Astrophysics of Galaxies
The SPHINX public data release. II. Using low-ionisation absorption lines and dust attenuation to predict Lyman continuum escape
Valentin Mauerhofer, Jérémy Blaizot, Thibault Garel et al. (+11 more)
Low-ionisation state (LIS) absorption lines, such as SiII 1526, are widely used to trace the properties of the interstellar medium (ISM) in
galaxies. These lines provide crucial insights into
galaxy evolution, including feedback mechanisms, metal enrichment, and the escape fraction of ionising
photons ($f_{\rm{esc}}$). We expand our understanding of LIS absorption lines as diagnostic tools for ISM properties and $f_{\rm{esc}}$. Using the SPHINX20 cosmological radiation-hydrodynamics simulation, we generated a comprehensive synthetic
dataset of LIS absorption lines and tested their predictive power for $f_{\rm{esc}}$ in
star-forming
galaxies. Synthetic SiII 1260 and SiII 1526 lines were computed with the radiative transfer code RASCAS, incorporating resonant scattering of
photons, fluorescent emission, and interactions with
dust grains. The simulated data enhance the public SPHINX20
dataset with high-resolution LIS lines for the full 1380
galaxies and ten viewing angles per
galaxy. We analysed correlations between line properties,
dust attenuation, and $f_{\rm{esc}}$. We also tested our predictions on observed data using the LzLCS and CLASSY surveys. We found a strong correlation between the
dust-corrected residual flux of SiII 1526, $\tilde{R} \equiv \rm{R_{flux}^{1526}} \cdot 10^{-0.4A_{1500}}$, and $f_{\rm{esc}}$. We found $f_{\rm{esc}} \approx 1.041\tilde{R}^{1.887} - 0.002$, with small error bars. When we applied observational conditions, the error increased, but the escape fraction was still well recovered. We show by applying common tools for fitting the spectral energy distribution to our mock data that the inferred
dust attenuation is often far from the correct value, with an underestimation of the attenuation when the effect of
dust is strongest. Our results demonstrate that the residual flux of SiII 1526 is a powerful predictor of the escape fraction of ionising
photons.
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All authors Valentin Mauerhofer, Jérémy Blaizot, Thibault Garel, Anne Verhamme, Simon Gazagnes, Josephine Kerutt, Leo Michel-Dansac, Kaelee S. Parker, Joakim Rosdahl, Alberto Saldana-Lopez, Maxime Trebitsch, Taysun Kimm, Pierre Ocvirk, Romain Teyssier
Solar and Stellar Astrophysics
The Physics of Mass Transfer in Substellar and Low-Mass Binaries
Samuel Whitebook, Jim Fuller, Kevin Burdge et al. (+3 more)
Several dozen binary ultracool and brown
dwarf systems have been identified to date. These systems represent valuable probes of
star and
planet formation at the lowest mass scales. To date, the study of these ultracool binaries has been constrained to the non-interacting case. In this paper, we investigate the dynamics, stability, and
evolution of mass transferring ultracool binaries using numerical simulations with accepted equations of state for brown
dwarfs. We find that there exists a donor mass inversion, above which the donor
dwarf is more massive than the accretor, but below which the accretor is more massive than the donor. Below the hydrogen burning limit, objects with mass ratios $q \sim 1$ are unstable, but slight deviations from this mass ratio are stable at the onset of mass transfer and remain stable throughout extended periods. We compute theoretical mass transfer rates using several angular momentum loss prescriptions and predict lifespans of $\sim 100$ Myrs. We predict that all mass transferring ultracool binaries are tidally locked and possess orbital periods ranging from just under $1$ hour to $3.5$ hours. We find that mass transfer proceeds via direct impact onto the accretor forming a UV or optically bright hotspot on the surface of the accretor.
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All authors Samuel Whitebook, Jim Fuller, Kevin Burdge, Thomas R. Marsh, Dimitri Mawet, Thomas Prince
Solar and Stellar Astrophysics
Stars stably accreting from substellar objects
Aaron Householder, Kaitlyn Shin, Kevin B. Burdge et al. (+11 more)
Substellar objects such as brown
dwarfs and
planets are generally expected to remain detached from their main-sequence host
stars unless orbital decay or
stellar expansion brings them into contact, leading to rapid engulfment and destruction. Such a fate is predicted for the Earth and other rocky
planets in our
solar system; however, in certain cases, theory also allows for stable long-lived mass transfer from a substellar object onto its main-sequence host, though such
accretion has never been directly observed. Here we report the first direct observations of stable mass transfer from a substellar object onto a main-sequence
star. In particular, we identify two binaries, ZTF J0440+2325 and ZTF J1444+4820, with orbital periods of just 87 and 67 minutes, respectively, in which a brown
dwarf stably transfers mass onto an M
dwarf companion. These systems demonstrate that the fate of some substellar objects is not rapid engulfment and destruction, but instead gradual consumption for potentially billions of years.
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All authors Aaron Householder, Kaitlyn Shin, Kevin B. Burdge, Thomas R. Marsh, Saul A. Rappaport, Kareem El-Badry, Joheen Chakraborty, Emma Chickles, Fei Dai, Matthew J. Graham, S.R. Kulkarni, Pablo Rodríguez-Gil, Andrew Vanderburg, Samuel Whitebook
Solar and Stellar Astrophysics
A Mass Transferring Brown Dwarf Binary on a 57 Minute Orbit
Samuel Whitebook, Antonio C. Rodriguez, Kevin Burdge et al. (+9 more)
Mass transfer in
stellar binaries has been well studied in most
stellar mass ranges, with the notable exception of ultracool
stars and substellar brown
dwarfs. We report the discovery of ZTF J1239+8347 with the Zwicky Transient Facility (ZTF), a brown
dwarf binary currently undergoing stable mass transfer with an orbital period of 57.41 minutes. Optical time-series photometry reveals an extremely high amplitude ($> 2$ magnitude peak-to-trough) variability at short wavelengths indicative of an orbiting hot spot slightly buried inside the atmosphere of the accretor. We use parallax measurements from
Gaia along with optical and near infrared spectra to infer an
accretion temperature of $T_\mathrm{eff} = 8904 \pm 54$ K, an atmospheric temperature of the accretor of $T_\mathrm{atmo} \approx 1500$ K, and a slightly inflated accretor radius of $R_{\rm acc} = 1.20^{+0.15}_{-0.11} \, \RJup$. ZTF J1239+8347 is a direct impact accretor, typically only seen in double degenerate white
dwarf binaries, which are approximately a million times denser than the components in ZTF J1239+8347. The existence of an accreting brown
dwarf binary suggests that angular momentum loss can be strong enough to make ultracool binaries interact in a Hubble time. The observed faintness ($\sim 20$ mag) and relative proximity ($\approx 300$ pc) of ZTF J1239+8347 suggests that many similar systems are likely to be found by the upcoming Rubin Observatory Legacy Survey of Space and Time (LSST).
