Astrophysics of Galaxies
From Primordial Stars to Early Galaxies: A Semi-Analytic Model Calibrated with Aeos and Renaissance
Ryan Hazlett, Jennifer Mead, Eli Visbal et al. (+6 more)
We present an extension of our semi-analytic model that follows the formation of Population III
stars and their metal-enriched descendants, incorporating dark matter
halo merger trees from cosmological $N$-body simulations and feedback from reionization. Our extended model is calibrated using two complementary cosmological hydrodynamical simulations: Aeos, which resolves individual Population III and II
stars to $z\sim14.6$, and Renaissance, which is lower resolution but follows large-scale metal-enriched
star formation to $z \sim 11$. With a combined calibration, we capture small-scale physics of
primordial star formation over a large range in
halo mass. We find good agreement between our calibrated model and Aeos, reproducing the
evolution in number of
star-forming
halos and total
stellar mass. Achieving this agreement requires increasing the normalization of, flattening the
redshift dependence of, and adding scatter to the commonly used critical mass threshold $M_{\mathrm{crit}}$. Our treatment of the delay between Pop III
stellar death and subsequent Pop II
star formation emphasizes the need to account for
halos that have yet to transition to Pop II, since incomplete sampling of this delay in simulations limits physically motivated calibrations. Finally, we apply our model to larger-volume dark matter only simulations and predict $\sim10$ active Pop III sources at $z = 10$ lie within the area strongly lensed by
galaxy cluster MACS J0416 with a magnification exceeding $\mu > 30$. These results demonstrate that semi-analytic approaches, when calibrated to hydrodynamical simulations, can provide accurate, computationally efficient predictions for the earliest stages of
cosmic star formation.
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All authors Ryan Hazlett, Jennifer Mead, Eli Visbal, Greg L. Bryan, Mordecai-Mark Mac Low, Mihir Kulkarni, Eric P. Andersson, Kaley Brauer, John H. Wise
Astrophysics of Galaxies
JADES Dark Horse: demonstrating high-multiplex observations with JWST/NIRSpec dense-shutter spectroscopy in the JADES Origins Field
Francesco D'Eugenio, Erica J. Nelson, Daniel J. Eisenstein et al. (+40 more)
We present JWST/NIRSpec dense-shutter spectroscopy (DSS). This novel observing strategy with the NIRSpec/MSA deliberately permits a high number of controlled spectral overlaps to reach extreme multiplex while retaining the low background of slit spectroscopy. In a single configuration over the JADES Origins Field, we opened shutters on all faint (mF444W$<$30 mag) z$_\mathrm{phot}>$3 candidates, prioritising emission-line science and rejecting only bright continuum sources. Using 33.6 and 35.8 ks on-source in G235M and G395M, we observed a single mask with $\sim$850 sources, obtaining spectroscopic
redshifts for $\sim$540
galaxies over 2.5$<$z$<$8.9. The per-configuration target density in DSS mode is 4-5x higher than standard no- and low-overlap MSA strategies ($<$200 sources), with no loss in
redshift precision or accuracy. Line-flux sensitivities are 30 percent lower at fixed exposure time, matching the expected increase in background noise, but the gain in survey speed is 5x in our setup, more than justifying the penalty. The measured line sensitivity exceeds NIRCam/WFSS by at least $\sim$5x ($\sim$25x in exposure time) at $\lambda\sim4\,\mu$m, demonstrating that DSS is a compelling method to gain deep, wide-band spectra for large samples. Crucially, NIRSpec/MSA could deliver even higher target allocation densities than those used here. We derive H$\alpha$-based SFRs, gas-phase
metallicities (including a large sample suitable for strong-line calibrations), and identify rare mini-quenched
galaxies and broadline AGN. DSS is immediately applicable wherever deep imaging enables robust pre-selection and astrometry, providing an efficient method to obtain large samples of faint emission-line
galaxies, a compelling middle ground between the completeness of slitless surveys and the sensitivity and bandwidth of NIRSpec/MSA.
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All authors Francesco D'Eugenio, Erica J. Nelson, Daniel J. Eisenstein, Roberto Maiolino, Stefano Carniani, Jan Scholtz, Mirko Curti, Christopher N. A. Willmer, Andrew J. Bunker, Jakob M. Helton, Ignas Juodžbalis, Fengwu Sun, Sandro Tacchella, Santiago Arribas, Alex J. Cameron, Stéphane Charlot, Emma Curtis-Lake, Kevin Hainline, Benjamin D. Johnson, Brant Robertson, Christina C. Williams, Chris Willott, William M. Baker, Jacopo Chevallard, A. Lola Danhaive, Yuki Isobe, Xihan Ji, Zhiyuan Ji, Gareth C. Jones, Nimisha Kumari, Tobias J. Looser, Jianwei Lyu, Eleonora Parlanti, Michele Perna, Dávid Puskás, Pierluigi Rinaldi, Charlotte Simmonds, Yang Sun, Hannah Übler, Giacomo Venturi, Joris Witstok, Zihao Wu, Yongda Zhu
Cosmology and Nongalactic Astrophysics
Cristian Joana and Zi-Yan Yuwen
Primordial black holes (PBHs) are a compelling dark matter candidate and a unique probe of small-scale cosmological fluctuations. Their formation is usually attributed to large positive
curvature perturbations, which collapse upon Hubble re-entry during radiation domination. In this work we investigate instead the role of negative
curvature perturbations, corresponding to the growth of
primordial void (PV) like regions. Using numerical relativity simulations, we show that sufficiently deep PV can undergo a nonlinear rebounce at the center, generating an effective overdensity that eventually collapses into a PBH. We determine the critical threshold for this process for a variety of equations of state, and demonstrate that the resulting black holes obey a scaling relation analogous to the standard overdensity case. These results establish
primordial voids as a novel channel for PBH formation and highlight their potential impact on PBH abundances and cosmological signatures.
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Solar and Stellar Astrophysics
Precise boron abundance in a sample of metal-poor stars from far-ultraviolet lines
Monique Spite, Beatriz Barbuy and Kefeng Tan
The light elements beryllium (Be; $Z=4$) and boron (B; $Z=5$) are mainly produced by spallation reactions between
cosmic rays and carbon (C; $Z=6$), nitrogen (N; $Z=7$), and oxygen (O; $Z=8$)
nuclei. Only traces of Be or B would have been produced in the Big Bang, but there could be a contribution from the $\nu$-process in type II
supernovae. Their abundances at very low
metallicities have been debated in the literature, with the aim of understanding their origin. Our aim is to derive the boron abundance in a sample of metal-poor
stars based for the first time on observations with the STIS spectrograph on board the Hubble Space
Telescope, using clean B lines measured in space ultraviolet. We identified a measurable line of B I at 2089.6 A. In our sample of metal-poor warm
stars, this line is practically free from blending lines, and for this reason the precision of the presently derived boron abundances is unprecedented. We find that in the interval -2.6<[Fe/H]<-1.0, the slope of the relation A(B) versus [Fe/H] is significantly larger than 1, and thus steeper than that obtained with Be abundances. As a consequence, we find in this interval of
metallicity a B/Be ratio that slightly increases with [Fe/H]. Since at [Fe/H]=-1 the abundance of B is already close to the
solar abundance, there should be a break in the B enrichment at a
metallicity of about [Fe/H]=-1.
