Astrophysics of Galaxies
The Prevalence of Bursty Star Formation in Low-Mass Galaxies at z=1-7 from H{\alpha}-to-UV Diagnostics
Marissa N. Perry, Anthony J. Taylor, Oscar A. Chavez Ortiz et al. (+15 more)
We present an analysis of bursty
star-formation histories (SFHs) of 346
star-forming
galaxies at $1\lesssim z<7$, selected from JWST/NIRSpec G395M and PRISM spectroscopy provided by the CEERS and RUBIES surveys. We analyze the correlation of
star-formation rate vs.
stellar mass (the
star-forming main sequence, SFMS) for our sample and find no significant difference between the intrinsic scatter in the H$\alpha$-based SFMS and the UV-continuum-based SFMS. However, the diagnostic power of the SFMS is limited at high
redshift and low
stellar mass due to observational biases that exclude faint, quenched
galaxies. To more directly probe
star-formation variability, we examine the
dust-corrected H$\alpha$-to-UV ratio, which is assumed to trace deviations a from constant SFH over the past $\sim100$ Myr. In our sample, $73^{+4}_{-4}$% of
galaxies exhibit H$\alpha$-to-UV ratios inconsistent with a constant SFH. We do not observe any statistically significant
evolution in the H$\alpha$-to-UV ratio with
redshift. Additionally, lower-mass
galaxies ($7\leq\text{log}(M_*/M_{\odot})<8.5$) are $30 \pm 1$% more likely to lie above this
equilibrium range – indicative of a recent ($\lesssim 100$ Myr) burst of
star formation – compared to higher-mass systems ($8.5\leq\text{log}(M_*/M_{\odot})\leq10.9$). These results suggest that bursty SFHs are more common in low-mass
galaxies at $z\sim 1$-$7$ and that this remains relatively stable across $\sim0.8$-$6$ Gyr after the Big Bang.
Read the full abstract ▾
All authors Marissa N. Perry, Anthony J. Taylor, Oscar A. Chavez Ortiz, Steven L. Finkelstein, Gene C. K. Leung, Micaela B. Bagley, Vital Fernandez, Pablo Arrabal Haro, Katherine Chworowsky, Nikko J. Cleri, Mark Dickinson, Richard S. Ellis, Jeyhan S. Kartaltepe, Anton M. Koekemoer, Fabio Pacucci, Casey Papovich, Nor Pirzkal, Sandro Tacchella
Cosmology and Nongalactic Astrophysics
Large-scale peculiar velocities in the universe
Christos G. Tsagas, Leandros Perivolaropoulos and Kerkyra Asvesta
Observations have repeatedly confirmed the presence of large-scale peculiar motions in the universe, commonly referred to as “bulk flows”. These are vast regions of the observable universe, typically spanning scales of several hundred Mpc, that move coherently with speeds of the order of several hundred km/sec. While there is a general consensus on the direction of these motions, discrepancies persist in their reported sizes and velocities, with some of them exceeding the predictions of the standard $\Lambda$CDM model. The observed large-scale peculiar-velocity fields are believed to have originated as weak peculiar-velocity perturbations soon after equipartition, which have subsequently grown by structure formation and by the increasing inhomogeneity of the post-recombination universe. However, the
evolution and the implications of these bulk velocity fields remain poorly understood and they are still a matter of debate. For instance, it remains a challenge for the theoreticians to explain the high velocities measured by several bulk-flow surveys, like those recently reported using the CosmicFlows-4 data. Such extensive and fast velocity fields could have played a non-negligible role during structure formation and they might have also “contaminated” our observations. After all, in the history of astronomy, there are examples where relative-motion effects have led us to a serious misinterpretation of reality (shortened abstract due to length limits).
Read the full abstract ▾
Solar and Stellar Astrophysics
Observation and modeling of a geo-effective event observed on 2011 May 28 from the solar surface to 1au
Nishu Karna and Tatiana Niembro
In this study, we present a comprehensive observational and modeling study of a geo-effective event with D_ST index of -80 nT observed on 2011 May 28 when a coronal hole was bordering an active region. We analyze HMI and EUV images and found that this event involved two filament eruptions ~8 hours apart from two different active region closed to each other. We produce 3D
magnetic field configurations for the active regions that are consistent with the observations and employ numerical models to track the CME/ICME propagation up to 1\,au. From our,
magnetic models we found that the nearby coronal hole reduced the stability threshold of the flux ropes, with axial flux values approximately three times lower than in comparable cases without coronal holes. A derivative analysis applied to STEREO coronagraph and OMNI database in situ data revealed no evidence of CME-CME interaction during the early stages of their
evolution and identified distinct signatures of two CMEs, along with the interacting flow associated with the nearby coronal hole at 1 au. Moreover, we used hydrodynamic simulations constrained by remote sensing and in situ data to track the different structures in the
solar wind. We found a good agreement between data and the models. Additionally, we found that the presence of the coronal hole may have suppressed interactions between CMEs, with the transients subsequently propagating along the
solar wind streams emerging from the coronal hole.
Read the full abstract ▾
Astrophysics of Galaxies
Declining metallicity and extended HeII in the outflow of an epoch of reionization analogue galaxy
M. J. Hamel-Bravo, D. B. Fisher, D. A. Berg et al. (+5 more)
We present VLT/X-shooter spectroscopy of the extremely metal-poor starburst
galaxy SBS 0335-052E, a nearby (D $\sim$54 Mpc) analog of high-
redshift systems, probing its
outflow up to a distance of $\sim$2.6 kpc. Using direct-method oxygen abundances, we find a complex
metallicity profile that generally declines with distance, decreasing by 0.37 dex from the
galaxy center out to 2.4 kpc into the
outflow. This implies a metal-loading factor roughly an order of magnitude lower than predictions based on the mass-
metallicity relation for low-mass
galaxies. We also detect extended HeII emission, including a broad, redshifted component beyond 2 kpc, distinct from narrow emission associated with
star clusters. No H$\beta$ emission is detected associated with the broad redshifted component, implying extremely high HeII/H$\beta$ ratios (0.7–4.8). Such extreme values, combined with the decreasing
metallicity, challenge current models for
stellar feedback. The contribution of an intermediate-mass black hole could simultaneously account for the declining
metallicity and the unusually extended HeII emission.
