Astrophysics of Galaxies
Little Red Dots at z~2 in EIGER reveal a gentle decline with respect to their peak number density at z~5
Shrriya Kapoor, Jorryt Matthee, Alberto Torralba et al. (+10 more)
We report the discovery of a sample of little red dots (LRDs) at $z \approx 2$ identified from deep JWST/NIRCam imaging and wide-field slitless spectroscopy over $140$ arcmin$^2$ from the EIGER survey. With an improved blind broad-line identification
algorithm, we select 19 sources at spectroscopic
redshifts $z = 1.55-3.18$ identified via rest-frame near-infrared lines (Paschen-$\beta$, HeI+Pa$\gamma$ and OI). Based on a range of spectro-photometric criteria, we classify five of these sources as LRDs and the other 14 as classical active
galactic nuclei (AGNs). This classification is corroborated by some X-ray detections among the AGNs. Classical AGNs dominate the number counts above optical luminosities M$_{5100}<-22.5$, whereas the LRD fraction among broad-line sources reaches 100 % at M$_{5100}\approx-20$. The LRDs span the range in Balmer break strengths seen in the higher
redshift populations. Blue-shifted HeI absorption is detected in the two reddest sources. The HeI/Pa$\gamma$ ratio cleanly separates LRDs from classical AGNs and seems to anti-correlate with Balmer break strength, likely tracing HeI self-absorption at higher gas column densities. Our LRD sample has a similar optical luminosity range as their high-
redshift counterparts, corresponding to black hole masses of $\sim10^{6}$ M$_{\odot}$ at the Eddington luminosity. We measure LRD number densities of $\approx 7\times10^{-6}$ cMpc$^{-3}$ at $z = 1.9-2.5$, which indicates that LRDs represent $\lesssim 3$ % of the AGN population at these epochs. Our results confirm the previously reported decline in the LRD number density with respect to $z \approx 5$ based on photometric surveys, although we find the decline to be more gentle than earlier emphasized.
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All authors Shrriya Kapoor, Jorryt Matthee, Alberto Torralba, Ivan G. Kramarenko, Rongmon Bordoloi, Jenny E. Greene, Edoardo Iani, Daichi Kashino, Zhaoran Liu, Ruari Mackenzie, Sara Mascia, Rohan P. Naidu, Rob Simcoe
High Energy Astrophysical Phenomena
Decoding the Early-Time Light Curves of Type Ia Supernovae. II. Population Parameters of One Thousand ZTF Supernovae
Chang Liu, Adam A. Miller, Nikhil Sarin et al. (+13 more)
Early-time light curves of Type Ia
Supernovae (SNe Ia) encode critical information about their progenitor systems. We characterize the rise of normal SNe Ia using a volume-complete sample of 972 events from the Zwicky Transient Facility Data Release 2, an order of magnitude larger than any previous
dataset for similar analyses. Fitting light curves up to $30\%$ of peak flux with a power-law model under a hierarchical
Bayesian framework, we provide robust population-level constraints on the rise time ($t_\mathrm{rise}$; $\mu=18.55\pm0.08$ days, $\sigma=1.42\pm0.07$ days), rise index ($\alpha$; $\mu=2.10\pm0.04$, $\sigma=0.48\pm0.03$ in ZTF $r$), and $g-r$ color
evolution ($\alpha_g - \alpha_r$; $\mu=0.20\pm0.02$, $\sigma=0.17\pm0.02$). These power-law fits are sensitive to the chosen truncation epoch if data beyond $\sim$$40\%$ of peak flux are included, but generally converge when restricted to earlier epochs. The relation between rise morphology and light-curve width ($\texttt{SALT2}$ $x_1$ stretch) bifurcates into two distinct regimes: high-stretch SNe Ia show clear trends where a higher $x_1$ correlates with shallower rises and more persistent blue colors, whereas low-stretch SNe Ia lack such trends. While rise times correlate positively with $x_1$ overall, this relation flattens significantly within the high-stretch population. Searching for anomalies, we identify several normal SNe Ia with unusually long rise times, which potentially exhibit short-duration ($\lesssim$2 days) flux excesses over a smooth rise. Long-duration ($\sim$5 days) flux excesses appear common within the high-stretch population and are tied to the shallow rises and early blue colors, pointing to widespread outward $^{56}$Ni mixing. Multi-dimensional explosion models with more realistic progenitor setups are needed to fully reproduce the observed dichotomy in rise morphology and stretch.
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All authors Chang Liu, Adam A. Miller, Nikhil Sarin, Kate Maguire, Tomás E. Müller-Bravo, Ping Chen, L. Galbany, Young-Lo Kim, Jesper Sollerman, Eric C. Bellm, Joahan Castaneda Jaimes, Tracy X. Chen, Matthew J. Graham, David Hale, Mansi M. Kasliwal, Josiah Purdum
Earth and Planetary Astrophysics
White dwarf planets in star clusters: gravitational scattering versus mass-loss effects
Richard J. Parker and Dimitri Veras
White
dwarfs are unique laboratories for understanding the formation,
evolution and survivability of planetary systems. Post-main sequence mass-loss will change planetary orbital properties and stir up debris discs, leading to the observed pollution of white
dwarf atmospheres. However, to date, very few studies have investigated the impact of the
stellar birth environment on white
dwarf planetary systems. In this paper we simulate the
evolution of
giant planets around white
dwarf progenitors from their formation in a
star-forming region until 1Gyr, when the most massive
stars ($>$2M$_\odot$) have left the main sequence. Our simulations self-consistently model $N$-body interactions between
stars and
planets while
stars evolve into white
dwarfs within the cluster lifetime. We find that although scattering interactions in dense
star-forming regions create free-floating
planets, and alter the orbital properties of up to 20 per cent of the surviving
planets, the effects of mass-loss from the
star dominate the dynamics. This behaviour is independent of the
stellar density of the birth
star-forming region, and largely independent of the initial
planet orbital properties. Our simulations produce both captured
planets around white
dwarfs (potentially similar to WD 0806-661b), and triple systems with white
dwarfs and
planets (potentially similar to PSR B1620-26(AB)b), and our results yield a population synthesis of
giant planets from 1 - 100au that may be relevant to Roman,
Gaia and JWST observations.