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All authors Samuel Whitebook, Antonio C. Rodriguez, Kevin Burdge, Thomas Prince, Dimitri Mawet, Sam Rose, Pablo Rodríguez-Gil, Anica Ancheta, Ariana Pearson, Sage Santomenna, Aaron Householder, Jerry W. Xuan
High Energy Astrophysical Phenomena
Optical outburst evolution of the transient black hole X-ray binary Swift J1727.8-1613: Disc response to jet ejections and late-outburst emergence of powerful disc winds
N. Castro Segura, K. Solomons, J. M. Corral-Santana et al. (+22 more)
Swift J1727.8$-$1613 is a newly discovered transient low-mass X-ray binary harbouring a
stellar-mass ($\sim 10M_\odot$) black hole. We present state-resolved VLT/X-Shooter optical spectroscopy of its 2023 outburst, sampling the luminous hard-to-soft and late soft-to-hard transitions. During the onset of the brightest
radio flare, He\,ii flux rises relative to adjacent epochs, with reduced peak-to-peak separation and full-width-half-maximum, consistent with enhanced irradiation shifting line emissivity to larger radii. We detect no contemporaneous change in the line base tracing the inner disc. The most dramatic change occurs at the onset of the dim-hard state, when strong, broad (higher-order) Balmer lines appear in absorption, and He\,ii remains in emission, but becomes highly asymmetric. While the hardening of the X-ray spectrum likely promotes the reappearance of an underlying disc photosphere, the kinematic
alignment between the Balmer absorption ($v_w\sim-750\,\mathrm{km\,s^{-1}}$) and the suppressed blue peak of He\,ii suggests a unified origin in a massive, cool ($T\lesssim10^{4}\,\mathrm{K}$)
accretion disc wind. Radiative transfer simulations demonstrate that such asymmetric He\,ii profiles are naturally produced in a rotating and accelerating
outflow. Using the Sobolev approximation, we estimate the wind mass-loss rate to be $\dot{M}_w\gtrsim10^{-9}\,M_\odot\,\mathrm{yr^{-1}}$, comparable to the instantaneous
accretion rate and a significant fraction of the secular mass-transfer rate from the donor. If persistent at quiescent-level X-ray luminosities, this
outflow could strongly impact the system's secular
evolution.
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All authors N. Castro Segura, K. Solomons, J. M. Corral-Santana, C. Knigge, P. A. Charles, M. Brigitte, S. Fijma, M. Diaz-Trigo, A. Gúrpide, D. A. H. Buckley, F. Carotenuto, A. J. Castro-Tirado, D. L. Coppejans, M. Georganti, A. Hughes, K. S. Long, J. Matthews, I. Monageng, I. Pelisoli, T. D. Russell, D. Steeghs, J. Svoboda, A. J. Tetarenko, F. M. Vincentelli, A. G. W. Wallis
High Energy Astrophysical Phenomena
Ultrahigh-Energy Gamma-Ray Sources Need Not Be Hadronic PeVatrons
Zachary Curtis-Ginsberg, Dan Hooper and Justin Vandenbroucke
Ultrahigh-energy gamma rays ($E_{\gamma}>100 \, {\rm TeV}$) have been detected from a handful of astrophysical sources. Due to the Klein-Nishina suppression of inverse Compton scattering at such high energies, it has sometimes been argued that these sources must be accelerators of PeV-scale
protons, making them the long-sought-after
Galactic ”PeVatrons.” Here, we challenge this conclusion, demonstrating that these sources can be straightforwardly explained by simple leptonic models. In this context, we consider the microquasar SS 433, the
Galactic Center, and TeV
halos, showing in each case that the observation of PeV-scale gamma rays from these sources does not indicate that they are accelerators of hadronic
cosmic rays. We also note that the measured angular extension of SS 433 is in good agreement with the predictions of our model, favoring a leptonic origin for the gamma-ray emission from this source. A definitive identification of a PeVatron would require additional information, such as the combined observation of the pion bump and synchrotron peak, the spatial correlation of gamma-ray emission with gas, or the detection of
neutrinos with $E_{\nu} \gtrsim 100 \, {\rm TeV}$.
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Solar and Stellar Astrophysics
Confirming Nunki as the closest core collapse progenitor candidate to the Sun
Idel Waisberg and Boaz Katz
We have recently suggested that Nunki=Sigma Sagittarii is the closest core collapse progenitor candidate to the Sun based on a VLTI/
GRAVITY observation that unveiled it as a $6.5+6.3 M_{\odot}$ binary at a projected separation of 0.60 au. Here we combine this observation with three VLTI/PIONIER archival and one previous MAPPIT observation to solve for the orbit of Nunki, finding $a=1.26\pm0.05 \text{ au}$ ($P=134.779\pm0.025 \text{ days}$) and thereby confirming it as a close binary. The low orbital inclination $i=19.7\pm1.9^{\circ}$ coupled with the high projected rotational velocity $v \sin i \simeq 160 \text{ km}\text{ s}^{-1}$ and the absence of a decretion disk are a strong hint for
spin-orbit misalignment. The significant eccentricity $e=0.492\pm0.003$ will cause the system to undergo eccentric Roche lobe overflow once the primary expands to $R\simeq50 R_{\odot}$, so that a merger into a $M \gtrsim 10 M_{\odot}$
star is a possible outcome. Therefore, we conclude that Nunki at a distance $d \approx 69 \text{ pc}$ can indeed be considered the closest core collapse progenitor candidate to the Sun as it is closer than Spica and Bellatrix both at $d \approx 77 \text{ pc}$. Furthermore, we also report on a VLTI/
GRAVITY observation of Bellatrix that shows that it does not have any close companion with a K band flux ratio higher than 1%; in particular, it is not a close equal mass binary as previously suspected. Two archival spectra of Nunki illustrate how equal-mass binaries with rapidly rotating components can easily hide to become virtually spectroscopically undetectable when the radial velocity separation is several times smaller than the individual line widths.
