Astrophysics of Galaxies
A Census of the 200 Most Massive Galaxies Spectroscopically Observed with JWST at zspec $\sim$3-15
Mengyuan Xiao, Pascal A. Oesch, Longji Bing et al. (+26 more)
Massive
galaxies provide strong tests of
galaxy formation models, yet a comprehensive spectroscopic view of their properties and demographics in the early Universe has remained elusive. Here we present a JWST spectroscopic census of the 200 most massive
galaxies at zspec~3-15, selected using an evolving
stellar-mass threshold motivated by the
halo mass function and anchored at log(Mstar)>10 at z~5. These
galaxies represent the top 3% most massive systems among all publicly available prism observations. We derive their physical properties through joint SED fitting of spectroscopy and photometry, and construct a clean massive
galaxy sample after removing LRDs and broad-line AGN contaminants. We find that the massive
galaxy population evolves strongly with
redshift: normal SFGs (Av<1 mag) dominate at z>~6, while dusty SFGs (Av>1 mag) and QGs become more common toward lower
redshift.
Dust attenuation decreases systematically toward higher
redshift. We identify 29 massive QGs, including a population of recently quenched systems whose
star formation declined rapidly within the past ~100 Myr. We further show that both the traditional UVJ and recently proposed (ugi)s selections suffer substantial inconsistency with the most massive
galaxies at z>3, motivating a revised (ugi)s criterion calibrated using our spectroscopic sample. The inferred formation histories suggest at least two pathways toward quiescence: a
dust-enriched pathway linking normal SFGs, dusty SFGs, and QGs, and a more direct pathway connecting normal SFGs and QGs. Massive normal SFGs appear to grow through both relatively gradual and rapid assembly modes. Together, these results suggest that rapid
stellar-mass assembly,
dust enrichment, and quenching were already shaping the evolutionary pathways of the most massive
galaxies within the first billion years after the Big Bang.
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All authors Mengyuan Xiao, Pascal A. Oesch, Longji Bing, Rashmi Gottumukkala, Rui Marques-Chaves, Gabriel Brammer, Miroslava Dessauges-Zavadsky, David Elbaz, Songnan Qi, Anurag Amol Sawarkar, Manuel Aravena, Matthieu Béthermin, Rachel Bezanson, Rychard Bouwens, Caitlin Casey, Pieter van Dokkum, Andreas L. Faisst, Yoshinobu Fudamoto, Anna de Graaff, Olivier Ilbert, Garth Illingworth, Guilaine Lagache, Benjamin Magnelli, Jorryt Matthee, Yurina Nakazato, Daniel Schaerer, Sune Toft, Katherine E. Whitaker, Christina C. Williams
Earth and Planetary Astrophysics
The GAPS programme at TNG: LXXVI. TOI-1533: a compact system hosting a super-Neptune-mass pair with disparate radii
G. Mantovan, V. Nascimbeni, S. Desidera et al. (+49 more)
The present-day architecture of planetary systems contains information about their formation and migration histories. The origin of hot Jupiters (HJs, P $\lesssim$ 10 d, $R_{\rm p} > 8 R_\oplus$) has long been a matter of debate. While most of them are found to be “lonely”, there is a rare population of HJs hosting small companions on inner orbits (eight known as of May 2026). Their peculiar architecture suggests a gentle disc-migration mechanism. In this study, we present the discovery and characterisation of the multi-
planet system TOI-1533, comprising an inner sub-Neptune (TOI-1533 b, $P_{\rm orb} = 3.63$ d, $R_{\rm p} = 3.15 R_\oplus$) and an outer hot
giant planet (TOI-1533 c, $P_{\rm orb} = 8.06$ d, $R_{\rm p} > 7.5 R_\oplus$) with substantial H/He by mass ($\rho_{\rm p} < 0.48$ g cm$^{-3}$), both transiting an active K-
dwarf star ($T_{\rm eff} \approx$ 5130 K; $V$ (mag) $\approx$ 11). Our joint modelling of
stellar activity and planetary signals from radial velocities (HARPS-N) and transits (TESS) allows us to detect their Keplerian signals (approximately $10~\sigma$) and to isolate the
stellar modulation. The inclusion of simultaneous photometry in the multi-dimensional Gaussian processes formalism was a fundamental addition to the spectroscopic activity indicators, enabling the disentanglement of
stellar activity from planetary signals. The mass ratio of the two confirmed
planets ($M_{\rm b} / M_{\rm c}$ about 0.8), together with the super-Neptune mass of the large outer companion ($M_{\rm c} \approx 40 M_\oplus$), makes this system unusual compared to the other few HJs with low-mass inner companions.
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All authors G. Mantovan, V. Nascimbeni, S. Desidera, L. Malavolta, J. J. Lissauer, P. Leonardi, T. Azevedo Silva, C. Guerra, D. Polychroni, L. Borsato, M. Baratella, K. Biazzo, D. Nardiello, K. A. Collins, M. Damasso, J. De Leon, M. E. Everett, D. Gandolfi, S. Giacalone, L. Naponiello, G. Piotto, G. Scandariato, K. Stassun, S.W. Yee, L. Affer, F. Amadori, A. Bignamini, S. Colombo, M. D'Arpa, C. D. Dressing, A. Fukui, A. Ghedina, J. Higuera, K. Ikuta, Kawauchi, J. Korth, V. Lorenzi, L. Mancini, M. Mori, F. Murgas, N. Narita, E. Palle, H. Parviainen, A. Ruggieri, A. Savel, R. P. Schwarz, A. Shporer, G. Srdoc, Stockdale, D. Watanabe, R. Zambelli, T. Zingales
High Energy Astrophysical Phenomena
NLTE Spectral Modelling of the Nearby Stripped-Envelope Supernova 2024ehs
Wilmer Sand Hellman, Seán J. Brennan, Stan Bartmentloo et al. (+7 more)
We present a detailed study of the Type IIb
supernova 2024ehs, discovered in March 2024 in the nearby
galaxy NGC 3443 at a distance of $23.8\pm 0.9$ Mpc. Using photometric and spectroscopic observations spanning 10 months, we analyse its light curve, spectral
evolution, and physical properties with the SUMO radiative transfer code. SN 2024ehs exhibits a narrow light-curve peak, rapid decline, and weak helium lines, distinguishing it from typical Type IIb
supernovae. Comparisons with other objects, including SNe 1993J and 2020acat, and modelling of nebular spectra suggest a low ejecta mass, high velocities ($\sim$20,000 \kms), and a $^{56}$Ni mass just below $\sim0.1 \, \mathrm{M}_{\odot}$. Furthermore, the nebular spectral models indicate a progenitor with a helium core mass of $\sim 6 \, \mathrm{M}_{\odot}$, consistent with a zero-age main-sequence mass of $\sim 23\, \mathrm{M}_{\odot}$. The composition of spectra is explored through photospheric modelling, finding a link between expansion velocity and the relative strength of different element lines. This work discusses further the diversity of stripped-envelope
supernovae and the role of binary interactions for their progenitors, and demonstrates the need for further modelling to refine $^{56}$Ni mass estimates and to understand the physical mechanisms driving their
evolution.