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Astrophysics of Galaxies
Hot or Cold? Radial Redistribution of Stars in FIRE Simulations of Milky Way-Mass Galaxies and the Asymmetry of Inward versus Outward Migrators
Cecilia Steel, Andrew Wetzel, Rori Kang et al. (+3 more)
Stars can radially redistribute (migrate) within
galactic disks. The degree to which this occurs as dynamically `cold' (preserves orbital eccentricity) or `hot' (increases eccentricity) remains debated. Many models presume that radial redistribution occurs primarily via cold torquing, resulting in changes in angular momentum without dynamical heating. We test the net dynamical heating associated with redistribution over
stellar lifetimes using the FIRE cosmological zoom-in simulations of 12 Milky Way-mass
galaxies. We select
star particles today that underwent significant changes in orbital angular momentum, j_phi, since birth. We investigate net changes in their orbital eccentricity, e, and we quantify the `cold-torqued' fraction of
star particles with |Delta j_phi/j_phi,birth| > 0.2 that preserved eccentricity (|Delta e| < 0.1) since birth. The direction of radial redistribution is most critical: outward-migrating
stars experienced smaller net changes in eccentricity, whereas inward-migrating
stars almost always heat since birth. For
stars born on near-circular orbits (e_birth < 0.2), the cold-torqued fraction decreases rapidly with age today and is generally < 50% at ages >~2 Gyr.
Stars born on moderately eccentric orbits (e_birth ~ 0.4) are the most likely to preserve their birth eccentricity. However, the cold-torqued fraction is higher in earlier-forming and/or dynamically-colder disks. Significantly, we identify a population of
stars that dynamically `cooled', decreasing in eccentricity since birth: this is the primary way that
stars end up on near-circular orbits today. Overall, a
star's migration direction, its e_birth, and its age primarily determine whether it was dynamically heated, cooled, or unchanged. In general, radial redistribution in FIRE is typically not cold between birth and today.
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All authors Cecilia Steel, Andrew Wetzel, Rori Kang, Fiona McCluskey, Sarah Loebman, Kathryne J. Daniel
High Energy Astrophysical Phenomena
Decoding the Early-Time Light Curves of Type Ia Supernovae. I. A Hierarchical Bayesian Framework for Demographic Inference
Chang Liu and Adam A. Miller
Light curves of Type Ia
Supernovae (SNe Ia) in the days following explosion encode the diversity of progenitor systems and explosion physics. We present a hierarchical
Bayesian framework to robustly constrain the population-level light-curve morphology of SNe Ia by fitting a large light-curve
dataset simultaneously to power-law rises. Using a multivariate Gaussian population prior, this framework automatically down-weights sparsely sampled SNe and noisy measurements in the inference, obviating the need for restrictive quality cuts that introduce selection biases. Validation on simulated power-law light curves demonstrates that the population prior effectively suppresses the volume-projection bias from the asymmetric likelihood: compared to the classic two-step approach of fitting individual SNe and then aggregating the results, the hierarchical approach dramatically reduces the bias on the population-level parameters (mean, scatter, and correlation). When fitting the power-law model to light curves with more realistic morphologies, while the rise time can be mildly underestimated due to model misspecification, the recovered population scatter remains reliable. Furthermore, SNe with early flux excesses can emerge as outliers in the inferred parameter space, offering a potential diagnostic for identifying such events. Finally, we show that the inferred population distribution can also improve individual-event inference. Restricting the population prior to nuisance amplitudes, while preserving the complete correlation structure, regularizes fits to individual SNe without shrinking the physically meaningful rise time and rise index toward their population means.
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Cosmology and Nongalactic Astrophysics
Magneto-Thermal Instability in Galaxy Clusters – III. The Limit of Adiabatic Stratification
Lorenzo Maria Perrone and Henrik Latter
In the hot and dilute intracluster medium of
galaxy clusters, large-scale buoyancy instabilities can develop due to the transport of heat along
magnetic field lines. In particular, the peripheries of
galaxy clusters are unstable to the magneto-thermal instability (MTI), which may contribute to the observed levels of
turbulence. Recent theoretical and numerical work has revealed that the stable background
entropy stratification controls the nonlinear saturation of the instability, by setting the strength and the integral scale of the resulting turbulent state. However, observations of the periphery of
galaxy clusters show that the radial
entropy profiles near the virial radii $R_{500}$ may be flatter than predicted by models of smooth gravitational
accretion. This motivates us to investigate the saturation of the MTI in adiabatic (buoyantly neutral) atmospheres, using both phenomenological approaches and Boussinesq numerical simulations, carried out with the pseudospectral code SNOOPY. We find that the adiabatic MTI saturates in a state characterised by the formation of large-scale plumes and their destruction by shear instability, yielding a new scaling law for the saturated turbulent kinetic energy, $\sim$$\chi \omega_T$, as the adiabatic limit is approached, where $\chi$ is the effective thermal diffusivity and $\omega_T$ is the MTI frequency. This predicts that the MTI plumes may achieve near sonic speeds in cluster outskirts, thus providing significant turbulent pressure support, even in the face of suppressed thermal conduction.
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Cosmology and Nongalactic Astrophysics · Cross-listed from hep-ph
Precision Solar System Dynamics for Ultralight Dark Matter Search
Jonas Frerick, Hyungjin Kim and Felix Kling
Ultralight dark matter exhibits an order-one density fluctuation at the scale of its wavelength. This density fluctuation exists across the entire dark matter
halo and interacts with
stars and
planets, perturbing their motion via gravitational interactions. We investigate the possibility of using precision
solar system dynamics to search for ultralight dark matter. We examine this possibility with interplanetary
radio range measurements. We show that the precision of current range measurements can probe ultralight dark matter at masses around $10^{-15}\,$eV, had its density in the
solar system been $10^5$ larger than the so-called local dark matter density. This limit complements other constraints, such as the one from analyses of
pulsar timing observations.
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High Energy Astrophysical Phenomena
An Analytical Toy Equation of State for Neutron Stars Consistent with Current Observations
Tian-Shun Chen, Xiao-Ding Zhou and Kilar Zhang
Fast analytic and semi-analytic studies of
neutron stars often require an equation of state that is convenient to evaluate while producing relativistic
stellar sequences compatible with current multimessenger constraints. We construct such a
benchmark by scanning a smooth double polytropic relation for the energy density as a function of pressure, $\hat\epsilon (\hat p)=a_1\hat p^{\Gamma_1}+a_2\hat p^{\Gamma_2}$. The parameters are selected with filters based on massive
pulsars,
tidal deformability from the binary-
neutron-
star event GW170817, and NICER mass-radius measurements. A single polytropic baseline scan finds no model passing all filters, whereas a double-polytrope scan identifies a viable region. A curve-integral score, evaluated against public NICER and GW170817 posterior data sets, is then used to choose
benchmark equations of state within this region. The selected representatives support $M_{\max}=2.44$–$2.49\,M_\odot$, with $R_{1.4}\simeq 11.3$ km and $\Lambda_{1.4}=485$–$512$, and remain causal on the stable branch. This compact analytic family provides reference cases for relativistic
stellar-structure tests at current observational scales.
