Earth and Planetary Astrophysics · Cross-listed from cs.LG
Connecting the Dots: A Machine Learning Ready Dataset for Ionospheric Forecasting Models
Linnea M. Wolniewicz, Halil S. Kelebek, Simone Mestici et al. (+8 more)
Operational
forecasting of the ionosphere remains a critical space weather challenge due to sparse observations, complex coupling across geospatial layers, and a growing need for timely, accurate predictions that support Global
Navigation Satellite System (GNSS), communications, aviation safety, as well as satellite operations. As part of the 2025 NASA Heliolab, we present a curated, open-access
dataset that integrates diverse ionospheric and heliospheric measurements into a coherent, machine learning-ready structure, designed specifically to support next-generation
forecasting models and address gaps in current operational frameworks. Our workflow integrates a large selection of data sources comprising
Solar Dynamic Observatory data,
solar irradiance indices (F10.7),
solar wind parameters (velocity and interplanetary
magnetic field), geomagnetic activity indices (Kp, AE, SYM-H), and NASA JPL's Global Ionospheric Maps of Total Electron Content (GIM-TEC). We also implement geospatially sparse data such as the TEC derived from the World-Wide GNSS Receiver Network and crowdsourced Android smartphone measurements. This novel heterogeneous
dataset is temporally and spatially aligned into a single, modular data structure that supports both physical and data-driven modeling. Leveraging this
dataset, we train and
benchmark several spatiotemporal machine learning architectures for
forecasting vertical TEC under both quiet and geomagnetically active conditions. This work presents an extensive
dataset and modeling pipeline that enables exploration of not only ionospheric dynamics but also broader Sun-Earth interactions, supporting both scientific inquiry and operational
forecasting efforts.
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All authors Linnea M. Wolniewicz, Halil S. Kelebek, Simone Mestici, Michael D. Vergalla, Giacomo Acciarini, Bala Poduval, Olga Verkhoglyadova, Madhulika Guhathakurta, Thomas E. Berger, At{\i}l{\i}m Güneş Baydin, Frank Soboczenski
Astrophysics of Galaxies
Further correction to the STARFORGE methods paper: Planck-mean dust opacities
Michael Y. Grudić, Dávid Guszejnov, Philip F. Hopkins et al. (+2 more)
The model for the Planck-mean
dust opacity $\kappa_{P}$ given in Appendix C of the STARFORGE simulations methods paper does not extrapolate well to low radiation temperature $T_{\rm rad}$, so we provide an updated calculation suitable for general use. We also clarify the role of the
dust and radiation temperatures in setting the
dust opacity, and provide code and calculations of the Planck- and Rosseland- mean
dust opacity as a function of both the
dust temperature $T_{\rm d}$ and the radiation temperature $T_{\rm rad}$.
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All authors Michael Y. Grudić, Dávid Guszejnov, Philip F. Hopkins, Stella S. R. Offner, Claude-André Faucher-Giguère
Astrophysics of Galaxies
Understanding the Origin and Dynamical Evolution of the Unique Open Star Cluster Berkeley 20 using FIRE Simulations
Alessa I. Wiggins, Jamie R. Quinn, Micah Oeur et al. (+11 more)
Open clusters (OCs) act as key probes that can be leveraged to constrain the formation and
evolution of the Milky Way (MW)'s disk, as each has a unique chemical fingerprint and well-constrained age. Significant
Galactic dynamic interactions can leave imprints on the orbital properties of OCs, allowing us to use the present day properties of long-lived OCs to reconstruct the MW's dynamic history. To explore these changes, we identify OC analogs in FIRE-2 simulations of MW-mass
galaxies. For this work, we focus on one particular FIRE-2 OC, which we identify as an analog to the old, subsolar, distant, and high
Galactic latitude MW OC, Berkeley 20. Our simulated OC resides ~6 kpc from the
galactic center and ultimately reaches a height $|Z_{\mathrm{max}}|>2$ kpc from the
galactic disk, similar to Berkeley 20. We trace the simulated cluster's orbital and environmental history, identifying key perturbative episodes, including: (1) an interaction with a gas overdensity in a spiral arm that
prompts an outward migration event and (2) a substantial interaction with a Sagittarius
Dwarf Spheroidal
Galaxy-mass satellite that causes significant orbital modification. Our simulated OC shows significant resilience to disruption during both its outward migration and the satellite-driven heating event that causes subsequent inward migration. Ultimately, we find these two key processes – migration and satellite heating – are essential to include when assessing OC orbital dynamics in the era of
Gaia.
