High Energy Astrophysical Phenomena
SDSSJ110546.07+145202.4: The first long-duration radio changing-look NLS1 galaxy
S. Komossa, D. Grupe, A. Kraus et al. (+12 more)
SDSSJ110546.07+145202.4 stands out as a unique
radio changing-look Narrow-line Seyfert 1 (NLS1)
galaxy that has brightened dramatically and shows an exceptionally long duration of its "on" phase. We present the first high-frequency
radio observations, the first simultaneous
radio spectral energy distributions (SEDs), the first optical–UV–X-ray SEDs, and the first X-ray monitoring and spectroscopy of this recently discovered event. Importantly for understanding the nature of the outburst, we show that the X-ray spectrum is soft with a
photon index Gamma_X=2.5; line-of-sight absorption and extinction are low or absent; the
radio SED is peaked at low frequencies ~2 GHz; and the
radio outburst emission is very long-lived (t > 8 yr) and roughly constant. The softness of the X-ray spectrum, low supermassive black hole (SMBH) mass, and high Eddington ratio all corroborate the optical NLS1 classification. We discuss multiple outburst scenarios, including
lensing, absorption, a binary SMBH merger, a long-duration
giant-
star tidal disruption, a newly ignited active
galactic nucleus (AGN), and an
accretion-rate change. While most of them can be either excluded or are deemed too rare and lack positive evidence so far, most or all types of these transients are expected to be detected in ongoing VLA and upcoming SKA surveys. SDSSJ110546.07+145202.4 itself is well explained by an
accretion rate change that triggered the powerful
radio jet emission. The low
redshift and SMBH mass of this system offer a unique perspective of the physical processes of
radio-jet ignition that are expected to operate in the early Universe around growing SMBHs.
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All authors S. Komossa, D. Grupe, A. Kraus, P.G. Edwards, E.F. Kerrison, K. Rose, R. Soria, T. An, M.J. Hardcastle, K.E. Gabanyi, S. Panda, D.W. Xu, J. Wang, S. Frey, A. Mezosi
Earth and Planetary Astrophysics
Oort Cloud Ecology – IV. Exchanging Asteroids
Erwan Hochart and Simon Portegies Zwart
Aims. Investigate the influence of cluster environments on asteroids, with special
attention towards captured material. Methods. Using numerical methods, a sub-virial fractally distributed
star-forming region and a virialised Plummer distributed
star-forming region are simulated. Both models are initialised with a virial radius of 0.5pc and 150
stars.
Stellar populations and their corresponding planetary systems are identical between cluster models.
Stars initially host 500 asteroids and those with mass M_* <= 2.0 MSun are also orbited by 1 - 8
planets. Clusters are integrated until 30 Myr. Results. The sub-virial fractal cluster exhibits richer dynamics, with asteroids and
planets more frequently acquiring high eccentricities and inclinations, along with a larger fraction of captured and rogue objects. Additionally, this cluster configuration has its extreme trans-Neptunian object and Sednoid analogues occupy regions of phase-space in semi-major axis, eccentricity and inclination commonly frequented by captured asteroids. Although the virialised Plummer model can produce such objects, by being less dynamically active, the vast majority of asteroids occupying these regions are native rather than captured. Lastly, neither model efficiently form an Oort Cloud, indicating that Oort Cloud assembly is strongly suppressed in both dynamically hot and more quiescent cluster
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Solar and Stellar Astrophysics
IZ Tel and UW Vir: Southern oscillating eclipsing Algol systems with active mass transfer
Alexios Liakos, David J. W. Moriarty, Julian F. West et al. (+1 more)
This study is an in-depth examination of IZ Tel and UW Vir which are semi-detached oscillating Eclipsing Algol binary systems (oEA
stars). The radial velocities of both components of each system were derived using spectra observed with the Australian National University's 2.3 m
telescope. The spectral types of the IZ Tel primary and secondary components were determined as F2V and K2IV; and those of UW Vir were determined as A7V and K6IV, respectively. Spectroscopy revealed mass transfer in progress which was confirmed by the photometric analysis for both cases and also by Eclipse-Timing Variation analysis in the case of UW Vir. Data from the Transiting
Exoplanet Survey Satellite (TESS) and ground-based observations enabled detailed light-curve modelling and pulsation analysis. We determined component masses of $M_1=1.48$ M_sun and $M_2=0.33$ M_sun for IZ Tel, and $M_1=2.39$ M_sun and $M_2=0.67$ M_sun for UW Vir from the simultaneous solution of the light and radial velocity curves. Spectra during total eclipses of the primary components revealed H$\alpha$ emission was present. Both primary components are $\delta$ Sct
stars. That of IZ Tel pulsates with a dominant frequency of 13.56 d$^{-1}$, which is revealed as non-radial pressure mode, as well as in another 16 combination frequencies. The primary component of UW Vir oscillates in three main frequencies within the range 34.9-43.3 d$^{-1}$ and in more than 50 another combination frequencies. Mode coupling was detected in the three main frequencies, which showed amplitude and phase modulations within a time span of approximately four years. The physical and pulsational properties of the $\delta$ Sct
stars of both systems were compared with other members of oEA
stars.