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High Energy Astrophysical Phenomena
Search For a Counterpart to the Subsolar Mass Gravitational Wave Candidate S251112cm
Nicholas Vieira, Noah Franz, Bhagya Subrayan et al. (+49 more)
The recent candidate gravitational-wave (GW) alert from a compact object merger involving at least one subsolar mass (SSM) object has prompted questions about their origins. S251112cm is reported by LIGO/Virgo with a false alarm rate of 1 per 6.2 years, nearby luminosity distance $93 \pm 27$ Mpc, and probability of containing a SSM object of 100%. Such a system, if astrophysical, likely did not involve the supersolar
neutron stars or black holes invoked to explain kilonovae. One must then also invoke hitherto unobserved and speculative models to produce SSM mergers which may have electromagnetic (EM) counterparts. We introduce a framework which vets and scores candidate counterparts to SSM GW events to inform follow-up in search of any among the zoo of potential EM transients: kilonovae, kilonovae-within-
supernovae, super-kilonovae, or AGN
flares from binary black hole mergers. We use a suite of
telescopes to perform tiling,
galaxy-targeted observations, and photometric/spectroscopic follow-up of promising candidates. In near-real time, we ingest candidates reported by the community, including some of the first observations reported by the Vera C. Rubin Observatory. We vet and score a total of 456 candidates, including 67 from Rubin, but find no likely counterpart. We nonetheless highlight candidates which demonstrate the ability of our framework to distinguish between different transient types and describe strategies to maximize the chances of detecting a counterpart to the next SSM event. Our framework will be implemented in the forthcoming Multimessenger Tool for Rapid Object Vetting and Examination (TROVE).
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All authors Nicholas Vieira, Noah Franz, Bhagya Subrayan, Charles D. Kilpatrick, David J. Sand, Wen-fai Fong, Griffin Hosseinzadeh, Kate D. Alexander, K. Azalee Bostroem, Jillian Rastinejad, Kerry Paterson, Manisha Shrestha, Phillip Noel, P. Darc, Jeniveve Pearson, Aysha Aamer, A. Souza Santos, Luidhy Santana-Silva, Clecio R. Bom, Regis Cartier, Hemanth Bommireddy, Ósmar Rodríguez, Jennifer E. Andrews, Conor Ransome, Vasileios Paschalidis, Jay Strader, Aldana Grichener, J. Quirola-Vásquez, Sergiy Vasylyev, Marcelle Soares-Santos, Collin T. Christy, Brian Hsu, D. Carson Fuls, Yize Dong, Daniel E. Reichart, Jonathan Pineda-García, Kathryne J. Daniel, Daryl Janzen, C. E. Fields, Ann Zabludoff, Nicolas Meza, Felipe Olivares E., Kristine Spekkens, Benjamin Weiner, Maia Williams, Alex R. Gibbs, Frank Shelly, Aravind P. Ravi, Saurabh W. Jha, Stefano Valenti, Joshua Haislip, David E. Trilling
Cosmology and Nongalactic Astrophysics
What Shape is the Inflationary Bispectrum?
Oliver H. E. Philcox
Non-linear interactions during inflation generate non-Gaussianities in the distribution of
primordial curvature. In many theories, the physics is scale-invariant, such that the induced three-point function depends solely on a dimensionless shape function $S(x,y)\sim k^6B_\zeta(kx,ky,k)$. To confront such models with observations, one typically builds specialized
estimators for each shape, then applies them to
cosmic microwave background
datasets at significant computational expense. In this Letter, we take a different approach, directly reconstructing $S(x,y)$ from observations using an efficient logarithmically-binned
estimator in
primordial-space (motivated by the modal program). Applying this to temperature and polarization maps from Planck, we obtain high-resolution shape measurements across the full $(x,y)$-plane, including squeezed limits. Our approach is close-to-optimal, highly interpretable, and preserves the information content on (optimally-analyzed) standard templates within $\approx 10\%$; moreover, we can use it to assess the scale-dependence of our constraints, finding that Planck is sensitive to $\approx 6$ $e$-folds of non-Gaussian
evolution with a peak sensitivity around $0.1h\,\mathrm{Mpc}^{-1}$. Since we work directly in shape-space, data and theory can be compared in milliseconds. As an example, we perform a search for massive particle exchange using a suite of over $20\,000$ theoretical templates computed with exact bootstrap methods across a wide range of masses,
spins, and sound-speeds; the
spin-two analysis yields a maximum significance of $2.6\sigma$. Our approach can be used to probe a wide range of scale-invariant models in orders-of-magnitude less time than with direct
estimators, facilitating new exploration of the inflationary paradigm.
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Solar and Stellar Astrophysics
Anti-Solar Differential Rotation May Have Revived Magnetic Braking in the Subgiant 31 Aquilae
Travis S. Metcalfe, Jennifer L. van Saders, Thomas R. Ayres et al. (+16 more)
Recent observations have shown that sufficiently slow rotation disrupts the organization of large-scale
magnetic field in older main-sequence
stars, leading to weakened
magnetic braking (WMB) and a collapse in the efficiency of the global
stellar dynamo. Recent simulations predict a shift from
solar-like to anti-
solar differential rotation (DR) at slower rotation rates, which typically do not occur on the main-sequence due to WMB. However, physical expansion on the subgiant branch can eventually slow the
stellar rotation beyond this threshold, yielding a non-cycling large-scale field that revives
magnetic braking. We combine asteroseismology from the Transiting
Exoplanet Survey Satellite (TESS) with spectropolarimetry from the Large Binocular
Telescope (LBT) to test these predictions in the old metal-rich subgiant 31 Aql. The LBT observations reveal a strong large-scale
magnetic field in this
star, and archival measurements of its chromospheric emission over 50 years confirm that it is non-cycling, as predicted. The
star exhibits a variety of rotation periods during different observing seasons, consistent with DR but with no means of distinguishing between
solar-like and anti-
solar patterns. We incorporate the TESS observations to estimate the current wind braking torque of 31 Aql, demonstrating that it supports revived
magnetic braking in this old subgiant. We also use rotational
evolution modeling to place a preliminary constraint on the
stellar Rossby number for the transition to anti-
solar DR. Future refinements in both asteroseismic observations and rotational modeling may yield improvements to this initial analysis.