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All authors Alessa I. Wiggins, Jamie R. Quinn, Micah Oeur, Sarah R. Loebman, Peter M. Frinchaboy, Kathryne J. Daniel, Fiona McCluskey, Jonah M. Otto, Hannah R. Woodward, Elena D'Onghia, Andrew Wetzel, Hanna Parul, Binod Bhattarai, Maximilian Cozzi
High Energy Astrophysical Phenomena
Constraining the Jet Energetics of the Transient X-ray Binaries MAXI J1348-630 and MAXI J1820+070 through Calorimetry
Pau Bosch-Cabot, Alexandra J. Tetarenko, Erik Rosolowsky et al. (+6 more)
We present Atacama Large Millimeter/Submillimeter Array (ALMA) observations aimed at identifying potential jet-ISM interaction sites in the vicinity of the transient black hole X-ray binaries MAXI J1348-630 and MAXI J1820+070, both of which have recently undergone an outburst, and displayed powerful large scale jets. Using this
dataset, we construct molecular line emission maps. By analyzing the morphological, spectral, and kinematic properties of the detected emission, we identify a molecular structure that provides compelling evidence for a jet-driven cavity in the local environment of MAXI J1348-630 but find no significant emission in the local environment of MAXI J1820+070. We use the properties of the detected molecular emission surrounding MAXI J1348-630 to constrain the jet power, finding our results to be consistent with other independent studies of this source, and further validating the utility of astrochemistry for constraining jet energetics. Additionally, our findings provide the first assessment on the formation timescales for jet-ISM interaction regions in the transient black hole X-ray binary population.
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All authors Pau Bosch-Cabot, Alexandra J. Tetarenko, Erik Rosolowsky, Francesco Carotenuto, James Miller-Jones, David M. Russell, Stéphane Corbel, Thomas D. Russell, Gregory R. Sivakoff
Solar and Stellar Astrophysics
Proton specific entropy as a proxy for the $O^{7+}/O^{6+}$ charge state ratio over heliocentric distance
Jack D. Collard, Tamar Ervin, Ryan M. Dewey et al. (+10 more)
While the fast
solar wind has well-established origins in coronal holes, the source of the slow
solar wind remains uncertain. Compositional metrics, such as heavy ion charge state ratios are set in the lower corona, providing insights into
solar wind source regions. However, prior to the launch of
Solar Orbiter, in situ measurements of heavy ion charge state were limited to distances of 1 AU and beyond. We investigate
proton specific
entropy as a proxy for the oxygen charge state ratio ($O^{7+}/O^{6+}$),which generally becomes frozen-in below ~1.8 Rsun, leveraging observations from
Solar Orbiter's Heavy Ion Sensor and
Proton and Alphas Sensor covering 0.28 to 1 AU. Our analysis confirms a strong anti-correlation between specific
entropy and the oxygen charge state ratio that persists over a broad range of distances in the inner heliosphere. We categorize observed
solar wind into fast
solar wind, slow Alfvenic
solar wind, and slow
solar wind, identifying clear distinctions in specific
entropy values and charge state ratios across these types. The work demonstrates the potential to use
proton specific
entropy as a classifier of
solar wind source regions throughout the heliosphere. By establishing the $S_p$-$O^{7+}/O^{6+}$ relationship and quantifying its radial dependence, the specific
entropy can be used as a quantity to identify the
solar wind source region in the absence of in-situ charge state measurements. This motivates future studies as to the applicability of this proxy to near-Sun observations (such as Parker
Solar Probe) and throughout the inner heliosphere.
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All authors Jack D. Collard, Tamar Ervin, Ryan M. Dewey, Yeimy J. Rivera, Aidan J. Nakhleh, Jean-Baptiste Dakeyo, Samuel T. Badman, Trevor A. Bowen, John W. Bonnell, Nicholeen M. Viall, Susan T. Lepri, Jim M. Raines, Stuart D. Bale
Instrumentation and Methods for Astrophysics · Cross-listed from physics.flu-dyn
Computational and Experimental Comparison of CLF5605 and roamx-0201 Martian Helicopter Rotor Airfoils
Lidia Caros, Witold J. F. Koning, Takayuki Nagata et al. (+7 more)
This study compares aerodynamic performance of the CLF5605 rotor airfoil – which flew on Ingenuity from 2021 to 2024 – with that of a new optimized roamx-0201 airfoil designed for Martian conditions at NASA Ames. Specifically, performance is studied at a Reynolds number of 20,000 and a Mach number of 0.60, across a range of angles of attack, using three independent state-of-the-art methodologies: implicit large eddy simulations (ILES) using NASA's OVERFLOW solver, direct numerical simulations (DNS) using the high-order GPU-accelerated PyFR solver, and experimental testing in the Mars Wind Tunnel at Tohoku University. Discrepancies between results obtain using the various methodologies are analyzed and explained. Across all methodologies it can be seen that the roamx-0201 airfoil is able to achieve a given lift with less drag compared to the CLF5605 airfoil. Moreover, OVERFLOW and PyFR results show that the roamx-0201 airfoil has superior stall characteristics, and can achieve a maximum lift ~20% higher than that achieved by the CLF5605 airfoil. The work provides a strong body of evidence to support further studies into use of rotors based on the optimized roamx-0201 airfoil for future Mars helicopter missions.