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All authors Alexios Liakos, David J. W. Moriarty, Julian F. West, Ahmet Erdem
Cosmology and Nongalactic Astrophysics
Model-independent consistency tests of DESI DR2 BAO and SN Ia
Hyeok Woo, William Luke Matthewson and Arman Shafieloo
Cosmic distances can be measured using two complementary probes: Type Ia
supernovae (SN Ia), serving as standard candles, and
baryon acoustic oscillations (BAO), serving as standard rulers. The luminosity distance derived from
supernovae and the angular diameter distance obtained from BAO must be mutually consistent if these data are to be combined for cosmological inference. Hence, the existence of potential discrepancies, whether arising from systematics in either
dataset or from violation of the
cosmic duality relation (in an unconventional cosmology), remains an important issue to address. Testing consistency under a particular cosmological model can be limiting, as the model may not be sensitive to every kind of inconsistency possible in the data. Thus, in this work we use a model-independent Crossing Statistics framework to test the consistency, using DESI DR2 BAO, and the Pantheon+ and Union3 SN Ia
datasets. We find adding up to two additional degrees of freedom, using Crossing Statistics on the LambdaCDM distance-
redshift relation, to be statistically justified. In these cases, the two probes remain mutually consistent at the 1-2 sigma level. Having established this statistical consistency, we combine the
datasets to reconstruct the expansion history of the Universe and the inferred
evolution of dark energy. The reconstructions obtained using different crossing variables show compatible behaviour where the data constraints are strongest, particularly at low
redshift. Overall, the results are suggestive of a dark energy component that is evolving at low
redshift, compatible with results from other reconstruction methods.
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High Energy Astrophysical Phenomena
Exploring the central region of SNR 0540-69.3 with JWST I: 3D morphology
J. Larsson, C. Tegkelidis, C. Fransson et al. (+3 more)
The young
supernova remnant SNR 0540-69.3 in the Large Magellanic Cloud offers a detailed view of an energetic
pulsar-wind nebula interacting with the surrounding ejecta. We present infrared observations of the central region of SNR 0540-69.3 obtained with the JWST NIRSpec and MRS integral field units. From the observations we reconstruct the 3D morphology of the strongest emission lines in the inner ejecta ($\lesssim$ 1000 km/s), which reveals the distribution of H I, He I, [Ne II], [Ne III], [S III], [S IV], [Fe II], and [Ni II]. The 3D morphology of most lines is dominated by two highly fragmented lobes of approximately similar size. Based on the assumption that the lobes are symmetric around the
pulsar, we infer a
pulsar kick velocity of ~300 km/s away from the observer. There are differences in the 3D morphologies of individual emission lines due to a combination of varying physical conditions and abundances. The detection of H I 1.8756 $\mu$m in the inner ejecta confirms the classification of the SN as a Type II and shows that hydrogen was mixed down to low velocities of < 400 km/s in the explosion. We compare the results to the Crab nebula and conclude that asymmetries originating in the explosion most likely play a major role in shaping the PWNe.
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All authors J. Larsson, C. Tegkelidis, C. Fransson, P. Lundqvist, J. Sollerman, J. Spyromilio
Astrophysics of Galaxies
HOTDISK. Finding Massive Protostellar Disks with Water and Refractory Molecular Species
Kai Yang, Yichen Zhang, Kei E. I. Tanaka et al. (+16 more)
We present high-angular-resolution ($\sim0.05^{\prime\prime}$, $\sim 60-250$ au) ALMA Band~6 observations from the HOTDISK project (Hot-Origin Tracer survey of DISKs of massive protostars) aimed at investigating the "hot-disk" chemical pattern traced by vibrationally excited water, NaCl, SiS, and SiO in the innermost regions around massive protostars. Ten targets were selected based on strong CH$_3$CN emission exhibiting clear rotational signatures and centrally concentrated SiO emission from lower-resolution observations. We detect vibrationally excited water emission toward 7 of the 10 sources. In all detections, the blueshifted and redshifted components are compact and located on opposite sides of the 1.3 mm continuum peak, with velocity gradients approximately perpendicular to the
outflow axes, consistent with rotation on disk scales. Emission from NaCl and SiS is detected toward 5 of these 7 sources and exhibits similar kinematics, further supporting the presence of compact rotating structures. In contrast, commonly used hot-core tracers (e.g., CH$_3$CN and SO$_2$) primarily probe larger-scale envelope gas. These results demonstrate that vibrationally excited water, NaCl, and SiS are powerful tracers of disk structures on $\sim$100 au scales, when observed at sufficient angular resolution and sensitivity. The high detection rate suggests that hot-disk chemical patterns – and thus compact rotating disks – are common in massive
star-forming regions, at least among sources with well-developed rotating envelopes.
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All authors Kai Yang, Yichen Zhang, Kei E. I. Tanaka, Tie Liu, Nami Sakai, Ziwei E. Zhang, Gyuho Lee, Kee-Tae Kim, Adam Ginsburg, Lile Wang, Yao Wang, Yongzhi Tang, Yu Cheng, Hongli Liu, Wenyu Jiao, Fengwei Xu, Xunchuan Liu, Xiaofeng Mai, Dongting Yang
Earth and Planetary Astrophysics
Physical Analysis of Bennu Samples Reveals Regolith Production by Collisional Disruption on Near-Earth Asteroids
R.-L. Ballouz, A.J. Ryan, R.J. Macke et al. (+26 more)
Owing to the extremely low
gravity of small near-Earth asteroids (NEAs), it has been assumed that impact-generated rock fragments escape into space and thus do not contribute to the accumulation of regolith. However, centimeter-sized stones returned from the small NEA Bennu by NASA's OSIRIS-REx mission exhibit impact craters up to a few millimeters wide, implying that impact fragments and impact-processed rocks are retained despite the microgravity environment. To understand how, we combined detailed physical analysis of Bennu samples, laboratory experiments of impacts into simulant rocks, and 3D numerical simulations of disruptive impacts into boulders. We find that the majority (85% by mass) of impact fragments eject toward and penetrate the asteroid's weak, porous surface, leading to their retention. In addition, crater depth-to-diameter ratios (d/D) suggest that the Bennu samples (median crater d/D = 0.36 $\pm$ 0.1) are structurally representative of the asteroid's large boulders (median crater d/D = 0.33 $\pm$ 0.08, measured previously). Our analyses indicate that most of Bennu's surface rocks (those with diameters $\lesssim$ 20 m) could be products of in situ collisional disruption. This impact-driven mechanism of regolith production likely occurs on other small NEAs with highly porous surfaces.
