Astrophysics of Galaxies
On Constraining the Proposed Hierarchical Triple Scenario for an Eccentric Milli-Second Pulsar Binary PSR J1618-3921
Adya Shukla, A. Gopakumar and Paramasivan Arumugam
A very recent and meticulous timing effort suggests that an eccentric millisecond
pulsar (eMSP) binary, namely PSR J1618-3921, is likely to be a part of a hierarchical triple (HT) system with a $0.6M_{\odot}$ companion in a $\sim 300$yr orbit. We investigate observational implications of the proposed HT scenario for PSR J1618-3921 and our ability to constrain the scenario. We model the MSP-Helium White
Dwarf binary to be a part of bound point-mass HT, while incorporating the effects due to the quadrupolar interactions between the inner and outer binaries, along with dominant order general relativistic contributions to the periastron precession of the inner binary. If the proposed HT system is indeed undergoing Kozai oscillations at the present epoch, the orbital eccentricity ($e$) would be expected to decrease, while the rate of periastron advance ($\dot{\omega}$) would correspondingly increase, for plausible ranges of the HT parameters. Furthermore, the fractional variations in $e$ are anticipated to be at the level of a few parts in $10^{5}$-a magnitude that is substantially larger than the current measurement precision of $e$. We find that, for this eccentric MSP binary, the HT configurations that minimize the temporal
evolution of orbital eccentricity and argument of periastron are mutually incompatible. This indicates that the continued high-precision timing of PSR J1618-3921-when analyzed within the framework introduced here-should place stringent limits on the presence and properties of a potential third body in the system.
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Cosmology and Nongalactic Astrophysics · Cross-listed from gr-qc
Inflationary assessment of $F(\mathcal{R},\tilde{\mathcal{R}})$ Einstein-Cartan models
Theodoros Katsoulas and Kyriakos Tamvakis
In the framework of $F(\mathcal{R},\tilde{\mathcal{R}})$ Einstein-Cartan
gravity with an action depending both of the
Ricci scalar and the so-called Holst-invariant
curvature we consider models that include cubic terms of the latter in the action and study their inflationary behavior. These terms can have a considerable effect either positive or negative in relation to the agreement with present observational data, depending on parameters. In parameter regions where the quadratic models fail to produce results consistent with observational data, the presence of these additional cubic terms can lead to compatible predictions.
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High Energy Astrophysical Phenomena
VHE FSRQs with Fermi-LAT: VHE and even brighter states in high-z FSRQs due to an HBL-like component?
Megha and Pankaj Kushwaha
Very high-energy (VHE) detected flat-spectrum
radio quasars (FSRQs) are relatively few despite being the most persistent bright MeV-GeV sources. Focusing on VHE emission, we investigated the spectral and temporal properties of VHE-detected FSRQs using 14-year
Fermi-LAT data. All are highly variable (flux-amplitude$>$100) with VHE detection associated with brighter flux states and relatively harder spectra. Above a flux limit, flux anti-correlates with spectral index, exhibiting a bluer-when-brighter trend. The low-flux state spectral energy distributions (SEDs) for all resembles a power-law, while high-flux and VHE-associated states resemble a log-parabola, accompanied by an almost nil (PKS0736+017, PKS1510-089) to marginal (4C+21.35, 3C279) to significant (B21420+32, TON0599, PKS1441+25, S30218+35, PKS0346-27, OP313) MeV-GeV peak-upshift – more prominent in high-
redshift sources. For no/marginal peak-upshift, the VHE emission is consistent with external Comptonization of infrared
photons (EC-IR) driven primarily by a power-law continuation of the particle spectrum to higher energies. For those with a significant MeV-GeV peak-upshift, PKS0346-27 and OP313 shows peak-upshift in the synchrotron spectrum, and thus VHE is EC-IR origin, while for others without synchrotron-peak upshift, we attribute the VHE to an HBL-like component with a Compton-Dominance (CD) like FSRQs, with VHE driven primarily by particle spectrum continuation. In some, even high-state SEDs seem to require an HBL-like component. Thus, VHE activities in FSRQs mainly result from particle spectrum continuation, aided by spectral transition or a new HBL-like component with FSRQ-like CD. Such spectral changes naturally brighten the GeV-VHE flux, overcoming extragalactic background light absorption without requiring extraordinary brightening under the traditional EC-IR scenario than normally exhibited.