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All authors Wilmer Sand Hellman, Seán J. Brennan, Stan Bartmentloo, Christoffer Fremling, Anjasha Gangopadhyay, Anders Jerkstrand, Ragnhild Lunnan, Josiah Purdum, Steve Schulze, Jesper Sollerman
Earth and Planetary Astrophysics
High-resolution detection of reflected light from the exo-Neptune LTT-9779 b
F. Borsa
While high-resolution spectroscopy is routinely used to probe exoplanetary atmospheres, detecting reflected starlight remains highly challenging due to the extremely low
planet-to-
star optical flux ratios. We report the detection of reflected light from the ultra-hot exo-Neptune LTT-9779 b using high-resolution spectroscopy with ESPRESSO in its 4UT mode. By combining multiple epochs and applying a cross-correlation analysis with a theoretical reflection kernel, we were able to identify a faint signal matching the expected morphological and kinematic profile of the planetary reflection. This signature, whose presence has been detected at a signal-to-noise ratio of $\sim$5.4, exhibits a radial velocity semi-amplitude consistent with the expected orbital motion. We measured the
planet-to-
star flux ratio from the ratio of the equivalent widths of the planetary and
stellar cross-correlation functions, finding $F_{\mathrm{p}}/F_\star = 102^{+29}_{-30}$ ppm for the ESPRESSO 380–770 nm wavelength range. Assuming a Lambertian phase function, this corresponds to a
geometric albedo of $A_{\mathrm{g}} = 0.88 \pm 0.25$. The inferred albedo is consistent with previous space-based photometric measurements, suggesting a highly reflective atmosphere potentially dominated by scattering processes or high-altitude clouds. While we show that reflectivity is enhanced towards blue wavelengths, a detailed spectroscopic characterization of the planetary atmosphere from the reflected-light signal remains out of reach. This result highlights the scientific potential of future high-resolution spectrographs on extremely large
telescopes, paving the way for systematic reflected-light detections across a broader
exoplanet population, including cooler and smaller
planets.
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Astrophysics of Galaxies
JWST spectroscopy of galaxies at $z>10$: Damped Ly$\alpha$ absorbers reveal efficient star formation and hidden redshift biases
Kasper E. Heintz, Clara L. Pollock, Joris Witstok et al. (+23 more)
Recent observations with JWST have revealed a remarkable population of surprisingly luminous
galaxies at
redshifts $z>10$. Their abundance exceed predictions from simulations and empirical extrapolations from lower
redshifts, suggesting a transition in the physical conditions under which the first
stars formed. Here we investigate the physical conditions of a select sample of 25
galaxies with robust
redshift measurements at $z_{\rm spec}\geq 10$ observed with JWST/NIRSpec Prism. We characterize their
star-formation efficiency, `burstiness', and presence of strong rest-frame UV nebular lines in relation to the density of the local neutral atomic hydrogen (HI) gas reservoirs they are embedded in. We find that the prominence of strong rest-UV lines are correlated with the burstiness of the
galaxies, defined as ${\rm SFR_{10\,Myr} / SFR_{100\,Myr}}$. In contrast, there are no strong connections between the HI gas column density derived from the damped Ly$\alpha$ absorption (DLA) and the $M_{\rm UV}$ brightness, ${\rm SFR_{10\,Myr} / SFR_{100\,Myr}}$, and prominence of rest-UV lines. The most bursty
galaxies show a large variation in
star-formation efficiencies and HI gas surface densities, though typically with very short depletion timescales, $t_{\rm dep} \lesssim 20$\,Myr. This necessites rapid gas depletion times and external replenishment from infalling, pristine gas, powering starburst episodes on equally short timescales. We further quantify the impact of strong DLAs in
galaxy spectra on photometric and Ly$\alpha$-break
redshift-inferences, finding average
redshift biases of $\langle z \rangle =0.39$ and $0.14$, respectively, when not incorporating DLAs on the emergent spectra. We show the effect of this bias on new measurements of the
cosmic UV luminosity density, $\rho_{\rm UV}$, derived here at $z>10$, finding that this has a marginal impact on the UV luminosity function.
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All authors Kasper E. Heintz, Clara L. Pollock, Joris Witstok, Rychard J. Bouwens, Sandro Tacchella, Pascal A. Oesch. Pratika Dayal, Sownak Bose, Gabriel B. Brammer, Johan P. U. Fynbo, Rashmi Gottumukkala, Matthew J. Hayes, Akio K. Inoue, Benjamin Johnson, Harley Katz, Peter Laursen, Rohan P. Naidu, Desika Narayanan, Lucie E. Rowland, Nial R. Tanvir, Chamilla Terp, Sune Toft, Francesco Valentino, Fabian Walter, John R. Weaver, Arjen van der Wel, Mengyuan Xiao
Cosmology and Nongalactic Astrophysics
Numerical polology: towards next-generation model-building for cosmology
Will Barker, Will Handley, Michael Hobson et al. (+4 more)
The dark sector need not be restricted to simple field content. Indeed, simple bosonic configurations, such as scalar-tensor or dark
photon models, contrast with the much richer picture painted by many ultraviolet scenarios. Polology is the study of propagator poles, which correspond to particle states in any given theory. We outline a numerical polology framework for discovering perturbative, ghost-free models with consistent interactions, which produces theoretical model priors by sampling the coupling space. The method is tested on tensor field theories of up to rank three. Subsequent observational constraint pipelines are illustrated for black hole superradiance (M33 X-7), dynamical dark energy (DESI DR2, Pantheon and SH0ES) and gravitational waves (GWTC-3).
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All authors Will Barker, Will Handley, Michael Hobson, Anthony Lasenby, Carlo Marzo, Alessandro Santoni, Leonardo Torcellini
High Energy Astrophysical Phenomena
Filippo D'Ammando
Identifying the sources of the high-energy astrophysical
neutrinos has been one of the main topics in astrophysics since the first observation of high-energy
neutrinos by the IceCube
Neutrino Observatory. Active
Galactic Nuclei (AGN) are sources of high-energy gamma-rays and are considered to be promising candidates to be sources of high-energy
neutrinos and ultra-high energy
cosmic rays as well. However, several studies suggest that the
neutrino emission from the $\gamma$-ray blazar population only accounts for a small fraction of the total astrophysical
neutrino flux. We present and discuss recent results on the search for correlations between astrophysical
neutrinos and both gamma-ray and
radio bright AGN. The IceCube Collaboration has reported high-energy
neutrino events that may come from both the
radio-loud AGN TXS 0506+056 and the
radio-quiet AGN NGC 1068. Other cases of possible associations between high-energy
neutrino events and individual blazars were claimed with controversial results. We discuss the properties of these sources together with the different
neutrino production mechanisms proposed for those sources. Finally, we outline future prospects in the field, focusing on remaining open questions, the development of upcoming
neutrino facilities, and the evolving multi-frequency landscape within the multi-messenger era.