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All authors R.-L. Ballouz, A.J. Ryan, R.J. Macke, O.S. Barnouin, M. Lê, J. Moreno, S. Eckley, L. Hanton, A. Hildebrand, V. Toy-Edens, R.M. Meier, M. Berkson, E. Asphaug, S. Cambioni, C.G. Hoover, K. Jardine, E.R. Jawin, N. Lunning, J.L. Molaro, M. Pajola, K. Righter, K.T. Ramesh, F. Tusberti, K.J. Walsh, C.W.V. Wolner, D.N. DellaGiustina, H.C. Connolly, Jr., D.S. Lauretta
Cosmology and Nongalactic Astrophysics
Merger rate of initially clustered primordial black holes for the two-body channel
Kentaro Kasai, Masahiro Kawasaki, Kai Murai et al. (+1 more)
Primordial black holes (PBHs) may form an initially clustered population depending on their production mechanism. Motivated by binary black-hole merger events observed by gravitational-wave interferometers, we revisit the evaluation of the merger rate of PBH binaries and extend the formalism to include the effects of clustering. We show that, in the presence of relatively weak PBH clustering, the LIGO-Virgo-KAGRA events can be explained with a smaller value of $f_{\mathrm{PBH}}$ than in scenarios with Poisson-distributed PBHs, at least in the early two-body channel. However, for stronger clustering, the merger rate in the two-body channel is significantly suppressed due to the formation of three-body systems.
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All authors Kentaro Kasai, Masahiro Kawasaki, Kai Murai, Shunsuke Neda
Solar and Stellar Astrophysics
Rapidly oscillating Ap stars observed with TESS. The LAMOST Ap sample and 49 Cam
Inês Rolo, Daniel L. Holdsworth, Margarida S. Cunha et al. (+4 more)
The rapidly oscillating chemically peculiar A-type (roAp)
stars offer valuable insights into the internal physical processes of all
stars, but their study is challenged by their rarity. The large-scale TESS surveys have allowed for the collection of data for a sizeable
dataset of roAp
stars. Nevertheless, asteroseismic data obtained with TESS and
Gaia has not been explored to its full potential. We develop an
algorithm capable of analysing large quantities of data to search for new roAp
stars and increase the current sample. We focus on data products that have not been previously explored for the search of roAp
stars, namely the 200-s FFIs and 20-s cadence light curves. 20-s and 200-s cadence light curves of target
stars are retrieved from the MAST server and cleaned. DFTs are computed for each light curve which are used to pre-whiten the data to remove any low frequency signals. A final DFT is calculated which is used to classify
stars as non-pulsating (NP), delta Scuti or roAp based on the remaining signal. We apply our
algorithm to two independent
datasets: i) ~2700 Ap
stars spectroscopically classified with LAMOST and observed by TESS in the 200-s FFIs and ii) all TESS 20-s cadence light curves available for known or candidate roAp
stars. These two samples have no overlap, i.e. none of the LAMOST
stars have been observed with 20-s cadence. We identify four new roAp
stars: TIC 312111544, TIC 252881095, TIC 46054683, and 49 Cam (TIC 393276640). We find evidence in TESS data that TIC 252881095 may be part of a binary system. If the tentative ~30-d orbital signal is confirmed, TIC 252881095 could be one of the shortest-period roAp binary currently known. Furthermore, the detection of high-frequency pulsations in 49 Cam is particularly relevant, as this well-known roAp candidate
star is here confirmed to be roAp based on TESS 20-s cadence data.
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All authors Inês Rolo, Daniel L. Holdsworth, Margarida S. Cunha, Victoria Antoci, Donald W. Kurtz, Rahul Jayaraman, Ângela R. G. Santos
Earth and Planetary Astrophysics
The Ophiuchus DIsc Survey Employing ALMA (ODISEA). Substructures as a function of SED Class and disc mass in 100 systems
Trisha Bhowmik, Lucas Cieza, J. M. Miley et al. (+17 more)
Current high-resolution studies of protoplanetary discs are biased toward small samples of the brightest (flux > 50 mJy at 225 GHz) and largest systems. We present a complete flux-limited high-resolution study of about 100 discs from the Ophiuchus Disc Survey Employing ALMA (ODISEA), spanning fluxes of about 4-400 mJy at 225 GHz. We investigate substructures as a function of SED Class and disc mass using ALMA Band 8 continuum observations (410 GHz, 0.7 mm). The survey extends to faint discs containing as little as about 2 Earth masses of
dust. Given the flux-size relation, sources with flux >= 20 mJy were observed at about 20 au resolution, while fainter sources were observed at three times higher resolution. We used the Frankenstein code to fit non-parametric models to the visibilities, achieving sub-beam resolution. We classify substructures into an evolutionary sequence linking morphology with stages of
giant planet formation, from featureless discs (Stage 0) to inflection-point discs, gap-ring systems, and discs with central cavities. Despite higher optical depths, Band 8 efficiently traces substructures and recovers gaps and cavities seen at longer wavelengths with shorter integration times. Discs with
dust masses above about 10 Earth masses show structures consistent with this sequence, even at modest resolution. The fraction of evolved substructures increases from 23 percent (6 of 26) in Class I sources to at least 53 percent (17 of 32) in Class II objects. In contrast, lower-mass discs rarely show such features, likely due to the steep flux-size relation and limited resolution. These results support a link between substructures in discs above about 10 Earth masses and
giant planet formation, and highlight Band 8 as a powerful probe of disc substructures.
