TOI-481 b, whose period is recovered with a higher significance compared to the standard GLS approach. The code is available on GitHub.
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Astrophysics of Galaxies
An Optical Illusion: High Electron Densities Create Extremely Metal-Poor Galaxy Impostors
Tiger Yu-Yang Hsiao, Danielle A. Berg, Steven L. Finkelstein et al. (+8 more)
JWST has enabled the discovery of dozens of extremely metal-poor
galaxies (EMPGs) with
metallicities below $5\%\,Z_{\odot}$, representing a significant leap toward detecting the first
galaxies without metals. However, accurate
metallicity measurements require careful determination of physical conditions in the ionized gas. In this paper, we study four
galaxies that appear to be EMPGs when analyzed using the direct $T_e$ method with the common low-density assumption ($n_e=10^3\,{\rm cm}^{-3}$). To test whether their metal-poor status holds when accurately measuring the density, we apply the direct method with a self-consistent determination of electron temperature ($T_e$) and density ($n_e$) in the high-ionization zone using the [OIII]$\lambda$5008, [OIII]$\lambda$4364, and [OIII]$\lambda$1666 lines, using JWST/NIRSpec data from the SPURS program in the Abell 2744 lensed field. We find that three out of four
galaxies in our sample have extremely high electron densities ($n_e \sim 10^{5}-10^{6}\,{\rm cm^{-3}}$), which suppress the [OIII]$\lambda$5008 line and lead to underestimates of
metallicity by up to $\sim1.1\,$dex when this density is not accounted for, and have true
metallicities of 12+log(O/H) $\sim7.3-8.2$. Failure to account for high densities can therefore lead to systematic misclassification of metal-poor
galaxies and biased conclusions about early chemical enrichment.
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All authors Tiger Yu-Yang Hsiao, Danielle A. Berg, Steven L. Finkelstein, Ansh R. Gupta, Zorayda Martinez, Anthony J. Taylor, Hollis B. Akins, Oscar A. Chavez Ortiz, John Chisholm, Lukas J. Furtak, Vasily Kokorev
Cosmology and Nongalactic Astrophysics · Cross-listed from cond-mat.quant-gas
Imaging the vacuum fluctuations of a quantum field
Yansheng Zhang, Feiyang Wang, Yi Jiang et al. (+5 more)
Heisenberg uncertainties lead to inevitable fluctuations in the measurement outcomes for
quantum-mechanical observables. For
quantum fields, these uncertainties result in random spatial structures in snapshots of a field, even when the field is in its ground (
vacuum) state. Such `
vacuum fluctuations' are at the heart of a wide range of phenomena, from spontaneous decay processes to the Casimir force and Hawking radiation. Their existence is a key manifestation of the quantumness of the physical world, but usually it is only their consequences that are directly observed. Here, we directly observe spatial
vacuum fluctuations of a bosonic
quantum field. Our experiments are based on a homogeneous planar atomic Bose–Einstein condensate. The condensate comprises two coherently coupled interacting components (
spin states), and the
quantum field describes its
spin degrees of freedom. In the regime where the interactions dominate over the coherent coupling, our system emulates a (massive relativistic) sine-Gordon field. Images of the field reveal simultaneous fluctuations on different length scales, with scale-dependent amplitudes consistent with theoretical predictions for a
vacuum state. Observing such fluctuations in the sine-Gordon limit opens many possibilities for laboratory simulations of relativistic fields in regimes that are presently not theoretically tractable.