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All authors Lidia Caros, Witold J. F. Koning, Takayuki Nagata, Keisuke Asai, Oliver Buxton, Natalia Perez Perez, Ethan A. Romander, Taku Nonomura, Haley V. Cummings, Peter Vincent
High Energy Astrophysical Phenomena
Simulations of a Conducting Sphere Moving through Magnetized Plasma: Alfvén Wings, Slow Magnetosonic Wings, and Drag Force
Nicholas Corso and Dong Lai
Plasma-mediated interaction between astrophysical objects can play an important role and produce electromagnetic radiation in various binary systems, ranging from
planet-moon and
star-
planet systems to binary compact objects. We perform 3D magnetohydrodynamic numerical simulations to study an ideal magnetized
plasma flowing past an unmagnetized conducting sphere. Such flow generates
magnetic disturbances and produces a drag force on the sphere, and we explore the corresponding drag coefficient as a function of the flow speed relative to Alfvén speed and the $\beta$ parameter of the background
plasma. We find that the drag is generally well-described by the Alfvén wing model, but we also show that slow magnetosonic waves provide a correction through their own wing-like features. These give rise to a nontrivial dependence of the drag coefficient on the
plasma $\beta$, as well as enhanced drag as the flow speed approaches the Alfvén speed.
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High Energy Astrophysical Phenomena
SN 2023taz: Implications for the UV Diversity of Superluminous Supernovae
Aysha Aamer, Matt Nicholl, Charlotte Angus et al. (+21 more)
Superluminous
supernovae (SLSNe) are some of the brightest explosions in the Universe representing the extremes of
stellar deaths. At the upper end of their distribution is SN\,2023taz, one of the most luminous SLSNe discovered to date with a peak absolute magnitude of $M_{g,\rm{peak}}=-22.75 \pm 0.03$ and a lower limit for energy radiated of $E=2.9 \times 10^{51}$\,erg. Magnetar model fits reveal individual parameter values typical of the SLSN population, but the combination of a low $B$-field and ejecta mass with a short
spin period places SN\,2023taz in a unusual region of parameter space, accounting for its extreme luminosity. The optical data around peak are consistent with a temperature of $\sim$17\,000\,K but SN\,2023taz shows a surprising deficit in the UV compared to other events in this temperature range. We find no indication of
dust extinction that could plausibly explain the UV deficit. The lower level of UV flux is reminiscent of the absorption seen in lower-luminosity events like SN\,2017dwh, where Fe-group elements are responsible for the effect. However, in the case of SN\,2023taz, there is no evidence for a larger amount of Fe-group elements which could contribute to line blanketing. Comparing to SLSNe with well-observed UV spectra, an underlying temperature of $8000-9000$\,K would match the UV spectral slope, but is not consistent with the optical colour temperatures of these events. The most likely explanation is enhanced absorption by intermediate-mass elements, challenging previous findings that SLSNe exhibit similar UV absorption line equivalent widths. This highlights the need for expanded UV spectroscopic coverage of SLSNe, especially at early times, to build a framework for interpreting their diversity and to enable classification at higher
redshifts where optical observations will exclusively probe rest-frame UV emission.
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All authors Aysha Aamer, Matt Nicholl, Charlotte Angus, Shubham Srivastav, Jeff Cooke, Natasha Van Bemmel, Frédérick Poidevin, Stefan Geier, Joseph P. Anderson, Thomas de Boer, Kenneth C. Chambers, Ting-Wan Chen, Mariusz Gromadzki, Claudia P. Gutiérrez, Erkki Kankare, Réka Könyves-Tóth, Chien-Cheng Lin, Thomas B. Lowe, Eugene Magnier, Paolo Mazzali, Kyle Medler, Paloma Minguez, Tomás E. Müller-Bravo, Ben Warwick
Astrophysics of Galaxies
Dynamics in the Cores of Self-Interacting Dark Matter Halos: Reduced Stalling and Accelerated Core Collapse
Frank C. van den Bosch and Shashank Dattathri
Self-interacting dark matter (SIDM) is an intriguing alternative to the standard cold dark matter (CDM) paradigm, which predicts that dark matter
halos typically have large, isothermal cores. Numerical simulations have shown that dynamical friction ceases to operate in cores of (roughly) constant density, a phenomenon known as core stalling. In addition, such cores often are unstable to a dipole instability that gives rise to dynamical buoyancy, causing massive central objects to move outward. Thus far, these manifestations of core dynamics have only been demonstrated in collisionless systems. In this paper, we use idealized N-body simulations to study whether core stalling and dynamical buoyancy operate in SIDM
halos. We find that if the self-interactions are sufficiently strong, neither core stalling nor buoyancy are present, and a massive perturber will quickly sink all the way to the center of its host. In doing so, it gravitationally contracts the core, catalyzing a strongly accelerated core collapse. The reason why core dynamics are so different in SIDM
halos is that self-interactions drive the
halo's distribution function to a featureless exponential, removing any inflections or plateaus that are responsible for the dipole instability and core stalling in the case of CDM. We discuss implications of our finding for constraining the nature of dark matter by using observations of massive objects such as supermassive black holes (SMBHs), globular clusters, and
nuclear star clusters in the central regions of
galaxies.