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All authors Trisha Bhowmik, Lucas Cieza, J. M. Miley, P. H. Nogueira, Camilo González-Ruilova, Prachi Chavan, Anibal Sierra, Anuroop Dasgupta, Simon Casassus, Grace Batalla-Falcon, Gioele Di Lernia, Antonio S. Hales, Jeff Jennings, Santiago Orcajo, Sebastian Perez, Dary Ruíz-Rodriguez, Yangfan Shi, Jonathan P. Williams, Ke Zhang, Alice Zurlo
High Energy Astrophysical Phenomena
Numerical Studies of Accretion Flows onto a Neutron Star Engulfed in a Massive Star
Daiyu Sakurai, Ryuichiro Akaho and Shoichi Yamada
Massive
stars commonly form binaries that can evolve into compact systems via common envelope
evolution (CEE), a critical but poorly understood phase – especially when the companion is a
neutron star. Understanding the drag force exerted on a
neutron star during CEE is a key to the quantitative evaluation of orbital decay, merger timescale, and compactness of the resultant binary. In this paper, we conduct general-relativistic hydrodynamical simulations under a novel strategy of multi-layer domain-decomposition to treat the vast disparity of $10^4$–$10^7$ between the
neutron star radius and the
accretion radius. Our 10-model survey spans diverse physical conditions that the
neutron star encounters in the envelope of a massive
star. We find that nested bow shocks with alternating orientations commonly form. This configuration is qualitatively different from those in the conventional picture and results in an enhancement of the drag force by one to two orders of magnitude from what the Bondi–Hoyle–Lyttleton formula predicts. Moreover, the direction of the net force can reverse depending on the envelope conditions, contrary to the standard picture in which the drag always decelerates the companion. These results will serve as a basis for improvements of the drag force prescription in CEE modeling, and have implications for binary
evolution theory.
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Earth and Planetary Astrophysics
Conceptual Design and Analysis of a NanoTug Swarm for Active Debris Removal
F. Alnaqbi, S. Biktimirov and G. Gaias
This paper investigates a swarm-based concept in which a number of nanosatellites, referred to as NanoTugs, are deployed by a mother spacecraft to capture and cooperatively stabilize and de-orbit space debris. The study focuses on the stabilization and de-orbiting phases of the mission, where each NanoTug is equipped with thrusters to perform the de-orbiting maneuver. An analytical method is developed to provide a preliminary understanding of the relationship between swarm system parameters, debris properties, and mission performance, which is subsequently verified through numerical simulations. Two NanoTug distribution strategies, random and predefined, are considered, and their influence on mission performance is evaluated. De-orbiting is achieved by thrusting along the direction that maximizes the reduction of the semi-major axis, as obtained from Gauss variational equations, while the attitude of the combined debris-NanoTugs system is controlled using a Lyapunov-based control law. A task allocation strategy is implemented to assign on-off commands to individual thrusters. Simulation results demonstrate the applicability of the analytical swarm sizing approach; however, a margin in system sizing is required due to the simplifying assumptions used in the first-order estimation. The proposed control approach for debris de-orbiting is shown to be feasible through representative mission simulations. In terms of NanoTug distribution across the debris surface, the predefined strategy provides improved performance, requiring fewer NanoTugs and offering more predictable behavior, whereas the random distribution results in frequent switching between NanoTug thrusters. Overall, the results highlight the feasibility of the swarm-based NanoTug concept for cooperative debris stabilization and de-orbiting.
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Astrophysics of Galaxies
VLTI-GRAVITY observations of blazars
Talvikki Hovatta, Elina Lindfors, Heidi Korhonen et al. (+5 more)
Parsec-scale jets of blazars have so far been spatially resolved only in millimeter and submillimeter wavelengths, where very long baseline interferometry can be used to obtain milliarcsecond-scale images of the jets. We have attempted to spatially resolve the near-infrared emission in jet-dominated blazars for the first time. We used the VLTI-
GRAVITY instrument to obtain milliarcsecond-scale near-infrared interferometric observations of a flaring blazar Ton 599. Additionally, we observed four non-flaring blazars using the
GRAVITY-wide mode, where a nearby bright
star is used as a fringe tracker. We modeled the squared visibilities of Ton 599 and found that they are incompatible with a single unresolved point source unless there is a significant amount of additional unknown coherence loss in the instrument. With the present data, we cannot distinguish between a model with an unresolved point source and extended emission or coherence loss and a model with a single Gaussian component. This suggests that we are seeing the unresolved or only partially resolved jet-base in near-infrared wavelengths. The wide-field mode of
GRAVITY was challenging for the additional relatively faint targets, resulting in either non-detections or poor-quality data that could not be modeled. Our observations demonstrate that it is possible to detect the compact jet emission in blazars with near-infrared interferometry, suggesting that with the improved
GRAVITY+ instrument it will be possible to spatially resolve and image the near-infrared emission of blazar jets.