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Astrophysics of Galaxies
JWST/MIRI-MRS view of the metal-poor galaxy CGCG 007-025: the spatial location of PAHs and very highly ionized gas
Macarena G. del Valle-Espinosa, Matilde Mingozzi, Bethan James et al. (+16 more)
Polycyclic Aromatic Hydrocarbons (PAHs) are key diagnostics of the physical conditions in the interstellar medium and are widely used to trace
star formation in the mid-infrared (mid-IR). The relative strengths of mid-IR PAH emission features (e.g., 6.2, 7.7, 11.3 um) are sensitive to both the size and ionization state of the molecules and can be strongly influenced by the local radiation field. However, at low
metallicities ( Z < 0.2 Zsun), detecting PAHs remains notoriously difficult, likely reflecting a combination of suppressed formation and enhanced destruction mechanisms. We present new JWST/MIRI MRS observations of the metal-poor (Z = 0.1 Zsun)
dwarf galaxy CGCG 007-025. We confirm the tentative PAH detection previously reported from Spitzer data and, for the first time, identify a compact (approx. 50 pc) PAH-emitting region nearly co-spatial with the newly detected [NeV](I.P. = 97 eV) emission and the
galaxy's most metal-poor, strongly
star-forming region. The 11.3 and 12.7 um PAH features are detected, while no emission is found from the other typically brighter features, suggesting a PAH population dominated by large, neutral molecules resilient to hard ionizing fields. When compared with models, mid-IR line ratios involving [NeIII], [OIV], and [NeV] can only be reproduced by a combination of
star formation and AGN ionization, with the latter contributing 4–8%. The [OIV] and [NeV] luminosities exceed what massive
stars or shocks can produce, highlighting a puzzling scenario in line with recent JWST observations of similar
galaxies. This work provides a crucial reference for studying the physical conditions of the
dust and
star formation in low-
metallicity starburst regions, environments typical of the early universe.
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All authors Macarena G. del Valle-Espinosa, Matilde Mingozzi, Bethan James, Ruben Sanchez-Janssen, Juan Antonio Fernandez-Ontiveros, Ryan J. Rickards Vaught, Ricardo O. Amorin, Leslie Hunt, Alessandra Aloisi, Karla Z. Arellano-Cordova, Danielle A. Berg, John Chisholm, Matthew Hayes, Svea Hernandez, Alec Hirschauer, Logan Jones, Crystal L. Martin, Livia Vallini, Xinfeng Xu
Solar and Stellar Astrophysics
NGTS-EB-8: A double-lined eclipsing M+M binary discovered by citizen scientists
Sean M. O'Brien, Megan E. Schwamb, Christopher A. Watson et al. (+54 more)
We report the identification and characterization of a new binary system composed of two near-equal mass M-
dwarfs. The binary NGTS-EB-8 was identified as a
planet candidate in data from the Next Generation Transit Survey (NGTS) by citizen scientists participating in the
Planet Hunters NGTS project. High-resolution spectroscopic observations reveal the system to be a double-lined binary. By modeling the photometric and radial velocity observations, we determine an orbital period of 4.2 days and the masses and radii of both
stars to be $M_A=0.250^{+0.005}_{-0.004}$ M$_{\odot}$, $M_B=0.208^{+0.005}_{-0.004}$ M$_{\odot}$, $R_A=0.255^{+0.004}_{-0.005}$ R$_{\odot}$, $R_B=0.233^{+0.006}_{-0.005}$ R$_{\odot}$. We detect Balmer line emission from at least one of the
stars but no significant
flare activity. We note that both components lie in the fully convective regime of low-mass
stars ($<0.35$ M$_{\odot}$), therefore can be a valuable test for
stellar evolutionary models. We demonstrate that the photometric observations, speckle imaging and initial radial velocity measurements were unable to identify the true nature of this system and highlight that high-resolution spectroscopic observations are crucial in determining whether systems such as this are in fact binaries.
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All authors Sean M. O'Brien, Megan E. Schwamb, Christopher A. Watson, Louise D. Nielsen, Edward M. Bryant, Sarah L. Casewell, Matthew R. Burleigh, Lucy Fortson, Samuel Gill, Chris J. Lintott, Katlyn L. Hobbs, Ioannis Apergis, Daniel Bayliss, Jorge Fernández Fernández, Maximilian N. Günther, Faith Hawthorn, James S. Jenkins, Alicia Kendall, James McCormac, Ernst J. W. de Mooij, Toby Rodel, Suman Saha, Laura Trouille, Richard G. West, Peter J. Wheatley, Marius Constantin Agafitei, Deniz Rüzgar Apayd{\i}n, Elisabeth Baeten, Bruce Baller, Jeff Carabott, Sallyann Chesson, Sebastián Alejandro Freigeiro, Virgilio Gonano, Matthias Hanke, Pete Hermes, Avery Hildebrand, John S. Langley, See Min Lim, Leo Ryan McCarthy, Graham Mitchell, Ken O'Neill, Charles R. Pearson, Nolan Reket, Jeanne Riethmiller, Juergen Saeftel, Arttu Sainio, Charlie Steiner, Amanda Strickland, Christopher Tanner, Ivan A. Terentev, Ernest Jude P. Tiu, Sergey Y. Tumanov, Marciniak Urszula, Pia Vahlenkamp, Femke de Vroome, Paweł Wantuch, Timothy Woodruff
Cosmology and Nongalactic Astrophysics
$O_k$ null test with multi-task Gaussian processes: cosmic curvature and data compatibility
Yungui Gong, Qing Gao, Xuchen Lu et al. (+1 more)
The $O_k$ null test can not only assess whether the
cosmic curvature is zero, therefore if true reducing degeneracies between
cosmic curvature and other cosmological parameters, but also provide a model-independent check of compatibility between different data sets. However, traditional implementations often require absolute distance data from Type Ia
supernovae (SNe Ia) or
baryon acoustic oscillation (BAO) measurements, limiting their applicability because such absolute distance data usually are not accessible. The BAO Alcock Paczynski (AP) parameter $F_{AP}$ is a measurement of a distance ratio, making the Dark Energy Spectroscopic Instrument (DESI) AP measurements particularly well suited for the $O_k$ null test because no absolute distance measurements are required. We propose a novel null test of
cosmic curvature tailored to DESI BAO data that combines $F_{AP}$ with ratios such as $D_V'/D_V$ or $D_M'/D_M$. Crucially, this construction eliminates the need for absolute distance measurements. We further develop multi-task Gaussian processes to perform the null test. This approach can also be applied to a joint DESI BAO and SNe Ia
dataset, and we find that DESI BAO and SNe Ia data are compatible. Although there is $\sim 2\sigma$ evidence of nonzero
curvature at low
redshift $z\lesssim 0.5$, this result is not conclusive largely due to the lack of observational data in the corresponding
redshift range.
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All authors Yungui Gong, Qing Gao, Xuchen Lu, Zhu Yi
Solar and Stellar Astrophysics
Asteroseismic investigation of HD 140283: The Methuselah star
M. S. Lundkvist, J. R. Larsen, Y. Li et al. (+12 more)
HD 140283 is a well-studied metal-poor subgiant and a
Gaia benchmark star, often used for testing
stellar models due to its proximity, brightness, and low
metallicity ([Fe/H] = -2.3 dex). Here we present the first asteroseismic analysis of HD 140283, providing improved constraints on its fundamental properties. The
star was observed by TESS in 20-second cadence during Sector 51. We extracted a custom light curve and performed a frequency analysis, revealing a rich spectrum of
solar-like oscillations including mixed modes. These were combined with parameters from the literature to provide constraints on our model inference performed with BASTA. Using a dense grid of models, we find a mass of $0.75 \pm 0.01 \ \mathrm{M}_\odot$, a radius of $2.078 \substack{+0.012\\-0.011} \ \mathrm{R}_\odot$, and an age of $14.2 \pm 0.4$ Gyr, in agreement with the upper limit set by the age of the Universe within $1\sigma$. The observed frequency of maximum power, $\left(\nu_\mathrm{max}\right)_\mathrm{obs} = 611.3 \pm 7.4 \ \mu\mathrm{Hz}$, is significantly higher than predicted from standard scaling relations ($\left(\nu_\mathrm{max}\right)_\mathrm{mod} = 537.2 \substack{+2.9\\-1.8} \ \mu\mathrm{Hz}$), extending known deviations into the metal-poor regime. To our knowledge, the oscillations in HD 140283 have the highest $\nu_\mathrm{max}$ of any metal-poor
star to date, which will help to advance our understanding of oscillations in metal-poor
stars in general. The results demonstrate the value of asteroseismology for precise age determination in old
halo stars and taking custom abundances and opacities into account during the modelling is probably important for further improving models of such
stars. In addition, a detailed characterisation of metal-poor
stars, such as HD 140283, will also help advance our understanding of Population III
stars and their impact on future
stellar generations.