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High Energy Astrophysical Phenomena
Tidal Disruption Events
Brenna Mockler, Erica Hammerstein, Eric R. Coughlin et al. (+1 more)
Stars that orbit too close to a black hole can be ripped apart by strong tides, producing a type of luminous transient event called a “
tidal disruption event" (TDE).
Tidal disruption events of
stars by supermassive black holes (SMBHs) provide windows into the
nuclei of
galaxies at size scales that are difficult to observe directly outside our own
galactic neighborhood. They provide a unique opportunity to study these supermassive black holes under feeding conditions that change dramatically over ~week-month timescales, and that regularly reach super-Eddington mass inflow rates. Their light curves are dependent on the properties of the disrupting black hole, and can be used to help constrain the lower mass end of the SMBH mass function – a region of parameter space that is difficult to access with classic dynamical mass measurements.
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All authors Brenna Mockler, Erica Hammerstein, Eric R. Coughlin, Matt Nicholl
Cosmology and Nongalactic Astrophysics · Cross-listed from hep-ph
Improved cosmological constraints on axion-lepton interactions
Marcin Badziak, Adam Gomułka, Maxim Laletin et al. (+1 more)
We present updated cosmological constraints on
axion-
lepton interactions based on state-of-the-art computations of the thermal
axion abundance. By combining Planck
Cosmic Microwave Background (CMB) data with
baryon acoustic oscillation (BAO) measurements from DESI DR2, we derive improved limits on both
lepton-
flavor-conserving (LFC) and
lepton-
flavor-violating (LFV)
axion couplings. Incorporating finite
axion mass effects substantially strengthens the bounds for
axion masses above 0.1 eV compared to those inferred from the $\Delta N_{\rm eff}$ constraint alone. The bounds on the LFC
axion-tau coupling and LFV
axion couplings to tau and
muon or electron are improved by several orders of magnitude and the lower bound on the
axion decay constant may exceed $10^6$ and $10^8$ GeV, respectively, for
axion masses above 1 eV. Our cosmological constraints on LFC
axion couplings to
muons and taus and LFV
axion couplings to tau and
muon or electron are stronger than all other constraints for masses above 0.3 eV. In particular, they are stronger than recent
collider constraints from Belle-II on $\tau \rightarrow la$ decays, where $l=e$ or $\mu$. The
collider constraints on $\mu \rightarrow ea$ decays are weaker than the cosmological constraints for
axion masses above 100 eV. Our results are relevant for both the QCD
axion and
axion-like particles (ALPs).
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All authors Marcin Badziak, Adam Gomułka, Maxim Laletin, Krzysztof Szafrański
High Energy Astrophysical Phenomena
Radio properties of the quasi-periodic eruption source RXJ1301.9+2747 at parsec scales
S. D. von Fellenberg, R. Arcodia, P. Benke et al. (+6 more)
Quasi-periodic eruptions (QPEs) are repeating soft X-ray
flares associated with
galactic nuclei. Several recent works have found evidence that the
accretion flow in the
galactic nuclei of QPEs is of recent origin, and that it is unlike canonical active
galactic nuclei (AGN). A precursor
tidal disruption event has been observed in a few cases. In this work we report new
radio observations of the QPE host
galaxy RXJ\,1301.9+2747 taken at 5.0\,GHz with the High Sensitivity Array (HSA), to complement archival 1.7\,GHz observations reported previously. Our new observations confirm the presence of a highly compact
radio source in RXJ\,1301.9+2747, which is smaller than $0.9\times0.4~\mathrm{pc}$ at 5.0\,GHz. The nonsimultaneous very long baseline interferometry (VLBI) compact flux of the source is consistent with a negative spectral index, and thus is similar to the larger non-VLBI scale
radio spectral index. Contrary to earlier results at 1.7\,GHz, we find the 5\,GHz emission offset from the optical
Gaia position, which may be due to
dust extinction in the host
galaxy. In addition, there is a significant offset between the 1.7 and 5.0\,GHz data, which may result from astrophysical uncertainties in the calibration source. This sheds new light on the elusive properties of the
radio-detected QPE sources. Consistent with previous results, our observations disfavor a
star formation or jet-core-region origin of the
radio emission. We cannot rule out a reconnection-driven scenario for the
radio emission, but we favor a remnant jet or
outflow scenario. This is overall in agreement with the
radio properties of
radio-detected QPE sources at lower angular resolution.