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All authors Talvikki Hovatta, Elina Lindfors, Heidi Korhonen, Preeti Kharb, Markus Wittkowski, Aaron Labdon, Tapio Pursimo, Kaj Wiik
Cosmology and Nongalactic Astrophysics
Cosmological constraints on TeV-scale dark matter subcomponents decaying between recombination and reionisation
Markus R. Mosbech, Cristina Benso and Felix Kahlhoefer
The Dark Ages and the
Cosmic Dawn are an untapped well of information about the particle physics properties of dark matter, which may become accessible with future
radio telescopes able to probe the 21-cm signal from atomic hydrogen. In this work we study the impact on cosmological observables of a dark matter subcomponent composed of TeV-scale particles that decay into electrons,
photons or
neutrinos with a lifetime shorter than the age of the universe. We re-evaluate constraints from the
Cosmic Microwave Background (CMB) on these scenarios using the most recent data sets and estimate the sensitivity of future detections of the global 21-cm signal. Our main result is that the latter is potentially more sensitive to the effects of decaying dark matter with a lifetime $\tau \gtrsim 10^{15} \, \mathrm{s}$. This effect is strongest for the case of decays into
neutrinos due to the different spectral distribution of the injected electromagnetic energy. For DM masses well above the TeV-scale, these differences become less pronounced and the sensitivity of both the CMB and the 21-cm signal depend primarily on the total amount of injected electromagnetic energy.
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High Energy Astrophysical Phenomena
Identifying Merger-Driven and Collapsar-Driven Gamma-Ray Bursts with Precursor based Solely on Prompt Emission
Si-Yuan Zhu, Pak-Hin Thomas Tam, Fu-Wen Zhang et al. (+2 more)
Gamma-ray bursts (GRBs) are generally classified as Type~I GRBs, which originate from compact binary mergers, and Type~II GRBs, which originate from massive collapsars. The traditional correspondence between short–Type~I GRBs and long–Type~II GRBs, separated by a duration of 2 seconds, has been challenged by recent observations of long GRBs associated with kilonovae (i.e., Type~I-L GRBs) and a short GRB associated with a
supernova. In this paper, we focus on GRBs with precursor emission (PE) and compile 366 GRBs detected by
Fermi/GBM. Applying the unsupervised machine learning methods t-SNE and UMAP, we are able to distinguish Type~I (including subclass Type~I-L) and Type~II GRBs for the first time and identify PE as a key feature for distinguishing GRBs of different origins. Inspired by results of machine learning, we propose a diagnostic parameter, the $E_{\rm p,ME}$-precursor index ($EPI$), defined as ${\rm log_{10}}(E_{\rm p,ME}^{2}/(T_{\rm 100,PE}T_{\rm 100,QE1}^{1/2}T_{\rm MVT,PE}))$, where most Type~I GRBs have $EPI > 6.2$ and most Type~II GRBs have $EPI < 6.2$. This parameter can help the community to diagnose the origin of any GRB with PE based solely on its
prompt emission and rapidly plan for follow-up observations. The validation using Swift GRBs provides illustrative evidence that our method may also be applicable to GRBs observed by instruments other than
Fermi.
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All authors Si-Yuan Zhu, Pak-Hin Thomas Tam, Fu-Wen Zhang, Hui-Ying Deng, Bing Zhang
Earth and Planetary Astrophysics
A tidally detached super Neptune on a strongly misaligned retrograde orbit
G. Mantovan, L. Malavolta, A. F. Lanza et al. (+18 more)
The obliquity between a
planet's orbital axis and its host
star's
spin axis provides crucial insights into planetary formation and migration.
Planets with scaled semi-major axes ($a/R_\star$) large enough to be unaffected by
tidal alterations ("tidally detached"), offer a unique opportunity to study the original obliquity in which the system formed. We therefore observed TOI-1710 b ($a/R_\star \approx 36$) in-transit using HARPS-N + GIANO-B, collecting high-precision radial velocities to measure the Rossiter-McLaughlin (RM) effect. Spectral analysis of the H$\alpha$ and HeI triple lines was also pursued to evaluate atmospheric photoevaporation. Using our knowledge of the
star rotation period ($21.5 \pm 0.2$ d), we estimated a true obliquity of $\psi = 149 ^{+11}_{-10}$ deg, which indicates a retrograde motion and places TOI-1710 b among the most misaligned systems – and the only one known orbiting a cool
star in retrograde motion. The strong misalignment favours a high-eccentricity migration (HEM) origin for this low-density super-Neptune
planet in the savanna region, challenging previous findings that claimed a minor role of HEM in this period-radius(-density) domain. Moreover, the strong misalignment and lack of a detected close
stellar companion suggests a purely planetary post-migration misalignment, likely due to
planet-
planet scattering followed by
planet-
planet Kozai-Lidov oscillations and
tidal circularisation.