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High Energy Astrophysical Phenomena
Radiation-pressure instability is an artifact of constant-$\alpha$ closure. Implications for AGN disk tensions
M. H. Naddaf, M. Ghasemnezhad, H. Ghanbarnejad et al. (+2 more)
The standard $\alpha$-disk formalism parametrizes turbulent angular momentum transport through a dimensionless coefficient $\alpha$, assumed to be spatially and thermodynamically invariant. While analytically convenient, this assumption leads to the well-known thermal and viscous instabilities in radiation-pressure dominated (RPD) regions. We show that this instability is not the consequence of radiation pressure, but is due to enforcing a constant $\alpha$ across distinct thermodynamic regimes. Requiring the steady thin-disk (TD) to remain thermally stable and single-valued in the $\dot{M}$–$\Sigma$ plane yields a necessary condition on the stress response, expressed as $\eta_{\rm x} \equiv d\ln\alpha_{\rm x}\,/\,d\ln X > 4/7$, where $X \equiv P_{\rm gas}/P_{\rm rad}$. The resulting viscosity law $\alpha_{\rm x} \equiv \alpha(X)$ emerges directly from the internal consistency of TD equations, without modifying the stress law or invoking any additional physics. $\alpha_{\rm x}$ removes the RPD unstable branch. The disk structure becomes smooth and globally single-valued, with higher $\Sigma$ and $\tau$ in the inner RPD disk, while preserving the standard effective-temperature profile. This increases thermal and inflow timescales, offering a natural route to
accretion-state dependent variability without large-amplitude radiation-pressure limit cycles. It also motivates revisiting AGN disk tensions, including microlensing sizes and continuum reverberation lags with improved radiative-transfer modeling. The results show that the RPD instability, and possibly some associated AGN disk tensions, reflect an inconsistent viscosity closure.
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All authors M. H. Naddaf, M. Ghasemnezhad, H. Ghanbarnejad, D. Hutsemékers, B. Czerny
Instrumentation and Methods for Astrophysics
The filter exchange system of the LSSTCam at the Vera C. Rubin Observatory
Alexandre Boucaud, Pierre Antilogus, Éric Aubourg et al. (+26 more)
The Filter Exchange System of the LSSTCam at the Vera C. Rubin Observatory is a critical subsystem enabling the Legacy Survey of Space and Time (LSST) by performing rapid, repeatable exchanges among five large-format filters within a highly constrained in-camera volume. Since the start of on-sky operations in April 2025, the FES has routinely performed up to 40 filter exchanges per night, completing each change in under 90 seconds with a positioning repeatability of 100 micrometers in the focal plane. Safety and reliability are ensured through a dedicated software architecture. Drawing on over a year of operational experience, we report on the in-situ performance of this sophisticated system within the observatory environment, characterize the key performance metrics, and discuss how specific design choices have influenced system behavior and reliability in practice.
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All authors Alexandre Boucaud, Pierre Antilogus, Éric Aubourg, Antoine Bernard, Johan Bregeon, Patrick Breugnon, Julien Cordian, Hervé Croizet, Guillaume Daubard, Kevin Fanning, Fabrice Gallo, Anthony S. Johnson, Claire Juramy-Gilles, Pierre Karst, Mile Kusulja, Eric Lagorio, Travis Lange, Didier Laporte, Juan-Carlos Lazarte, Margaux Lopez, Aurélien Marini, Stuart Marshall, Dmitry Onoprienko, Hannah M. M. Pollek, Max Turri, Yousuke Utsumi, Francis Vezzu, Françoise Virieux, Téo Weicherding
Instrumentation and Methods for Astrophysics · Cross-listed from math.NA
GQL-Based Physical-Constraint-Preserving High-Order Finite Difference Schemes for Special Relativistic Hydrodynamics in Arbitrary Dimensions
Linfeng Xu, Shengrong Ding and Kailiang Wu
High-order accurate simulations of special relativistic hydrodynamics (RHD) are prone to numerical breakdown if intrinsic physical constraints (positive rest-mass density/pressure and subluminal velocity) are violated near strong discontinuities. In this work, we develop a robust and efficient physical-constraint-preserving (PCP) flux-limiting framework for high-order schemes, using finite-difference WENO as a representative example. By leveraging the
geometric quasilinearization (GQL) representation, which equivalently reformulates the nonlinear RHD constraints into a family of linear inequalities, we integrate a Zalesak-type Flux-Corrected Transport (FCT) update into a scalar-style limiter that acts directly on conservative variables. A critical innovation is the explicit, non-iterative determination of limiting parameters via a rational stereographic parameterization of the GQL normal vector. This technique transforms the required worst-case minimization over auxiliary variables into a generalized Rayleigh-quotient formulation, allowing the optimal parameters to be obtained by solving small symmetric
eigenvalue problems ($2\times2$ in 1D; $(d+1)\times(d+1)$ in $d$ dimensions). Relaxed variants are further introduced to reduce computational costs in multidimensions while retaining the PCP guarantee. Extensive numerical
benchmarks ranging from 1D to 3D, including ultra-relativistic Riemann problems and astrophysical jets, demonstrate that the proposed method robustly enforces physical admissibility, sharply resolves discontinuities, and maintains design-order accuracy for smooth solutions.
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Cosmology and Nongalactic Astrophysics
Joint inference of weak lensing convergence map and cosmology with diffusion models
Benjamin Remy, Chihway Chang and Rebecca Willett
We present a method for joint inference of cosmological parameters and convergence maps from weak
lensing observations, targeting the full posterior conditioned on the observed shear field. Our approach uses implicit inference with
diffusion models, learning the joint distribution from simulations, without the need to have an explicit and differentiable forward model for gradient-based MCMC sampling. We introduce a
transformer-based architecture that operates in pixel space and treats cosmological parameters as additional
tokens in a unified sequence, enabling efficient
multimodal processing within a single network. At inference time, the trained model generates posterior samples of joint convergence maps and cosmological parameters conditioned on observed noisy shear fields. We demonstrate the method on simulated weak
lensing data generated from log-normal fields in a wcdm cosmology. The model accurately reconstructs convergence maps and recovers cosmological posteriors that agree with traditional MCMC, while remaining well calibrated across the prior, with a MIRA calibration score of $0.635 \pm 0.017$ on the joint posterior (where $0.667$ is optimal). The inferred fields reproduce the correct two-point statistics as well as non-Gaussian statistics such as the one-point distribution. This work establishes
diffusion-based implicit inference as a viable route toward full field-level cosmological analyses, paving the way for applications to more realistic, non-differentiable simulators.
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Astrophysics of Galaxies
COSMOS-Web: does halo mass alone shape the clustering of star-forming and quiescent galaxies?