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All authors S. D. von Fellenberg, R. Arcodia, P. Benke, A. Goodwin, Y. Y. Kovalev, E. Ros, M. Janssen, M. Giustini, G. Miniutti
High Energy Astrophysical Phenomena
Large Language Model-driven Analysis of General Coordinates Network (GCN) Circulars
Vidushi Sharma, Ronit Agarwala, Judith L. Racusin et al. (+9 more)
The General Coordinates Network (GCN) is NASA's time-domain and multimessenger alert system. GCN distributes two data products: automated "Notices" and human-generated "Circulars" that report the observations of high-energy and multimessenger astronomical transients. The flexible and nonstructured format of GCN Circulars, comprising more than 40,500 Circulars accumulated over three decades, makes it challenging to manually extract observational information, such as
redshift or observed wave bands. In this work, we employ large
language models (LLMs) to facilitate the automated parsing of transient reports. We develop a neural topic modeling pipeline with open-source tools for the automatic clustering and summarization of astrophysical topics in the Circulars archive. Using neural topic modeling and contrastive fine-tuning, we classify Circulars based on their observation wave bands and messengers. Additionally, we separate gravitational-wave event clusters and their electromagnetic counterparts from the Circulars archive. Finally, using the open-source Mistral model, we implement a system to automatically extract gamma-ray burst (GRB)
redshift information from the Circulars archive, without the need for any training. Evaluation against the manually curated Neil Gehrels Swift Observatory GRB table shows that our simple system, with the help of
prompt-tuning, output parsing, and
retrieval augmented generation (RAG), can achieve an accuracy of 97.2% for
redshift-containing Circulars. Our neural search-enhanced RAG pipeline accurately retrieved 96.8% of
redshift Circulars from the manually curated archive. Our study demonstrates the potential of LLMs to automate and enhance astronomical text mining and provides a foundational work for future advances in transient alert analysis.
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All authors Vidushi Sharma, Ronit Agarwala, Judith L. Racusin, Leo P. Singer, Tyler Barna, Eric Burns, Michael W. Coughlin, Dakota Dutko, Courey Elliott, Rahul Gupta, Ashish Mahabal, Nikhil Mukund
High Energy Astrophysical Phenomena · Cross-listed from hep-ph
511 keV Gamma Ray Echo from Particle Decays in Supernovae
Garv Chauhan and Cecilia Lunardini
The formation of a hot and dense core in a core-collapse
supernova (SN) can produce massive Beyond Standard Model (BSM) particles. These particles can decay in the
stellar envelope, generating positrons either directly or through secondary processes involving
neutrinos or
photons. We show for the first time that such positrons regardless of their production channel, can thermalize and annihilate at rest with ambient electrons in the outer SN envelope, producing a characteristic echo of 511 keV gamma rays. For
axion-like particles (ALPs), we derive bounds on the ALP-
photon coupling ($G_{a \gamma}$) using Pioneer Venus Orbiter observations of SN 1987A. We also evaluate the sensitivity of upcoming MeV gap gamma-ray
telescopes in the 511 keV range, such as COSI and AMEGO, for future
Galactic SNe, which can improve existing constraints or enable ALP discovery. The echo signal is a generic prediction for any particle species that efficiently produces positrons near the
stellar surface.
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Astrophysics of Galaxies
Photometric Constraints on Intermediate-mass Black Holes in the Galactic Centre
Tamojeet Roychowdhury, Sebastiano D. von Fellenberg, Joseph M. Michail et al. (+14 more)
JWST/MIRI observations can place photometric limits on the presence of an intermediate-mass black hole (IMBH) near the
Galactic Centre. The
stellar complex IRS 13E, a co-moving conglomerate of young and massive
stars, is a
prime location to study because it has been speculated to be bound by an IMBH. Assuming a standard radiatively inefficient
accretion flow (RIAF) and a minimum fractional variability of 10% of intrinsic luminosity, the wavelength of peak emission in the spectral energy distribution for an IMBH would lie in the mid-infrared ($\sim$ 5-25 $\mu$m), and variability would be detectable in MIRI time-series observations. Monitoring fails to detect such variable emission (other than from Sgr A*) in and around the IRS 13E complex, and upper limits on a putative IMBH's intrinsic variability on timescales of minutes to about 1 hour are $\lesssim$1 mJy at 12 $\mu$m and $\lesssim$2 mJy at 19 $\mu$m. These translate to luminosities $\lesssim 25 \times 10^{32}$ erg/s. The resulting limits on the IMBH mass and
accretion rate rule out any IMBH with mass $\gtrsim 10^3$ M$_\odot$ accreting at $\gtrsim 10^{-6}$ times Eddington rate at the location of IRS 13E. Further, the observations rule out an IMBH anywhere in the central 6" $\times$ 6" region that is more massive than $\approx$ 2 $\times 10^3$ M$_\odot$ and accreting at $\gtrsim 10^{-6}$ of the Eddington rate. Assuming Bondi
accretion scaled to typical RIAF-
accretion efficiencies, albeit somewhat uncertain, also allows us to rule out IMBHs moving with typical velocities of about 200 km/s and masses $\gtrsim 2 \times 10^3$ M$_\odot$. These methods showcase the effectiveness of photometric variability measurements in constraining the presence of accreting black holes in
Galactic centre-like environments.