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Astrophysics of Galaxies
A SHARP Look at Quenching and Bulge-Disk Growth in Massive Galaxies at Cosmic Noon
Chiara Mancini, Adriana Gargiulo, Alvio Renzini et al. (+11 more)
The physical mechanisms that quench
star formation in massive
galaxies remain poorly understood. At
cosmic noon (1<z<3), when
star formation and AGN activity peak,
galaxies rapidly evolve from
star-forming disks into quiescent, bulge-dominated systems. While quenching correlates with
stellar mass and bulge growth, the causal link between bulge assembly,
star-formation suppression, and feedback processes remains unclear.
Stellar population analysis from spatially resolved spectroscopy of
galaxies caught during quenching is crucial to advance on this issue. We show that the SHARP-VESPER Integral-Field Spectrograph (IFS) can efficiently fill this gap by combining ELT-class sensitivity, 31 mas spatial resolution (>3x sharper than JWST) and broad near-IR wavelength coverage with 12-IFU multiplexing. This will enable, for the first time, a simultaneous bulge-disk decomposition of
stellar populations and spatially resolved mapping of ionised gas in massive
galaxies (log $M_*/M_{\odot}\geq 11$) at 2.2<z<3.5, targeting systems on the main sequence shortly before quenching or already in the green valley. With typical exposure times of 15 hr, we will obtain S/N>15-20 per spectral resolution element, on the inner bulge, and outer disk extracted spectral continuum, and S/N>5 for nebular lines ([OII], H$\beta$, [OIII], H$\alpha$) on sub-kpc scales. These observations will allow us to reconstruct independent bulge and disk
star-formation histories, ages,
metallicities, and $\alpha$-enhancements, while mapping spatially resolved
star formation, gas kinematics, and feedback-driven
outflows. By directly comparing the timing of bulge growth and
star-formation suppression across
galaxy components, this programme will test whether quenching proceeds inside-out, distinguish fast and slow quenching pathways, and link structural transformation to feedback processes in the most massive
galaxies at
cosmic noon.
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All authors Chiara Mancini, Adriana Gargiulo, Alvio Renzini, Emanuele Daddi, Stefano Zibetti, Fabio R. Ditrani, Anna R. Gallazzi, Susanna Bisogni, Paolo Franzetti, Giustina Vietri, Louis Gabarra, Fabrizio Gentile, Marcella Longhetti, Marco Scodeggio
Astrophysics of Galaxies
Unveil the nature of JWST-AGN and Little Red Dots with SKAO continuum surveys
Giovanni Mazzolari, Dharam V. Lal, Isabella Prandoni et al. (+6 more)
The advent of JWST has revealed a large population of AGN at $z>4$, which are $\sim1$ dex more abundant than previously expected, including also the enigmatic population of Little Red Dots (LRDs). Remarkably, the vast majority of JWST-discovered AGN and LRDs are not detected in X-rays, and most of them also show faint rest-frame UV continua and faint high-ionization emission lines, as well as unusually faint emission in the Mid and Far infrared. Recent studies investigating their
radio properties have reported no significant detections, even in deep stacking analyses, reaching sensitivities of 0.5-0.1 $\mu$Jy at $z\sim 5-6$, corresponding to $L_{R}\lesssim 10^{39}\rm \ erg\ s^{-1}$. While these non-detections may be consistent with a standard
radio-quiet nature, some results suggest that the
radio emission might instead be significantly suppressed by other physical phenomena. Three main scenarios have been proposed in the literature to explain the physical properties of these objects across the electromagnetic spectrum: Compton-thick absorption by a broad-line region with high covering-factor, intrinsically weak emission driven by high
accretion rates, or the presence of a cocoon of dense ionized gas that produces strong scattering effects. The unprecedented sensitivity of SKAO will enable the detection of the
radio emission of these AGN in all three cases. Because each scenario is expected to produce distinct
radio signatures, future SKAO continuum surveys will be able to distinguish between them, uncovering the physical processes responsible for their peculiar properties. Observations spanning a wide range of integration times (1-1000 hours) and frequencies with SKA-Mid and SKA-Low (0.2-11 GHz) will allow us to characterize these objects from the local Universe to high
redshift, investigate possible
radio variability, and test alternative scenarios to black hole
accretion.
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All authors Giovanni Mazzolari, Dharam V. Lal, Isabella Prandoni, Roberto Gilli, Roberto Maiolino, Hannah Übler, Ivan Delvecchio, Marcella Brusa, Marco Mignoli
Solar and Stellar Astrophysics
Parameterizing the Standing Accretion Shock Instability for Inference with Galactic Supernova Neutrino Signals at IceCube
Dwaipayan Mukherjee, Mohamed Rameez and Basudeb Dasgupta
Simulations of core-collapse
supernovae have revealed an epoch of hydrodynamic instability in which the matter of the collapsing
star undergoes quasi-periodic oscillations, known as the standing
accretion shock instability (SASI).
Neutrinos produced in the core of the
star travel through this oscillating matter, and information about this epoch is encoded in their high-statistics event rate observable at
neutrino observatories. We propose a parametrization of the SASI-modulation to study its broad features, enabling statistical inference of SASI parameters. For the
benchmark Galactic supernovae considered, we show that IceCube can identify this epoch of instability and reconstruct its parameters with precision at the sub-percent level for the SASI frequency, percent level for the peak time, and a few to ten percent level for the amplitude and duration.
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High Energy Astrophysical Phenomena
Prospects for Improving the Theoretical Uncertainty for Tests of General Relativity with the EHT
Lia Medeiros, George N. Wong and Feryal Ozel
We characterize the relationship between the size of the bright ring observed in simulated black hole images and the size of the analytic black hole shadow. Calibrating this relationship is crucial for mass measurements and, when independent mass measurements are available, for tests of general relativity using Event Horizon
Telescope (EHT) images. We perform this calibration using a large set of high-resolution simulated images generated with different
accretion-flow modeling approaches and spanning a wide range of system parameters and initial conditions. We show that the theoretical uncertainty in this relationship can be reduced significantly through future observations, improved imaging techniques, and the application of astrophysical or model-based constraints. In particular, the uncertainty decreases compared to existing measurements when (i) observing at 345 GHz, (ii) applying
geometric image constraints, such as the ring width inference from the PRIMO image reconstruction
algorithm, (iii) incorporating astrophysical constraints such as the black hole
spin axis in M87 being aligned (or anti-aligned) with the large-scale jet observed at longer
radio wavelengths, and (iv) assuming that the
accretion flow can be described by a magnetically arrested field configuration. Finally, we quantify how the uncertainty is expected to decrease as additional observations are obtained in subsequent years and identify dwell-time filtering, i.e., evaluating the persistence of a
geometric measurement over time, as a promising avenue for improving the precision of the calibration.