Read the full abstract ▾
All authors M. J. Hamel-Bravo, D. B. Fisher, D. A. Berg, A. J. Cameron, J. Chisholm, G. G. Kacprzak, B. Mazzilli Ciraulo, H. Katz
High Energy Astrophysical Phenomena
On the statistical characterization of the synchrotron multi-zone polarization of blazars
Andrea Tramacere
Multiwavelength polarimetric observations of blazars reveal complex, energy-dependent polarization behavior, including a decrease in polarization fraction from X-rays to millimeter bands and significant variability in the electric vector position angle (EVPA). These trends challenge simple single-zone synchrotron models and suggest a more intricate, turbulent jet structure with multiple emission zones. We develop a statistical framework to model the observed energy-dependent polarization patterns in blazars, focusing on the behavior captured by IXPE in the X-ray band and RoboPol in the optical. The goal is to statistically characterize multi-zone models in terms of the distributions of
cell size and the physical parameters of the electron energy distribution (EED). A Monte Carlo approach, implemented with the JetSeT code, is used to generate synthetic multi-zone synchrotron emission from a spherical region filled with turbulent
cells with randomly distributed physical properties. Simulations explore scenarios ranging from identical
cells to power-law distributions of
cell sizes and EED parameters with variable cutoff and low-energy slopes. The results show that a purely turbulent, multi-zone model can reproduce the observed energy-dependent polarization without requiring correlations between
cell size and EED parameters. The polarization degree is primarily determined by the effective, flux-weighted, number of emitting
cells, modulated by the dispersion in
cell properties, particularly the EED cutoff energy at high frequencies and the low-energy spectral index at low frequencies. With a fractional dispersion in cutoff energy of about 90% and a low-energy spectral index dispersion of ~0.5-1.5, the model reproduces the chromatic mm-to-X-ray polarization trends seen by IXPE and the optical polarization limiting envelope observed in the RoboPol
dataset.
Read the full abstract ▾
Astrophysics of Galaxies
ILLUSTRating red nugget assembly through observations and simulations
Micheli T. Moura, Anna Ferré-Mateu, Ana L. Chies-Santos et al. (+2 more)
The properties of massive and compact early-type
galaxies provide important constraints on early
galaxy formation. Among these, massive relic
galaxies, characterized by old
stellar populations and minimal late-time
accretion, are considered preserved compact
galaxies from the high-$z$ Universe. We investigate compact and massive
galaxies (CMGs) using the TNG50 cosmological simulation, applying uniform selection criteria matching observational surveys at $z=0$, $z=0.3$, and $z=0.7$, enabling direct comparisons with observed compact
galaxies. CMGs are classified according to their
stellar mass assembly histories to examine how compactness relates to dynamical properties and chemical enrichment across
cosmic time. Our results show that simulated CMGs follow the observed mass-size relation, with the number of objects increasing at higher
redshifts, in line with observational trends. Dynamically, while observations suggest relic
galaxies are outliers in the
stellar mass-velocity dispersion plane, simulated compacts show relatively uniform velocity dispersions across different
accretion histories. Observed relics are more metal-rich than other compact
galaxies with extended
star formation, deviating from the local mass-
metallicity relation. In contrast, simulated CMGs are overall more metal-rich than the quiescent population, regardless of
accretion history. The deviation from the mass-
metallicity relation decreases with
redshift. These results suggest that the extreme characteristics of CMGs in TNG50, particularly in
metallicity and dynamics, are less pronounced than in observed relics. Nonetheless, these results offer a theoretical framework to assess the properties of such extreme objects from different epochs, highlighting both
alignment with and deviations between the models.
Read the full abstract ▾
All authors Micheli T. Moura, Anna Ferré-Mateu, Ana L. Chies-Santos, Cristina Furlanetto, Michael A. Beasley
Instrumentation and Methods for Astrophysics
Wavefront Error Recovery and Companion Identification with the James Webb Space Telescope
Matthew De Furio, Marie Ygouf, Alexandra Greenbaum et al. (+8 more)
The James Webb Space
Telescope is orders of magnitude more sensitive than any other facility across the near to mid-infrared wavelengths. Many approved programs take advantage of its highly stable point spread function (PSF) to directly detect faint companions using diverse high-contrast imaging (HCI) techniques. However, periodic re-phasing of the Optical
Telescope Element (OTE) is required due to slow thermal drifts distorting to the primary mirror backplane along with
stochastic tilt events on individual mirror segments. Many programs utilize observations of a reference
star to remove the
stellar contribution within an image which can typically take half of the total allocated time. We present a high-contrast imaging technique for the NIRISS instrument that uses the measured wavefront error (WFE) from a phase calibration observation (performed roughly every 48 hours) as prior information in a
Bayesian analysis with nested sampling. This technique estimates the WFE of a given observation and simultaneously searches for faint companions, without using a reference
star. We estimate the wavefront error for both full aperture and aperture masking interferometry (AMI) imaging modes using three low order Zernike coefficients per mirror segment, using the Hexike basis, to generate synthetic PSFs and compare to simulations. We compare our technique to traditional interferometric analysis in realistic NIRISS F430M simulations both relative to the
photon noise limit, and through recovering an injected companion with $\Delta$F430M= 8 mag at 0.2”. With future testing, this technique may save significant amounts of observing time given the results of our current implementation on NIRISS simulations.
Read the full abstract ▾
All authors Matthew De Furio, Marie Ygouf, Alexandra Greenbaum, Graça Rocha, Michael Meyer, Charles Beichman, Jorge Llop-Sayson, Gael Roudier, Steph Sallum, Jarron Leisenring, Anand Sivaramakrishnan
High Energy Astrophysical Phenomena
Scalarized Hot Neutron Stars Containing Hyperons and $\Delta$-Resonances in Different Evolution Regimes
Fahimeh Rahimi, Zeinab Rezaei and Adamu Issifu
Scalar-tensor
gravity models are among the
prime candidates to explain
cosmic acceleration, and compact
stars provide unique laboratories for testing such theories. Predictions of scalar-tensor
gravity in compact
stars can be examined during the
evolution of
neutron stars. Spontaneous scalarization in relativistic
stars is influenced by different properties of
stellar matter in various
evolution regimes. In the present study, we investigate the scalarization of
neutron stars in different stages of the evolvement. For this aim, we apply the isentropic equations of state for the
neutron star matter including nucleons, hyperons, and $\Delta$- resonances in
neutrino-trapped,
neutrino diffusion, and
neutrino-transparent stages as well as cold-catalyzed
neutron star. Our equations of state are based on the relativistic model within the mean-field approximation. To emphasize the role of scalar-tensor theories in exploring the properties and structure of compact
stars, we calculate the structure of
neutron stars with hyperons and $\Delta$-resonances in different snapshots of the
neutron star evolution in the scalar-tensor
gravity. Our calculations confirm that the
neutron star scalarization is affected by the hyperons as well as the $\Delta$-resonances. Moreover, the properties of scalarized
neutron stars depend on the stage of the
star evolution.