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All authors Travis S. Metcalfe, Jennifer L. van Saders, Thomas R. Ayres, Derek Buzasi, Jeremy J. Drake, Ricky Egeland, Rafael A. Garcia, Oleg Kochukhov, Steven H. Saar, Keivan G. Stassun, Sarbani Basu, J. M. Joel Ong, Amalie Stokholm, Timothy R. Bedding, Sylvain N. Breton, Ilya V. Ilyin, Pascal Petit, Marc H. Pinsonneault, Klaus G. Strassmeier
High Energy Astrophysical Phenomena · Cross-listed from hep-ph
Is the Turner Window Open? Seeking Closure with Resonant Absorption of Galactic Axions in NaI Dark Matter Detectors
W. C. Haxton, Xing Liu, Anupam Ray et al. (+1 more)
Motivated by the DAMA/LIBRA annual modulation signal, the dark matter community has invested heavily in ultra-clean underground NaI detectors to search for light WIMPs. We point out a new target of opportunity for these detectors –
axions produced by the carbon-burning
stars within our
galaxy. These
stars synthesize large quantities of $^{23}$Na, keeping it at temperatures $\sim 10^9$K for periods up to tens of thousands of years. Under these conditions, $^{23}$Na radiates 440 keV
axions through repeated photo-excitation and axio-deexcitation of its first excited state. Upon reaching a NaI detector, the process is reversed: the
axion is resonantly absorbed, producing a 440 keV deexcitation
photon. NaI thus serves as both $\gamma$ source and $\gamma$ detector. We find that existing NaI detectors can probe
axion-nucleon couplings $|g_{aNN}^\mathrm{eff~^{23}Na}| \approx g_{app} \sim 10^{-6}$–$10^{-2}$, including QCD
axions with $m_a \gtrsim 10$ eV. While there are several astrophysical constraints on
axions with these couplings, our re-examination of these bounds shows that substantial gaps remain, providing strong motivation for the proposed searches.
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All authors W. C. Haxton, Xing Liu, Anupam Ray, Evan Rule
High Energy Astrophysical Phenomena · Cross-listed from gr-qc
The imitation game (r)evolutions: $Q$-star effective shadow from GRMHD analysis
Víctor Jaramillo, Laura Meneses, Héctor R. Olivares Sánchez et al. (+3 more)
$Q$-
stars are a class of
boson stars arising in scalar-field theories with interacting potentials, minimally coupled to
gravity. We show that, in certain regions of parameter space, the angular velocity of stable timelike circular geodesics around $Q$-
stars can attain a maximum at a nonzero radius. Notably, this behaviour may occur for stable configurations. This feature has been argued to produce effective shadows, but so far it has only been investigated for unstable solutions. We test this possibility by performing general relativistic magnetohydrodynamic evolutions for a representative stable $Q$-
star model. A low-density, low-luminosity central region is indeed observed to form and persist – at least until the
evolution becomes affected by numerical viscosity. As a proof of principle, this suggests that families of stable bosonic
stars can act as black hole mimickers. Moreover, for the model at hand, a heuristic analysis shows that the effective shadow has a comparable size to that of a Schwarzschild black hole with the same mass. Importantly, this mechanism for generating an effective shadow does not rely on the object being ultracompact, or an ad hoc chosen
accretion disk.
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All authors Víctor Jaramillo, Laura Meneses, Héctor R. Olivares Sánchez, Carlos Herdeiro, Darío Núñez, Shuang-Yong Zhou
Astrophysics of Galaxies
Ram-pressure-induced star formation in low-mass galaxies infalling on-to the Coma cluster: insights from DESI
Kirill A. Grishin, Igor V. Chilingarian, Gary A. Mamon et al. (+2 more)
Ram-pressure stripping is a key driver of
galaxy morphological transformation in clusters, contributing to the formation of quenched, especially
dwarf, populations. Ram-pressure compression can also induce a starburst prior to quenching and build up significant
stellar mass in an initially gas-rich
galaxy. The detailed physics of these processes remains poorly understood, especially in the low-mass regime. Here we demonstrate that the key factor for a ram-pressure induced starburst in a low-mass
galaxy is its angular momentum within a host cluster. In this study, we select a sample of 41 post-starburst
galaxies (PSGs) in the Coma cluster using the DESI EDR spectroscopic data, extending to low luminosities ($M_g < -14$). This sample is at least 90% complete down to $M_g \approx -14.8$, which enabled us a systematic analysis of their properties. For each
galaxy, we use projected cluster-centric distances and line-of-sight velocities to constrain the normalized orbital angular momentum and a 3D radial coordinate to the cluster center, assuming zero orbital energy. The resulting probability distributions show that while
star-forming
galaxies are split into two populations favoring intermediate and high angular momentum, almost all PSGs prefer high angular momentum. Our analysis statistically demonstrates that ram-pressure-induced starbursts are more efficient on tangential orbits, where gas stripping proceeds slowly enough to allow substantial
star formation before gas removal.
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All authors Kirill A. Grishin, Igor V. Chilingarian, Gary A. Mamon, Andrea Biviano, Aleksandra Sharonova
Astrophysics of Galaxies
MIGHTEE-HI: Mass Models and Dark Matter properties
Anastasia A. Ponomareva, P. E. Mancera Piña, A. A. Vărăşteanu et al. (+17 more)
Measuring
galaxy rotation curves is critical for inferring the properties of dark-matter
haloes in the Lambda Cold Dark Matter ($\Lambda$CDM) paradigm. We present HI rotation curves and mass models for 20
galaxies from the MIGHTEE survey. Using extended HI kinematics, we construct resolved mass models that include
stellar, gaseous, and dark-matter components.
Stellar masses are derived using 3.6 $\mu$m imaging under fixed mass-to-light ratio ($\Upsilon_{*} = M/L$) assumptions and are complemented, for the first time for a HI-selected sample, by spatially resolved $M/L$, obtained from multi-wavelength SED fitting. We examine the ratio of baryonic to observed rotation velocity ($V_{\rm bar}/V_{\rm obs}$) at the characteristic radius $R_{2.2}$. Adopting a fixed $\Upsilon_\star = 0.5\,M_\odot/L_\odot$ yields a clear dependence of $V_{2.2}/V_{\rm obs}$ on
galaxy luminosity, while adopting $\Upsilon_\star = 0.2\,M_\odot/L_\odot$ substantially weakens this trend. In contrast, the resolved $M/L$ analysis preserves the luminosity dependence while modifying the
stellar contribution on a
galaxy-by-
galaxy basis, providing a more accurate representation of the underlying relation. We model the dark-matter
haloes using Navarro-Frenk-White profiles and find that the different assumptions for a fixed a $M/L$ systematically shift
galaxies relative to the theoretical
stellar-to-
halo mass and baryonic-to-
halo mass relations, while the spatially varying $M/L$ yields the closest agreement with theoretical
benchmarks within $\Lambda$CDM. We therefore demonstrate that future investigations of the dark matter properties of
galaxies using rotation curves need to account for varying $M/L$ across individual
galaxy profiles and between
galaxies in order to obtain accurate measurements of the dark matter, and therefore test $\Lambda$CDM.