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All authors G. Mantovan, L. Malavolta, A. F. Lanza, F. Marzari, L. Naponiello, K. Biazzo, R. Cosentino, M. C. D'Arpa, S. Desidera, G. Guilluy, D. Nardiello, A. Sozzetti, S. Vissapragada, R. Aloisi, S. Benatti, L. Borsato, R. Claudi, S. Jenkins, V. Nascimbeni, G. Piotto, T. Zingales
Solar and Stellar Astrophysics
A General Framework for Radial Velocity Calibration in Low-Resolution Spectroscopic Surveys: Correcting Wavelength-Dependent and Global Systematics with Application to LAMOST DR9
Jinming Zhang, Haibo Yuan and Zhijia Tian
Radial velocity (RV) is crucial for
stellar kinematics and
Galactic archaeology. The Large Sky Area Multi-Object Fiber Spectroscopic
Telescope (LAMOST) has obtained over ten million low-resolution spectra ($R \sim 1800$), yielding RVs for millions of
stars, but these suffer from (1) wavelength-dependent inconsistencies (relative shifts between spectral segments) and (2) global zero-point offsets (uniform shifts of entire spectra). In this work, we comprehensively characterize and correct both. Each spectrum is first divided into eight segments of about 500 Angstrom. We organize the data at the spectrograph and fiber levels, measure segment-wise RV offsets relative to the full spectrum at each level, and then fit these offsets with low-order
polynomials to correct wavelength-dependent systematics. We then correct zero-points hierarchically: at the spectrograph level by minimizing a joint chi-squared constrained by repeat observations and cross-matches with APOGEE and
Gaia RVS, and at the fiber level by averaging seasonal offsets. After correction, RV precision improves significantly: for cross-night repeats, the standard deviation of RV differences at high signal-to-noise ratios drops by a factor of two from about 3.6 to about 1.8 km s$^{-1}$, implying a single-measurement precision of about 1.3 km s$^{-1}$. External checks with APOGEE and
Gaia show dispersions drop from about 4.0 to about 2.0 km s$^{-1}$. The precision approaches, though slightly below, the theoretical limit at $R \sim 1800$. We release a value-added RV catalog with corrected velocities for about 5.7 million spectra, providing a homogeneous and systematically corrected
dataset. The framework established in this work is also applicable to RV calibration in other large-scale spectroscopic surveys.
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Astrophysics of Galaxies
Investigation of Hourglass-shaped Magnetic fields in the G35.20-0.74 Star-Forming Complex
O. R. Jadhav, L. K. Dewangan, A. K. Maity et al. (+7 more)
To investigate the role of
magnetic fields toward the G35N and G35S sub-regions in the G35.20-0.74
star-forming complex, we utilized multi-wavelength polarimetric observations from the SOFIA/HAWC+ at 154 $\mu$m and ACT at 220 GHz/1.3 mm. The ACT 220 GHz polarization data (resolution $\sim$1$'$) show an hourglass-shaped plane-of-sky
magnetic field morphologies toward both the sub-regions, although with distinct
symmetry axes. SOFIA/HAWC+ 154 $\mu$m data (resolution $\sim$13.6$''$) confirm an hourglass morphology in G35N, whereas G35S displays a different
magnetic field configuration compared to the ACT observations. An hourglass morphology identified at clump scales ($\sim$pc) toward G35N is consistent with the previously reported B-field morphology at core scales ($\sim$0.05 pc), supporting the scenario of a magnetically regulated collapse. Using the SOFIA/HAWC+ data, we estimate
magnetic field strengths of $\sim$600 $\pm$ 200 $\mu$G in G35N and $\sim$850 $\pm$ 310 $\mu$G in G35S. Energy balance analysis suggests that
gravity and
magnetic fields contribute comparably in G35N, while in G35S the gas dynamics are dominated by
magnetic field, followed by
gravity and
turbulence. The higher field strength in G35S likely results from compression by the expanding HII region, highlighting the impact of
stellar feedback. The derived
magnetic field strengths and corresponding
magnetic energies should be treated as upper limits due to unresolved beam-scale correlations and the limited fitting range of the polarization angle structure function. Overall, our results show that
magnetic fields decisively regulate
star formation, with G35N shaped by magnetically controlled collapse and G35S being strongly influenced by
stellar feedback.
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All authors O. R. Jadhav, L. K. Dewangan, A. K. Maity, Sanhueza Patricio, D. K. Ojha, Saurabh Sharma, Ram Kesh Yadav, A. Haj Ismail, Moustafa Salouci, Ian Stephens
Astrophysics of Galaxies
What is Powering the Enigmatic He II Emitter Hebe: The First Stars or Black Holes?
Junehyoung Jeon, Tae Bong Jeong, Saiyang Zhang et al. (+1 more)
Recent high-resolution spectroscopy with the James Webb Space
Telescope (JWST) has confirmed the presence of a strong He II $\lambda1640$ emitting clump in the vicinity of GN-z11, with only upper limits on its
metallicity. To explain the peculiar properties of this source, now termed Hebe, a cluster of metal-free, Population III (Pop III)
stars has been invoked. A less likely source for the hard UV ionizing radiation could be an accreting supermassive black hole (SMBH) embedded inside Hebe. We here provide further constraints on what could power the observed emission lines in Hebe. Comparing with cosmological simulations of Pop III
star cluster formation, we assess the maximum Pop III
stellar mass that could plausibly form at the location of Hebe, finding
stellar masses of a few $10^5\,M_{\odot}$, consistent with those inferred from the observations. Modeling the continuum spectral energy distribution arising from an accreting SMBH, we derive He II and H I ionizing rates and the resulting recombination line luminosities, providing a less natural fit for the combined observations. We thus confirm the interpretation of Hebe as a remarkable,
primordial object, with the most plausible power source provided by a massive cluster of Pop III
stars, at the limit of what is allowed within the standard model of first
star formation.