Read the full abstract ▾
Astrophysics of Galaxies
Galaxy sizes and compactness at Cosmic Dawn
P. Cataldi, S. Pedrosa, L. J. Pellizza et al. (+2 more)
The James Webb Space
Telescope has found an unexpected population of high-mass
galaxies ($\log (M^\star / {\rm M} _\odot) \gtrsim 10$) with extremely small effective radii ($\sim 100\,\rm pc$) at $z \gtrsim 6$. Also, the existence of an unusual size–mass relation has been claimed. These observations are only partially reproduced by current models, and the physics responsible for the observed relations is still under debate. We expect to unveil the formation channels of the observed compact
galaxies. We analyse 7605 snapshots for 169
galaxies of the state-of-the-art cosmological simulation suite FirstLight. We find that
galaxies undergo an expansion–compaction–re-expansion process. This process operates in a specific mass range; compaction starts at $\log (M^\star_ {\rm on} / {\rm M}_\odot) \sim 8.5$ and ends at $\log (M^\star_{\rm off} / \mathrm{M}_\odot) \sim 9.5$. In between these masses, the size–mass relation becomes inverted, with a negative slope. The physical mechanism driving this process in our simulations involves a self-reinforced inflow of gas from the outer regions, that triggers a strong, localised starburst at the centre (within $1\, {\rm kpc}$). This contraction continues until conditions favour
star formation in a broader area, and the normal inside-out growth pattern resumes. We present evidence for the existence of a universal wet compaction operating at
Cosmic Dawn. This mechanism is driven by spherical
accretion triggered by the change of the state of the central matter of
galaxies, from dark matter- to
baryon-dominated. We also propose an analytical expression for the infall process, suitable for use in semi-analytic models. Contrary to low-
redshift galaxies, in high-
redshift systems compaction ends without gas depletion and
star-formation quenching.
Read the full abstract ▾
All authors P. Cataldi, S. Pedrosa, L. J. Pellizza, D. Ceverino, L. A. Bignone
High Energy Astrophysical Phenomena
Gamma-ray Bursts
Andrew J. Levan
Gamma-ray bursts are flashes of high-energy radiation lasting from a fraction of a second to several hours. Military satellites made the first detections of GRBs in the late 1960s. The $\gamma$-ray emission forms from shocks in a relativistic jet launched from a compact central engine. In addition to the emission of $\gamma$-rays, the interaction of the jet with the surrounding medium yields afterglow emission that can be observed across the electromagnetic spectrum.
Redshift measurements from these afterglows place GRBs from the local to the distant Universe. The central engines of GRBs are thought to be either a hyperaccreting black hole or a highly magnetized
neutron star (magnetar). There is now strong observational evidence that this central engine is created either in the core collapse of a rapidly rotating massive
star or via the merger of two compact objects (
neutron stars or a
neutron star with a black hole). The combination of
stellar scale events with extreme energies and luminosities makes GRBs powerful probes of the extreme physics involved in their production and of other areas of astrophysics and cosmology. These include as the electromagnetic counterparts of gravitational wave sources, the production and acceleration of relativistic jets, the synthesis of heavy elements, the study of the interstellar and intergalactic medium, and the identification of the collapse of early generations of
stars.
Read the full abstract ▾
High Energy Astrophysical Phenomena
First X-ray and radio polarimetry of the neutron star low-mass X-ray binary GX 17+2
Unnati Kashyap, Thomas J. Maccarone, Eliot C. Pattie et al. (+5 more)
We report the first polarimetric results of the
neutron star (NS) low-mass X-ray binary (LMXB) Z-source GX 17+2 using the Imaging X-ray Polarimetry Explorer (IXPE) and the Very Large Array (VLA). We find that the X-ray source was polarized at PD = 1.9 +/- 0.3 % (1-sigma errors) with a polarization angle of PA = 11 +/- 4 degree (1-sigma errors). Simultaneous
Nuclear Spectroscopic
Telescope Array (NuSTAR) observations show that the source was in the normal branch (NB) during our IXPE observations. The X-ray spectro-polarimetry results suggest a source geometry comprising an
accretion disk component, a Comptonization component, and a reflection component. The VLA
radio polarization study shows a PD = 2.2 +/- 0.2 % with a Faraday-corrected intrinsic polarization angle of 1 +/- 5 degree, which is an indication of the jet axis. Thus, we find the estimated X-ray PA from the source is consistent with the
radio PA. We discuss the
accretion geometry of the Z-source in light of our X-ray spectro-polarimetry and
radio findings.
Read the full abstract ▾
All authors Unnati Kashyap, Thomas J. Maccarone, Eliot C. Pattie, Mason Ng, Swati Ravi, Alexandra J. Tetarenko, Pau Bosch Cabot, Herman L. Marshall
Earth and Planetary Astrophysics
Water solubility in silicate melts: The effects of melt composition under reducing conditions and implications for nebular ingassing on rocky planets
Maggie A. Thompson, Paolo A. Sossi, Dan J. Bower et al. (+3 more)
Rocky
planet atmospheres form and evolve through interactions between the
planet's surface and interior. If a growing rocky
planet acquires enough mass prior to the dissipation of the nebular gas disk, it can gravitationally capture a `primary' atmosphere dominated by H2. At the same time, these young, rocky bodies are likely to have partial or global magma oceans as a result of the heat from
accretion, core formation and radioactive decay of short-lived major element isotopes. During this magma ocean stage, the dissolution of volatile, life-essential elements, such as hydrogen in the form of water or H2, into the magma is critical in determining the extent to which a rocky
planet can maintain these elements over time. However, our ability to quantify the amount of hydrogen dissolved in the magma oceans of rocky
planets is limited by the lack of experimental constraints on H-bearing species' solubilities at relevant pressure and temperature conditions, including those expected for the early Earth. Here we experimentally determine the solubility of water in silicate melts of various compositions in the Ca-Mg-Al-Si-Fe-O system at a total pressure of 1 bar and temperatures from 1673-1823 K, synthesized in a H2-CO2 gas-mixing furnace. We use
Bayesian parameter estimation to derive a robust water solubility law that includes the effects of melt composition and temperature. Using this solubility law, we estimate that ~100 ppm of hydrogen can dissolve into a 1 MEarth
planet with a surface pressure of ~300 bars set by
accretion of
solar-like nebular gas. For rocky
planets in general, ingassing of a primary atmosphere may be an important source and initial storage mechanism for hydrogen-bearing species in a
planet's interior, provided it grew to a sufficient mass within the lifetime of the
solar nebula.