Louise Paquereau, Clotilde Laigle, Henry Joy McCracken et al. (+29 more)
While
stellar mass correlates strongly with
halo mass, it remains unclear whether
halo mass alone governs
galaxy star-formation activity, or whether secondary
halo properties and environment also play a role. We investigate these effects beyond
halo mass by measuring the auto- and cross-correlations of
star-forming and quiescent
galaxies in the COSMOS-Web survey from $z = 5$ to the present day. To isolate environmental contributions, we introduce a method that matches the
halo mass distributions of both populations using the UniverseMachine model. We find that quiescent
galaxies remain more strongly clustered than
star-forming systems by at least $0.5-1$ dex at all
redshifts, even after controlling for
halo mass. At $z \le 2$, this excess clustering increases towards lower
stellar masses, with the most clustered objects being $\log(M_\star/{\rm M}_\odot) \le 9.5$ quiescent
galaxies. This points to environmental quenching significantly affecting low-mass
galaxies at $z \le 2$, likely driven by ram-pressure stripping or the suppression of cold gas
accretion, as these objects show disky morphologies. Cross-correlations further reveal one-
halo conformity up to $z \simeq 2$: low-mass (or satellite) quiescent
galaxies are more strongly clustered around massive (or central) quiescent
galaxies than around
star-forming centrals of the same
halo mass. This signal may arise from quenching mechanisms affecting both centrals and satellites, correlated assembly histories prior to infall, or dependencies on secondary
halo properties. Both environmental quenching and conformity appear to vanish between $z \simeq 5$ and $2$. Together, these results challenge the common assumption that clustering and
star-formation activity depend solely on
halo mass.
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All authors Louise Paquereau, Clotilde Laigle, Henry Joy McCracken, Olivier Ilbert, Hollis B. Akins, Rafael C. Arango-Togo, Nguyen Binh, Caitlin M. Casey, Yohan Dubois, Maximilien Franco, Ghassem Gozaliasl, Santosh Harish, Michaela Hirschmann, Baptiste Jego, Aidan Kaminsky, Jeyhan S. Kartaltepe, Anton Koekemoer, Damien Le Borgne, Joseph S. W. Lewis, Daizhong Liu, Georgios Magdis, Jed McKinney, Wilfried Mercier, Lauro Moscardini, Thibaud Moutard, Jason D. Rhodes, Brant E. Robertson, Sogol Sanjaripour, Marko Shuntov, Greta Toni, Maxime Trebitsch, Laurence Tresse
Cosmology and Nongalactic Astrophysics
Constraining dark energy with complementary probes of large-scale structure
Neel Shah, Kazuya Koyama, Johannes Noller et al. (+1 more)
To observationally pin down the nature of dark energy, it is essential to consistently model cosmological perturbations in the presence of dark energy alongside the background expansion and constrain this joint theory space with a large array of complementary probes. Here, we achieve this by constraining a model in the Effective Field Theory of Dark Energy (EFTofDE) framework by supplementing probes of the expansion history with several probes of large-scale structure:
redshift space distortions (RSD) from DESI DR1, $3\times2$pt measurements from DES Y3, and the Integrated Sachs-Wolfe effect from cross-correlating CMB temperature anisotropies with
galaxy number counts or CMB
lensing. We demonstrate the complementarity of different probes which leads to strong improvements on constraints on DE perturbations. For our most constraining
dataset combination that supplements CMB+BAO+SNe probes with DESI DR1 RSD, DES Y3 $3\times2$pt and ISW cross-correlations between CMB temperature and
galaxy counts, we find an improvement in the Figure of Merit (FoM) for the DE perturbation parameters $\{c_B, c_M\}$ by a factor of 2.69. We show the phenomenological implications of these constraints by mapping them to the present-day values of the phenomenological functions $\{\mu(z), \Sigma(z)\}$, where we see an FoM improvement by a factor of 3.37. We find a significant interdependence between the posteriors of $\{w_0, w_a\}$ and $\{c_B, c_M\}$, caused by the theoretical prior imposed by the gradient stability condition within the EFTofDE framework. Finally, we compute the significance of deviation from $\Lambda$CM for the EFTofDE model when constrained with CMB+BAO+SNe
datasets, finding it to be at 2.9$\sigma$. This significance is nontrivially similar to the significance for the $w_0w_a$CDM model for the same
dataset combination which we find to be 3.1$\sigma$.
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All authors Neel Shah, Kazuya Koyama, Johannes Noller, Lanyang Yi
Cosmology and Nongalactic Astrophysics · Cross-listed from hep-ph
Reheating in No-Scale Models of Inflation
Ignatios Antoniadis, John Ellis, Dimitri V. Nanopoulos et al. (+2 more)
Analogously to the suppression of inflaton decays into conformally-coupled scalar fields in the original Starobinsky $R + R^2$ model of inflation, inflaton decays to Standard Model fields are also suppressed in minimal no-scale models of inflation with field space
curvature $\mathcal{R} = 2/3$. We study how this suppression can be avoided in generalized no-scale inflationary models. These include models in which the field space
curvature $\mathcal{R} = 2/(3\alpha)$ with $\alpha \ne 1$ as exemplified by models derived from string theory, as well as models with non-minimal gauge kinetic terms and anomaly-induced couplings. We analyze direct and anomaly-induced inflaton couplings to gauge
bosons and gauginos and demonstrate the Kähler-frame invariance of the physical gauge coupling. We determine the resulting reheating temperatures and the corresponding predictions in the $(n_s,r)$ plane. Finally, we consider an $R^3$ deformation of Starobinsky supergravity, which modifies the inflaton and stabilizer sectors but does not, by itself, generate new tree-level inflaton couplings to visible matter fields.
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All authors Ignatios Antoniadis, John Ellis, Dimitri V. Nanopoulos, Keith A. Olive, Sarunas Verner
Astrophysics of Galaxies
Caught in the act: interaction-driven evolution in the nearby compact galaxy group Roberts Quartet (SCG0018-4854)
Saili Keshri, Sudhanshu Barway, Mousumi Das et al. (+1 more)
We present a spatially resolved multiwavelength study of the compact
galaxy group Roberts Quartet (RQ, SCG0018-4854), aimed at understanding interaction-driven
galaxy evolution in a dense environment. RQ comprises of four
galaxies (NGC 87, NGC 88, NGC 89, and NGC 92) that span a range of masses and evolutionary states. Using UV-to-IR data from GALEX, DECaLS, MUSE/VLT (IFU), VISTA/VIRCAM, 2MASS, and WISE, we investigate the interplay between kinematics,
star formation, and
stellar populations across the group. The spatially resolved analysis reveals disturbed
stellar and gas kinematics, enhanced
turbulence, and asymmetric structures in all members, consistent with repeated gravitational interactions. The most massive
galaxy, NGC 92, exhibits prominent
tidal features, a bar, and ring-like
star-forming structures, indicative of interaction-driven gas inflows. Another massive member, NGC 89, shows suppressed
star formation and signatures of AGN-driven feedback, while the lower-mass
galaxies NGC 88 and the
dwarf galaxy NGC 87 display enhanced
star formation and kinematic decoupling between
stellar and gas component consistent with recent gas
accretion. Combining UV age estimates with non-parametric
star formation histories, we constrain the recent interaction timescale of the group to <= 500 Myr, whereas the crossing timescale is 424 Myr. These results indicate that RQ is a dynamically young system undergoing ongoing assembly, where interactions, gas exchange, and feedback processes are actively shaping
galaxy evolution. The dynamical complexity of the group further suggests that its present configuration may involve more than four progenitor components. In this context, RQ provides a nearby analogue of compact, rapidly evolving groups observed at high
redshift by recent JWST observations, offering a resolved view of the physical processes governing
galaxy assembly in the early Universe.