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Astrophysics of Galaxies
Wrinkles in Time. II. Stellar Age Trends in Kinematic Signatures from Transient Spiral Structure
Amy Smock, Kathryne J. Daniel, Rayna Rampalli et al. (+4 more)
Spiral arms in the disks of
galaxies like the Milky Way can generate kinematic signatures, which appear as ridges or wrinkles in action space. Such signatures have proven difficult to disentangle using kinematic measures alone. In this study, we investigate how including
stellar age as an additional dimension for analysis may provide a novel insight into the physical characteristics, timescales, and nature of the progenitors of such perturbations, where these novel insights could contribute to our understanding of the history of spiral arms in the Milky Way. We used a suite of tracer particle simulations that modeled a variety of prescriptions for spiral arms to characterize observable trends. The Lindblad resonances of nonwinding spirals produce signature overdensities, or wrinkles, in a kinematic space that is typically associated with older
stellar populations (high radial action). We find that these wrinkles are preferentially populated with
stars that were initially in nearly circular orbits, kinematics that is generally correlated with younger
stellar ages. It follows that the
stellar age distribution of wrinkle populations could serve to place constraints on the past passage of a transient spiral pattern in the
solar neighborhood. For example, our simulations suggest that a physically motivated spiral pattern could significantly populate a wrinkle with zero-age
stars in orbits typically occupied by
stars much older than the Sun.
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All authors Amy Smock, Kathryne J. Daniel, Rayna Rampalli, Elisabeth R. Newton, Olivia McAuley, Sóley Hyman, Lipika Chatur
Astrophysics of Galaxies
A Pixel-by-Pixel Path to Population III Discovery with JWST
Patricia Iglesias-Navarro, Thomas Harvey, Marc Huertas-Company et al. (+11 more)
The identification of the first generation of metal-free
stars, known as Population III (Pop~III), remains a primary goal of modern observational astronomy. While JWST has discovered an abundance of UV-bright
galaxies at $z > 10$, distinguishing
primordial stellar populations from early metal-enriched systems is a significant challenge. We present an end-to-end framework that combines physically motivated forward modelling from Yggdrasil
primordial models with simulation-based inference (SBI) to test Pop~III detectability in JWST-like observations, from isolated sources to realistic overlap with enriched (Pop~II) hosts. Our analysis spans several Pop~III initial mass function (IMF) assumptions, nebular configurations, and Lyman-$\alpha$ transmission scenarios, while mocking the noise properties and filter coverage of the JWST Advanced Deep Extragalactic Survey (JADES). We find that unresolved or integrated analyses are strongly limited by host-
galaxy contamination, whereas spatially resolved, pixel-based model comparison substantially improves recoverability. In our resolved experiments, detectability is highest for young and massive Pop~III clumps in nearly-quenched hosts at larger projected separations from their centres, reaching $\sim 90\%$ recovery in favourable configurations, while older and centrally embedded clumps are rarely recovered. Applying the framework to a literature candidate yields spatially differentiated behaviour: a compact blue companion is preferentially described by Pop~III-like models, while the host is better explained by fiducial Pop~I/II models. Our pipeline provides practical criteria for future searches and motivates imaging-first, spectroscopy-assisted strategies for identifying
primordial stellar populations in JWST data.
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All authors Patricia Iglesias-Navarro, Thomas Harvey, Marc Huertas-Company, Christopher C. Lovell, Johan H. Knapen, Christopher Conselice, Brant Robertson, Andrew J. Bunker, Stéphane Charlot, Natalia C. Villanueva, Hannah Übler, Zhiyuan Ji, Kevin Hainline, Christina C. Williams
Solar and Stellar Astrophysics
The forgotten bright star: Theta Eridani as a millenary stellar transient observed by Hipparchus, Ptolemy and al-Sufi
Idel Waisberg and Boaz Katz
Theta Eridani is a V=2.9
star that was nonetheless reported as one of the thirteen brightest
stars in the night sky by both Ptolemy in his Almagest (137 AD) and by al-Sufi in his The Book of Fixed
Stars (964 AD), in addition to being previously referred by Hipparchus (129 BC) as a particularly bright
star. The discrepancy between its historical and modern visual magnitude $\Delta V \sim 2.7$ is the highest among the $\sim 1000$
stars in the Almagest. Theta Eridani is actually a triple
star system, and here we combine interferometric data from VLTI/PIONIER and VLTI/
GRAVITY, spectroscopic data from ESPaDOns and FEROS, and photometric data from TESS in order to solve for the orbital parameters, masses and radii of the close inner binary Theta Eridani Aa+Ab. We find that it is a tight eccentric binary ($a=0.083 \text{ au}$, $e=0.105$) of intermediate-mass
stars ($M_{Aa}\simeq 2.3 M_{\odot}$, $M_{Ab}\simeq 2.2 M_{\odot}$) that are extended to $\sim 80\%$ of their Roche lobe radii ($R_{Aa}\simeq 4.3 R_{\odot}, R_{Ab} \simeq 4.0 R_{\odot}$), resulting in prominent ellipsoidal oscillations in the lightcurve. We also find that the primary is in a very special phase of its
evolution in which it has just finished core hydrogen burning. The remarkable combination of orbital and
stellar parameters hints that the historical brightening of Theta Eridani was due to a millenary transient phase powered by orbital energy extraction during a long-lived “common envelope” stage triggered by eccentric Roche lobe overflow in a previously more eccentric binary ($e\simeq0.6$). This strengthens the case that the apparent brightening was real and not due to an error by three different ancient observers, as has been commonly claimed in the past.
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Astrophysics of Galaxies
Introducing AuriGLOBES: The effects of compressive tides, compact object-induced mass loss, and size evolution on modelling globular clusters
Pablo Contreras Guerra, Robert J. J. Grand, Marta Reina-Campos et al. (+1 more)
Globular clusters (GCs) are long time survivors of
galaxy assembly and
evolution yet their emergence from an initial cluster population is still poorly constrained. We present the Auriga GLOBular clustEr Simulations (AuriGLOBES) a physically motivated subgrid model for
star cluster (SC) formation and
evolution that includes enhanced mass loss from compact object remnants. With this model, implemented in the Auriga cosmological
galaxy formation model, we run a suite of zoom-in cosmological simulations comprising 9 Milky Way mass and 5 lower mass
galaxies. We demonstrate that our model produces plausible GC populations compared to the Milky Way/M31 systems and reproduces the empirical GC system mass –
halo mass relation within a 2$\sigma$ scatter. We show that the formation of SCs in tidally compressive, high-pressure gas in addition to enhanced mass loss from compact object remnants heating is required to capture the transformation of an initial Schechter mass function to the characteristic observed GC mass function in the Milky Way/M31 systems. The resulting GC populations show spatial and
metallicity distributions qualitatively similar to the Milky Way/M31 systems, as well as a variety of age distributions that correlate with the
star formation history of the simulated
galaxies. However, the peak of the age distribution of Milky Way GCs is older than any of our simulated Milky Way-mass
galaxies, which is attributed to unrepresented
star formation and
galaxy assembly histories. AuriGLOBES represents a reliable framework for the study of GC populations through
cosmic history and a robust foundation for future applications for a model of
stellar streams arising from GCs disruption.