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All authors M. S. Lundkvist, J. R. Larsen, Y. Li, M. L. Winther, T. R. Bedding, H. Kjeldsen, T. R. White, M. B. Nielsen, G. Buldgen, C. Guillaume, A. L. Stokholm, D. Huber, J. L. Rørsted, P. Mani, F. Grundahl
Earth and Planetary Astrophysics
MANGOS II: Five new giant planets orbiting low-mass stars
G. Dransfield, M. Timmermans, D. Sebastian et al. (+47 more)
Giant planets orbiting low-mass
stars on short orbits present a conundrum, as in the most extreme cases their existence cannot be reconciled with current models of core
accretion. Therefore, surveys dedicated to finding these rare
planets have a key role to play by growing the sample to overcome small number statistics. In this work we present MANGOS, a programme dedicated to the search for
giant objects (
planets, brown
dwarfs, and low-mass
stars) orbiting M
dwarfs. We report on the discovery of five new
giant planets (TOI-3288 Ab, TOI-4666 b, TOI-5007 b, TOI-5292 Ab, TOI-5916 b) first detected by TESS, and confirmed using ground-based photometry and spectroscopy. The five
planets have radii in the range 0.99-1.12 $\mathrm{R_{Jup}}$, masses between 0.49–1.69~$\mathrm{M_{Jup}}$, and orbital periods between 1.43 and 2.91 days. We reveal that TOI-3288 and TOI-5292 are wide binaries, and in the case of TOI-5292 we are able to characterise both
stellar components. We demonstrate that the
planets presented are suitable for further characterisation of their obliquities and atmospheres. We detect a small but significant eccentricity for TOI-5007 b, although for this to be more robust, more observations are needed to fully sample the orbit. Finally, we reveal a correlation between
stellar metallicity and
planet bulk density for
giant planets orbiting low-mass
stars.
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All authors G. Dransfield, M. Timmermans, D. Sebastian, B. V. Rackham, A. Burgasser, K. Barkaoui, A. H. M. J. Triaud, M. Gillon, J. M. Almenara, S. L. Casewell, K. A. Collins, A. Fukui, C. Jano-Munoz, S. Kanodia, N. Narita, E. Palle, M. G. Scott, A. Soubkiou, A. Stokholm, J. Audenaert, G. Á. Bakos, Y. Beletsky, Z. L. de Beurs, Z. Benkhaldoun, A. Burdanov, R. P. Butler, D. Caldwell, J. D. Crane, Y. T. Davis, B.O. Demory, E. Ducrot, Y. Gómez Maqueo Chew, M. Gachaoui, J. D. Hartman, M. J. Hooton, E. Jehin, S. Mercier, F. Murgas, C. Murray, P. P. Pedersen, F. J. Pozuelos, M. Rice, G. Ross, S. A. Shectman, E. Softich, M. Tala Pinto, A. M. Vanderburg, J. Villasenor, J. de Wit, S. Zúñiga-Fernández
Earth and Planetary Astrophysics
Characterizing planetary systems with SPIRou: questions about the magnetic cycle of 55 Cnc A and two new planets around B
C. Moutou, P. Petit, P. Charpentier et al. (+12 more)
One of the first
exoplanet hosts discovered thirty years ago, the
star 55 Cnc has been constantly observed ever since. It is now known to host at least five
planets with orbital periods ranging from 17 hours to 15 years. It is also one of the most extreme metal rich
stars in the neighbourhood and it has a low-mass secondary
star. In this article, we present data obtained at the Canada-France-Hawai'i
Telescope with the SPIRou spectropolarimeter on both components of the 55 Cnc
stellar system. We revisit the long-period radial-velocity signals of 55 Cnc A, with a focus on the role of the
magnetic cycle, and propose the existence of a sixth
planet candidate, whose period falls close to that of the
magnetic cycle, or half of it. The other massive outer
planet has a revised period of 13.15 years and a minimum mass of 3.8 MJup. Although some uncertainty remains on these outer
planets, the characterization of the four inner
planets is very robust through the combination of many different data sets, and all signals are consistent in the nIR and optical domains. In addition, the
magnetic topology of the
solar-type primary component of the system is observed by SPIRou at the minimum of its activity cycle, characterized by an amplitude ten times smaller than observed during its maximum in 2017. For the low-mass component 55 Cnc B, we report the discovery of two
exoplanets in the system, with a period of 6.799+-0.0014 and 33.75+-0.04 days and a minimum mass of 3.5+-0.8 and 5.3+-1.4 MEarth, respectively. The secondary
magnetic field is very weak and the current data set does not allow its precise characterization, setting an upper limit of 10 G. The system 55 Cnc stands out as the sixth binary system with planetary systems around both components, and the first one with non equal-mass
stellar components.
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All authors C. Moutou, P. Petit, P. Charpentier, P. Cristofari, C. Baruteau, P. Thébault, L. Arnold, E. Artigau, A. Carmona, N.J. Cook, F. Debras, X. Delfosse, J.-F. Donati, L. Malo, M. Ould-Elhkim
Earth and Planetary Astrophysics
The GAPS programme at TNG LXXI. A sub-Neptune suitable for atmospheric characterization in a multiplanet and mutually inclined system orbiting the bright K dwarf TOI-5789 (HIP 99452)
A. S. Bonomo, L. Naponiello, A. Sozzetti et al. (+37 more)
Sub-Neptunes with planetary radii of $R_{p} \simeq 2-4 R_{\oplus}$ are the most common
planets around
solar-type
stars in short-period ($P<100$ d) orbits. It is still unclear, however, what their most likely composition is, that is whether they are predominantly gas
dwarfs or water worlds. The sub-Neptunes orbiting bright host
stars are very valuable because they are suitable for atmospheric characterization, which can break the well-known degeneracy in
planet composition from the
planet bulk density, when combined with a precise and accurate mass measurement. Here we report on the characterization of the sub-Neptune TOI-5789 c, which transits in front of the bright ($V=7.3$ mag and $K_{s}=5.35$ mag) and magnetically inactive K1V
dwarf HIP 99452 every 12.93 days, thanks to TESS photometry and 141 high-precision radial velocities obtained with the HARPS-N spectrograph. We find that its radius, mass, and bulk density are $R_{c}=2.86^{+0.18}_{-0.15} R_\oplus$, $M_{c}=5.00 \pm 0.50 M_\oplus$, and $\rho_{c}=1.16 \pm 0.23$ g cm$^{-3}$, and we show that TOI-5789 c is a promising target for atmospheric characterization with both JWST and, in the future, Ariel. By analyzing the HARPS-N radial velocities with different tools, we also detected three additional non-transiting
planets, namely TOI-5789 b, d, and e, with orbital periods and minimum masses of $P_{b}=2.76$ d, $M_{b}\sin{i}=2.12 \pm 0.28 M_\oplus$, $P_{d}=29.6$ d, $M_{d}\sin{i}=4.29 \pm 0.68 M_\oplus$, and $P_{e}=63.0$ d, $M_{e}\sin{i}=11.61 \pm 0.97 M_\oplus$. TOI-5789 is a mutually inclined system as the difference between the orbital inclinations of
planets b and c must be higher than $\sim4$ deg. Nevertheless, from sensitivity studies based on both the HARPS-N and archival HIRES radial-velocity measurements, we can exclude that these relatively high mutual inclinations are due to the perturbation by an outer gaseous
giant planet.