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All authors Saili Keshri, Sudhanshu Barway, Mousumi Das, Abhishek Paswan
Instrumentation and Methods for Astrophysics
An overview of stray light findings and interpretation during on-sky commissioning of LSSTCam
Gabriele Rodeghiero, Alex Drlica-Wagner, Alessio Taranto et al. (+78 more)
Wide-field
telescopes are intrinsically difficult to shield from unwanted stray and scattered light, while the search to identify sources of contaminating light is frequently a challenging task. The Vera C.~Rubin Observatory, which achieved its first
photon with the LSST Camera (LSSTCam) on April 15, 2025, will initiate a revolutionary era for the study of dark matter, dark energy, the transient sky, the
Solar System, and the Milky Way. LSSTCam will provide near seeing-limited images of the sky in six bands ($u,g,r,i,z,y$) over a $3.^\circ 5$-diameter field of view, and over the course of a decade, it will execute the Legacy Survey of Space and Time (LSST). This work provides an overview of the dedicated stray and scattered light test campaign that has been undertaken since the start of Rubin commissioning. In particular, we highlight the processes used to characterize, model, and mitigate stray light present in LSSTCam images. The Rubin commissioning team created a series of testing and analysis tools to track stray light artifacts from their initial discovery through reproduction with timely observations, simulation using ray tracing to identify opto-mechanical origins, and finally devising corrective actions. The complex stray light features encountered by Rubin provide a wealth of experience for the future wide-field and extremely wide-field observatories. This work covers the many stages of a long journey that started with conceiving an innovative and challenging optical design, followed by the engineering and system engineering efforts to build it, to finally delivering an optimized and revolutionary cutting-edge facility.
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All authors Gabriele Rodeghiero, Alex Drlica-Wagner, Alessio Taranto, Luca Rosignoli, Hannah Pollek, Aashay Pai, Lynne Jones, Erin Howard, Sean MacBride, John Andrew, Douglas Neill, Travis Lange, Andrew Rasmussen, Aaron Roodman, Brian Johnson, Elana Urbach, Parker Fragelius, Eli Rykoff, Tomislav Vucina, Christopher Stubbs, Robert Lupton, Charles Claver, Joshua Meyers, Anastasia Alexov, Keith Bechtol, Lee Kelvin, Brian Stalder, Pierre Antilogus, Alexandre Boucaud, Aurelien Marini, Alexander Broughton, Leanne Guy, Tiago Ribeiro, Erik Dennihy, Bruno Quint, Aaron Watkins, Alysha Shugart, Lukas Eisert, Kevin Fanning, Marina Pavlovich, Yijung Kang, Hye Park, Paulo Lago, Kristopher Mortensen, Paulina Venegas Salas, Minhee Hyun, Karla Peña Ramírez, David Sanmartim, Shuang Liang, Gonzalo Aravena, Kshitija Kelkar, Kate Napier, Jacqueline Seron Navarrete, Carlos Morales Marín, Danica Žilková, Narayan Khadka, Eric Christensen, Yousuke Utsumi, Merlin Fisher-Levine, Yusra Alsayyad, Colin Slater, Fritz Müller, William O'Mullane, Enrico Giro, Rodolfo Canestrari, Guillem Homar Megias, Sandrine Thomas, Kevin Reil, Roberto Tighe, Mario Rivera, Juan Lopez, Claudio Araya Cortes, David Jiménez Mejías, Hernán Herrera, Freddy Muñoz Arancibia, Dimitri Buffat, Johan Bregeon, Jacques Sebag, Holger Drass, Pablo Zorzi, Massimo Brescia
Instrumentation and Methods for Astrophysics
Investigation and Mitigation of a Prominent Off-Axis Stray Light Path in Rubin Observatory Commissioning
Alex Drlica-Wagner, Alessio Taranto, Gabriele Rodeghiero et al. (+12 more)
The "scratched tape" stray light feature is the most prominent and prevalent stray light artifact identified during the commissioning of the Vera C. Rubin Observatory. The scratched tape feature originates when light from large off-axis angles (~20 deg) passes between the mid-level and center-section light baffles, reflects off the primary mirror, and illuminates the LSST Camera focal plane. This scenario represented an unobstructed stray light path to the sky during Rubin commissioning due to delays in the integration of the dome slit light-wind screen. This document describes the identification, modeling, characterization, and mitigation of the scratched tape stray light artifact.
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All authors Alex Drlica-Wagner, Alessio Taranto, Gabriele Rodeghiero, Joshua E. Meyers, John Andrew, Douglas R. Neill, Christian Aguilar, Brian Stalder, Robert H. Lupton, Aashay Pai, Lee S. Kelvin, Aaron E. Watkins, Luca Rosignoli, Hannah M. M. Pollek, Anastasia Alexov
Cosmology and Nongalactic Astrophysics · Cross-listed from hep-ph
PBHs and GWs from Scaling Monopoles
Daiki Aburatani, Wakutaka Nakano and Wen Yin
Monopoles with sufficiently weak gauge couplings, or from global
symmetries, can form scaling networks in the early Universe whose average energy density tracks the cosmological background. In this work, we find, by performing classical
lattice simulations to estimate the overdensities, that
primordial black holes (PBHs) with a broad mass spectrum can be produced during this
evolution if the
Higgs expectation value $v$ satisfies $v\gtrsim 0.1 M_{\rm pl}$. The formation is driven by the
stochastic realization of the monopole number in Hubble patches causing the overdensities. We also show that gravitational waves (GWs) generated by the scaling dynamics are produced at the same epoch, with spectra correlated with the PBH spectra and with amplitudes testable in future observations. Interestingly, if the scaling regime is terminated by the gauge
boson mass for the gauged monopole, a non-negligible fraction of the PBHs can carry
magnetic charge, and the resulting
magnetic Coulomb force between such charged PBHs is predicted to be comparable to the gravitational force. Together with the PBH and GW signals, this provides a smoking-gun signature of the scenario. We also point out simple cosmological scenarios, which may also apply to PBH formation from scaling
cosmic strings, that allow PBHs to constitute dominant dark matter.