Read the full abstract ▾
All authors Maggie A. Thompson, Paolo A. Sossi, Dan J. Bower, Anat Shahar, Christian Liebske, Julien Allaz
Astrophysics of Galaxies
Ionization Sources of the Local Interstellar Clouds: Two B-stars, Three White Dwarfs, and the Local Hot Bubble
J. Michael Shull, Rachel M. Curran, Michael W. Topping et al. (+1 more)
The dominant sources of photoionizing radiation in the extreme ultraviolet (EUV) incident on the exterior of the local interstellar clouds include two nearby early B-type
stars, $\epsilon$ CMa ($124\pm2$ pc) and $\beta$ CMa ($151\pm5$ pc), three hot
dwarfs, and the local hot bubble (LHB). Line emission (170-912A) from highly ionized metals (Fe, Ne, Mg) in million-degree LHB
plasma may be responsible for the elevated ionization fractions of helium ($n_{\rm HeII}/n_{\rm He} \approx 0.4$) compared to hydrogen ($n_{\rm HII} / n_{\rm H} \approx 0.2$) in the local clouds. We update the
stellar parameters and ionizing flux for $\beta$ CMa, after correcting the EUV spectra for intervening HI column density, $N_{\rm HI} = 1.9\pm0.1\times10^{18}~{\rm cm}^{-2}$, and its hotter effective temperature, $T_{\rm eff} \approx 25,000$K vs. 21,000K for $\epsilon$ CMa. These two
stars produce a combined H-ionizing
photon flux $\Phi_{\rm H} \approx 6800\pm1400$ cm$^{-2}$ s$^{-1}$ at the external surface of the local clouds. The hot bubble could produce comparable fluxes, $\Phi_{\rm H} =$ 2000-9000 cm$^{-2}$ s$^{-1}$, depending on the amount of metal depletion into
dust grains that survive sputtering. The radial velocities and proper motions of $\beta$ CMa and $\epsilon$ CMa indicate that both
stars passed within $10\pm1$ pc of the Sun $4.4\pm0.1$ Myr ago, with 100-200 times higher local ionizing fluxes. At that time, the local clouds were likely farther from the Sun, owing to their transverse motion. Over the last few Myr, EUV radiation from these two
stars left a wake of highly ionized gas in a hot, low-density cavity produced by past
supernova explosions in the Sco-Cen OB association and connected with the LHB.
Read the full abstract ▾
All authors J. Michael Shull, Rachel M. Curran, Michael W. Topping, Jonathan D. Slavin
Astrophysics of Galaxies
Self-interacting dark matter in the center of a Local Group dwarf galaxy and its satellites
Thales A. Gutcke, Giulia Despali, Stephanie O'Neil et al. (+3 more)
We present a detailed comparison of a Local Group
dwarf galaxy analogue evolved in two cosmological models: the standard $\Lambda$CDM and a self-interacting dark matter (SIDM) model with a velocity-dependent cross-section. Both simulations are run with the high-resolution, hydrodynamical LYRA
galaxy formation model, allowing us to explore the global and substructure properties of the
dwarf in a consistent context. While the overall
halo growth, final mass, and subhalo mass functions remain largely unchanged across models, SIDM produces a central dark matter core extending to $\sim$1 kpc, which does not significantly vary with the inclusion of
baryons. Baryonic properties, however, differ notably. The SIDM model leads to a 25% reduction in
stellar mass and retains more gas within the
stellar half-mass radius due to a prolonged quiescent phase in
star formation. The
stellar distribution is less centrally concentrated, and a population of in-situ
star clusters form at late times. Substructure analysis reveals fewer luminous satellites and more
stellar-only systems in SIDM, driven in part by
tidal stripping that affects the dark matter more than the
stars. A subset of satellites undergoes
tidal-triggered core collapse after infall, enhancing the diversity of SIDM satellite rotation curves. These differences offer potential observational signatures of SIDM in low-mass
galaxies.
Read the full abstract ▾
All authors Thales A. Gutcke, Giulia Despali, Stephanie O'Neil, Mark Vogelsberger, Azadeh Fattahi, David B. Sanders
Astrophysics of Galaxies
Central Massive Black Holes Are Not Ubiquitous in Local Low-Mass Galaxies
Fan Zou, Elena Gallo, Anil C. Seth et al. (+13 more)
The black-hole occupation fraction ($f_\mathrm{occ}$) defines the fraction of
galaxies that harbor central massive black holes (MBHs), irrespective of their
accretion activity level. While it is widely accepted that $f_\mathrm{occ}$ is nearly 100% in local massive
galaxies with
stellar masses $M_\star \gtrsim 10^{10}~M_\odot$, it is not yet clear whether MBHs are ubiquitous in less-massive
galaxies. In this work, we present new constraints on $f_\mathrm{occ}$ based on over 20 years of Chandra imaging data for 1606
galaxies within 50 Mpc. We employ a
Bayesian model to simultaneously constrain $f_\mathrm{occ}$ and the specific
accretion-rate distribution function, $p(\lambda)$, where the specific
accretion rate is defined as $\lambda=L_\mathrm{X}/M_\star$, and $L_\mathrm{X}$ is the MBH
accretion luminosity in the 2-10 keV range. Notably, we find that $p(\lambda)$ peaks around $10^{28}~\mathrm{erg~s^{-1}}~M_\odot^{-1}$; above this value, $p(\lambda)$ decreases with increasing $\lambda$, following a power-law that smoothly connects with the probability distribution of bona-fide active
galactic nuclei. We also find that the occupation fraction decreases dramatically with decreasing $M_\star$: in high mass
galaxies ($M_\star \approx 10^{11-12}M_\odot$), the occupation fraction is $>93\%$ (a $2\sigma$ lower limit), and then declines to $66_{-7}^{+8}\%$ ($1\sigma$ errors) between $M_\star\approx10^{9-10}M_\odot$, and to $33_{-9}^{+13}\%$ in the
dwarf galaxy regime between $M_\star\approx10^{8-9}~M_\odot$. Our results have significant implications for the normalization of the MBH mass function over the mass range most relevant for
tidal disruption events, extreme mass ratio inspirals, and MBH merger rates that upcoming facilities are poised to explore.