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All authors Tamojeet Roychowdhury, Sebastiano D. von Fellenberg, Joseph M. Michail, S. P. Willner, Nicole M. Ford, Zach Sumners, Sophia Sanchez-Maes, Tuan Do, Macarena Garcia Marin, Sera Markoff, Giovanni G. Fazio, Daryl Haggard, Joseph L. Hora, Bart Ripperda, Nadeen B. Sabha, Howard A. Smith, Gunther Witzel
Astrophysics of Galaxies
Mid-infrared extinction toward the Galactic center
Sebastiano D. von Fellenberg, Joseph M. Michail, S.P. Willner et al. (+10 more)
We determine the mid-infrared (MIR, $\sim$5~\mu m–22~\mu m) extinction towards the
Galactic center using MIRI/MRS integral field unit (IFU) observations of the central $3''\times3''$ region (near 5~\mu m) to $7''\times7''$ region (near 22~\mu m). To measure the MIR extinction, we employ two approaches: modeling the intrinsic-to-observed
dust thermal spectrum and assessing the differential extinction between hydrogen recombination lines. Expanding on prior work, we directly model the
dust-opacity distribution along the line of sight, and we make available a Python code that provides a flexible tool for deriving intrinsic
dust emission spectra. We confirm the spatial variability of extinction across the field, demonstrating that dusty sources–such as IRS~29N–exhibit higher local extinction. Furthermore, we verify the absence of PAH emission features in the
Galactic center MIR spectra. Using the two complementary methods, we derive a refined “best guess” MIR extinction law for Sgr A* and the surrounding
Galactic-center region. By applying the extinction law to a MIR
flare measurement discussed in a companion paper Michail et al. 2025, we estimate a residual relative extinction uncertainty for the short MIRI/MRS grating on the order of $0.2~\mathrm{mag}$ {from $\sim$5 to $\sim$18~\mu m\ and $\sim$0.3~mag from $\sim$18 to $\sim$22~\mu m}, consistent with our uncertainty estimate.
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All authors Sebastiano D. von Fellenberg, Joseph M. Michail, S.P. Willner, Braden Seefeldt-Gail, Tamojeet Roychowdhury, Macarena Garcia Marin, Giovanni G. Fazio, Nicole M. Ford, Daryl Haggard, Joseph L. Hora, Howard A. Smith, Zach Sumners, Gunther Witzel
High Energy Astrophysical Phenomena · Cross-listed from hep-ph
Low-frequency radio telescopes sensitivity to light dark matter
Ruben Zatini, Francesca Calore and Pasquale Dario Serpico
Ground-based
radio telescopes are routinely used to search for light dark matter (DM) candidates such as
axion-like particles or dark
photons. These instruments face however inherent limitations to push the searches to masses below $10^{-7}$ eV, due to the effect of the Earth's ionosphere. The extant and planned space- or Moon-based
radio telescopes motivate this study: We systematically investigate their sensitivity to resonant conversion of light DM into
radio signals from three
solar system targets: the Sun, the Earth, and Jupiter. The perspectives are especially encouraging for dark
photon searches using the Sun as a target, and for
axion-like particles conversion in Jupiter's magnetosphere.
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Astrophysics of Galaxies
J-HERTz: J-PLUS Heritage Exploration of Radio Targets at z $<$ 5
D. Fernández Gil, J. A. Fernández-Ontiveros, C. López-Sanjuan et al. (+17 more)
We introduce J-HERTz (J-PLUS Heritage Exploration of
Radio Targets at $z < 5$), a new multi-wavelength catalog that combines optical narrow-band photometry from J-PLUS, infrared observations from WISE, and deep low-frequency
radio data from LoTSS for nearly half a million sources across 2,100 deg$^2$ of the northern sky. Key innovations of J-HERTz include
Bayesian neural network classifications for 390,000
galaxies, 31,000
quasars, and 20,000
stars, along with significantly improved photometric
redshifts for 235,000
galaxies compared to previous J-PLUS DR3 and LoTSS DR2 estimates. We identify 831 candidate
Galactic radio stars, which, if confirmed, would constitute a significant addition to the number of
radio-emitting
stars identified to date. Among
radio-loud
galaxies with spectroscopic observations, $\gtrsim$20% lack Seyfert or LINER signatures, indicating a substantial population of optically quiescent
radio galaxies, in agreement with previous works. Spectral energy distribution fitting of their host
galaxies using J-PLUS photospectra reveals systematically low specific
star formation rates, consistent with quenched
stellar populations. J-HERTz thus provides a powerful
dataset to exploit
radio-optical synergies, enabling studies that span from the origin of
stellar radio emission to the AGN life cycle and the role of jet activity in shaping host
galaxy evolution.