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High Energy Astrophysical Phenomena
A Suppressed Volumetric Rate of High-Luminosity Mid-Infrared Selected Tidal Disruption Events
Prajna Nair, Christos Panagiotou, Megan Masterson et al. (+4 more)
Tidal Disruption Events (TDEs) serve as direct probes of the population of supermassive black holes in the center of
galaxies and are nowadays regularly detected in optical wide-field time-domain sky surveys. Recent studies have demonstrated that a large fraction of TDEs can be uniquely identified in the infrared (IR) waveband, but these studies have to date been limited to relatively nearby events. In this work, we searched for highly luminous IR-bright TDEs that are rare and thus missed by searches in the local universe. We performed a systematic search of the NEOWISE archive and developed a new selection criterion based on the
evolution of the W1-W2 color to select TDE candidates. We identified 10 IR bright TDEs with peak luminosities above $L_{\rm peak\, W2} \simeq 3 \times 10^{43}$ erg s$^{-1}$ and estimated an event rate of $1.2^{+0.5}_{-0.4}\times10^{-10}$ Mpc$^{-3}$year$^{-1}$ for the luminosity range of our sample. Compared to the existing local luminosity function of lower luminosity events, we detect a suppressed rate for these highly luminous events. This turn-over in the luminosity function can be naturally explained by the suppressed amount of TDEs taking place in systems with larger black hole masses, thereby confirming the TDE nature of our sources.
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All authors Prajna Nair, Christos Panagiotou, Megan Masterson, Kishalay De, Erin Kara, Eleanor Winkler, M. Subhi Abo Rdan
Astrophysics of Galaxies
Unveiling the Cosmic Dawn with SHARP: Probing extended Lyman-$\alpha$ nebulae in a Universe less than 600 Myr old
Susanna Bisogni, Giustina Vietri, Enrico Piconcelli et al. (+5 more)
The existence of luminous
quasars just a few hundred million years after the Big Bang challenges our understanding of both black hole growth and
galaxy formation and
evolution. These objects harbour supermassive black holes exceeding a billion
solar masses (M$_{BH} > 10^{9} M_{\odot}$) by
redshift $z\sim 6.5$-$7.5$, powered by extreme gas
accretion. At the same time, their host
galaxies are also undergoing intense
star formation, consuming gas at the rate of hundreds of
solar masses per year. Characterising the circumgalactic medium (CGM) and intergalactic medium (IGM) surrounding high-
redshift quasars becomes an essential tool to understand the conditions that enable the rapid formation and
evolution of these extreme sources. While in the last decades spatially resolved observations in the optical band have targeted CGM through Ly$\alpha$ nebulae surrounding $z \sim 2-6$
quasars, current instrumental limitations hamper observations of high-z ($z>8$)
quasars that will be discovered by Euclid/Roman/LSST surveys. Despite the large fraction of neutral hydrogen at the epoch of reionisation, in the last decade several surprising Ly$\alpha$ detections have been obtained from sources deep in the epoch of reionisation. The unprecedented collecting area of ELT, coupled with the resolution and wavelength coverage of SHARP, specifically VESPER, will enable us to map for the first time $z>9$ Ly$\alpha$ emission down to the structures of size $\sim$150 pc, while simultaneously capturing their large-scale structure up to 100 kpc for the first time at this
redshift. This will allow a major and long-awaited step forward in the exploration of
quasars and
galaxies formation and
evolution deep in the epoch of reionisation.
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All authors Susanna Bisogni, Giustina Vietri, Enrico Piconcelli, Federica Ricci, Andrea Travascio, Paolo Franzetti, Adriana Gargiulo, Chiara Mancini
Instrumentation and Methods for Astrophysics
Mechanical Studies of an Additional Light Baffle for the LSST Camera
Hannah Mary Margaret Pollek, Gabriele Rodeghiero, John Andrew et al. (+11 more)
Commissioning the NSF-DOE Vera C. Rubin Observatory consisted of engineering operation and on-sky data-taking, initially with the Commissioning Camera followed by the commissioning run of the LSST Camera (LSSTCam). As with other wide-field astronomical projects, the Rubin team anticipated a significant amount of stray light effects which would necessitate investigation and systematic mitigation. This led the Rubin stray light working group to develop tools, including a robust model of the entire observatory in Zemax, to trace the light paths of stray light artifacts back to their sources. This model along with the other efforts of the working group enabled significant improvements in stray light mitigation leading up to the commencement of the Legacy Survey of Space and Time (LSST). One such potential source was identified as a small chamfer on the L3 lens, for which it was hypothesized that a simple baffle added inside of the LSSTCam near the L3 should prove beneficial to the quality of data being collected in the LSST. Initial Zemax models proved this hypothesis to be correct, but it is important to weigh the improvements made versus the effort, risk, and cost especially when considering any hardware modifications to an instrument that is already running and collecting immense amounts of data each night. This paper investigates the impacts of installing an L3 baffle via a collection of mechanically focused studies, where the principal areas of focus are installation feasibility, baffle geometry, materials & coating selection, and potential impacts to the purge system.
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All authors Hannah Mary Margaret Pollek, Gabriele Rodeghiero, John Andrew, Alex Drlica-Wagner, Alessio Taranto, Luca Rosignoli, Aashay Pai, Douglas R. Neill, Travis Lange, Andrew P. Rasmussen, Aaron Roodman, Pierre Antilogus, Alexandre Boucaud, Martin Nordby
High Energy Astrophysical Phenomena
High Frequency Wideband Study of FRB 20240114A with the Allen Telescope Array
Param Joshi, Vishal Gajjar, Joel Earwicker et al. (+14 more)
We present a high-frequency, wideband observing campaign of the hyperactive repeating fast
radio burst FRB 20240114A with the Allen
Telescope Array. Between 27 January and 29 October 2024, we obtained 1167 hr of on-source observations across 1344 MHz of simultaneous bandwidth covering frequencies from approximately 900 MHz to 7620 MHz. We detected 97 bursts between ~900 MHz and ~5 GHz, including a strong S-band activity episode, while no bursts were detected in the highest-frequency tunings above ~5 GHz despite substantial exposure. This campaign provides one of the very few extended samples of repeating-FRB activity above 3 GHz, a regime that remains sparsely sampled. We find that the burst rate varies strongly with both observing frequency and epoch, confirming that the emission from FRB 20240114A is highly chromatic and band-limited. We measure the spectro-temporal properties of the bursts and their sub-components, confirming that fractional bandwidth remains approximately scale-invariant. Sub-burst durations decrease toward higher frequencies, and the magnitude of the downward drift rate increases with frequency. The cumulative spectral-energy-density distribution above our completeness threshold is well described by a shallow power law, indicating that high-energy bursts contribute substantially to the observed energy output. We also compare our detections with recently proposed long-timescale frequency-modulation models and find that the ATA high-frequency burst storm is not consistent with a strictly phase-coherent modulation inferred from other
datasets. Our results demonstrate that incomplete time-frequency coverage can bias interpretations of burst activity and highlight the need for sustained, simultaneous wideband monitoring of hyperactive repeaters.