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Astrophysics of Galaxies
The Large Sky Area Multi-object Fiber Spectroscopic Telescope (LAMOST) Quasar Survey: Quasar Properties from Data Release 10 to 12
Bing Lyu, Xue-Bing Wu, Jun-Jie Jin et al. (+9 more)
We present the
quasar catalog from Data Releases 10 to 12 of the Large Sky Area Multi-Object Fiber Spectroscopic
Telescope (LAMOST)
Quasar Survey, comprising
quasars observed between September 2021 and June 2024. We robustly identified $11,346$
quasars, of which $5,386$ are newly discovered objects not present in the Million
Quasars catalog. This release brings the total number of
quasars identified by the 12-year LAMOST survey to $67,521$, of which $29,513$ are newly discovered. While the absolute flux calibration for LAMOST
quasar spectra from Data Releases 6 to 9 was previously performed using the SDSS/PanSTARRS1 multi-band photometric data, the inherent variability of
quasars can affect the flux accuracy. To address this limitation, we recalibrated the LAMOST spectra using (quasi-)simultaneous photometric data from Zwicky Transient Facility (ZTF), which has conducted high-cadence sky monitoring since March 2018. Based on the recalibrated single-epoch spectra, we estimated the emission line fluxes, continuum fluxes, and virial black hole masses. These improved spectra facilitate direct comparison with the spectra of common
quasars from the Sloan Digital Sky Survey (SDSS), enabling searches for rare
quasars, such as changing-look
quasars exhibiting the appearance or disappearance of broad emission lines and broad absorption line
quasars. The combined
dataset of photometry and multi-epoch spectra will enhance the detections of AGN-related transients, such as Bowen fluorescence
flares and extreme variability
quasars, thereby improving our understanding of
quasar variability.
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All authors Bing Lyu, Xue-Bing Wu, Jun-Jie Jin, Yuming Fu, Yuxuan Pang, Huimei Wang, Rui Zhu, Su Yao, Yan-Li Ai, Yan-xia Zhang, Hai-long Yuan, Zhi-ying Huo
Astrophysics of Galaxies
Direct observational evidence that higher-luminosity type 1 active galactic nuclei are most commonly triggered by galaxy mergers
Yongmin Yoon, Yongjung Kim, Dohyeong Kim et al. (+2 more)
We examine the connection between
galaxy mergers and the triggering of active
galactic nuclei (AGNs) using a sample of 614 type 1 AGNs at $z<0.07$, along with a control sample of inactive
galaxies matched to the AGNs for comparison. We used
tidal features, detected in deep images from the DESI Legacy Imaging Survey, as direct evidence of recent mergers. We find that the fraction of type 1 AGN hosts with
tidal features ($f_T$) is higher for AGNs with higher luminosities and (to a lesser extent) more massive black holes. Specifically, $f_T$ rapidly increases from $0.05\pm0.03$ to $0.75\pm0.13$ as the luminosity of the $[\mathrm{O\,{\scriptstyle III}}]$ $\lambda$5007 emission line ($L_{[\mathrm{O\,{\scriptstyle III}}]}$), an indicator for bolometric AGN luminosity, increases in the range $10^{39.5}\lesssim L_{[\mathrm{O\,{\scriptstyle III}}]}/(\mathrm{erg\,s}^{-1}) \lesssim10^{42.5}$. In addition, $f_T$ increases from $0.13\pm0.03$ to $0.43\pm0.09$ as black hole mass ($M_\mathrm{BH}$) increases in the range $10^{6.0}\lesssim M_\mathrm{BH}/M_{\odot}\lesssim10^{8.5}$. The fraction $f_T$ also increases with the Eddington ratio, although the trend is less significant compared to that with $L_{[\mathrm{O\,{\scriptstyle III}}]}$ and $M_\mathrm{BH}$. The excess of $f_T$, defined as the ratio of $f_T$ for AGNs to that of their matched inactive counterparts, exhibits similar trends, primarily increasing with $L_{[\mathrm{O\,{\scriptstyle III}}]}$ and weakly with $M_\mathrm{BH}$. Our results indicate that, in the local Universe,
galaxy mergers are the predominant triggering mechanism for high-luminosity AGNs, whereas they play a lesser role in triggering lower-luminosity AGNs. Additionally, strong events, such as
galaxy mergers, may be more necessary to activate massive black holes in more massive
galaxies due to their lower gas fractions.