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All authors Anastasia A. Ponomareva, P. E. Mancera Piña, A. A. Vărăşteanu, M. Glowacki, H. Desmond, M. J. Jarvis, T. Yasin, I. Heywood, N. Maddox, E. A. K. Adams, M. Baes, A. Gebek, S. Kurapati, M. Maksymowicz-Maciata, K. A. Oman, H. Pan, I. Prandoni, S. H. A. Rajohnson, I. Ruffa, K. Spekkens
Astrophysics of Galaxies
The birth of the intracluster medium: the evolution of multiphase gas and Lyman-$\alpha$ haloes in a simulated $z\sim3$ protocluster
Jake S. Bennett, Aaron Smith, Fabrizio Arrigoni-Battaia et al. (+3 more)
Galactic haloes host a complex, multiphase circumgalactic medium (CGM), and at high
redshift are fed by cold, filamentary inflows. In contrast, mature
galaxy clusters are dominated by a hot, enriched, X-ray emitting intracluster medium (ICM), with cold gas largely confined to member
galaxies. However, the transition between these regimes remains poorly constrained. We present a cosmological zoom-in simulation of a massive cluster progenitor evolved to $z=2.7$, with enhanced CGM resolution to better trace the
accretion, mergers and feedback events that precede the birth of the ICM. We connect this
evolution to mock MgII, CII, OVI and OVII absorption, tracing low and high ionisation gas phases. We also study Lyman-$\alpha$ (Ly$\alpha$) and Balmer-$\alpha$ (H$\alpha$)
haloes in emission, using radiative transfer in post-processing. Between $z\sim4.4$ and $2.7$, a major merger and AGN feedback drive an inside-out transformation, redistributing gas to larger radii and flattening density, temperature and
metallicity profiles. Intermediate column MgII absorbers are rapidly destroyed, leaving a clumpier cold gas distribution associated with satellites, while gas is ionised beyond OVII as the inner
halo enters the X-ray regime. An extended Ly$\alpha$
halo remains detectable even without AGN photoionisation, and evolves from filamentary to more spherical as inflowing gas is disrupted. Our fiducial model underpredicts observed central Ly$\alpha$ emission - we likely require more efficient Ly$\alpha$ production in the
nuclear region, either through more effective escape of
stellar Ly$\alpha$
photons or through enhanced conversion of AGN-powered ionisation into Ly$\alpha$ emission. H$\alpha$
haloes are dimmer and smaller than Ly$\alpha$, but with JWST may provide a complementary probe of the evolving CGM at this critical epoch.
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All authors Jake S. Bennett, Aaron Smith, Fabrizio Arrigoni-Battaia, Debora Sijacki, Cassandra Lochhaas, Lars Hernquist
Instrumentation and Methods for Astrophysics
Trajectory Stability and Signature Diagnostics for Comet-Based Interstellar Navigation
Bo Pieter Johannes Andrée
Interstellar objects (ISOs) motivate a coupled mission-design and inference question relevant to spacecraft dynamics and control in extreme environments: if volatile-rich, rotating comet-like bodies were used for sustained deep-space
navigation by exploiting pre-existing
hyperbolic motion and in-situ propellant, what stability requirements arise under non-gravitational forcing, and what astrometric signatures might distinguish active stabilization from uncontrolled natural dynamics? We develop a stability-theoretic framework for trajectory tracking with jet-actuated correction, and show that high-speed transit geometry – including debris-belt avoidance and encounter phasing – tightly constrains feasible trajectories, making long-horizon tracking stability mission-critical. We model tracking residuals as the balance of disturbances and corrective action, and derive stability conditions across four levels: disturbance-energy stability, outer-loop contraction, actuator-
memory stability, and rotation-mediated (Floquet) stability. The analysis implies residual diagnostics that can motivate empirical tests: under comparable forcing, effective stabilization is expected to strengthen short-horizon error correction, reduce event-conditioned persistence and variance clustering, regularize standardized innovations, and yield bounded post-shock recovery. More broadly, the framework provides a reference for deep-space guidance and control under nonlinear, multi-field disturbances and for planetary-defense concepts involving attitude shaping or impulsive kinetic impact.
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Instrumentation and Methods for Astrophysics
A Minimal Four-Thruster System for Comet-Based Interstellar Navigation
Bo Pieter Johannes Andrée
Interstellar comets arrive with key ingredients for deep-space platforms already in place: volatile inventories convertible to propellant, natural rotation providing continuous attitude variation, and
hyperbolic trajectories that carry them through the inner
Solar System and back out to interstellar space. Rather than constructing spacecraft from scratch, we ask what minimal modification is required to steer such a body along a controlled trajectory. The answer is surprisingly modest. By relaxing full six-degree-of-freedom control to forward-cone steering – sufficient for practical
navigation – we show that four thrusters suffice: one primary jet and three secondary jets at $120^\circ$ intervals. The secondary jets synthesize continuous in-plane steering, while the primary jet provides low-bandwidth attitude shaping: as the body rotates, the primary-jet torque direction sweeps predictably over a cycle, enabling out-of-plane steering via phase-scheduled firing. We formalize reachability under bounded-
curvature constraints, characterize the rotation-mediated steering envelope, discuss enabling requirements including non-
solar power at large heliocentric distances, and identify operational regimes and observable signatures implied by active trajectory control. The setting of a nutating axis is briefly considered and conjectured to preserve core results. The findings contribute to the broader effort of understanding the dynamics and control of small-body missions and offer a reference architecture relevant to long-horizon deep-space exploration and to potential planetary-defense concepts.
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Cosmology and Nongalactic Astrophysics · Cross-listed from gr-qc
Extended Theories of Electrodynamics in $f(R)$ Gravity
Francesco Bajardi, Micol Benetti, Salvatore Capozziello et al. (+1 more)
Within the general framework of $f(R)$
gravity, we introduce a function of the electromagnetic
curvature invariant $f(\mathbb{F})$ that couples minimally to gravitation to ensure a consistent treatment of
curvature functions in these theories. We show that one of the solutions leads to field equations that are a generalization of the Klein-Gordon equation while the other leads to a typically non-linear massless solution. Focusing on flat spacetime, our formalism recovers the Plebanski family of models and Bopp-Podolsky electrodynamics as specific limits. These extensions may have phenomenological consequences in extreme environments, such as the early universe or near charged compact objects, where deviations from classical electrodynamics might be probed.