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All authors D. Fernández Gil, J. A. Fernández-Ontiveros, C. López-Sanjuan, F. Arizo-Borillo, A. del Pino, A. Hernán-Caballero, A. Lumbreras-Calle, P. T. Rahna, David Sobral, H. Vázquez Ramió, A. J. Cenarro, A. Marín-Franch, R. E. Angulo, A. Ederoclite, D. Cristóbal-Hornillos, R. A. Dupke, C. Hernández-Monteagudo, M. Moles, L. Sodré Jr, J. Varela
Astrophysics of Galaxies
Probing the influence of the protocluster environment on galaxy morphology at z = 2.23
Emmet Golden-Marx, Zheng Cai, Dongdong Shi et al. (+7 more)
As
galaxies evolve in dense cluster and protocluster environments, they interact and quench their
star formation, which gradually transforms the
galaxy population from
star-forming
galaxies to quiescent
galaxies. This transformation is identifiable by observing
galaxy colors and can be seen in the morphological transformation of late-type
galaxies into early-type
galaxies, which creates the morphology-density relation seen when comparing populations in clusters to co-eval field
galaxies. However, high-z (z > 2)
galaxy morphology studies are hindered by the high angular resolution necessary to characterize morphology. We present a study of HST WFC3 F160W observations of protoclusters from the MAMMOTH survey (BOSS1244 and BOSS1542) at z ~ 2.23 with populations of previously identified HAEs. By measuring the Sersic index of 151 HAEs, we look for the early morphological transformation of
star-forming
galaxies in these well-studied, large, non-virialized protoclusters, which we believe are precursors of present-day clusters. We find the morphology of the populations of
star-forming protocluster
galaxies does not differ from the co-eval field. However, we identify a population of clumpy, potentially merging
galaxies, which could lead to an increase in the population of early-type
galaxies in these structures. Additionally, in BOSS1244, which has two previously identified massive quiescent
galaxies including a BCG, we find an abundance of early-type
galaxies near both the BCG and two co-eval high-z
quasars. Although we find a strong similarity between the morphology of field and protocluster
galaxies, the population of early-type
star-forming
galaxies surrounding the spectroscopically confirmed quiescent BCG in BOSS1244, something not seen in BOSS1542, may point to differences in the evolutionary state of these co-eval protoclusters and be a sign of an early forming cluster core in BOSS1244.
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All authors Emmet Golden-Marx, Zheng Cai, Dongdong Shi, Xin Wang, Brian C. Lemaux, Benedetta Vulcani, Boris Haussler, Pablo Renard, Lu Shen, Finn Giddings
Astrophysics of Galaxies
Variability-selected AGN in dwarf galaxies: the incidence of AGN in dwarf and massive galaxies is similar
S. Kaviraj, D. De Cicco, I. Lazar et al. (+4 more)
We use the VST-COSMOS survey to identify, via their optical broadband variability, 30 AGN in nearby (z<0.4)
dwarf (10^8 MSun < M < 10^10 MSun)
galaxies. VST-COSMOS offers a 1 deg^2 survey footprint, a single visit depth of 24.6 mag and 68 r-band visits spanning an eleven-year temporal baseline. Compared to a control sample matched in
stellar mass and
redshift, the
dwarf AGN population shows an elevated fraction of early-type
galaxies but a similar fraction of interacting objects, suggesting that interactions do not play a significant role in triggering these AGN.
Dwarf AGN hosts do not show strong differences in their distances to nodes, filaments and massive
galaxies compared to the controls, which indicates that AGN triggering, at least in this sample, is not strongly correlated with environment. Finally, by combining the true number of
galaxies, the detectability of AGN and the measured numbers of variable sources in
dwarf and massive (M > 10^10 MSun)
galaxies, we estimate the relative frequency of AGN in these two mass regimes. Our results suggest that the incidence of AGN in
dwarfs and massive
galaxies is similar (within less than a factor of 2 of each other), with some evidence that the AGN fraction increases with
stellar mass in the
dwarf population.
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All authors S. Kaviraj, D. De Cicco, I. Lazar, B. Bichang'a, A. E. Watkins, G. Martin, S. Koudmani
High Energy Astrophysical Phenomena · Cross-listed from gr-qc
The Physics of Black Holes and Their Environments: Consequences for Gravitational Wave Science
Vitor Cardoso, Shauvik Biswas and Subhodeep Sarkar
Ten short years ago, we had the rare privilege of witnessing the onset of a renaissance in science: humanity finally succeeded in its arduous quest to directly detect gravitational waves. This breakthrough did not occur in a
vacuum: it was the natural culmination of decades of research dedicated towards understanding the nature of gravitation based on Einstein's General Theory of Relativity. It is a story of false starts, perseverance, and remarkable insights, propelled as much by technological progress as by human curiosity. We now proudly live in the new golden age of gravitational physics. The detection of gravitational wave signals from the merger of binary black holes and
neutron stars are becoming routine. Coupled with our theoretical understanding of phenomena in the strong
gravity regime, black hole physics has become a precision science. The purpose of these lecture notes is to help the reader understand the
language and framework of this rapidly evolving subject, and to develop the ability to interpret, think, and discuss ideas that lie at the confluence of gravitational wave astronomy and black hole physics. It is our hope that these notes will prepare students and colleagues for the next revolution when gravitational wave events become commonplace and we begin to observe unexpected features in the signal, indicating either surprising astrophysical scenarios or a strong need to modify the theoretical description of gravitational interactions. We provide first principles analysis of black hole and gravitational wave physics, and sometimes a very personal interpretation of results. We share with the readers a number of notebooks that will allow them to reproduce some of the most important results in the field, and could even help in carrying out state-of-the-art research. We also include a few original results that we think are helpful in understanding the broader picture.