Read the full abstract ▾
All authors Fan Zou, Elena Gallo, Anil C. Seth, Edmund Hodges-Kluck, David Ohlson, Tommaso Treu, Vivienne F. Baldassare, W. N. Brandt, Jenny E. Greene, Piero Madau, Dieu D. Nguyen, Richard M. Plotkin, Amy E. Reines, Alberto Sesana, Jong-Hak Woo, Jianfeng Wu
Earth and Planetary Astrophysics
The First Dedicated Survey of Atmospheric Escape from Planets Orbiting F Stars
Morgan Saidel, Shreyas Vissapragada, Heather Knutson et al. (+9 more)
Hydrodynamic escape can strip the envelopes of close-in
exoplanets, but most observations of atmospheric mass loss to date have been confined to
planets orbiting K and M
dwarfs. A growing body of detections of atmospheric escape from
planets orbiting early-type
stars indicates that they may have significantly stronger and more extended
outflows than
planets orbiting cooler
stars. However, it is unclear whether this limited sample of
planets is representative of all gas
giants orbiting early-type
stars. Motivated by this question, we initiated the first dedicated survey of atmospheric escape from gas
giants orbiting F
stars in order to understand how their distinct radiation environments shape planetary
outflows. We observed ten transits of six
planets in an ultra-narrowband filter centered on the metastable helium line using Palomar/WIRC. We report strong ($>3\sigma$) detections of atmospheric escape for WASP-12~b and WASP-180~A~b, tentative ($>2\sigma$) detections for WASP-93~b and HAT-P-8~b, and non-detections for WASP-103~b and KELT-7~b. We fit these measurements with a 1D Parker wind model to derive corresponding mass-loss rates, and combine our results with literature measurements to obtain an updated picture of mass loss from
planets orbiting early-type
stars. Our results indicate that the observed variation in mass-loss rates can be explained by a combination of Roche filling factor and XUV luminosity, and disfavors NUV-driven escape models.
Read the full abstract ▾
All authors Morgan Saidel, Shreyas Vissapragada, Heather Knutson, Ethan Schreyer, Mike Greklek-McKeon, Jonathan Gomez Barrientos, W. Garrett Levine, Carlos Gascón, George King, Morgan MacLeod, Haedam Im, Nick Tusay
High Energy Astrophysical Phenomena
From X-rays to High-Energy Gamma-rays: A Comprehensive Multi-Wavelength Study of Early Gamma-Ray Burst Afterglows
P. Tiwari, B. Banerjee, D. Miceli et al. (+8 more)
Gamma-ray Bursts (GRBs) generate powerful relativistic jets that inject a large amount of energy into their surrounding environment, producing blast waves that accelerate particles to high energies. The GRB afterglow radiation provides a powerful means to investigate the microphysics of relativistic shocks and to probe the medium surrounding the progenitor of the burst. In this study, we present a comprehensive multiwavelength analysis of 31 GRBs observed between 2008 and 2024 from the Neil Gehrels Swift Observatory (X-ray
Telescope and Burst Alert
Telescope) and the
Fermi Large Area
Telescope, covering
photon energies from 0.3 keV to 300 GeV. Our goal is to characterize the broadband spectral properties of GRB afterglows in soft X-rays, hard X-rays, and high-energy gamma rays. We investigate correlations between spectral shape and energy output across different parts of the spectrum. The observed emission is modeled using a forward shock scenario that includes both synchrotron and synchrotron self-Compton (SSC) radiation losses. The results favor an SSC-dominated radiation model in a wind-like medium, consistent with expectations for long-duration GRBs. Crucially, this work provides new
benchmarks for the microphysical parameters governing the emission, particularly indicating a notably low
magnetic energy fraction, which refines previous estimates. By modeling broadband data, this study offers one of the most detailed SSC analyses in a wind-like environment to date. Notably, our results naturally account for the comparable energy output observed in both the soft X-ray and TeV bands, consistent with the previously detected TeV-GRBs.
Read the full abstract ▾
All authors P. Tiwari, B. Banerjee, D. Miceli, G. Oganesyan, A. Ierardi, S. Macera, M. Branchesi, L. Nava, S. Mohnani, S. Agarwal, A. Shukla
Instrumentation and Methods for Astrophysics
Interpreting anomaly detection of SDSS spectra
Edgar Ortiz Manrique and Médéric Boquien
The increasing use of ML in astronomy introduces important questions about interpretability. Due to their complexity and non-linear nature, it can be challenging to understand their decision-making process. While these models can effectively identify unusual spectra, interpreting the physical nature of the flagged outliers remains a major challenge. We aim to bridge the gap between anomaly detection and physical understanding by combining deep learning with interpretable ML (iML) techniques to identify and explain anomalous
galaxy spectra from SDSS data. We present a flexible framework that uses a variational autoencoder to compute multiple anomaly scores, including physically-motivated variants of the mean squared error. We adapt the iML LIME
algorithm to spectroscopic data, systematically explore
segmentation and perturbation strategies, and compute explanation weights that identify the features most responsible for each detection. To uncover population-level trends, we normalize the LIME weights and apply clustering to the top 1% most anomalous spectra. Our approach successfully separates instrumental artifacts from physically meaningful outliers and groups anomalous spectra into astrophysically coherent categories. These include dusty, metal-rich starbursts; chemically-enriched H\,II regions with moderate excitation; and extreme emission-line
galaxies with low
metallicity and hard ionizing spectra. The explanation weights align with established emission-line diagnostics, enabling a physically-grounded taxonomy of spectroscopic anomalies. Our work shows that interpretable anomaly detection provides a scalable, transparent, and physically meaningful approach to exploring large spectroscopic
datasets. Our framework opens the door for incorporating interpretability tools into quality control, follow-up targeting, and discovery pipelines in current and future surveys.
Read the full abstract ▾
Astrophysics of Galaxies
MEGATRON: how the first stars can create an iron metallicity plateau in the smallest dwarf galaxies
Martin P. Rey, Harley Katz, Corentin Cadiou et al. (+23 more)
We study the
stellar mass-iron
metallicity relation of
dwarf galaxies in the new high-resolution MEGATRON cosmological radiation-hydrodynamics simulations. These simulations model
galaxy formation up to $z\approx8$ in a region that will collapse into a Milky-Way-like
galaxy at $z=0$, while self-consistently tracking Population III and II (Pop.~III, Pop.~II)
star formation, feedback and chemical enrichment. MEGATRON
dwarf galaxies are in excellent agreement with the observed
stellar mass-
metallicity relation at $z=0$, including an over-abundance of
dwarfs along a flat plateau in
metallicity ($\langle [\rm{Fe}/\rm{H}] \rangle \approx -2.5$) at low
stellar masses ($M_{\star} \leq 10^5 \, \rm{M}_{\odot}$). We tie this feature to the chemical enrichment of
dwarf galaxies by Pop.~III pair-instability
supernova (PISN) explosions. The strong Lyman-Werner background (LW) from the protogalaxy ensures that PISNe occur in
haloes massive enough ($\approx 10^7\, \rm{M}_{\odot}$) to retain their ejecta. We also predict a tail of $\approx 20\%$ of iron-deficient ($\langle [\rm{Fe}/\rm{H}] \rangle \leq - 3$)
dwarf galaxies. We show that both plateau and tail (i) are robust to large variations in Pop.~II feedback assumptions, and (ii) survive in bound satellites surrounding the central
galaxy at $z=0$.