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All authors Pablo Contreras Guerra, Robert J. J. Grand, Marta Reina-Campos, Claudio Dalla Vecchia
Solar and Stellar Astrophysics
Star-Planet Interactions: Observational Techniques and Methods
P. Figueira, H. Korhonen, A. Buccino et al. (+8 more)
This chapter summarizes the techniques and methods used to study
star-
planet interaction (SPI) from the observational point of view. SPI can produce a wide range of observational signatures, from localized
stellar activity enhancements to changes in planetary atmospheric escape and transmission spectra. This chapter reviews the main observational techniques used to detect and characterize SPI, emphasizing the methodological challenges involved in separating
planet-induced signals from intrinsic
stellar variability. We discuss radial-velocity diagnostics, including cross-correlation, template matching, line-by-line methods, and activity indicators, highlighting their sensitivity to line-profile distortions and chromatic variability. We then review precision photometry as a tool to search for orbit-locked variability,
flare modulation, and active-region occultations during planetary transits. Chromospheric diagnostics, including Ca II, Halpha, He I, and Na II lines, are presented as tracers of
magnetic variability at different atmospheric heights and as potential probes of intermittent SPI signatures. We also discuss transmission spectroscopy as a complementary approach, since planetary atmospheric tracers such as H I Lyalpha, Balmer lines, C II, and He I can encode information about the
stellar high-energy environment,
stellar wind, and
magnetic coupling. In addition,
radio observations provide a promising avenue to probe
magnetic SPI directly through coherent emission mechanisms. Finally, we examine time-series analysis techniques commonly employed in SPI searches, including generalized Lomb-Scargle periodograms, rolling periodograms, harmonic analyses, and bootstrap-based significance estimation. (abridged)
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All authors P. Figueira, H. Korhonen, A. Buccino, P. Chaturvedi, R. Fares, A. García-Muñoz, B. Montet, L. Peña-Moñino, M. Pérez-Torres, D. Revilla, A. Valio
Astrophysics of Galaxies
ALMA visits the QSO MUSEUM: Connecting molecular gas and the cool circumgalactic medium around 37 z~3 quasars
Jelena Ritter, Fabrizio Arrigoni Battaia, Bo Peng et al. (+5 more)
Extended Ly$\alpha$ emission is ubiquitous around
quasars and traces the cool circumgalactic medium, providing insights into
halo gas dynamics and active
galactic nucleus feedback. However, its connection to the cold molecular gas of the host
galaxies remains largely unexplored. We characterize the molecular gas reservoirs of
quasars at
cosmic noon and investigate their connection to extended Ly$\alpha$ emission using ALMA CO(4-3) observations of 37
quasars at $z\sim3$ from the QSO MUSEUM survey, previously mapped in Ly$\alpha$ with VLT/MUSE. We derive molecular gas masses and gas fractions, explore correlations with Ly$\alpha$ nebula and
quasar properties, and search for CO-emitting companions. We detect 21/37
quasars in CO(4-3), with gas masses of $M_\mathrm{gas}\approx(3-40) \times10^9\,\mathrm{M_\odot}$.
Quasars with the most massive molecular gas reservoirs are associated with the centrally dimmest Ly$\alpha$ nebulae, while those hosting the centrally brightest Ly$\alpha$ nebulae are generally not detected in CO. This suggests that gas and
dust in the hosts regulate Ly$\alpha$ escape and consequently affect the emission from
halo gas. We find evidence that lower-Eddington-ratio
quasars harbor more massive gas reservoirs, while strongly accreting
quasars ($\lambda_\mathrm{Edd} \gtrapprox 0.9$) likely deplete their gas; for example, through powerful
quasar-driven
outflows. Despite their higher molecular gas masses within the sample, CO-detected low-Eddington
quasars exhibit low gas fractions with a median $M_\mathrm{gas}/M_* \sim 0.10$, below what is typically found for inactive
star-forming
galaxies. Six
quasars are marginally resolved in CO, with effective radii up to $\sim 8\,\mathrm{kpc}$. In addition, we detect 14 high-fidelity companion
galaxies, indicating overdense
quasar environments with a
quasar-
galaxy cross-correlation length of $9.81^{+2.22}_{-2.05}\,h^{-1}\mathrm{cMpc}$.
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All authors Jelena Ritter, Fabrizio Arrigoni Battaia, Bo Peng, Jay González Lobos, Chian-Chou Chen, Aura Obreja, Nahir Muñoz-Elgueta, Chiara Circosta
Cosmology and Nongalactic Astrophysics · Cross-listed from hep-ph
Dynamical evolution of the pressure on the bubble wall
Benoit Laurent and Miguel Vanvlasselaer
First-order phase transitions in the early Universe are pivotal for gravitational wave production, baryogenesis, and dark matter generation. A central question is whether bubble walls reach a subjouguet or ultra-relativistic velocity - a distinction governed by hydrodynamic obstruction, where
plasma heating counteracts the
vacuum pressure driving the wall. Traditional analyses assume steady-state fluid profiles, but these may fail during the wall's acceleration phase. We study the dynamical
evolution of the pressure on the bubble wall in local thermal
equilibrium (LTE), combining analytical approximations with numerical hydrodynamic simulations. Our results reveal that the heating wave's formation time often exceeds the wall's acceleration timescale, invalidating steady-state predictions near the Jouguet velocity. We derive a revised criterion for the maximal driving pressure, which separates deflagration/hybrid regimes from detonations/runaway walls. This criterion, validated by simulations, shows that hydrodynamic obstruction is less restrictive than steady state LTE predictions suggest.
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Cosmology and Nongalactic Astrophysics
Fuzzy Dark Matter Halo Mass Functions at Cosmic Dawn
Raghunath Ghara, Adam Lidz, Daniel Grin et al. (+1 more)
In fuzzy dark matter (FDM) cosmological models, wave effects impact astrophysical length scales, suppressing the abundance of small mass dark matter
halos, and delaying the earliest phases of
galaxy formation during
Cosmic Dawn. Current and upcoming James Webb Space
Telescope (JWST) measurements of the
galaxy ultraviolet luminosity function (UVLF) will allow unprecedented tests of this suppression, yet significant uncertainties remain in theoretical models of the FDM
halo mass function. We run a new suite of N-body simulations with FDM particle masses of $mc^{2}=10^{-22}\,{\rm eV} - 2 \times 10^{-21}$ eV and mixed FDM-cold dark matter (CDM) models with FDM mass fractions of $f_{\mathrm{F}} = 0.3-1$. We identify and remove spurious
halos from discreteness noise and quantify the associated systematic uncertainty. We provide a new
halo mass function fitting formula, calibrated over $z=6-11$, applicable to pure FDM and mixed dark matter scenarios. Our results are in better agreement with previous simulation-based fitting formulas than with current semi-analytic mass function models. Nevertheless, for $m c^{2} = 10^{-21}$ eV and $M \sim 3 \times 10^9 M_\odot$ we find a $\sim 30\%$ weaker suppression than earlier simulation-based formulas predict, which we attribute to their extrapolation beyond the $m_{\rm FDM}$ range previously simulated. Applying our fitting formula to the UVLF, we find that upcoming JWST observations behind foreground
lensing clusters, probing $M_{\rm UV} \gtrsim -13$ at $z \gtrsim 10$, will provide a powerful test of FDM and mixed dark matter models.