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Earth and Planetary Astrophysics
Stellar Obliquities of Young Systems, Atmospheres Undergoing Contraction and Escape (SOYSAUCE): a likely aligned orbit for the 3 Myr planet TIDYE-1 b
Madyson G. Barber, Andrew W. Mann, Marshall C. Johnson et al. (+12 more)
Despite the wide range of
planet-
star (mis)
alignments in the mature population of transiting
exoplanets, the small number of known young transiting
planets are nearly all aligned with the rotation axes of their host
stars, as determined by the sky-projected obliquity angle. The small number of young systems with measured obliquities limits statistical conclusions. Here we determine the sky-projected obliquity ($\lambda$) of the 3 Myr transiting
planet with a misaligned outer protoplanetary disk, TIDYE-1 b (IRAS 04125+2902 b), using the Rossiter-McLaughlin (RM) effect. Our
dataset lacks a pre-transit baseline and ingress, complicating a blind RM fit. Instead, we use contemporaneous spectra and photometry from a mass-measurement campaign to model the
stellar activity trend across the transit and provide an external prior on the velocity baseline. We determine $|\lambda|=11.8^{+5.9\,\circ}_{-5.0}$. Combined with the published rotational velocity of the
star, we find a true three-dimensional obliquity of $\psi=15.2^{+7.3\,\circ}_{-5.7}$. Our result is consistent with an aligned orbit, suggesting the
planet remains aligned to its
star even though the outer disk is misaligned, though additional RM observations are needed to exclude the low-probability tail of misaligned ($>30^{\circ}$) scenarios present in our posterior.
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All authors Madyson G. Barber, Andrew W. Mann, Marshall C. Johnson, Mayuko Mori, John Livingston, Daniel M. Krolikowski, Norio Narita, Akihiko Fukui, Teruyuki Hirano, Andrew Vanderburg, Adam L. Kraus, Benjamin M. Tofflemire, Sydney Vach, Sarah Blunt, Lissa Haskell
High Energy Astrophysical Phenomena
First Mid-infrared Detection and Modeling of a Flare from Sgr A*. II. Mid-IR Spectral Energy Distribution and Millimeter Polarimetry
Joseph M. Michail, Sebastiano D. von Fellenberg, Garrett K. Keating et al. (+20 more)
S. D. von Fellenberg et al. (2025a, Paper I) reported the first mid-infrared detection of a
flare from Sgr A*. The JWST/MIRI/MRS observations were consistent with an orbiting hotspot undergoing electron injection with a spectrum that subsequently breaks from synchrotron cooling. However, mid-infrared extinction measurements appropriate for these data were not yet determined, and therefore the temporal
evolution of the absolute spectral index remained unknown. This work applies new
Galactic Center extinction measurements to the
flare observations. The
evolution of the spectral index after the peak is fully consistent with that reported in Paper I with a maximum absolute mid-infrared spectral index $\alpha_{\rm{MIR}}=0.45\pm0.01_{\rm{stat}}\pm0.08_{\rm{sys}}$ during the second mid-infrared
flare peak, matching the known near-infrared spectral index during bright states ($\alpha_{\rm{NIR}}\approx0.5$). There was a near-instantaneous change in the mid-infrared spectral index of $\Delta\alpha_{\rm{MIR}}=0.33\pm0.06_{\rm{stat}}\pm0.11_{\rm{sys}}$ at the
flare onset. We propose this as a quantitative definition for this infrared
flare's beginning, physically interpreted as the underlying electron distribution's transition into a hard power-law distribution. This paper also reports the SMA millimeter polarization during the
flare, which shows a small, distorted, but overall clockwise-oriented Stokes Q–U loop during the third mid-infrared peak. Extrapolating the mid-infrared flux power law to the millimeter yields a variable flux consistent with the observed 220 GHz emission. These results, together with the Paper I modeling, plausibly suggest a single hotspot produced both the mid-infrared and millimeter variability during this event. However, additional
flares are required to make a general statement about the millimeter and mid-infrared connection.
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All authors Joseph M. Michail, Sebastiano D. von Fellenberg, Garrett K. Keating, Ramprasad Rao, Tamojeet Roychowdhury, S. P. Willner, Nicole M. Ford, Daryl Haggard, Sera Markoff, Alexander Philippov, Bart Ripperda, Sophia Sánchez-Maes, Zach Sumners, Gunther Witzel, Mayura Balakrishnan, Sunil Chandra, Kazuhiro Hada, Macarena Garcia Marin, Mark A. Gurwell, Giovanni G. Fazio, Joseph L. Hora, Braden Seefeldt-Gail, Howard A. Smith