Read the full abstract ▾
All authors Martin P. Rey, Harley Katz, Corentin Cadiou, Mahsa Sanati, Oscar Agertz, Jeremy Blaizot, Alex J. Cameron, Nicholas Choustikov, Julien Devriendt, Uliana Hauk, Alexander P. Ji, Gareth C. Jones, Taysun Kimm, Isaac Laseter, Sergio Martin-Alvarez, Kosei Matsumoto, Autumn Pearce, Yves Revaz, Francisco Rodriguez Montero, Joki Rosdahl, Aayush Saxena, Adrianne Slyz, Richard Stiskalek, Anatole Storck, Oscar Veenema, Wonjae Yee
Earth and Planetary Astrophysics
Orbital decay candidates reconsidered: WASP-4 b is not decaying and Kepler-1658 b is not a planet
Joshua N. Winn and Gu{\dh}mundur Stefánsson
The fate of hot Jupiters is thought to be engulfment by their host
stars, the outcome of
tidal orbital decay. Transit timing has revealed a few systems with apparently shrinking orbital periods, but such signals can be mimicked by light travel-time effects (LTTE) of a distant companion. By combining transit timings with precise radial-velocity data, including new data, we reassessed three reported cases of orbital decay: WASP-4, WASP-12, and Kepler-1658. For WASP-4, the period change is best explained by LTTE due to an ~7 Jupiter-mass companion at ~8 AU, with no need to invoke orbital decay. For WASP-12, in contrast, the data firmly exclude LTTE and confirm genuine orbital decay. For Kepler-1658, spectroscopic and photometric anomalies reveal the "
planet" to be an eclipsing K/M binary bound to the F-type primary, with LTTE explaining the observed period change. Thus, among the known hot Jupiters, only WASP-12 b currently shows compelling evidence for orbital decay.
Read the full abstract ▾
Astrophysics of Galaxies
Constraints on Radial Gas Flows in the Milky Way Disk Revealed by Large Stellar Age Catalogs
James W. Johnson
Disk
galaxies like the Milky Way are expected to experience gas flows carrying matter toward their centers. This paper investigates the role of these radial gas flows in models of
Galactic chemical
evolution (GCE). We follow five different parameterizations of the Galactocentric radial velocity, $v_{r,g}$, of the interstellar medium (ISM). Relative to the $v_{r,g}=0$ limit, all models predict
stellar metallicity to decline less significantly with age in the outer disk and more significantly in the inner disk. This outcome arises because radial flows cannot remove gas from one region of the
Galaxy without placing it elsewhere, leading to opposing effects on enrichment timescales between the inner and outer
Galaxy. This prediction is at odds with recent observational constraints, which indicate remarkably minimal decline in
metallicity ($\lesssim$$0.1$ dex) between young ($\sim$$0-2$ Gyr) and old populations ($\sim$$8-10$ Gyr) across the entire
Galactic disk. Radial gas flows cannot be the sole explanation of this result at all Galactocentric radii. Our models reproduce this result at $R\gtrsim6$ kpc if the flow velocity is relatively constant in both radius and time near $v_{r,g}\approx-1$ km/s. In agreement with previous GCE models, all of our flow prescriptions lead to lower
metallicities and steeper radial gradients relative to static models. Exploiting this universal outcome, we identify mixing effects and the relative rates of
star formation and metal-poor
accretion as the processes that establish the ISM
metallicity at low
redshift. We provide a suite of analytic formulae describing radial
metallicity gradient
evolution based on this connection.
Read the full abstract ▾
Astrophysics of Galaxies
EIGER VIII: First stars signatures in the connection between OI absorption and Galaxies in the Epoch of Reionization
Jack Higginson, Rongmon Bordoloi, Robert A. Simcoe et al. (+8 more)
We investigate the association between
galaxies and neutral OI absorption systems at z~6, which trace metal-enriched gas during the epoch of reionization. We identify 40
galaxies across six
quasar fields, residing in 15 overdensities within 300 kpc of the background sightlines. Five OI absorption systems are associated with five of these overdensities, yielding a covering fraction of $0.27^{+0.13}_{-0.10}$ within 300 kpc. The absorption occurs beyond typical virial radii, indicating that the gas traces extended overdensity environments rather than individual
galaxy halos, unlike the z~0 CGM which is largely bound to
halos. These
galaxy-associated absorbers account for $\sim35\%$ of all OI systems seen in blind
quasar surveys, implying the remainder arise in lower-mass
galaxies below our detection threshold or in dense neutral IGM pockets. The CGM around these
galaxies contains $\gtrsim 2\times10^6~M_{\odot}$ of oxygen, comparable to the ISM oxygen mass of the
galaxies themselves, suggesting that the surrounding environment holds as much metal mass as the
galaxies. All five
galaxy-associated systems show significantly higher $\log(N_{\rm CII}/N_{\rm OI})$ ratios than absorbers lacking
galaxy associations. Furthermore, relative abundance ratios ([Si/O], [C/O]) reveal that four of the five exhibit enrichment patterns consistent with Population III nucleosynthesis at the outskirts of
galaxy overdensities.. These rare systems offer a unique window into the role of first-generation
stars in shaping the early metal enrichment of
galaxies and their environments.
Read the full abstract ▾
All authors Jack Higginson, Rongmon Bordoloi, Robert A. Simcoe, Jorryt Matthee, Daichi Kashino, Ruari Mackenzie, Ivan Kramarenko, Simon J. Lilly, Anna-Christina Eilers, Rohan P. Naidu, Minghao Yue
Cosmology and Nongalactic Astrophysics
QML-FAST – A Fast Code for low-$\ell$ Tomographic Maximum Likelihood Power Spectrum Estimation
Yurii Kvasiuk, Anderson Lai, Moritz Münchmeyer et al. (+1 more)
We present a novel implementation for the quadratic maximum likelihood (QML) power spectrum
estimator for multiple correlated scalar fields on the sphere. Our
estimator supports arbitrary binning in
redshift and multipoles $\ell$ and includes cross-correlations of
redshift bins. It implements a fully optimal analysis with a pixel-wise covariance model. We implement a number of optimizations which make the
estimator and associated covariance
matrix computationally tractable for a low-$\ell$ analysis, suitable for example for kSZ velocity reconstruction or
primordial non-Gaussianity from scale-dependent bias analyses. We validate our
estimator extensively on simulations and compare its features and precision with the common pseudo-$C_\ell$ method, showing significant gains at large scales. We make our code publicly available. In a companion paper, we apply the
estimator to kSZ velocity reconstruction using data from ACT and DESI Legacy Survey and construct full set of QML
estimators on 40 correlated fields up to $N_{\text{side}}= 32$ in timescale of an hour on a single 24-core CPU requiring $<256\ \mathrm{Gb}$ RAM, demonstrating the performance of the code.