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All authors Francesco Bajardi, Micol Benetti, Salvatore Capozziello, Abedennour Dib
Cosmology and Nongalactic Astrophysics · Cross-listed from hep-ph
New benchmarks for direct detection of freeze-in dark matter in vector portal models
David Cerdeño, Patrick Foldenauer, Rafael López Noé et al. (+1 more)
We investigate the freeze-in of MeV-scale fermionic dark matter (DM) that couples to the Standard Model via a new vector mediator to assess the potential that future direct detection experiments have to observe new physics in either the DM or
neutrino sectors. We study the minimal kinetic mixing dark
photon of a secluded $U(1)_D$ as well as gauge
bosons of the anomaly-free $U(1)_{L_i-L_j}$, with $i,j=e,\mu,\tau$, and $U(1)_{B-L}$ gauge extensions, exploring the impact of low reheating temperatures on the DM production rates. For the ultralight dark
photon scenario, we show that current experimental constraints from electron
recoil data in DAMIC-M and PandaX-4T can be avoided if the DM
fermion is only a subcomponent (smaller than 40%) of the total cold DM and that future detectors can be sensitive to a DM fraction below 1% for masses above 1 MeV. For a massive dark
photon, there are allowed regions of the parameter space with masses in the range 50 MeV $\lesssim m_{\rm DM}\lesssim$ 500 MeV that can be within the reach of direct detection experiments through
nuclear recoils if freeze-in occurred at a low reheating temperature. Finally, the case of $U(1)_{L_i-L_j}$ and $U(1)_{B-L}$ is particularly interesting since the discovery of new physics can come from either the DM or the
neutrino sector, which features new interactions. We find that freeze-in at low reheating temperatures can reproduce the observed abundance in large parts of the parameter space up to gauge couplings of $g_X\sim10^{-2}$ for MeV DM. Most notably, direct detection experiments will be sensitive to considerable parts of this parameter space in
nuclear recoils for 50 MeV $\lesssim m_{\rm DM}\lesssim$ 500 MeV. Additionally, the enhanced signal from
solar neutrino coherent scattering is observable in these scenarios, which can serve as a further handle to identify the underlying particle physics model.
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All authors David Cerdeño, Patrick Foldenauer, Rafael López Noé, Óscar Zapata
Cosmology and Nongalactic Astrophysics
Beyond $\Lambda$CDM with a Logistic RG-like Flow of the Low Redshift Cosmic Evolution
Shibendu Gupta Choudhury and Anjan A Sen
Recent observations hint at possible late-time deviations from $\Lambda$CDM. We introduce a minimal phenomenological framework in which the total equation of state $w_{\rm T}(z)$ follows a logistic
evolution motivated by renormalization-group-like flow between cosmological fixed points. Using DESI-DR2 BAO, DES
supernova data, and CMB distance priors, we find that this parametrization provides an improved description of the expansion history relative to $\Lambda$CDM. The reconstructed
evolution, though model specific, also shows statistically strong low-
redshift deviations from $\Lambda$CDM.
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High Energy Astrophysical Phenomena
Type Ia supernovae interacting with a close circumstellar material (SNe Ia-CSM) are SNe Ia inside planetary nebulae (SNIPs)
Noam Soker
I show that a newly estimated fraction of normal type Ia
supernovae (SNe Ia) that interact within about 100 days of explosion with circumstellar material (CSM), called SNe Ia-CSM, is compatible with a recently estimated fraction of normal SNe Ia that interact with an old planetary nebula, hence, supporting the core-degenerate (CD) scenario for normal SNe Ia. According to the CD scenario, a white
dwarf (WD) merges with the core of an asymptotic
giant branch
star at the end of common envelope
evolution (CEE) and forms a massive WD remnant close to the Chandrasekhar mass. The CEE ejects a planetary nebula that the WD remnant ionizes. Most explosions occur within a merger-to-explosion delay (MED) time of less than a million years, before the planetary nebula material disperses to the interstellar medium, leading to a SN Ia inside a planetary nebula (SNIP). I discuss two plausible MED time distributions and show that the newly determined SNe Ia-CSM fraction of all normal SNe Ia, ~0.04%, is compatible with the SNIP fraction of ~80%. Therefore, although the fraction of SNe Ia-CSM is very small, it does not require a rare evolutionary pathway. I argue that SNe Ia-CSM follow the same scenario that accounts for 70%-90% of all normal SNe Ia, namely, the CD scenario.
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Astrophysics of Galaxies
A Unified Origin of Faraday Rotation toward 3C 84: The Circumnuclear Ambient Medium within the Parsec-Scale Bondi Radius of the Host Galaxy NGC 1275
Minchul Kam, Jongho Park, Sascha Trippe et al. (+11 more)
We present multi-frequency polarimetric observations of 3C 84 obtained with the Korean VLBI Network at 43-141 GHz, the Very Long Baseline Array at 43 GHz, and the High Sensitivity Array at 8 GHz from 2015 to 2024. We find that the Faraday rotation measure (RM) decreases systematically with distance from the black hole over 1-8 pc, following a single power-law trend of RM proportional to r^{-2.7+/-0.2}. Notably, RM measurements from earlier studies across the same distance range follow the same relation. This consistency across epochs, frequencies, and independent
datasets indicates a common and stable external Faraday screen. These results naturally identify the circumnuclear ambient medium within the parsec-scale Bondi radius of the host
galaxy NGC 1275 as the origin of the Faraday rotation, thereby resolving a long-standing question about its physical origin. From the RM profile, we derive radial distributions of the electron density and
magnetic-field strength in the circumnuclear ambient medium that are consistent with independent constraints. The derived density lies below that of the free-free absorption disk and, when extrapolated inward, remains below the density of the broad-line region. The
magnetic-field strength gradually increases from 0.1-1.5 microgauss at the Bondi radius to milligauss-to-gauss levels toward the black hole, providing the first spatially resolved constraint on the
magnetic-field strength at parsec-scale distances in an elliptical
galaxy. Together, these results present a spatially resolved and physically consistent picture of the circumnuclear environment in NGC 1275.