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All authors Yongmin Yoon, Yongjung Kim, Dohyeong Kim, Kyungwon Chun, Woowon Byun
Astrophysics of Galaxies
SDSS-V LVM: Resolving Physical Conditions in the Trifid Nebula
Natascha Sattler, J. Eduardo Méndez-Delgado, Kathryn Kreckel et al. (+18 more)
The chemical abundance of the interstellar medium sets the initial conditions for
star formation and provides a probe of chemical
galaxy evolution models. However, unresolved inhomogeneities in the electron temperature can lead to a systematic underestimation of the abundances. We aim to directly test this effect. We use the SDSS-V Local Volume Mapper to spatially map the physical conditions of the Trifid Nebula (M 20), a
Galactic H II region ionized by a single mid-type O
star, at 0.24 pc resolution. We exploit various emission lines (e.g., Hydrogen recombination lines and collisionally excited lines, including also faint auroral lines) and compute spatially resolved maps of [O II] and [S II] electron densities; [N II], [O II], [S II], [S III] electron temperatures; and the ionic oxygen abundances. We find internal variations of electron density that result from the ionization front, along with a negative radial gradient. However, we do not find strong gradients or structures in the electron temperature and the total oxygen abundance, making the Trifid Nebula a relatively homogeneous H II region at the observed spatial scale. We compare these spatially resolved properties with equivalent integrated measurements of the Trifid Nebula and find no significant variations between integrated and spatially resolved conditions. This isolated H II region, ionized by a single O-
star, represents a test case of an ideal Strömgren sphere. The physical conditions in the Trifid Nebula behave as expected, with no significant differences between integrated and resolved measurements.
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All authors Natascha Sattler, J. Eduardo Méndez-Delgado, Kathryn Kreckel, Christophe Morisset, Oleg Egorov, Evgeniya Egorova, Ahmad Nemer, Fu-Heng Liang, A.A.C. Sander, Alexandre Roman-Lopes, Carlos G. Román-Zúñiga, Evelyn J. Johnston, Sebastián F. Sánchez, José G. Fernández-Trincado, Niv Drory, Amrita Singh, Dmitry Bizyaev, Sumit K. Sarbadhicary, Pablo García, Alfredo Mejía-Narváez, Guillermo A. Blanc
High Energy Astrophysical Phenomena · Cross-listed from gr-qc
Quasinormal modes of a static black hole in nonlinear electrodynamics
Mohsen Fathi, Ariel Guzmán and J.R. Villanueva
We investigate the axial electromagnetic quasinormal modes of a static, asymptotically Anti–de Sitter (AdS) black hole sourced by a nonlinear electrodynamics model of Plebański type. Starting from the master equation governing axial perturbations, we impose ingoing boundary conditions at the event horizon and normalizable (Dirichlet) behavior at the AdS boundary. Following the approach of Jansen, we recast the radial equation into a linear generalized
eigenvalue problem by using an ingoing Eddington–Finkelstein formulation, compactifying the radial domain, and regularizing the asymptotic coefficients. The resulting problem is solved using a Chebyshev–Lobatto pseudospectral discretization. We compute the fundamental quasinormal mode frequencies for both the purely electric ($Q_m=0$) and purely
magnetic ($Q_e=0$) sectors, emphasizing the role of the nonlinearity parameter $\beta$ and the effective charge magnitude $Q$. Our results show that increasing either $\beta$ or $Q$ raises both the oscillation frequency $\omega_R$ and the damping rate $-\omega_I$, leading to faster but more rapidly decaying ringdown profiles. Nonlinear electrodynamics breaks the isospectrality between electric and
magnetic configurations:
magnetic modes are systematically less oscillatory and more weakly damped than their electric counterparts. For sufficiently large $\beta$ and small $Q_m$, the fundamental mode becomes purely imaginary ($\omega_R \approx 0$), in agreement with the absence of a trapping potential barrier in this regime. These findings reveal qualitative signatures of nonlinear electromagnetic effects on black hole perturbations and may have implications for high-field or high-charge astrophysical environments.