Read the full abstract ▾
All authors Yurii Kvasiuk, Anderson Lai, Moritz Münchmeyer, Kendrick M. Smith
Astrophysics of Galaxies
Resolved Profiles of Stellar Mass, Star Formation Rate, and Predicted CO-to-H$_2$ Conversion Factor Across Thousands of Local Galaxies
Jiayi Sun, Yu-Hsuan Teng, I-Da Chiang et al. (+9 more)
We present radial profiles of surface brightness in UV and IR bands, estimate
stellar mass surface density ($\Sigma_\star$) and
star formation rate surface density ($\Sigma_\mathrm{SFR}$), and predict the CO-to-H$_2$ conversion factor ($\alpha_\mathrm{CO}$) for over 5,000 local
galaxies with
stellar mass $M_\star\,{\geq}\,10^{9.3}\rm\,M_\odot$. We build these profiles and measure
galaxy half-light radii using GALEX and WISE images from the $z$0MGS program, with special care given to highly inclined
galaxies. From the UV and IR surface brightness profiles, we estimate $\Sigma_\star$ and $\Sigma_\mathrm{SFR}$ and use them to predict $\alpha_\mathrm{CO}$ with state-of-the-art empirical prescriptions. We validate our (kpc-scale) $\alpha_\mathrm{CO}$ predictions against observational estimates, finding the best agreement when accounting for CO-dark gas as well as CO emissivity and excitation effects. The CO-dark correction plays a primary role in lower-mass
galaxies, whereas CO emissivity and excitation effects become more important in higher-mass and more actively
star-forming
galaxies, respectively. We compare our estimated $\alpha_\mathrm{CO}$ to observed
galaxy-integrated SFR to CO luminosity ratio as a function of $M_\star$. A large compilation of literature data suggests that
star-forming
galaxies with $M_\star = 10^{9.5{-}11}\,M_\odot$ show strong anti-correlations of SFR/$L^\prime_\mathrm{CO(1{-}0)} \propto M_\star^{-0.29}$ and SFR/$L^\prime_\mathrm{CO(2{-}1)} \propto M_\star^{-0.40}$. The estimated $\alpha_\mathrm{CO}$ trends, when combined with a constant molecular gas depletion time $t_\mathrm{dep}$, can only explain ${\approx}1/3$ of these SFR/$L^\prime_\mathrm{CO}$ trends. This suggests that $t_\mathrm{dep}$ being systematically shorter in lower-mass
star-forming
galaxies is the main cause of the observed SFR/$L^\prime_\mathrm{CO}$ variations. (Abridged)
Read the full abstract ▾
All authors Jiayi Sun, Yu-Hsuan Teng, I-Da Chiang, Adam K. Leroy, Karin Sandstrom, Jakob den Brok, Alberto D. Bolatto, Jeremy Chastenet, Ryan Chown, Annie Hughes, Eric W. Koch, Thomas G. Williams
Instrumentation and Methods for Astrophysics
The Cosmic Infrared Background Experiment-2: An Intensity Mapping Optimized Sounding-rocket Payload to Understand the Near-IR Extragalactic Background Light
Michael Zemcov, James J. Bock, Asantha Cooray et al. (+37 more)
The background light produced by emission from all sources over
cosmic history is a powerful diagnostic of structure formation and
evolution. At near-infrared wavelengths, this extragalactic background light (EBL) is comprised of emission from
galaxies stretching all the way back to the first-light objects present during the Epoch of Reionization. The
Cosmic Infrared Background Experiment 2 (CIBER-2) is a sounding-rocket experiment designed to measure both the absolute photometric brightness of the EBL over 0.5 - 2.0 microns and perform an intensity mapping measurement of EBL spatial fluctuations in six broad bands over the same wavelength range. CIBER-2 comprises a 28.5 cm, 80K
telescope that images several square degrees to three separate cameras. Each camera is equipped with an HAWAII-2RG detector covered by an assembly that combines two broadband filters and a linear-variable filter, which perform the intensity mapping and absolute photometric measurements, respectively. CIBER-2 has flown three times: an engineering flight in 2021; a terminated launch in 2023; and a successful science flight in 2024. In this paper, we review the science case for the experiment; describe the factors motivating the instrument design; review the optical, mechanical, and electronic implementation of the instrument; present preflight laboratory characterization measurements; and finally assess the instrument's performance in flight.
Read the full abstract ▾
All authors Michael Zemcov, James J. Bock, Asantha Cooray, Shuji Matsuura, Dae-Hee Lee, Candice Fazar, Richard M. Feder, Grigory Heaton, Ryo Hashimoto, Phillip Korngut, Toshio Matsumoto, Chi H. Nguyen, Kazuma Noda, Won-Kee Park, Kei Sano, Kohji Takimoto, Toshiaki Arai, Seung-Cheol Bang, Priyadarshini Bangale, Masaki Furutani, Viktor Hristov, Yuya Kawano, Arisa Kida, Tomoya Kojima, Alicia Lanz, Chika Matsumi, Dale Mercado, Shunsuke Nakagawa, Tomoya Nakagawa, Shuta Nakahata, Ryo Ohta, Dorin Patru, Mai Shirahata, Hiroko Suzuki, Aoi Takahashi, Momoko Tamai, Serena Tramm, Kohji Tsumura, Yasuhiro Yamada, Shiang-Yu Wang
Cosmology and Nongalactic Astrophysics
DISCO-DJ II: a differentiable particle-mesh code for cosmology
Florian List, Oliver Hahn, Thomas Flöss et al. (+1 more)
The mildly non-linear regime of
cosmic structure formation holds much of the information that upcoming large-scale structure surveys aim to exploit, making fast and accurate predictions on these scales essential. We present the $N$-body module of DISCO-DJ (DIfferentiable Simulations for COsmology - Done with Jax), designed to deliver high-fidelity, GPU-accelerated, and differentiable particle-mesh simulations tailored for cosmological inference. Theory-informed time integrators such as the recently introduced BullFrog method allow for accurate predictions already with few time steps (e.g. $6$ steps for per-cent-level accuracy in terms of the present-day power spectrum at $k \approx 0.2 \, h / \mathrm{Mpc}$ using $N = 512^3$ particles, which takes just a few seconds). To control discreteness effects and achieve high accuracy, the code incorporates a suite of advanced techniques, for example a custom non-uniform FFT implementation for force evaluation. Both forward- and reverse-mode differentiation are supported, with
memory requirements independent of the number of time steps; in the reverse case, this is achieved through an adjoint formulation. We extensively study the effect of various numerical parameters on the accuracy. As an application of DISCO-DJ, we perform field-level inference by recovering $\sigma_8$ and the initial conditions from a noisy Gadget matter density field. Coupled with our recently introduced Einstein–Boltzmann solver, the DISCO-DJ ecosystem provides a self-consistent, fully differentiable pipeline for modelling the large-scale structure of the universe. The code is available at https://github.com/cosmo-sims/DISCO-DJ.