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All authors Raghunath Ghara, Adam Lidz, Daniel Grin, Jackson Sipple
Astrophysics of Galaxies
Gravitational-Electric Polarization as a Probe of Dark Matter and Modified Gravity
Nirupam Roy
Self-gravitating astrophysical
plasmas naturally achieve a state of global electrical polarization, known as the Bally-Harrison effect, where an induced electric field counteracts the preferential thermal escape of electrons. In this work, we revisit the phenomenon of gravitational-electric polarization in astrophysical
plasmas. By accounting for the dominant role of dark matter and comparing results across modified
gravity frameworks, including MOND and MOG, we provide new constraints on the global charge-to-mass ratios of
galaxies and clusters. We demonstrate that the effective charge-to-baryonic-mass ratio Q/M_bar is enhanced by a factor of 10 - 30 at the virial radii relative to purely baryonic predictions. By coupling gravitational polarization to
galactic rotation, we derive a structurally linked seed field that reaches ~10^{-23} G in high-
redshift proto-
galaxies, sufficient for rapid dynamo saturation. We demonstrate that the distinct spatial signatures of these fields across different
gravity theories provide a potential observational probe of the dark sector in the early universe. This enhancement may have significant implications in inferring properties of the intracluster medium and in determining the
primordial seed
magnetic field. The distinct radial and mass-dependent scaling laws predicted for each paradigm also provide a plausible diagnostic to distinguish between the presence of invisible mass and modifications to the gravitational law.
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Astrophysics of Galaxies
Jarrett Johnson, Phoebe Upton Sanderbeck, Nicole Lloyd-Ronning et al. (+2 more)
It has recently been suggested that a variety of data on active
galactic nuclei (AGN) can be explained if AGN disks are supported against gravitational fragmentation by
magnetic fields that are advected into the disk from the surrounding
galaxy. Here we derive the maximum timescales over which
accretion onto a black hole (BH) powering an AGN can be maintained at a given rate, both with and without
magnetic disk support. We then compare these timescales to the lifetimes of episodes of sustained luminous
accretion that are inferred from measurements of the photoionized proximity zones around high-
redshift quasars. While some of the shortest inferred
quasar lifetimes are consistent with pure gas pressure support, we find that some additional
magnetic support is likely required to explain the longest inferred
quasar lifetimes of > 10$^4$ yr. For these longest-lived AGN, we find that
magnetic pressure in their disks can be up to a hundred times higher than the gas pressure. In addition, the lack of inferred
quasar lifetimes that are definitively > 10$^6$ yr is consistent with gas pressure and advected
magnetic fields being the principal sources of disk support. This adds to the body of evidence that
magnetic fields play an important role in sustaining the rapid growth of supermassive BHs in the early universe.
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All authors Jarrett Johnson, Phoebe Upton Sanderbeck, Nicole Lloyd-Ronning, Madeline Marshall, Kelcey Davis
Solar and Stellar Astrophysics
The Companions to B and A Stars Snapshot (C-BASS) Survey: I. Discovery of a Young Brown Dwarf Companion to HIP 17453
Marah Brinjikji, Adam J. Smith, Jennifer Patience et al. (+26 more)
We report the detection of a new brown
dwarf companion to HIP 17453 A, a chemically peculiar A0V
star located at a distance of 81 pc. HIP 17453 A was observed with high-resolution adaptive optics imaging using the Near-Infrared Camera 2 on the Keck II
telescope as part of the Companions to B and A
Stars Snapshot (C-BASS) survey over a ten-year baseline, revealing the presence of a companion with proper motion consistent with the primary. We estimate the age of the HIP 17453 system as 280 $\pm$ 125 Myr, and with follow-up intermediate resolution (R~1800) spectroscopic observations with the Gemini Near Infra-Red Spectrograph (GNIRS) on the Gemini-North
telescope, we found the spectrum of HIP 17453 B to be consistent with a spectral type of L2 $\pm$ 1. Through interpolation of Sonora Diamondback evolutionary models, we calculate an effective temperature of $1953^{+84}_{-78}$ K and mass of $53^{+10}_{-8}$ $M_{Jup}$ for HIP 17453 B, which corresponds to a mass ratio of $q = 0.024 \pm 0.004$ for the HIP 17453 system. With its intermediate mass and young age, HIP 17453 B joins a small set of
benchmark brown
dwarf companions around early-type
stars that are suitable for follow-up atmospheric and evolutionary studies.
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All authors Marah Brinjikji, Adam J. Smith, Jennifer Patience, Eric Nielsen, Austin Ware, Jorge A. Sanchez, Robert J. De Rosa, Jasmine Garani, Emma Softich, Michael C. Liu, Bruce Macintosh, Thomas M. Esposito, Brendan P. Bowler, William M. Best, Sarah Blunt, Trent Dupuy, Justin Hom, Jessica A. Klusmeyer, Franck Marchis, Jayke S. Nguyen, Anne E. Peck, Mark W. Phillips, William Roberson, Jean-Baptiste Ruffio, William Thompson, Zahed Wahhaj, Samuel A. Walker, Jason J. Wang, Patrick A. Young
Astrophysics of Galaxies
A new era for Dual AGN science with SHARP
P. Severgnini, C. Vignali, A. De Rosa et al. (+21 more)
The search for and the characterization of ultra-compact dual active
galactic nuclei (AGN) are among the hottest topics of current extragalactic astrophysics. These systems involve two accreting massive black holes (MBHs) embedded within the same host
galaxy, with relative projected separations from a few hundred pc down to a few pc. They are central to understanding hierarchical
galaxy formation, black hole growth and demographics, and
accretion-feedback coupling in the most extreme interaction phases. Even more compellingly, such tight pairs are the most direct precursors of gravitationally bound binary MBHs (sub-pc scale separation), which are among the loudest emitters of gravitational waves (GWs) in the low-frequency ranges. SHARP will deliver the first statistical census and physical characterization of ultra-compact dual AGN up to
cosmic distances, finally bridging the observational gap between kpc-scale pairs and sub-pc GW-emitting binaries, and enabling a breakthrough understanding of MBH growth, feedback and co-
evolution across
cosmic time.