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All authors A. S. Bonomo, L. Naponiello, A. Sozzetti, S. Benatti, I. Carleo, K. Biazzo, P. E. Cubillos, M. Damasso, C. Di Maio, C. Dorn, N. Hara, D. Polychroni, M.-L. Steinmeyer, K. A. Collins, S. Desidera, X. Dumusque, A. F. Lanza, B. S. Safonov, C. Stockdale, D. Turrini, C. Ziegler, L. Affer, M. D'Arpa, V. Fardella, A. Harutyunyan, V. Lorenzi, L. Malavolta, L. Mancini, G. Mantovan, G. Micela, F. Murgas, D. Nardiello, I. Pagano, E. Pallé, M. Pedani, M. Pinamonti, M. Rainer, G. Scandariato, R. Spinelli, T. Zingales
Earth and Planetary Astrophysics
A Metal-Rich Atmosphere with a Super-Solar C/O Ratio for the Extreme Ultra-Hot Jupiter WASP-178b
Suman Saha and James S. Jenkins
The population of ultra-hot Jupiters (UHJs) provide unique opportunities to probe the extreme formation and evolutionary pathways in
exoplanets. Owing to their very high temperatures and inflated atmospheres, UHJs are among the most favorable targets for both transmission and emission spectroscopy, enabling detailed characterization of their atmospheric properties. Here, we present a reanalysis of the JWST NIRSpec/G395H transmission spectra of the extreme ultra-hot Jupiter (EUHJ) WASP-178b, aimed at precisely characterizing its atmospheric composition. Our approach combines data reduction using two independent pipelines, lightcurve modeling with robust detrending techniques, and rigorous atmospheric
retrievals. We report statistically significant detections of CO (7.24 $\sigma$) and CO$_2$ (7.22 $\sigma$), along with marginal evidence for C$_2$H$_2$ (1.34 $\sigma$), but no clear evidence for H$_2$O, suggesting depletion. From these retrieved abundances, we constrain the C/O ratio to a precise super-
solar value of 0.954$\pm$0.033, consistent with an emerging trend in other UHJs. We also infer a very high atmospheric
metallicity for a Jupiter-sized gas
giant$\unicode{x2014}$11.44$_{-6.94}^{+12.54}$ $\times$
solar$\unicode{x2014}$indicating unique atmospheric evolutions. These findings provide a critical
benchmark for an extreme
exoplanet atmosphere, offering a testbed for developing next-generation atmospheric
evolution models and enabling comparative population-level studies across the UHJ population.
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High Energy Astrophysical Phenomena
Proton-rich production of lanthanides: the $\nu i$ process
Xilu Wang, Amol V. Patwardhan, Yangming Lin et al. (+7 more)
The astrophysical origin of the lanthanides is an open question in
nuclear astrophysics. Besides the widely studied $s$, $i$, and $r$ processes in moderately-to-strongly
neutron-rich environments, an intriguing alternative site for lanthanide production could in fact be robustly $\textit{proton-rich}$ matter
outflows from core-collapse
supernovae under specific conditions – in particular, high-
entropy winds with enhanced
neutrino luminosity and fast dynamical timescales. In this environment, excess
protons present after charged particle reactions have ceased can continue to be converted to
neutrons by (anti-)
neutrino interactions, producing a
neutron capture reaction flow up to A~200. This scenario, christened the $\nu i$ process in a recent paper, has previously been discussed as a possibility. Here, we examine the prospects for $\nu i$ process through the lens of
stellar abundance patterns, bolometric lightcurves, and
galactic chemical
evolution models, with a particular focus on hypernovae as candidate sites. We identify specific lanthanide signatures for which the $\nu i$ process can provide a credible alternative to $r$/$i$ processes.
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All authors Xilu Wang, Amol V. Patwardhan, Yangming Lin, Junbo Zheng, Michael J. Cervia, Yanwen Deng, A. Baha Balantekin, Haining Li, Ian U. Roederer, Rebecca Surman
Astrophysics of Galaxies
Feeding the Dead: Neutral Gas Inflow in a Long-Quenched Ancient Massive Galaxy at $z\sim 2.7$ Observed with JWST/NIRSpec
Davide Bevacqua, Danilo Marchesini, Paolo Saracco et al. (+16 more)
We report the spectroscopic detection of neutral gas inflow into a massive ($M_* \simeq 4\times 10^{10} M_\odot$) quiescent
galaxy observed at $z_{\rm{spec}} = 2.6576$ with JWST. From the redshifted absorption of the NaI doublet at $\lambda \lambda 5890, 5896 $ Ang, we estimate an inflow velocity $v=278^{+79}_{-79}$ km s$^{-1}$ and a column density $\log(N_{NaI}/\rm{cm^2}) = 13.02^{+0.03}_{-0.03}$. We derive the inflowing mass of the gas $M_{in} = 1.6^{+0.1}_{-0.1} \times 10^8 M_\odot$ and rate $\dot{M}_{in} = 19^{+6}_{-7} \, M_\odot \, \rm{yr}^{-1}$. The presence of several surrounding
galaxies suggests that the
galaxy may be accreting gas from nearby companions. However, we cannot confirm it with current data and the intergalactic medium or
cosmic filaments are also viable sources of the inflowing gas. Despite the ongoing inflow, the
galaxy remains quiescent, with an upper limit to the
star formation rate of $0.2 \, M_\odot \, \rm{yr}^{-1}$. Moreover, its
star formation history suggests that the
galaxy has remained quiescent during the past $\sim1$ Gyr, with half of its
stars formed by
redshift $z_{50}=11^{+18}_{-3}$. We discuss that the inflow is not massive, dense, or long-lived enough to ignite significant
star formation, or it is fueling low-level AGN activity instead. This is direct evidence that quiescent
galaxies can accrete cold gas after their quenching while keeping their
star formation subdued. Follow-up observations with JWST and ALMA will be needed to constraint the nature of the inflowing gas.