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All authors Junehyoung Jeon, Tae Bong Jeong, Saiyang Zhang, Volker Bromm
High Energy Astrophysical Phenomena
A comprehensive framework for phase-coherent mapping of the gravitational-wave sky with pulsar timing arrays
Małgorzata Curyło, Eric Thrane, Paul D. Lasky et al. (+1 more)
We present a practical implementation of a phase-coherent mapping technique for
pulsar timing arrays that resolves the full complex polarisation state of the gravitational-wave sky as a function of direction and frequency. Unlike standard cross-correlation methods, this approach preserves the amplitude, phase, and polarisation of the signal in every sky pixel. The resulting maps constitute a compact, minimally processed summary of the data from which all subsequent analyses – characterisation of a
stochastic background, searches for anisotropy, and identification of individual sources – can be derived within a single unified framework. Our implementation is fully compatible with established
pulsar timing data analysis methods. We validate the framework through a series of realistic simulations with varying array configurations, noise properties, and signal types. We demonstrate robust recovery of source amplitudes and sky locations across different scenarios, and discuss the impact of polarisation leakage, noise, and direction-dependent array sensitivity on the recovery of astrophysical signals.
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All authors Małgorzata Curyło, Eric Thrane, Paul D. Lasky, Dawson S. Gaynor
Instrumentation and Methods for Astrophysics · Cross-listed from physics.ins-det
Three-dimensional recoil-electron reconstruction using combined optical imaging and waveform readout for electron-tracking Compton cameras
Tomonori Ikeda, Tatsuya Sawano, Naomi Tsuji et al. (+1 more)
Accurate reconstruction of
recoil-electron directions is critical for enhancing the point-spread function of electron-tracking Compton cameras (ETCCs) in gamma-ray imaging. Although full three-dimensional (3D) readout systems achieve high-precision reconstruction, they are impractical for large-area detectors because of the enormous data volume. This study proposes and demonstrates a practical alternative for inferring the 3D
recoil-electron direction in Compton scattering. This method combines a high-resolution two-dimensional optical image, a one-dimensional waveform signal, and a deep-learning-based method through simulations. The proposed method achieved an angular resolution of approximately $44^\circ$ for the
recoil-electron direction in the 40-50 keV range, corresponding to an improvement of a factor of about 1.3 compared with our previous strip-readout approach using pseudo-experimental data generated by Geant4 and MAGBOLTZ simulations for an argon-based gas time projection chamber. In addition, the starting-point resolution of the electron track was improved over the previous method across the 5-50 keV electron energy range. These results demonstrate that complementary information from the transverse image and longitudinal waveform can effectively recover the 3D track
topology without requiring full 3D readout. The proposed approach provides a realistic pathway for improving ETCC imaging performance.
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All authors Tomonori Ikeda, Tatsuya Sawano, Naomi Tsuji, Yoshitaka Mizumura
Instrumentation and Methods for Astrophysics
Seeing at Timau National Observatory Based on ERA5 Dataset
Rhorom Priyatikanto, Gerhana P. Putri, Clara Y. Yatini et al. (+7 more)
Understanding the seeing conditions is crucial for astronomical observations using a ground-based
telescope. This study analyzes long-term atmospheric data (2002-2021) from the ERA5
dataset to assess the seeing conditions at the new Timau National Observatory in Indonesia, which will house a 3.8-meter optical
telescope. While the ERA5
dataset shows good agreement with radiosonde data for temperature and wind speed, it tends to underestimate seeing at Eltari Airport, Kupang. Despite this discrepancy, the ERA5 data suggest a median seeing of 0.79 arcseconds at Timau, with optimal seeing conditions in March and December and greater variability during the May to September dry season. These findings are crucial for the planning and operation of the observatory, which requires excellent seeing conditions for its three-band optical imager and a near-infrared camera. Although the seeing at Timau is not as good as some other observatories, the conditions at Timau make it an observatory that has good prospects for equatorial regions.
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All authors Rhorom Priyatikanto, Gerhana P. Putri, Clara Y. Yatini, Isfahani Rusyda, Evan I. Akbar, Agustinus G. Admiranto, Ferdhiansyah Noor, Siti Maryam, Elyyani, Abd Rachman
Cosmology and Nongalactic Astrophysics
Estimating galactic foreground with the population of resolved galactic binaries
Yang Jiang and Qing-Guo Huang
The
stochastic gravitational wave background (SGWB) in the millihertz band constitutes a primary science target for future space-based interferometers. The detection of such a signal, however, poses substantial data-processing challenges, not least due to the overwhelming contribution from numerous compact binaries in our
Galaxy. Only a fraction of these binaries are sufficiently bright to be resolved as individual sources. The superposition of gravitational waves from the inspiral phases of the unresolved majority gives rise to a confusion foreground that must be accurately estimated. In this work, we model this foreground as an anisotropic SGWB and derive the variation of detector response intensity by analyzing the spatial distribution of binary systems. We further examine the distribution of resolved systems to assess whether they are representative of the total population. Finally, we perform parameter estimation to an injected
stochastic background using the modeled foreground within the Taiji Data Challenge II. Our results demonstrate that a foreground description based on the population properties of resolved
Galactic binaries can yield preliminarily viable estimates.