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All authors P. Severgnini, C. Vignali, A. De Rosa, E. Portaluri, F. Rigamonti, L. Battistini, L. Bertassi, E. Bertola, S. Bianchi, E. Bortolas, C. Cicone, Q. D'Amato, R. Della Ceca, I. Delvecchio, M. Dotti, J. Harms, I. Lamperti, F. Mannucci, M. Parvatikar, B. Sala, M. Scialpi, R. Serafinelli, J. Singh, M.V. Zanchettin
Astrophysics of Galaxies
AGN-driven outflows in dwarf galaxies from cosmological simulations: Internal properties and observational signatures
Elena Arjona-Gálvez, Arianna Di Cintio, Robert J. J. Grand et al. (+4 more)
While AGN feedback is a key driver of massive
galaxy evolution, its physical properties and observational signatures in the
dwarf regime remain poorly understood. We investigate the impact of AGN-driven
outflows on the ISM of
dwarf galaxies and assess whether these events can be robustly identified through emission-line diagnostics. We analysed a high-resolution cosmological magneto-hydrodynamical zoom-in simulation from the AURIGA project. We focused on a
dwarf galaxy with 1e9.7 M*/Msun hosting a BH of 1e7 Msun. We identified individual
outflow episodes via pressure peaks in the gas surrounding the central BH, tracked the thermodynamic and kinematic history of such gas, and computed synthetic, spatially resolved nebular emission using photoionisation models to construct BPT diagnostic diagrams. We show that AGN activity in this regime produces compact, over-pressurised central bubbles reaching >1e6 K temperatures. These structures accelerate the ISM up to 600km/s, exceeding those driven by
stellar feedback: the outflowing material does not escape the
halo, but instead decelerates and redistributes within 10kpc from the
galaxy center. Synthetic emission-line modelling reveals clear, time-dependent signatures of such AGN-driven feedback. Over its life cycle, the simulated AGN-hosting
galaxy traces the locus of observed
dwarf AGNs and migrates from the SF sequence in the BPT diagrams through the composite region into the AGN regime, highlighting a self-regulation mechanism in which the BH accretes its fuel supply, progressively moving towards the low-ionisation
nuclear region. Our results suggest that AGN-driven
outflows in
dwarfs primarily regulate the central ISM through episodic heating and rapid gas recycling, rather than large-scale gas ejection. These processes generate observable spectroscopic signatures, offering a promising avenue for identifying AGN feedback in low-mass
galaxies.
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All authors Elena Arjona-Gálvez, Arianna Di Cintio, Robert J. J. Grand, Laura V. Sales, Gabriela Canalizo, Teresa Matamoro Zatarain, Aswin P. Vijayan
High Energy Astrophysical Phenomena · Cross-listed from hep-ph
Boosted Dark Matter from Sagittarius A$^\star$
Javier F. Acevedo and Adam Ritz
It was recently demonstrated that black hole binaries can gravitationally accelerate ambient dark matter (DM), producing a continuous flux of particles with velocities far exceeding those of the
galactic halo. We extend this analysis to the Milky Way's
nuclear star cluster, where
stellar-mass black holes are expected to orbit in close proximity to the supermassive black hole Sagittarius A$^\star$. Using numerical simulations, we compute the flux of gravitationally-boosted DM sourced by this region. Because of the high DM density and large population of black holes orbiting deep within Sagittarius A$^\star$'s gravitational potential, the resulting DM ejecta attain substantially higher rates and energies compared to
galactic black hole binaries, with simulated particles reaching velocities of up to $\sim 25,\!000 \, \rm km/s$. We find that the
nuclear star cluster is therefore the dominant source of gravitationally-boosted DM in the Milky Way. Even under conservative assumptions about the DM profile in the inner
galaxy, the ejected DM flux from this region can render large-volume DM detectors competitive with lower-threshold experiments in the sub-GeV mass range, independently of the underlying DM particle model. The gravitational nature of the boost also opens up a sizable detection window into heavy inelastic DM scenarios that are otherwise largely inaccessible to conventional
halo DM searches.
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Earth and Planetary Astrophysics
Chemical Abundances of the Bioessential Elements C, O and S, and the Refractory Elements Fe and Ni, in Solar-type Exoplanet-hosting Stars from HARPS North and South
E. Costa-Almeida, L. Ghezzi, K. Cunha et al. (+2 more)
We determined atmospheric and evolutionary parameters, along with chemical abundances of C, O, S, Fe, and Ni for 290
solar-type
exoplanet hosting
stars using high-resolution HARPS-North and HARPS-South spectra, and radii for 373
exoplanets using literature transit depths. We find that
stars hosting
giant exoplanets (R$_{\text{pl}}>4\ \text{R}_{\oplus}$) show enhanced [X/H] abundances compared to small
exoplanet hosts for all elements analyzed. When considering only
exoplanets with $P_{\text{orb}}\leq30$ days, there is a statistically significant anti-correlation between host
star [Fe/H] and $P_{\text{orb}}$. However, [Fe/H] does not continue to decline as the orbital period increases, but rather rises again for
exoplanets with larger orbital periods.
Stars hosting only small
exoplanets or hosting at least one sub-Saturn show significant differences between the populations of hot and warm
exoplanets for all elements. In contrast,
stars hosting at least one Jupiter-sized
planet show no abundance differences. The host
star C/O ratios obtained vary from 0.17 to 0.95, with
giant exoplanet hosts exhibiting the lowest median C/O ratios (0.43$^{+0.02}_{-0.03}$), while the 3 – 4 R$_\oplus$ sub-Neptune hosts in our sample exhibit the highest median C/O ratios (0.55$^{+0.05}_{-0.01}$). Our sample has 199
exoplanets with estimated masses and we find correlations between host
star [O/H] and [S/H] and $\log(M_{\text{pl}}/\text{M}_\oplus)$. When segregating the sample into hot and warm
exoplanet hosts, these trends are only found for warm
exoplanets. Dividing the sample between low- (91
exoplanets) and high-[$\alpha$/Fe] (20
exoplanets)
stars, there are trends between host
star [O/H], [S/H], [Fe/H] and [Ni/H] and $\log(M_{\text{pl}}/\text{M}_\oplus)$ only for the low-[$\alpha$/Fe] sample.
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All authors E. Costa-Almeida, L. Ghezzi, K. Cunha, V. V. Smith, J. J. Fortney
Instrumentation and Methods for Astrophysics
SHARP – A spectrograph proposal to fully exploit ELT capabilities and look beyond JWST
P. Saracco, P. Conconi, C. Arcidiacono et al. (+47 more)
The Extremely Large
Telescopes (ELTs), with their large apertures and cutting-edge Multi-Conjugate Adaptive Optics (MCAO) systems, promise to deliver data that is both sharper and deeper than even the James Webb Space
Telescope (JWST) across large fields. SHARP is a concept study for a near-IR (0.95-2.45 $\mu$m) spectrograph specifically designed to fully exploit the collecting area and angular resolution capabilities of the upcoming ESO's ELT. The instrument concept is driven by the goal of tackling the most important questions in astrophysics and cosmology, from exploring
primordial galaxies to studying the formation of young
stellar object and planetary systems in the nearby
dust-enshrouded regions, bridging the gap between the local and the distant Universe. This requires versatility to accommodate diverse observational needs. SHARP is composed of two main units: NEXUS, a Multi-Object Spectrograph (MOS) optimized for detecting the faintest sources, and VESPER, a multi-object Integral Field Unit (multi-IFU) designed for brighter ones. This article provides an overview of the scientific design drivers, the solutions developed to meet them, and the resulting optical design that achieves the required performance.