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All authors Yansheng Zhang, Feiyang Wang, Yi Jiang, Alexander C. Jenkins, Paul H. C. Wong, Christoph Eigen, Gehrig Carlse, Zoran Hadzibabic
Astrophysics of Galaxies
The Nearby Star Formation and Supernova Histories Reconstructed from Young Star Clusters
Cameren Swiggum, Catherine Zucker, Michelangelo Pantaleoni González et al. (+8 more)
We reconstruct the recent
star formation and core-collapse
supernova (ccSN) histories of the Solar Neighborhood from the past trajectories of young
star clusters. Using a Gaia-based cluster sample with newly derived ages, masses, and bulk 3D velocities, we integrate orbits backward in an assumed axisymmetric Galactic potential and combine the trajectories with IMF sampling and stellar lifetimes to infer ccSN times and locations over the past 50 Myr. The result is an all-sky, 3D, time-resolved map of nearby ccSN activity for comparison with high-resolution 3D views of the local interstellar medium. The 0–15 Myr map shows strong enhancements toward Orion, Vela, Sco–Cen, and Cepheus, many within present-day cavities and shells. At earlier times, the dominant enhancements trace the Collinder 135, Messier 6, and Alpha Persei cluster families, showing how the remnants of massive
star-forming complexes have shaped the recent local feedback history. We recover a bursty
star formation history followed by a delayed, smoother ccSN history. Over the last 40 Myr, the mean
star formation and ccSN rates are \(823~M_\odot~\mathrm{Myr}^{-1}\) and \(7.7~\mathrm{Myr}^{-1}\), respectively, corresponding to a Milky Way rate of \(0.55\pm0.03~\mathrm{century}^{-1}\). Present-day OB-
star catalogs yield rates ranging from agreement with the cluster reconstruction to several times higher. Because the catalogs overlap weakly and require different corrections, we do not rescale the ccSN map. Our reconstruction provides an empirical framework for connecting the recent history of massive-
star feedback to the 3D structure and life cycle of gas in the nearby Milky Way.
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All authors Cameren Swiggum, Catherine Zucker, Michelangelo Pantaleoni González, Emily L. Hunt, Robert A. Benjamin, Sebastian Hutschenreuter, Alena K. Rottensteiner, Efrem Maconi, Lewis McCallum, João Alves, Sebastian Ratzenböck
Cosmology and Nongalactic Astrophysics
A blind spot in transverse BAO calibration
Domenico Sapone
Transverse baryon acoustic oscillation (BAO) measurements are increasingly used for cosmological inference, and carry a calibration that no such inference can constrain. A constant error in the transverse BAO scale is exactly degenerate with the combination $r_{\rm d} h$: it leaves the goodness of fit unchanged and the recovered parameters plausible, and is therefore invisible to any analysis that uses these measurements alone. The radial BAO sector removes this degeneracy, supplying $D_{\rm M}/r_{\rm d}$ by integration without reference to $H_0$ or to any model for the expansion rate. In flat Friedmann–Lemaître–Robertson–Walker (FLRW) geometry the relation between the two sectors is an identity, so the sound horizon and the dark-energy equation of state cancel as well. An integrated form of this identity reduces the consistency test to a straight line, whose slope measures a relative transverse calibration $\varepsilon$. A departure from $\varepsilon = 1$ cannot be produced by any dark-energy model, nor by spatial
curvature: it indicates an inconsistency in the measurement chain rather than in the cosmology. We apply the test to the two main SDSS transverse BAO compilations, which give $\varepsilon = 1.073 \pm 0.021$ and $1.021 \pm 0.029$. The first differs from unity at $3.8\sigma$ using the published independent errors, while the second is consistent with unity. The two compilations themselves differ by $(5.4 \pm 1.4)\%$, or $3.9\sigma$, and the offset is constant in
redshift. The test provides a direct diagnostic for current and future angular BAO measurements.
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Cosmology and Nongalactic Astrophysics
Non-Minimally Coupled Warm Inflation in the Defining Frame
Adrián Casado-Turrión, Paulo B. Ferraz, Mindaugas Karčiauskas et al. (+1 more)
Warm inflation in $F(\Phi)R$ scalar-tensor theories of
gravity is investigated in the `defining' frame, where the theory and its parameter values are specified. Translating the resulting dynamics to the Einstein frame, we find that the dissipation ratio is suppressed by the modified-
gravity effects. Thus, although the effective warm-inflation dynamics can be consistently analysed in either frame, the dissipative regimes need not coincide between them. In particular, we find that
quantum perturbations can dominate over thermal fluctuations in the scalar power spectrum even in a high-temperature, strong-dissipation regime in the defining frame. Finally, we compute the scalar spectral index and tensor-to-scalar ratio for a non-minimal coupling function $F(\Phi) = 1+\xi (\Phi/m_{\rm P})^2$ with a quartic potential and both constant and quadratic field-dependent dissipation coefficients, and identify
benchmark points compatible with current CMB constraints.
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All authors Adrián Casado-Turrión, Paulo B. Ferraz, Mindaugas Karčiauskas, José Jaime Terente Díaz