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Instrumentation and Methods for Astrophysics
The Gamma-Ray Monitor onboard the SVOM satellite
Jian-Chao Sun, Yong-Wei Dong, Jiang He et al. (+21 more)
The Gamma-Ray Monitor (GRM) is a key scientific payload onboard the Space-based Multi-band Variable Object Monitor (SVOM) satellite, designed specifically for the detection and study of gamma-ray bursts (GRBs). Launched into a 625 km low-Earth orbit on 22 June 2024, GRM serves as a large-area, wide-field-of-view instrument capable of observing the hard X-ray and soft gamma-ray emissions in the energy range of 15 keV to 5 MeV. Its primary scientific objectives include: promptly triggering and localizing GRBs (with particular sensitivity to short-hard GRBs), measuring spectral and temporal properties of bursts, monitoring charged particle fluxes in orbit. GRM successfully detected its first GRB (GRB 240627B) on 27 June 2024, and has since maintained a detection rate of more than 100 GRBs per year. Cross-instrument comparisons with detectors such as GECAM and
Fermi/GBM have validated the performance and data quality of GRM. This paper provides a comprehensive overview of GRM instrument design, reliability verification through ground testing, in-orbit triggering and localization
algorithms, performance calibration, and preliminary in-orbit results, demonstrating its capability as a versatile gamma-ray all-sky monitor.
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All authors Jian-Chao Sun, Yong-Wei Dong, Jiang He, Jiang-Tao Liu, Lu Li, Rui-Jie Wang, Xin Liu, Li Zhang, Min Gao, Yue Huang, Hao-Li Shi, Li-Ming Song, Wen-Jun Tan, Chen-Wei Wang, Jin Wang, Jin-Zhou Wang, Ping Wang, Xing Wen, Bo-Bing Wu, Shao-Lin Xiong, Juan Zhang, Shuang-Nan Zhang, Xiao-Yun Zhao, Shi-Jie Zheng
Astrophysics of Galaxies
Very Long Baseline Interferometry Search for Nuclear Radio Continuum Emission in the Barred Spiral Galaxy NGC 7479
Seppo Laine, Emmanuel Momjian, Emilia Järvelä et al. (+4 more)
We have obtained very high angular resolution (a few milliarcseconds or sub-parsec scale) Very Long Baseline Array (VLBA) and European Very Long Baseline Interferometry (VLBI) Network (EVN)
radio continuum images of the
nucleus in the barred spiral
galaxy NGC 7479, to search for possible
nuclear emission on parsec scales. The observations were taken using phase referencing. Previous Karl G. Jansky Very Large Array (VLA) and Multi-Element
Radio Linked Interferometer Network (MERLIN) observations revealed a large jet-like structure, apparently emanating from the
nucleus, and unresolved
nuclear emission at 0.1 arcsecond (about 15 pc at the assumed distance of 32 Mpc) scale, respectively. Our sensitive new VLBA and EVN images resolve the previously unresolved
nuclear source and reveal two distinct emission regions (VLBI components) that are separated by about 30 milliarcseconds. We also report an apparent change in separation of the two main emission regions over the ten years between EVN and VLBA observations, implying relativistic
radio jet motion or changes in shock illumination of gas by a
nuclear wind. We measure the spectral indices and brightness temperatures of the VLBI components, and discuss possible physical causes of the observed emission.
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All authors Seppo Laine, Emmanuel Momjian, Emilia Järvelä, Thomas P. Krichbaum, S. Komossa, Travis C. Fischer, Thomas G. Pannuti
Astrophysics of Galaxies
Revisiting the distance and the globular cluster system of the remarkable galaxy UDG1 in the NGC 5846 group
Duncan A. Forbes, Bas van Heumen and Yimeng Tang
Two studies that utilised the same HST/WFC3 imaging of NGC5846_UDG1 have reported quite different total counts for its globular cluster (GC) system, i.e. 54 $\pm$ 9 vs 33 $\pm$ 3 GCs. In both cases they counted all GCs, that met their selection criteria, down to the faintest magnitudes. They also disagree as to whether NGC5846_UDG1 lies in the NGC 5846 group or well outside the group, in the field. As an ultra diffuse
galaxy with one of the richest GC systems known, and therefore implications for its
halo mass, it is important to understand which of these is closer to the truth. Here we present a new SBF-based distance to NGC5846_UDG1 from HST/ACS imaging of 26.5 $\pm$ 2.7 Mpc, which places it squarely within the NGC 5846 group. Using this distance we adopt the standard approach of only counting GCs brighter than the turnover magnitude. This has the advantage of considering only the brighter GCs which are resolved in HST imaging and largely confirmed by spectroscopy, while also avoiding the fainter candidates for which contamination is potentially an issue. With this robust approach we find that the two studies are entirely consistent with each other. Both imply a total GC system of around 50 GCs and by inference a massive
galaxy halo of greater than 10$^{11}$ M$_{\odot}$. We also revisit the two previous photometric studies focusing on half a dozen intermediate magnitude objects that are selected by one study but excluded by the other. These objects have GC-like magnitudes, sizes and are nearly round with GC-like appearances. They are very unlikely to be background
galaxies or interloper GCs and thus bona fide GCs associated with NGC5846_UDG1.
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