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All authors P. Saracco, P. Conconi, C. Arcidiacono, H. Mahmoodzadeh, I. Di Antonio, E. Portaluri, P. Franzetti, A. Gargiulo, I. Arosio, L. Barbalini, G. Lops, E. Molinari, J. M. Alcala, S. Bisogni, R. Bonito, E. Bortolas, M. Cantiello, A. Caratti o Garatti, E. Cascone, V. Cianniello, E. M. Corsini, F. Damiani, F. D'Ammando, F. D'Alessio, E. Dalla Bonta, M. DallOra, V. De Caprio, G. De Lucia, B. Di Francesco, G. Di Rico, V. D'Orazi, C. Eredia, A. R. Gallazzi, M. G. Guarcello, L. Izzo, F. La Barbera, M. M. Lippi, M. Longhetti, A. Longobardo, C. Mancini, M. Mirabile, E. Piconcelli, A. Pizzella, L. Podio, L. Prisinzano, C. Tortora, G. Vietri, F. Vitali, H.-F. Wang, S. Zibetti
Astrophysics of Galaxies
Global trends in morphology from massive to dwarf galaxies
Ilin Lazar, Sugata Kaviraj, Christopher J. Conselice et al. (+7 more)
The morphological properties of
dwarf galaxies (Mstar < 10^9.5 MSun) remain largely unexplored, particularly outside the local neighbourhood. We explore how morphology changes across the massive to
dwarf-
galaxy regimes, using a mass-complete sample of ~1000
galaxies, with
stellar masses and
redshifts in the ranges 10^7 MSun < Mstar < 10^12 MSun and z < 0.15 respectively. By combining JWST-derived morphological parameters (concentration, asymmetry and clumpiness; `CAS') and visual morphological classifications, we explore: (1) how morphology changes with
stellar mass and effective surface brightness, (2) the connection between morphology and recent
star formation history, as a function of
stellar mass, (3) how bar frequency changes between the massive and
dwarf regimes and (4) how well the CAS parameters perform in separating early- and late-type
galaxies, as a function of
stellar mass. We demonstrate that
galaxies become less concentrated, more asymmetric and less clumpy with decreasing
stellar mass. In both mass regimes,
galaxies that are more concentrated and less asymmetric are more likely to be red (i.e. quenched). The decrease in concentration towards lower
stellar masses results in a loss of the leverage that this parameter can provide in separating early- and late-type
galaxies. Thus, while the CAS system successfully separates early- and late-type systems in the massive-
galaxy regime, these morphological classes become significantly more difficult to separate, using these parameters, in the
dwarf regime. Finally, the bar fraction declines steadily with decreasing
stellar mass and becomes consistent with zero at Mstar ~ 10^8 MSun, suggesting a lower limit for the
galaxy mass needed to induce bar formation.
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All authors Ilin Lazar, Sugata Kaviraj, Christopher J. Conselice, Lewi Westcott, Aaron E. Watkins, Sophie Koudmani, Garreth Martin, Thomas M. Sedgwick, Darshan Kakkad, Brian Bichang'a
Astrophysics of Galaxies
Tidal origin of dark-matter free dwarf galaxies in the NGC 1052 group
Francois Hammer and Yanbin Yang
The discovery of dark matter-free (DM-free)
dwarf galaxies in the NGC 1052 neighborhood has had a considerable impact on modern cosmology. The
galaxies have been explained through a
dwarf–
dwarf head-on collision, a rare event. We find that they could alternatively be associated with a head-on 1:1 merger after it was tuned to generate the E4 morphology of NGC 1052. Our simulations show that such mergers produce long-lived
tidal features, are associated with the remnant
galaxy, and are in the form of large
tidal tails, including
tidal dwarf galaxies (TDGs). We emphasise that such
tidal features are predicted by the hierarchical scenario in which massive
galaxies are formed by
galaxy mergers. The latter can reproduce both the
tidal features in the NGC1052 outskirts and the observed
dwarf galaxies. The simulated TDGs have sizes similar to those observed, while they are ten times smaller in the bullet
dwarf scenario. However, we cannot reproduce the luminous globular cluster systems due to resolution limitations. Resolving the radial distance between the DM-free
dwarfs is necessary to identify the scenario of their formation. We suggest that there should be many other examples of DM-free
dwarf galaxies in the neighbourhood of local massive
galaxies and
galaxy groups.
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Astrophysics of Galaxies
Hunting Wandering 3<z<8 Black Holes: Spatial Offsets in Ionization Ratio and Continuum Emission
Urvi Thakurdesai, Anthony J. Taylor, Steven L. Finkelstein et al. (+14 more)
The early growth and assembly of supermassive black holes (SMBHs) remain key topics of interest in
galaxy evolution. One of the scenarios predicted by theoretical models is that frequent minor mergers and asymmetric gas inflows may cause SMBHs to temporarily reside off-center within their host
galaxies in the early universe. To observationally test this scenario, we investigate whether spatially offset ionization signatures-which may be indicative of active
galactic nuclei (AGN)-can be identified. Using JWST NIRSpec PRISM spectroscopy from the
Cosmic Evolution Early Release Science (CEERS) survey, we analyze the 2D spectra of 90 high-
redshift galaxies (3 < z < 8), including two known broad-line AGN. By measuring key emission lines such as H{\alpha}, H{\beta}, [OIII]{\lambda}5007, [NeIII]{\lambda}3868, and [OII]{\lambda}{\lambda}3727, 3729 we derive spatial flux ratio profiles, and focus on [OIII]/H{\beta} as a tracer of high-ionization mechanisms that may indicate AGN activity. We identify 26
galaxies (~30% of the sample) with significant localized peaks in [OIII]/H{\beta}. Out of these 26
galaxies, 12 sources (~46%) exhibit significant spatial offsets between the peak [OIII]/H{\beta} ratio and the
stellar continuum center. Six of these sources show the highest amount (> 1.5) pixel spatial offsets. This spatial offset between ionization structure and
stellar centers offers a promising avenue to probe early SMBH
evolution and its connection to
galaxy formation.
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All authors Urvi Thakurdesai, Anthony J. Taylor, Steven L. Finkelstein, Gene C. K. Leung, Oscar A. Chavez Ortiz, Jonathan R. Trump, Bren E. Backhaus, Nikko J. Cleri, Francesco D'Eugenio, Fabio Pacucci, Anton M. Koekemoer, Pablo Arrabal Haro, Micaela Bagley, Mark Dickinson, Jeyhan Kartaltepe, Casey Papovich, Nor Pirzkal