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Solar and Stellar Astrophysics
Spectropolarimetric characterisation of exoplanet host stars in preparation of the $Ariel$ mission II. The magnetised wind environment of TOI-1860, DS Tuc A, and HD 63433
S. Bellotti, A. Lavail, D. Evensberget et al. (+10 more)
We update the status of the spectropolarimetric campaign dedicated to characterise the
magnetic field properties of a sample of known
exoplanet-hosting
stars included in the current target list of the $Ariel$ mission. We analysed spectropolarimetric data collected for 15 G-M type
stars with Neo-Narval, HARPSpol, and SPIRou to assess the detectability of the large-scale
magnetic field. For three
stars we reconstructed the
magnetic field
topology and its temporal
evolution via Zeeman-Doppler imaging (ZDI). Such reconstructions were then used to perform 3D MHD simulations of the
stellar wind and environment impinging on the hosted
exoplanets. We detected the
magnetic field of six
stars. Of these, we performed ZDI reconstructions for the first time of TOI-1860 and DS Tuc A, and for the second time of HD 63433, providing temporal information of its large-scale
magnetic field. Consistently with previous results on young ($\rm\sim 50-100~Myr$)
solar-like
stars, the large-scale
magnetic field is moderately strong (30-60 G on average) and complex, with a significant fraction of
magnetic energy in the toroidal component and high-order poloidal components. We found the orbit of TOI-1860 b to be almost completely sub-Alfvénic, the orbits of DS Tuc A b and HD 63433 d to be trans-Alfvénic, and the orbits of HD 63433 b and c to be super-Alfvénic. We obtained marginal detections of the
magnetic field for TOI-836 and TOI-2076, and detections for TOI-1136, but the number of observations is not sufficient for
magnetic mapping. A
magnetic star-
planet connection can occur for most of TOI-1860 b's orbit. This can happen more sporadically for DS Tuc A b and HD 63433 c given the lower fraction of their orbit in the sub-Alfvénic regime. The orbit of HD 63433 c is nevertheless more sub-Alfvénic than previously simulated owing to the temporal
evolution of the
stellar magnetic field.
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All authors S. Bellotti, A. Lavail, D. Evensberget, A.A. Vidotto, C. Danielski, B. Edwards, G.A.J. Hussain, T. Lüftinger, J. Morin, P. Petit, S. Boro Saikia, G. Micela, A. López Ariste
High Energy Astrophysical Phenomena
Search for persistent radio emission towards selected localised Fast Radio Burst positions using the MeerKAT Telescope
Thulo Letsele, Lebogang Mfulwane, Christo Venter et al. (+2 more)
Fast
Radio Bursts (FRBs) are millisecond-duration
radio pulses originating from cosmological distances, as indicated by their large dispersion measures. While numerous FRBs have now been localised to their host
galaxies, a distinct class of compact electromagnetic counterpart, a Persistent
Radio Source (PRS), has also been identified in some cases. Currently, only three, and possible a fourth repeating FRBs (FRB20121102A, FRB20190417A, FRB20190520B, and FRB20240114A) have confirmed associations with a PRS. Insight into progenitors, local environments, and the
evolution of FRBs can be clarified by characterising these PRSs. In this work, we present 2 detected candidate PRSs using MeerKAT
radio telescope data and one non-detection (as part of a larger study involving 25 FRB positions). Both FRB20221106 and FRB20181112 were found to have a host
galaxy, and whether the detected
radio continuum emission comes from the host
galaxy or PRS is still an open question. High-resolution observations from a
telescope such as e-MERLIN are required to resolve this question. If a compact PRS is detected, this
telescope will provide the size, and investigate the flux variability and spectral shape of this compact PRS. Lastly, in the case of FRB220190102, which was observed over two epochs, no
radio continuum was detected. However, a flux upper limit is provided for both epochs.
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All authors Thulo Letsele, Lebogang Mfulwane, Christo Venter, James O. Chibueze, Mechiel Christiaan Bezuidenhout
Solar and Stellar Astrophysics
Peculiar SN Ic 2022esa: An explosion of a massive Wolf-Rayet star in a binary as a precursor to a BH-BH binary?
Keiichi Maeda, Hanindyo Kuncarayakti, Takashi Nagao et al. (+4 more)
A class of
supernovae (SNe) termed `SN Ic-CSM' are characterized by late-time emergence of narrow emission lines of elements formed in the oxygen core of a massive
star. A popular scenario is the interaction of the SN ejecta and O-rich circumstellar medium (CSM), i.e., Circumstellar Interaction (CSI). Uncovering the progenitor system of SNe Ic-CSM plays a critical role in understanding the final
evolution of a massive
star to a bare C+O
star. In this Letter, we present observations of SN 2022esa which we show is an SN Ic-CSM. Surprisingly, a stable periodicity of ~32 days is found in its light-curve
evolution with a hint of a slowly increasing period over ~200 days. We argue that the main power source is likely the interaction of the SN ejecta and O-rich CSM, while the energy input by the post-SN eccentric binary interaction within the SN ejecta is another possibility. In either case, we propose a massive Wolf-Rayet (WR)
star as the progenitor, in a WR-WR or WR-BH (black hole) binary that will eventually evolve to a BH-BH binary. Specifically, in the CSI scenario, the progenitor system is an eccentric binary system with an orbital period of about a year, leading to the observed periodicity through the modulation in the CSM density structure. We also show that some other objects, superluminous SN I 2018ibb (a pair-instability SN candidate) and peculiar SN Ic 2022jli (the first example showing stable periodic modulation), show observational similarities to SNe Ic-CSM and may be categorized as SN Ic-CSM variants. Complemented with a large diversity in their light-curve
evolution, we propose that SNe Ic-CSM (potentially linked to SNe Ibn/Icn) are a mixture of multiple channels that cover a range of properties in the progenitor
star, the binary companion, and the binary orbit.