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All authors Minchul Kam, Jongho Park, Sascha Trippe, Do-Young Byun, Keiichi Asada, Hiroshi Nagai, Motoki Kino, Luis Ho, Andrew Fabian, Jeffrey Hodgson, Kunwoo Yi, Kenji Toma, Junghwan Oh, Taehyun Jung
Cosmology and Nongalactic Astrophysics
Selection–Clustering Coupling and Pair-Midpoint Anisotropy from Observer Motion
Tsutomu T. Takeuchi
Observer motion couples source selection, clustering, and
estimator normalization in cosmological pair statistics. Existing calculations distinguish the source-count dipole from the modulation of clustering, including selection-dependent bias. We develop an observable-level formulation that retains arbitrary marked pair kernels, nonfactorizable pair inclusion, and explicit reference measures. Its independent-selection limit expresses the residual as a covariance of the selection score with pair excess; in a rank-one bias model this is the logarithmic response of the selected mean bias and recovers the corresponding bias-derivative description. Two populations can have the same count-dipole coefficient and isotropic correlation but opposite two-point boost responses. We show that local division by endpoint means is not equivalent to a scalar normalization of integrated pair counts, and derive the contact terms and self-pair subtraction required for discrete harmonic
estimators. Exchange
symmetry permits pair-midpoint anisotropy but forbids an ordinary unordered same-tracer separation dipole. The known neighboring-multipole templates are recovered, with explicit conditions for velocity–selection degeneracy and its uncertainty cost. Finite-boost forward models independently test the response, including a nonfactorizable retained-pair example. The result is a common framework for bias-response limits, general pair selection, normalization, and covariance conventions; the numerical illustrations are controlled models rather than survey forecasts. An observational route is specified through
radio and infrared catalog selections, full-pipeline response calibration, and common-velocity consistency tests.
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High Energy Astrophysical Phenomena
The long-term accretion luminosity of V4641 Sgr through binary evolution simulations: implications for its ultrahigh-energy gamma-ray emission
Ruo-Yu Liu, Yong Shao and Yu-Dong Nie
Recent observations by LHAASO and HAWC have revealed extended ultrahigh-energy (UHE; $E>100$ TeV) gamma-ray emission associated with the black-hole X-ray binary (BHXRB) V4641 Sgr, with a spectrum extending up to $\sim0.8$ PeV. Interpreting this emission requires a very high time-averaged non-thermal particle power, significantly exceeding {the long-term observed X-ray luminosity which is commonly used as a proxy for the
accretion power}, leading to an apparent “energy crisis”. To address this, we perform detailed binary-
evolution simulations with MESA, constrained by the known system parameters inferred from observation. Across an extensive evolutionary grid, all tracks that match the current system parameters pass through a long-lasting, slow mass-transfer phase, with a time-averaged intrinsic X-ray luminosity of over evolutionary timescales of order $L_X\sim10^{38}$erg/s, far above the observed luminosity average over the last few decades. This is consistent with earlier suggestions of an extended obscuring/reprocessing envelope or
outflow in V4641 Sgr. The inferred intrinsic
accretion power can then readily supply the energy required to explain the UHE emission under the leptonic model, and is also marginally consistent with the requirement from the hadronic model, resolving the energy crisis. This supports V4641 Sgr as a
Galactic PeV particle accelerator.
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Astrophysics of Galaxies
Novel insights into the Coma cluster kinematics with DESI. I. Linking mass profile, orbital anisotropy, and galaxy populations
S. Pedratti, L. Pizzuti, M. Fossati et al. (+4 more)
We investigate the kinematic properties of the Coma
galaxy cluster using a new, large spectroscopic sample of member
galaxies, from the Dark Energy Spectroscopic Instrument (DESI). By means of the MG-MAMPOSSt code, based on the Jeans equation, we jointly reconstruct the total cluster mass profile and the velocity anisotropy profile. Assuming a Navarro-Frenk-White model, we estimate a virial mass $M_{200}=1.04_{-0.08}^{+0.07}~({\rm stat})\pm 0.09~({\rm syst})\times 10^{15}\,\mathrm{M}_\odot $, corresponding to $r_{200}=2.07 \pm 0.05\,\mathrm{Mpc}$ and a scale radius for the mass profile $r_{\rm s}=0.73^{+0.24}_{-0.30}\,\mathrm{Mpc}$, which provides the tightest robust kinematic mass profile constraint to date. By considering separately the mass of the hot gas and the
galaxy stellar mass, we determine the dark matter mass profile, with $M_{200}^{\rm DM}=8.6^{+1.2}_{-0.8}\times 10^{14}\,\text{M}_\odot$. We discuss the impact of the mass and number density parametrisations, the effect of different choices of the cluster's rest frame and of the radial range of the kinematic analysis, further comparing our results with previous estimates from the literature. The cluster dynamical state has also been assessed, using the spatial and line-of-sight velocity distributions of the members. We perform a kinematic study of different subsamples of
galaxy populations, based on their colour (red sequence, green valley, and blue cloud), focusing on the anisotropy profiles and line-of-sight velocity distributions. The orbits of green valley and blue cloud
galaxies appear to be more radial in the centre and in the outskirts, respectively, with the latter predicting a higher cluster virial mass. This study provides new insights on the interplay between dynamical and intrinsic properties of
galaxies in massive structures, fundamental to verify the tight connection between
galaxy evolution and environment.
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All authors S. Pedratti, L. Pizzuti, M. Fossati, A. Biviano, A. Boselli, A. Ragagnin, A. Carlin
Earth and Planetary Astrophysics
The shape and spin state of (275677) 2000 RS11 from ground-based radar and optical observations
Richard E. Cannon, Agata Rożek, Kaley Brauer et al. (+12 more)
Near-Earth asteroid (275677) 2000 RS11 was observed over 5 days in March 2014 with both the Arecibo (2380 MHz, 12.6 cm) and Goldstone (8560 MHz, 3.5 cm) planetary radar systems. The continuous-wave spectra and delay-Doppler images collected revealed a sub-km-sized object with a strongly bifurcated shape. We used these radar observations, in combination with 7 optical lightcurves collected in 2014 and one lightcurve from 2023, to create a comprehensive shape and
spin-state model for RS11. We find a rotation period of P = (4.445+-0.001) hours around a pole of lambda = (225+-80) and beta = (-80+-9) relative to the plane of the ecliptic. The shape of RS11 is unusual in that it does not resemble many of the other near-Earth asteroids modelled with ground-based radar. Whilst RS11 consists of a largely spherical, smaller lobe attached to an elongated, larger lobe via a narrow neck, the smaller lobe is not aligned with the long axis of the larger lobe, but is closer to the larger lobe's shortest principal axis. In combination with a large concavity observed on the outer face of the larger lobe, this may point to an unusual formation or event in the object's past. We estimate that RS11 has an
geometric albedo of (0.16+-0.06) and a radar albedo between 0.08 and 0.16. Analysis of its gravitational environment reveals that for standard S-type asteroid densities, we would not expect rotational instability and it is possible for RS11 to be a low tensile strength rubble-pile asteroid.