Read the full abstract ▾
All authors Florian List, Oliver Hahn, Thomas Flöss, Lukas Winkler
Cosmology and Nongalactic Astrophysics · Cross-listed from cs.LG
A Data-Driven Prism: Multi-View Source Separation with Diffusion Model Priors
Sebastian Wagner-Carena, Aizhan Akhmetzhanova and Sydney Erickson
A common challenge in the natural sciences is to disentangle distinct, unknown sources from observations. Examples of this source separation task include deblending
galaxies in a crowded field, distinguishing the activity of individual
neurons from overlapping signals, and separating seismic events from an ambient background. Traditional analyses often rely on simplified source models that fail to accurately reproduce the data. Recent advances have shown that
diffusion models can directly learn complex prior distributions from noisy, incomplete data. In this work, we show that
diffusion models can solve the source separation problem without explicit assumptions about the source. Our method relies only on multiple views, or the property that different sets of observations contain different linear transformations of the unknown sources. We show that our method succeeds even when no source is individually observed and the observations are noisy, incomplete, and vary in resolution. The learned
diffusion models enable us to sample from the source priors, evaluate the probability of candidate sources, and draw from the joint posterior of the source distribution given an observation. We demonstrate the effectiveness of our method on a range of synthetic problems as well as real-world
galaxy observations.
Read the full abstract ▾
Cosmology and Nongalactic Astrophysics · Cross-listed from hep-ph
Testing the arrow of time at the cosmo collider
Shuntaro Aoki and Alessandro Strumia
Normal particles carry a microscopic arrow of causality. Lee-Wick ghosts carry the reversed arrow, mediating characteristic
collider signals in flat space: opposite-sign scattering amplitudes that violate positivity bounds; acausality on time scales set by their negative decay rate. During inflation, the corresponding cosmo-
collider ghost signals are: opposite-sign non-Gaussianities; Boltzmann-unsuppressed local oscillatory signals without their non-local counterparts; IR-enhanced bi-spectrum and power spectrum, depending on the dimension of the interaction operator, which decreases if the ghost decay rate is comparable to the Hubble rate.
Read the full abstract ▾
Astrophysics of Galaxies
A systematic meta-analysis of physical parameters of Galactic supernova remnants
I. Chousein-Basia, A. Zezas, I. Leonidaki et al. (+1 more)
Supernova remnants (SNRs) are the aftermath of massive
stellar explosions or of a white
dwarf in a binary system, representing critical phases in the life cycle of
stars and playing an important role in
galactic evolution. Physical properties of SNRs such as their shock velocity, density and age are important elements for constraining models for their
evolution and understanding the physical processes responsible for their morphological appearance and emission processes. Our study provides, for the first time, a comprehensive statistical analysis of the physical parameters in 64
Galactic SNRs both as a population as well as regions within individual objects. These 64 objects represent the subset of the 310 known
Galactic SNRs for which there are published optical data, from which we compiled their physical parameters through an exhaustive literature survey. Through a systematic statistical analysis accounting for uncertainties and/or upper and lower limits in these parameters we obtain distributions of the electron density and shock velocity in the studied SNRs and regions within them. This information is combined with constraints on their age and type. Analysis of electron density and shock velocity distributions for the entire sample of SNRs shows that they are consistent with a log-normal distribution and a skewed log-normal distribution, respectively. Within individual remnants, our study reveals that electron density and shock velocity show larger scatter in younger objects, reflecting the varying conditions of the ambient medium immediately surrounding the explosion epicenter and their impact on SNR
evolution. Comparison of the dependence of the shock velocity and density on the
supernova age with expectations from theoretical models shows good agreement.
Read the full abstract ▾
All authors I. Chousein-Basia, A. Zezas, I. Leonidaki, M. Kopsacheili
Astrophysics of Galaxies
MEGATRON: Reproducing the Diversity of High-Redshift Galaxy Spectra with Cosmological Radiation Hydrodynamics Simulations
Harley Katz, Martin P. Rey, Corentin Cadiou et al. (+21 more)
We present the MEGATRON suite of cosmological radiation hydrodynamics simulations following the formation of Milky Way-mass
galaxies from the earliest
cosmic epochs when Population III
stars form to
Cosmic Noon. The suite represents the first set of cosmological simulations that couples a vast non-
equilibrium thermochemistry network of
primordial species, metals, and molecules to multifrequency, on-the-fly radiation transport, allowing us to directly predict the spectral properties of early
galaxies. By initializing the simulations at zero
metallicity, resolving
haloes well below the atomic cooling threshold, reaching parsec-scale resolution, and modeling a Milky Way-mass environment, we aim to address four key science themes: 1)
Star formation at
cosmic dawn, 2)
Galaxy formation and the interstellar medium in the epoch of reionization, 3) The circumgalactic medium towards
cosmic noon, and 4) Reionization in a local volume environment and near-field cosmology. In this introductory work, we present an overview of the physical characteristics of high-
redshift MEGATRON
galaxies and their environment at $z>8$. We present a library of $>175,000$ simulated
galaxy spectra and demonstrate how much of the diversity of
galaxy spectra seen by JWST is naturally reproduced in the context of a $\Lambda$CDM cosmology. Caveats are discussed, such as the lack of AGN in our simulations and the limitations of our adopted
stellar population and chemical yield models. This project represents a step towards making more direct comparisons between simulations and observations and is particularly applicable for optimizing methods to infer
galaxy properties from existing high-
redshift JWST spectra and imaging data.
Read the full abstract ▾
All authors Harley Katz, Martin P. Rey, Corentin Cadiou, Oscar Agertz, Jeremy Blaizot, Alex J. Cameron, Nicholas Choustikov, Julien Devriendt, Uliana Hauk, Gareth C. Jones, Taysun Kimm, Isaac Laseter, Sergio Martin-Alvarez, Kosei Matsumoto, Autumn Pearce, Francisco Rodríguez Montero, Joki Rosdahl, Mahsa Sanati, Aayush Saxena, Adrianne Slyz, Richard Stiskalek, Anatole Storck, Oscar Veenema, Wonjae Yee