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All authors Davide Bevacqua, Danilo Marchesini, Paolo Saracco, Francesco La Barbera, Richard Pan, Sirio Belli, Gabriel Brammer, Guido De Marchi, Fabio R. Ditrani, Giovanna Giardino, Karl Glazebrook, Valentina La Torre, Jamie Lin, Adam Muzzin, Namrata Roy, Paola Santini, Benedetta Vulcani, Peter J. Watson, Xin Wang
Cosmology and Nongalactic Astrophysics
Ly{\alpha} Intensity Mapping in HETDEX: Galaxy-Ly{\alpha} Intensity Cross-Power Spectrum
Maja Lujan Niemeyer, Eiichiro Komatsu, José Luis Bernal et al. (+18 more)
We present a measurement of the Lyman-$\alpha$ (Ly$\alpha$) intensity mapping power spectrum from the Hobby-Eberly
Telescope Dark Energy Experiment (HETDEX). We measure the cross-power spectrum of the Ly$\alpha$ intensity and Ly$\alpha$-emitting
galaxies (LAEs) in a
redshift range of $1.9 < z < 3.5$. We calculate the intensity from HETDEX spectra that do not contain any detected LAEs above a signal-to-noise ratio of $5.5$. To produce a power spectrum model and its covariance
matrix, we simulate the data using lognormal mocks for the LAE catalog and Ly$\alpha$ intensity in
redshift space. The simulations include the HETDEX sensitivity, selection function, and mask. The measurements yield the product of the LAE bias, the intensity bias, the mean intensity of undetected sources, and the ratio of the actual and fiducial
redshift-space distortion parameters, $b_\mathrm{g} b_I \langle I \rangle \bar{F}_{\rm RSD} / \bar{F}^{\rm fid}_{\rm RSD}= (6.7 \pm 3.1)$, $(11.7 \pm 1.4)$, and $(8.3 \pm 1.5) \times 10^{-22} \, \text{erg}\, \text{s}^{-1} \, \text{cm}^{-2} \, \text{arcsec}^{-2} \, \text{{\AA}}^{-1}$ in three
redshift bins centered at $\bar z=2.1$, 2.6, and 3.2, respectively. The results are reasonably consistent with cosmological hydrodynamical simulations that include Ly$\alpha$ radiative transfer. They are, however, significantly smaller than previous results from cross-correlations of
quasars with Ly$\alpha$ intensity. These results demonstrate the statistical power of HETDEX for Ly$\alpha$ intensity mapping and pave the way for a more comprehensive analysis. They will also be useful for constraining models of Ly$\alpha$ emission from
galaxies used in modern cosmological simulations of
galaxy formation and
evolution.
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All authors Maja Lujan Niemeyer, Eiichiro Komatsu, José Luis Bernal, Chris Byrohl, Robin Ciardullo, Olivia Curtis, Daniel J. Farrow, Steven L. Finkelstein, Karl Gebhardt, Caryl Gronwall, Gary J. Hill, Matt J. Jarvis, Donghui Jeong, Erin Mentuch Cooper, Deeshani Mitra, Shiro Mukae, Julian B. Muñoz, Masami Ouchi, Shun Saito, Donald P. Schneider, Lutz Wisotzki
High Energy Astrophysical Phenomena
Probing spectral variability in NGC 4490 ULX-8 over 24 years of XMM-Newton, Chandra and Swift-XRT observations
Tarang Vashisht, Aru Beri, Tanuman Ghosh et al. (+2 more)
We present a spectral variability study of the ultraluminous X-ray source NGC 4490 ULX-8 based on 14 Chandra, 6 XMM-Newton and 19 Swift-XRT observations obtained between 2000 and 2024. The X-ray spectra are modelled using absorbed power-law and absorbed multicolour disc blackbody models. The best-fit
photon indices span 0.9-2.7, while the inferred inner disc temperatures lie in the range 1.0-1.6 keV. We detect pronounced long-term variability in the unabsorbed X-ray luminosity on multi-year timescales, while variability within individual observations is comparatively modest. A Hardness-Intensity Diagram of the source shows no clear transition between hard and soft states; however, two recent observations taken on 2022 December 1 and 2024 May 4 show a sharp increase in brightness. The spectra across all observations are dominated by smooth, single-component
curvature in the 0.3-10 keV band, consistent with the broadened-disc regime of ultraluminous X-ray sources. A correlation analysis reveals a weak positive X-ray luminosity-
photon index trend that remains statistically supported after controlling for related degeneracies, indicating that it is not driven solely by fitting covariance. The luminosity-inner disc temperature relation is only weakly constrained, but remains compatible, within uncertainties, with both thin-disc and slim-disc scalings. Using disc parameters derived from higher-quality XMM-Newton spectra, we obtain model-dependent estimates of the characteristic inner disc radius and compact-object mass as functions of inclination and
spin. The reported results are consistent with a
stellar-mass black hole accretor operating at or near the Eddington limit.
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All authors Tarang Vashisht, Aru Beri, Tanuman Ghosh, Aman Upadhyay, Vikram Rana
Solar and Stellar Astrophysics
Observational study of chromospheric jets in and around a sunspot observed by NVST and SDO
Guotang Wu, Xiaoli Yan, Zhike Xue et al. (+8 more)
To better understand the characteristics, driving mechanisms, and potential heating contributions of chromospheric jets, we analyze two contrasting types: one originating from within the sunspot penumbra (inside jets), and the other originating from outside the penumbra (outside jets). Statistical analysis of 100 jets (50 inside jets and 50 outside jets) reveals that inside jets have a projected velocity range of 4–14~km\,s$^{-1}$, a length range of 1–4~Mm, a width range of 0.2–0.6~Mm, and a lifetime range of 135–450~s, with mean values of 7.90~km\,s$^{-1}$, 2.61~Mm, 0.41~Mm, and 260~s, respectively. About 52% of inside jets are associated with brightenings in H$\alpha$ blue wing images, and some show high-temperature signatures, suggesting a connection with localized energy release. In contrast, outside jets have higher velocities (8–50~km\,s$^{-1}$, average 19.04~km\,s$^{-1}$), greater lengths (average 6.26~Mm, up to 27.27~Mm), slightly larger widths (average 0.46~Mm), and longer lifetimes (135–630~s, average 327~s). They typically originate from regions of opposite
magnetic polarities and are associated with
magnetic flux emergence and EUV brightenings. Some outside jets correspond to coronal jets with inverted Y-shaped structures and temperatures exceeding one million Kelvin. Our results suggest that both jet types are driven by
magnetic reconnection occurring in distinct
magnetic field configurations and contribute to chromospheric and coronal heating.
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All authors Guotang Wu, Xiaoli Yan, Zhike Xue, Jincheng Wang, Zhe Xu, Liheng Yang, Yian Zhou, Liping Yang, Xinsheng Zhang, Qifan Dong, Zongyin Wu
Earth and Planetary Astrophysics
Reanalysis of the eclipses of LHS 1140 c: No evidence of an atmosphere and implications for the internal structure of the planet
Alexandra Rochon, Étienne Artigau, Drew Weisserman et al. (+4 more)
We present the reanalysis of three 15 micron JWST/MIRI secondary eclipses of LHS 1140 c, a warm super-Earth (R$_{\rm{p}}$ = 1.272 R$_{\oplus}$) in a 3.78-day orbit around an M4.5
dwarf. We present a novel method for data reduction that leverages spatial derivatives of the point-spread function and compare it to widely used aperture photometry. Both methods yield eclipse depth consistent within 1 sigma of the values reported in the literature. We measure an eclipse depth of 271$^{+31}_{-30}$ ppm corresponding to a brightness temperature of $T_B=595^{+33}_{-34}$ K, consistent with a bare rock. The secondary eclipse occurs 4.1$\pm$0.8 minutes before the circular-orbit predicted time. We explore the implications of our results on the internal structure of LHS 1140 c, the orbital architecture of the system and the possibility of future observations with JWST. We find a core-mass fraction (CMF) informed by the
stellar abundances of refractory elements of 0.34$\pm$0.11, inflated compared to the CMF from radius and mass measurements, suggesting the possible presence of bulk volatiles in the interior.