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All authors Param Joshi, Vishal Gajjar, Joel Earwicker, Sofia Z. Sheikh, Mohammed A. Chamma, Joe Bright, Luigi F. Cruz, Roy H. Davis, David R. DeBoer, R. A. Donnachie, Wael Farah, Phil Karn, Joao Paolo C. M. Oliveira, Karen I. Perez, Alexander W. Pollak, Andrew Siemion, Michael Snodgrass
Instrumentation and Methods for Astrophysics
Determining stress-based bending mode limits for the Vera C. Rubin Observatory M1M3 active mirror system
Malhar Sonaniskar, Douglas Neill, Ellie Hileman et al. (+1 more)
The Vera C. Rubin Observatory Simonyi Survey
Telescope's primary-tertiary mirror (M1M3) is an actively supported, 8.4-m cast borosilicate optic controlled by 156 pneumatic actuators. This work presents a rapid stress-estimation methodology based on the root-sum-square (RSS) combination of Finite Element Analysis to derive pre-computed unit bending mode stresses. Since the stress is proportional to strain, and strain is proportional to displacements, we theorized that since the bending mode displacements can be combined RSS, that the peak stresses would also combine by RSS. We validate the RSS-based major principal stress predictions against NASTRAN simulations for representative bending mode combinations, demonstrating agreement within a few percent for peak Principal major stress across the mirror glass substrate. Unit displacement and corresponding unit stress fields for the first 20 natural bending modes of the M1M3 system are generated using NASTRAN. Representative multi-mode corrections including combinations that include astigmatism, coma, and spherical modes of higher order are then analyzed to compare the resulting peak principal stresses with RSS-based predictions. The method enables near instantaneous evaluation of stress margins for active optics corrections, safety-limit checking, and actuator-force optimization during
telescope operations. This paper outlines the formulation, implementation workflow, validation results, and practical use cases for integrating RSS-based stress prediction into the Vera C. Rubin Observatory's M1M3 active optics system.
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All authors Malhar Sonaniskar, Douglas Neill, Ellie Hileman, Petr Kubánek
Astrophysics of Galaxies
AGN Feeding & Feedback Over the Galactic Scales
Filippo M. Maccagni, Vincenzo Mainieri, Isabella Prandoni et al. (+8 more)
Active
Galactic Nuclei (AGN) are key drivers of
galaxy evolution, triggered by cold gas accreting onto a super-massive black hole. However, the processes regulating this gas
accretion (feeding) and how AGN alter the interstellar medium to affect
star formation (feedback) remain poorly understood. A major observational challenge is the vast range of spatial scales involved: AGN fuelling and jet-ejection occur over the sub-pc scales, while AGN feedback shocks and heats the ISM preventing
star formation over the
galactic and circum-
galactic scales. Moreover, it is unclear how short
stochastic AGN episodes are connected with the long timescales of gas
accretion and
star formation. In this manuscript, we illustrate how SKAO will provide the unprecedented opportunity to solve the observational limitations of AGN feeding and feedback studies by observing hundreds of nearby AGN down to low
radio powers ($10^{21}$ W Hz$^{-1}$). Simultaneous SKA-Low and Mid observations of nearby
galaxies will trace the thermal emission associated with
star formation and AGN feedback and the synchrotron emission of their jets of relativistic
plasma. These broad-band
radio observations enable the detailed characterisation of the AGN duty-cycle, unravelling the time-scales of the
nuclear activities. Reaching in 10 hours neutral atomic hydrogen (HI) column density sensitivities $\sim 10^{19}$ cm$^{-2}$ at arcsecond resolution, SKA AA4 observations will trace the typical low column density of HI gas in AGN inflows and
outflows, to understand the impact AGN feedback over the full
galaxy and trace fuelling processes from the environment onto the SMBH. Combining SKA with mm, sub-mm and optical Integral Field Spectrographic observations at comparable arcsecond resolution will provide an exhaustive understanding of the link between multi-phase AGN feeding and feedback processes and
star formation.
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All authors Filippo M. Maccagni, Vincenzo Mainieri, Isabella Prandoni, Massimo Gaspari, W. J. G. de Blok, Ilaria Ruffa, Stanislav S. Shabala, Dipanjan Mukherjee, Mayur B. Shende, Antonino Marasco, Paolo Serra
Astrophysics of Galaxies
Distance to Sh2-106 from Gaia DR3 and its embedded radio population: implications for a candidate explosive outflow
Sergio A. Dzib
Sh2-106 has recently been proposed as a candidate explosive molecular
outflow (EMO), but the physical interpretation of the region depends critically on its distance. Published estimates span a wide range, leading to large uncertainties in the inferred size, energetics, and evolutionary timescale of the system. Using
Gaia DR3 astrometry, we identify a kinematically coherent
stellar population associated with Sh2-106 and derive a cluster parallax of $\varpi_{\rm corr}=0.607\pm0.013$\,mas, corresponding to a distance of $1.65\pm0.04$\,kpc. This value is significantly larger than the commonly adopted extinction-break estimate of 1.09\,kpc. At this revised distance, the inferred kinetic energy of the expanding ionized nebula increases by a factor of $\sim6.5$, reaching $E_{\rm exp}\simeq1.3\times10^{48}$\,erg and placing Sh2-106 in the same order-of-magnitude energetic regime as the Orion BN/KL explosive event, although at a substantially older dynamical age ($\sim3500$\,yr). Archived 5.8\,GHz Karl G. Jansky Very Large Array observations reveal ten compact
radio sources in the central region, identifying embedded
stellar objects that are suitable for future multi-epoch
radio astrometry. No unambiguous high-velocity
stellar ejecta are detected in
Gaia DR3, although S106\,IR shows a modest peculiar transverse velocity of $\sim5$\,km\,s$^{-1}$ relative to the cluster centroid. The
Gaia-based cluster distance, therefore, significantly revises the physical scale and energetics of Sh2-106 and provides the observational framework required to test whether the region represents an older analogue of the Orion BN/KL dynamical disintegration or a distinct explosive phenomenon.
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Instrumentation and Methods for Astrophysics
In Situ Measurements of the Reflectances of the LSSTCam Optics and Assessing the Impact of Optical Ghosts
Aashay Pai, Alex Drlica-Wagner, Lee S. Kelvin et al. (+4 more)
Optical ghosts are image artifacts caused by successive reflections of light between optical surfaces such as lenses, filters, and detectors. These artifacts are unavoidable due to the nonzero reflectances of optical elements and are a major source of contamination for low-surface-brightness science. We use optical ray tracing simulations tuned to observations from LSST Commissioning to quantify the impact of optical ghosts on the LSST data. In particular, we find that ~0.57% of the LSSTCam focal plane is impacted by optical ghosts when averaged across all bands. We also use data from the Collimated Beam Projector to measure the reflectances of various optical elements, generally confirming estimates of ~2% from the systems engineering throughput predictions.