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All authors Richard E. Cannon, Agata Rożek, Kaley Brauer, Michael W. Busch, Colin Snodgrass, Lance A. M. Benner, Marina Brozović, Jon D. Giorgini, Ellen Howell, Michael C. Nolan, Markus Rabus, Sedighe Sajadian, Alessondra Springmann, Patrick A. Taylor, Luisa Fernanda Zambrano-Marin
Cosmology and Nongalactic Astrophysics · Cross-listed from hep-ph
On the survival of strong nuggets in the early Universe
Haoyang Qi, Wen-Li Yuan, Yudong Luo et al. (+3 more)
Strong nuggets with a
baryon number of $A\sim 10^{10-30}$ could be able to survive from the
cosmic separation of the QCD phases, provided the transition from strange
quark matter to strangeon matter is accounted for, thereby evading evaporation in the early Universe. Such strangeon nuggets may serve as a dark matter candidate within particle standard model. We formulate the corresponding phase transition of
cosmic strange matter, establishing a parameter space which reasonably accommodates observational constraints on the dark-to-luminous matter ratio and the mass-radius relation, as well as
tidal deformability of compact objects.
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All authors Haoyang Qi, Wen-Li Yuan, Yudong Luo, Chao Chen, Shi Pi, Renxin Xu
Solar and Stellar Astrophysics
Stars with Plumbing Issues: The Multi-component Ejecta of Common Envelopes
Sarah V. Borges and Philip Chang
Common-envelope
evolution (CEE) is one of the major open problems in binary
stellar evolution, even though it is the primary channel for forming close binaries with at least one compact object. While CEE is often assumed to lack direct observational constraints, recent connections between CEE and the transient class, luminous red novae (LRNe), as well as the post-AGB systems known as Water Fountains (WFs), provide new opportunities to understand how this event unfolds. Collectively, these observations suggest that envelope ejection during CEE is neither spherically symmetric nor homologous, but rather produces complex ejecta, providing constraints for simulations of CEE. In this work, we present a series of three-dimensional hydrodynamical (non-MHD) simulations of CEE for a 2 Msun red-
giant-branch (RGB)
star and show that the event naturally produces multi-component ejecta including an extended radially expanding shell, a thick circumbinary disk (CBD), and collimated bipolar
outflows. Consistent with previous works in the literature, the bipolar
outflows in our simulations arise naturally through geometrical constraints imposed by the disk and do not require
magnetic fields. While we find that the formation of the collimated
outflows can be sensitive to the choice of Riemann solver, they appear across all resolutions and mass ratios tested in this work. We show that the multi-component ejecta formed during CEE simulations naturally reproduce some of the key properties of CEE observations, including the classical bipolar shape seen in some LRNe, WFs, and planetary nebulae.
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Instrumentation and Methods for Astrophysics · Cross-listed from physics.optics
Designing a low-loss high reflectivity mirror for gravitational waves detectors by combining a dielectric metasurface and a multilayer stack
Edith Hartmann, Michel Lequime, Jerome Degallaix et al. (+4 more)
The design of low-mechanical-loss, high reflectivity mirrors is crucial in the development of the next generation of gravitational-wave observatories. Currently, the amorphous multilayer reflective coatings which are deposited at the surface of the test masses in interferometric gravitational-wave detectors present a major limiting factor in detector sensitivity due to their thermal noise. These coatings require a large number of thin layers to achieve ultra-high reflectivity. However, the thermal noise generated by this type of stack increases with the number of layers used. These dielectric mirrors represent a very mature technology, with current research producing only incremental improvements, highlighting the need for new technical solutions that can address this specific issue. Here, we provide insights into the expected performance of mirrors that combine a resonant metasurface with a multilayer stack. The suggested mirror design ensures the high reflectivity required for interferometric gravitational wave detectors, while using fewer layers of properly selected materials. As a result, it significantly reduces the total coating thickness, making it a promising option for reducing thermal noise as well.
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All authors Edith Hartmann, Michel Lequime, Jerome Degallaix, Michael T. Hartman, Paul Rouquette, Claude Amra, Myriam Zerrad
High Energy Astrophysical Phenomena
Particle acceleration at recollimation shocks in sub-relativistic jets. A model for jets in Seyfert Galaxies, Microquasars and Protostellar Systems
Enrico Peretti, Elena Amato, Silvio Sergio Cerri et al. (+3 more)
Growing observational evidence suggests that subrelativistic (SR) astrophysical jets may accelerate particles at slowly evolving standing shocks. Recollimation shocks (RCS) are expected to develop when jets expand in dense environments; their formation may be mediated by the pressure of the cocoon surrounding the jet, while remaining compatible with a quasi-stationary behavior. Such shocks can be strong and can enable efficient particle acceleration. The aim of this work is to improve the general understanding of particle acceleration via diffusive shock acceleration at RCS by developing a versatile modeling framework applicable to different classes of astrophysical jets, including Seyfert
galaxies (SEY), microquasars (MQ), and protostellar systems (PS). We extended an analytic jet hydrodynamics model previously introduced in the literature to the SR regime and used it to identify the expected locations of the RCS and the jet head. Within this framework, we formulated a semi-analytic acceleration and transport model for particles injected at the RCS via diffusive shock acceleration. By solving the space-dependent transport equation, we obtained particle distributions and spectra along the jet, as well as robust predictions for the maximum energies achievable as a function of the intrinsic properties of the system and the source class. Our results indicate that RCS may play a central role in particle acceleration in SR jets. In SEY such shocks may accelerate particles from PeV up to EeV energies, while in MQ and PS maximum energies of respectively tens of PeV and up to TeV energies are expected. While leptonic emission may be associated with bright
knots along the jet, accelerated
protons are expected to escape the jet and interact with the surrounding cocoon. Depending on the properties of the system,
proton interactions can give rise to extended hadronic emission morphologies.
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All authors Enrico Peretti, Elena Amato, Silvio Sergio Cerri, Giovanni Morlino, Letizia Perfetta Pullano, Sarah Recchia