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All authors Alexandra Rochon, Étienne Artigau, Drew Weisserman, Lisa Dang, René Doyon, Charles Cadieux, Ryan Cloutier
High Energy Astrophysical Phenomena
Unveil A Peculiar Light Curve Pattern of Magnetar Burst with GECAM observations of SGR J1935+2154
Yue Wang, Chen-Wei Wang, Shaolin Xiong et al. (+28 more)
Magnetar X-ray Burst (MXB) is usually composed of a single pulse or multiple pulses with rapid rise and brief duration mostly observed in hard X-ray (soft gamma-ray) band. Previous work studied the temporal behavior of some magnetar bursts and employed the Fast Rise Exponential Decay (FRED) model to fit pulses of MXB. However, whether there is other kind of pulse shape has not been explored. In this study, we systematically examined light curve of MXBs from SGR J1935+2154 detected by GECAM between 2021 and 2022. We find that there are different light curve morphologies. Especially, we discover a peculiar and new pattern, Exponential Rise and Cut-Off Decay (ERCOD), which is significantly different from FRED and could be well described by a mathematical function we proposed. We find that MXBs with ERCOD shape are generally longer in duration, brighter in the peak flux, and harder in spectrum. We note that the ERCOD shape is not unique to SGR J1935+2154 but also present in other magnetars. This new light curve pattern may imply a special burst and radiation mechanism of magnetar.
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All authors Yue Wang, Chen-Wei Wang, Shaolin Xiong, Xiao Xiao, Yanqiu Zhang, Sheng-Lun Xie, Lin Lin, Yuan-Pei Yang, Haoxuan Guo, Ce Cai, Yue Huang, Cheng-Kui Li, Bing Li, Xiaobo Li, Jiacong Liu, Xiang Ma, Liming Song, Wen-Jun Tan, Ping Wang, Wang-Chen Xue, Shu-Xu Yi, Yun-Wei Yu, Zheng-Hang Yu, Jin-Peng Zhang, Peng Zhang, Shuang-Nan Zhang, Wen-Long Zhang, Zhen Zhang, Xiao-Yun Zhao, Chao Zheng, S.J. Zheng
Cosmology and Nongalactic Astrophysics
Islands in Simulated Cosmos: Probing the Hubble Flow around Groups and Clusters
David Benisty and Antonino Del Popolo
The local Hubble flow provides a valuable probe of the transition between
cosmic expansion and nonlinear gravitational dynamics. On large scales,
galaxies follow the linear Hubble law, but within group- and cluster-sized environments, gravitational interactions generate substantial deviations. Using the IllustrisTNG cosmological simulations, we test whether dark energy leaves measurable signatures in the local velocity radius relation. We model the kinematics with extensions of the Lemaître Tolman framework and use
Bayesian inference to recover
halo masses and the Hubble constant $H_0$. The fits exhibit systematic biases:
halo masses are recovered with a median ratio $\big\langle M_{\rm fit}/M_{\rm true}\big\rangle = 0.991 \pm 0.148$, while the inferred expansion rate peaks at $\big\langle H_{0,\text{fit}}/H_{0,\text{True}} \big\rangle =1.01 \pm 0.14$. Although both mass and $H_0$ can be constrained from the local flow, the different model variants, as the angular momentum, friction-like terms, or dark energy, remain statistically indistinguishable given the intrinsic environmental variance. Our results demonstrate both the potential and the fundamental limitations of using local kinematics as a precision diagnostic of dark energy.
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Solar and Stellar Astrophysics
Sunspot Observations in 1684-1702: John Flamsteed and Philippe de La Hire
Nadezhda Zolotova and Mikhail Vokhmyanin
In this work, we present an extensive review and detailed analysis of sunspot measurements, drawings, and engravings made by John Flamsteed and, mainly, by Philippe de La Hire during the Maunder minimum. All available information and contemporary knowledge about the sunspot nature are shown. The coordinates, areas, and numbers of sunspots and sunspot groups are reconstructed. Based on these observations, La Hire, Jean-Dominique Cassini, and his son Jacques Cassini regularly published results that shed light on the purpose of sunspot measurements and the scientific paradigm of that time. In particular, astronomers believed that sunspots were recurrent over decades. We compare the reconstructed time-latitude diagram with those obtained by Spoerer (Ueber die periodicitat der sonnenflecken seit dem Jahre 1618..., 1889) and Ribes and Nesme-Ribes (Astron. Astrophys. 276, 549, 1993). The sidereal differential rotation rate is estimated, and its latitudinal profile is reconstructed. We also evaluate the fraction of sunspot groups that obey or violate Joy's law.
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Astrophysics of Galaxies
JWST COSMOS-3D: Spectroscopic Census and Luminosity Function of [O III] Emitters at 6.75<z<9.05 in COSMOS
Romain A. Meyer, Feige Wang, Koki Kakiichi et al. (+39 more)
We present a catalogue of spectroscopically selected [OIII]+Hb emitters at 6.75<z<9.05 and the resulting [OIII] 5008 ÅLuminosity Function (LF) in the COSMOS field. We leverage the 0.33 deg$^2$ covered by COSMOS-3D using NIRCam/WFSS F444W to perform the largest spectroscopic search for [OIII] emitters at 6.75<z<9.05. We present our catalogue of 249 [OIII] emitters and their associated completeness function. The inferred constraints on the [OIII] LF enable us to characterise the knee of the [OIII] LF, resulting in improved [OIII] LF constraints at z~7,8. Notably, we find evidence for a decline of the [OIII] luminosity density between z~7 and z~8, which could be expected if the
metallicity of [OIII] emitters, as well as the
cosmic star-formation rate density, is declining at these
redshifts. We find that theoretical models that reproduce the z~7,8 [OIII] LF do not reproduce well the [OIII] equivalent width distribution, pointing to potential challenges in the modelling of[OIII] and other nebular lines in the early Universe. Finally, we provide the first constraints on the
cosmic variance of [OIII] emitters, estimating at 15% the fractional uncertainty for the z~7,8 [OIII] LF in the 0.33 deg$^2$ field. This estimate is in good agreement with that inferred from clustering, and shows that the [OIII] LF derived from smaller extragalactic legacy fields is strongly affected by
cosmic variance. Our results highlight the fundamental role that wide-area JWST slitless surveys play to map the
galaxy large-scale structure down into the reionisation era, serving as a springboard for a variety of science cases.
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All authors Romain A. Meyer, Feige Wang, Koki Kakiichi, Gabe Brammer, Jackie Champagne, Katharina Jurk, Zihao Li, Zijian Li, Marat Musin, Sindhu Satyavolu, Jan-Torge Schindler, Marko Shuntov, Yi Xu, Siwei Zou, Fuyan Bian, Caitlin Casey, Eiichi Egami, Xiaohui Fan, Danyang Jiang, Nicolas Laporte, Weizhe Liu, Pascal Oesch, Lidia Tasca, Jinyi Yang, Zijian Zhang, Hollis Akins, Zheng Cai, Dave A. Coulter, Jiamu Huang, Mingyu Li, Weizhe Liu, Yongming Liang, Bingcheng Jin, Xiangyu Jin, Jeyhan Kartaltepe, Anton M. Koekemoer, Jasleen Matharu, Maria Pudoka, Wei-Leong Tee, Callum Witten, Haowen Zhang, Yongda Zhu
High Energy Astrophysical Phenomena
Electromagnetic Observables of Weakly Collisional Black Hole Accretion
Vedant Dhruv, Ben Prather, Mani Chandra et al. (+2 more)
The black holes in the Event Horizon
Telescope sources Messier 87* and Sagittarius A* (SgrA*) are embedded in a hot, collisionless
plasma that is fully described in kinetic theory yet is usually modeled as an ideal, magnetized fluid. In this Letter, we present results from a new set of weakly collisional fluid simulations in which leading order kinetic effects are modeled as viscosity and heat conduction. Consistent with earlier, lower-resolution studies, we find that overall flow dynamics remain very similar between ideal and non-ideal models. For the first time, we synthesize images and spectra of SgrA* from weakly collisional models – assuming an isotropic, thermal population of electrons – and find that these remain largely indistinguishable from ideal fluid predictions. However, most weakly collisional models exhibit lower light curve variability, with all magnetically dominated models showing a small but systematic decrease in variability.