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All authors Aashay Pai, Alex Drlica-Wagner, Lee S. Kelvin, Joshua E. Meyers, Elana K. Urbach, Fritz Mueller, Robert H. Lupton
Instrumentation and Methods for Astrophysics
Early Telescope Throughput Results from the Collimated Beam Projector at the Vera C. Rubin Observatory
Nathan Amouroux, Parker Fagrelius, Thibault Guillemin et al. (+6 more)
The Vera C. Rubin Observatory LSST requires precise photometric calibration to meet its science goals, particularly for cosmological analyses based on Type Ia
supernovae. The Collimated Beam Projector (CBP) has been developed to support this effort by projecting monochromatic point sources of known wavelength and flux directly into the
telescope aperture, enabling direct in situ measurements of the full system throughput. We present initial results demonstrating the CBP capability to characterize the instrumental response of the Rubin
Telescope and to measure the transmission profiles of LSSTCam broadband filters. In particular, the CBP enables spatially resolved mapping of filter bandpass edge shifts across the focal plane, which can vary by several nanometers as a function of the ray angle of incidence. These early results establish the CBP as a powerful photometric calibration tool and lay the groundwork for continuous throughput monitoring throughout LSST operations.
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All authors Nathan Amouroux, Parker Fagrelius, Thibault Guillemin, Fritz Mueller, Jérémy Neveu, Eli Rykoff, Thierry Souverin, Christopher W. Stubbs, Elana Urbach
Instrumentation and Methods for Astrophysics
Design and Performance of the Carruthers Geocoronal Imager
Martin Sirk, Alex M. Zhang, Thomas J. Immel et al. (+13 more)
The GeoCoronal Imager (GCI) onboard the Carruthers Geocorona Observatory is the primary scientific instrument of the mission. It is designed to measure far ultraviolet light at 121.6 nm (Lyman-alpha) emitted by hydrogen (H) atoms in Earth's exosphere with the sensitivity, accuracy and precision to meet the mission's scientific objectives regarding the nature of terrestrial exospheric structure and dynamics on both global and regional scales. The GCI is comprised of two co-aligned UV imaging systems. The Narrow Field Imager (NFI) acquires nearly continuous images of exospheric Lyman-alpha radiance near and above the Earth's limb at relatively high spatial and temporal resolution, while the Wide Field Imager (WFI) uses relatively higher optical sensitivity and a wider field of view to detect faint Lyman-alpha emission from the exosphere's outermost extent. Both imaging channels feature identical active pixel sensor cameras, gain-intensifiers, and 6-position optical filter wheels. This paper outlines the instrument design requirements, informed by mission science goals, as well as its performance as measured in the
vacuum ultraviolet laboratory test and calibration.
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All authors Martin Sirk, Alex M. Zhang, Thomas J. Immel, Jason B. McPhate, William W. Craig, Cathy Chou, Kodi Rider, Edward H. Wishnow, Anna L. Butterworth, Ellen R. Taylor, Lara Waldrop, John T. Clarke, Evan M. Widloski, Pascal Blain, Jérémy Brisbois, Jean-François Vandenrijt
Instrumentation and Methods for Astrophysics
The On-Sky Performance of the LSST Camera CCD Array
Sean Patrick MacBride, Aaron Roodman, Stuart Marshall et al. (+88 more)
The focal plane of the LSST Camera contains 189 individual science CCDs, arranged into 21 raft tower modules, along with 4 wavefront and 8 guider CCDs located in 4 additional corner RTMs. Altogether, the LSST Camera CCDs compose the largest focal plane ever constructed. The LSST Camera is the primary instrument of Rubin Observatory, which will begin the Legacy Survey of Space and Time in 2026. In this paper, we describe the on-sky performance of the LSST Camera CCDs, from receipt at NSF/DOE Vera C. Rubin Observatory in May 2024 to on-sky observations during the first year of operations. We discuss the process to establish functionality of several CCDs which were affected by an electrical short and faulty analog-digital converter, optimizations of readout timing in response to changes in the survey strategy, and implementation of enhanced focal plane safety measures through an active clearing mechanism on the CCDs. Finally, we discuss sensor features observed on-sky, and global performance during the first year of operations. The operations to date of the LSST Camera CCDs have demonstrated the capability of performing a wide, fast, and deep optical imaging survey of the entire southern sky at the Rubin Observatory.
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All authors Sean Patrick MacBride, Aaron Roodman, Stuart Marshall, Yousuke Utsumi, Kevin Fanning, John Banovetz, Theo Schutt, Alexander Broughton, Shuang Liang, Andrew P. Rasmussen, Pierre Antilogus, John Gregg Thayer, Homer Neal, Anthony S. Johnson, Pierre Astier, Seth W. Digel, Andrew Bradshaw, Johan Bregeon, James Chiang, Céline Combet, Guillaume Dargaud, Johnny H. Esteves, Marcelle Soares-Santos, Thibault Guillemin, Claire Juramy-Gilles, Craig S. Lage, Myriam Migliore, Daniel Polin, J. Anthony Tyson, Renee Nichols, Steven M. Ritz, Eli S. Rykoff, Adrian Shestakov, Adam Snyder, Max Turri, Duncan Wood, Travis Lange, Martin Nordby, Hannah Mary Margaret Pollek, Shawn Osier, Boyd Bowdish, Diane Hascall, Margaux Lopez, Scott P. Newbry, Juan Carlos Lazarte, Vincent Lee, Michael Silva, Dave Kiehl, Andrew Hau, Tom Nieland, Nico Linton, David Shelley, Yongqiang Qiu, Mark Freytag, Stephen Cisneros, Chris Mendez, Stephen A. Tether, Alan M. Eisner, Dmitry Onoprienko, Owen Saxton, Kevin A. Reil, Vincent J. Riot, Justin Wolfe, Scott E. Winters, Brian J. Bauman, William Wahl, Paul O'Connor, Françoise Virieux, Alexandre Boucaud, Camille Parisel, Éric Aubourg, Eric Lagorio, Pierre Karst, Aurélien Marini, Didier Laporte, Francis Vezzu, Guillaume Daubard, Patrick Breugnon, Tim W. Bond, Eric Charles, Richard Dubois, Steven M. Kahn, Andrés A. Plazas Malagón, Rafe H. Schindler, Joanne Bogart, Hye Yun Park, Aurélien Barrau, Christopher Z. Waters, Merlin Fisher-Levine, Antoine Bernard, Mile Kusulja