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All authors Vedant Dhruv, Ben Prather, Mani Chandra, Abhishek V. Joshi, Charles F. Gammie
Cosmology and Nongalactic Astrophysics
Updated constraints on interacting dark energy: A comprehensive analysis using multiple CMB probes, DESI DR2, and supernovae observations
Tian-Nuo Li, Guo-Hong Du, Yun-He Li et al. (+4 more)
Recent DESI
baryon acoustic oscillation (BAO) measurements, combined with Planck
cosmic microwave background (CMB) data and DESY5 type Ia
supernova (SN) data, indicate a significant deviation from $\Lambda$CDM, which seems to suggest that this deviation can be explained by an interaction between dark energy and dark matter. In this work, we perform a comprehensive analysis by utilizing the latest DESI DR2 BAO data in conjunction with CMB data from ACT, SPT, Planck, and WMAP, along with SN data from PantheonPlus and DESY5. We consider four interacting dark energy (IDE) models with different forms of the interaction term $Q$. Our analysis indicates that CMB experiments other than Planck enhance the evidence for an interaction in the IDE models with $Q \propto \rho_{\rm de}$. In particular, when using the SPT+DESI+DESY5 data, the IDE model with $Q = \beta H_0 \rho_{\rm de}$ gives $\beta = -0.4170 \pm 0.1220$, with a deviation from zero reaching $3.4\sigma$ level. When replacing DESY5 with PantheonPlus, this deviation weakens to $2.1\sigma$ level, but remains relatively significant. Furthermore, the Bayes factors of the IDE model with $Q = \beta H_0 \rho_{\rm de}$ are positive in all cases, providing a moderate-to-strong preference over $\Lambda$CDM. Overall, our comprehensive analysis clearly suggests that the IDE models with $Q \propto \rho_{\rm de}$ (especially, $Q = \beta H_0 \rho_{\rm de}$) provide strong evidence supporting the existence of interaction and are more preferred by the current cosmological data.
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All authors Tian-Nuo Li, Guo-Hong Du, Yun-He Li, Yichao Li, Jia-Le Ling, Jing-Fei Zhang, Xin Zhang
Solar and Stellar Astrophysics
Variation of the disk thickness across ice bands: A method to determine ice abundances in highly inclined protoplanetary disks
Laurine Martinien, Gaspard Duchêne, François Ménard et al. (+6 more)
The James Webb Space
Telescope provides unprecedented information to study ices in protoplanetary disks. However, the saturation of ice bands in highly inclined disks hinders the measurement of ice abundances using classical spectroscopy. This is unfortunate as the presence and more importantly abundance of ices plays a key role in, e.g., the
evolution of
dust (because it modifies the sticking properties) and the composition of planetesimals and exoplanetary atmospheres. To overcome this issue and quantify the ice abundance within disks, we introduce a new method based on measuring the changes in the apparent disk thickness as a function of wavelength, which is directly and quantitatively related to the grain opacity. Specifically, we expect i) that the increased opacity within ice bands should result in a thicker disk than in the adjacent continuum, and ii) the thickness variations to be proportional to the abundance of ice. We extracted the disk thickness in model images of edge-on disks containing different abundances of water ice, as well as in James Webb Space
Telescope spectral imaging of four edge-on disks. For both models and observations, the disk thickness decreases toward longer wavelengths except across the positions of ice absorption features where the thickness is enhanced across the band. In the model images, we demonstrate that this effect increases with ice abundance without any hint of saturation. This definitely demonstrates the presence of the ice species within each disk and confirms our expectation that this method can be applied to estimate ice abundances. Thanks to this method, it will thus be possible to constrain the ice abundance in highly inclined disks with disks model fitting. Unlike spectroscopic analysis, this method is not subject to saturation and should therefore be more robust and applicable to all disks for which the two surfaces can be resolved.
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All authors Laurine Martinien, Gaspard Duchêne, François Ménard, Karl R. Stapelfeldt, Ryo Tazaki, Jennifer B. Bergner, Emmanuel Dartois, Jennifer A. Noble, William Thompson
Cosmology and Nongalactic Astrophysics
Locating Centers of Clusters of Galaxies with Quadruple Images: Witt's Hyperbola and a New Figure of Merit
Nixon Hanna, Paul L. Schechter, Michael A. McDonald et al. (+1 more)
For any elliptical potential with an external parallel shear, Witt has proven that the gravitational center lies on a rectangular hyperbola derived from the image positions of a single quadruply lensed object. Moreover, it is predicted that for an isothermal elliptical potential the source position both lies on Witt's Hyperbola and coincides with the center of Wynne's Ellipse (fitted through the four images). Thus, by fitting Witt's Hyperbolae to several quartets of images - ten are known in Abell 1689 - the points of intersection provide an estimate for the center for the assumed isothermal elliptical potential. We introduce a new figure of merit defined by the offset of the center of Wynne's Ellipse from Witt's Hyperbola. This offset quantifies deviations from an ideal elliptical isothermal potential and serves as a discriminant to exclude poorly fitted quadruples and assign greater weight to intersections of hyperbolae of better fitting systems. Applying the method to 10 quads (after excluding 7 poorly fitted quads) in Abell 1689, we find the potential is centered within 11" of the BCG, X-ray center, flexion-based center and the center found from a total strong
lensing analysis. The Wynne-Witt framework thus delivers a fast, analytic, and self-consistency-checked
estimator for centers in clusters with multiple quads.
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All authors Nixon Hanna, Paul L. Schechter, Michael A. McDonald, Marceau Limousin
High Energy Astrophysical Phenomena
Revisiting FRB 20121102A: milliarcsecond localisation and a decreasing dispersion measure
M.P. Snelders, J.W.T. Hessels, J. Huang et al. (+27 more)
FRB 20121102A is the original repeating fast
radio burst (FRB) source and also the first to be localised to milliarcsecond precision using very-long-baseline interferometry (VLBI). It has been active for over 13 years and resides in an extreme magneto-ionic environment in a
dwarf host
galaxy at a distance of ~1 Gpc. In this work, we use the European VLBI Network (EVN) to (re-)localise FRB 20121102A and its associated persistent
radio source (PRS). We confirm that the two are co-located – improving on previous results by a factor of ~4 and constraining the FRB and PRS co-location to ~12 pc transverse offset. Over a decade, the PRS luminosity on milliarcsecond scales remains consistent with measurements on larger angular scales, showing that the PRS is still compact. We also present the detection of 18 bursts with the Nancay
Radio Telescope (NRT) as part of our ÉCLAT monitoring program. These bursts, together with previously published results, show that the observed dispersion measure (DM) of FRB 20121102A has dropped by ~25 pc/cc in the past five years, highlighting a fractional decrease in the local DM contribution of >15%. We discuss potential physical scenarios and highlight possible future observations that will help reveal the nature of FRB 20121102A, which is one of only a few known FRBs with a luminous PRS.
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All authors M.P. Snelders, J.W.T. Hessels, J. Huang, N. Sridhar, B. Marcote, A.M. Moroianu, O.S. Ould-Boukattine, F. Kirsten, S. Bhandari, D.M. Hewitt, D. Pelliciari, L. Rhodes, R. Anna-Thomas, U. Bach, E.K. Bempong-Manful, V. Bezrukovs, J.D. Bray, S. Buttaccio, I. Cognard, A. Corongiu, R. Feiler, M.P. Gawroński, M. Giroletti, L. Guillemot, R. Karuppusamy, M. Lindqvist, K. Nimmo, A. Possenti, W. Puchalska, D. Williams-Baldwin
Astrophysics of Galaxies
REBELS-IFU: Linking damped Lyman-$\alpha$ absorption to [CII] emission and dust content in the EoR
Lucie E. Rowland, Kasper E. Heintz, Hiddo Algera et al. (+19 more)
Neutral gas in
galaxies during the Epoch of Reionisation regulates
star formation,
dust growth, and the escape of ionising
photons, making it a key ingredient in understanding both
galaxy assembly and reionisation. Yet, direct constraints on the HI content of
galaxies at z>6 have been scarce. With JWST, Ly$\alpha$ damping wings in
galaxy spectra can now provide a direct probe of this neutral component. We analyse JWST/NIRSpec prism spectra of 12 UV-luminous
galaxies from the REBELS-IFU program at z~6.5-7.7, deriving HI column densities by modelling Ly$\alpha$ damping wings. Significant damped Ly$\alpha$ absorption is detected in eight
galaxies, with $N_{\mathrm{HI}}\gtrsim10^{21}$ cm$^{-2}$. We use the column densities and sizes derived for these sources to estimate their HI mass and compare with $L_{\mathrm{[CII]}}$-$M_{\mathrm{HI}}$ calibrations. The resulting HI masses show a tentative correlation with those inferred from [CII], although the [CII]-based estimates are systematically larger, suggesting that the HI reservoirs may extend beyond the [CII]-emitting gas. We also combine the DLA-based measurements with FIR-derived
dust-to-gas ratios,
dust attenuation, and gas-phase
metallicities. No correlation is found between DLA-based and FIR-based
dust-to-gas ratios, but combining the REBELS-IFU sample with literature samples at lower
metallicities reveals a strong correlation between $A_{\mathrm{V}}/N_{\mathrm{HI}}$ and
metallicity. These findings suggest that by $z\sim7$ massive
galaxies can already host substantial, enriched reservoirs of neutral gas and
dust, consistent with $A_{\mathrm{V}}$/$N_{\mathrm{HI}}$-
metallicity trends at lower
redshift. At the highest
redshifts ($z>8$), however, we see tentative evidence for systematically lower $A_{\mathrm{V}}$/$N_{\mathrm{HI}}$ at fixed
metallicity, which may point to pristine gas
accretion or more efficient
dust destruction/expulsion.
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All authors Lucie E. Rowland, Kasper E. Heintz, Hiddo Algera, Mauro Stefanon, Jacqueline Hodge, Rychard Bouwens, Manuel Aravena, Elisabete da Cunha, Pratika Dayal, Andrea Ferrara, Rebecca Fisher, Valentino González, Hanae Inami, Olena Komarova, Ilse de Looze, Themiya Nanayakkara, Katherine Ormerod, Andrea Pallottini, Clara L. Pollock, Renske Smit, Paul van der Werf, Joris Witstok
Astrophysics of Galaxies
MSA-3D: Uncovering Weak AGNs and Resolved Outflows in Disguise in $z\sim1$ Star-Forming Galaxies
Namrata Roy, Alaina Henry, Tucker Jones et al. (+11 more)
We present spatially resolved rest-optical spectroscopy of 38
star-forming
galaxies at 0.5 < z < 1.7 from the JWST/NIRSpec MSA-3D survey, which uses slit-stepping to build IFU-like datacubes at 0.1” resolution. We map emission-line morphology, excitation, and kinematics of the warm ionized gas using [N II]/H$\alpha$, [S II]/H$\alpha$, and [O III]/H$\beta$. Relative to z$\sim$0
galaxies at fixed
stellar mass, our sources show systematically lower [N II]/H$\alpha$ and [S II]/H$\alpha$ and elevated [O III]/H$\beta$, consistent with harder radiation fields and lower
metallicities. Radially, [O III]/H$\beta$ profiles are typically flat or mildly positive, whereas [N II]/H$\alpha$ also remains flat or declines outward, mirroring
metallicity trends. On kpc scales, we find a strong positive correlation between [N II]/H$\alpha$ and velocity dispersion ($\sigma$), linking local excitation to turbulent or shock-driven kinematics. Six
galaxies ($\sim$ 16% of the sample) host spatially localized regions with elevated [N II]/H$\alpha$, high EW(H$\alpha$), and V_RMS = $\sqrt{V^2 + \sigma^2} > 200$ km/s, indicative of weak AGN activity, shocks, or
outflows. For these candidates we infer modest warm-ionized
outflow rates of 1-4 Msun/yr and kinetic powers $\sim$ 0.1-1% of the AGN bolometric luminosity (from central [O III] or H$\alpha$). These values place our sample at the low-energy tail of known AGN-driven
outflows yet in continuity with $\dot{M_{out}}-L_{AGN}$ scaling relations across 0 < z < 6. A completeness assessment shows MSA-3D is sensitive to AGN with $L_{AGN} \geq 10^{43}$ erg/s, underscoring both the promise and current limitations of detecting weak AGN activity in distant
galaxies with resolved spectroscopy.
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All authors Namrata Roy, Alaina Henry, Tucker Jones, Ivana Barisic, Ryan L. Sanders, Kevin Bundy, Matthew A. Malkan, Themiya Nanayakkara, Karl Glazebrook, Timothy Heckman, Juan M. Espejo Salcedo, Xin Wang, Danail Obreschkow, Tommaso Treu
Astrophysics of Galaxies
The chemodynamical memory of a major merger in a NIHAO-UHD Milky Way analogue – I. A golden thread through time and space
Sven Buder, Tobias Buck, Ása Skúladóttir et al. (+3 more)
Understanding how past major mergers shaped the Milky Way's present-day structure is a key goal of
Galactic archaeology. The
Galaxy's chemical and dynamical structure retains the imprint of such events, including a major
accretion episode around 8-10 Gyr ago. Recent findings suggest that present-day orbital energy correlates with
stellar chemistry and birth location within the merging progenitor
galaxy. Using a high-resolution NIHAO-UHD cosmological zoom-in simulation of a Milky Way analogue, we trace the birth positions, ages, and present-day orbits of
stars accreted in its last major merger. We show that
stars born in the progenitor's core are more tightly bound to the Milky Way and more chemically enriched, while those from the outskirts are less bound and more metal-poor. This supports the Skúladóttir et al. (2025) scenario that accreted progenitor
stars of different chemistry were deposited onto different orbital energies as the
galaxy was stripped from the outside in, now in a cosmological context. Quantitatively, we measure a
metallicity gradient with progenitor birth radius of $\mathrm{d[Fe/H]}/\mathrm{d}R_\mathrm{birth}^\prime \approx -0.05\,\mathrm{dex\,kpc^{-1}}$, demonstrating that abundance patterns retain measurable
memory of formation location within the disrupted satellite. This chemodynamical
memory is also evident in elemental planes such as [Al/Fe] vs. [Mg/Mn], consistent with gradients in progenitor
star formation efficiency. We further show that common integrals-of-motion selections systematically miss
stars from the chemically enriched core, biasing reconstructions toward the metal-poor outskirts. Together, our results demonstrate that chemodynamical
memory survives the merger and can reconstruct the accreted
galaxy's internal structure, while highlighting biases in current selections of accreted
stars.
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All authors Sven Buder, Tobias Buck, Ása Skúladóttir, Melissa Ness, Madeleine McKenzie, Stephanie Monty