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All authors Keiichi Maeda, Hanindyo Kuncarayakti, Takashi Nagao, Miho Kawabata, Kenta Taguchi, Kohki Uno, Kishalay De
Cosmology and Nongalactic Astrophysics · Cross-listed from hep-ph
Exploring Leptogenesis, WIMP Dark Matter, and Gravitational Waves in an extended Scalar Framework
Subhaditya Bhattacharya, Niloy Mondal and Arunansu Sil
We explore an extension of the Type-I seesaw framework in which a scalar mediator $\Phi$ connects the Standard Model (SM) to a dark sector consisting of right-handed
neutrinos or RHNs ($N_i$) and a complex scalar $S$. The interactions are governed by a phenomenologically viable $\mathcal{Z}_4 \times CP$
symmetry, allowing a dimension-5 effective operator involving the SM
lepton doublet,
Higgs, RHNs, and $\Phi$. Once $\Phi$ acquires a
vacuum expectation value, its couplings to the SM and RHNs affect the standard leptogenesis through $N_i$ decay, while electroweak
symmetry breaking (EWSB) subsequently induces
neutrino masses through the same structure. Furthermore, a $\Phi$-portal interaction induces a
vacuum expectation value for real (imaginary) component of $S$ opening additional annihilation channels for its imaginary (real) component, identified as dark matter (DM) in the GeV-TeV mass range (excluded in the simplest scalar singlet DM scenario). The spontaneous breaking of the associated discrete
symmetry can lead to domain wall formation, whose required early annihilation may generate observable gravitational wave signals, providing a way to ideate the
symmetry-breaking scale and its connection to
neutrino mass, baryogenesis, and dark matter.
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High Energy Astrophysical Phenomena
KM3NeT/ARCA stacking search for high-energy neutrinos from blazars
Francesco Carenini and Giulia Illuminati
Blazars are promising targets for
neutrino astronomy, as highlighted by IceCube's identification of TXS 0506+056 as a
cosmic neutrino source candidate. High-frequency-peaked BL Lacs (HBLs) stand out due to their characteristic electromagnetic high-energy emission properties, which makes them as well promising candidates for the production of high-energy
neutrinos. Such
neutrinos could be detected by KM3NeT/ARCA, a next-generation deep-sea Cherenkov detector under construction in the Mediterranean Sea. This contribution presents the results of a binned likelihood stacking analysis investigating high-energy
neutrino emissions from a subset of HBLs. A total of 232 sources have been selected from the 3HSP catalogue and targeted in the analysis of KM3NeT/ARCA data taken with several detector configurations, specifically in the period in which from 6 to 21 detection units were deployed. The analysis is based on
neutrino emission models of blazars developed using the LeHa-Paris numerical code, which simulates the spectral energy distribution of jetted active
galactic nuclei.
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High Energy Astrophysical Phenomena
The role of the galaxy stellar mass function in determining the cosmological distribution of astrophysical transients with applications to fast radio bursts and merging binary black holes
Sandeep Kumar Acharya
The cosmological distribution and formation rate of compact astrophysical objects such as fast
radio bursts (FRBs) are typically assumed to be proportional to a linear combination of cosmological
star formation rate and
stellar mass. In the literature, a template for
star formation rate, which is just a function of
redshift, is typically used. In this work, we point out the importance of
galaxy stellar mass function which captures the host
galaxy information of observed FRBs as well as the
redshift evolution of
galaxy stellar mass. Using this information and taking the
stellar mass distribution of a sample of localized FRBs at face value, we find that FRB formation efficiency per
stellar mass may have to be more efficient (by a factor of $\approx 3$) than previously calculated, in order to reproduce the observed volumetric rate of FRBs at $z=0$. We show that cosmological population studies of FRBs have to include host
galaxy information along with its
redshift evolution in order to obtain unbiased results. This consideration is also applicable to other transients, e.g. gamma-ray bursts and merging binary black hole events. We show that our approach may open up the possibility to distinguish between different scenarios of merging binary black holes formation with a detection of few thousand gravitational wave events.
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Astrophysics of Galaxies
Silicate emission in a type-2 quasar: JWST/MIRI constraints on torus geometry and radiative feedback
C. Ramos Almeida, A. Asensio Ramos, C. Westerdorp Plaza et al. (+13 more)
Type-2
quasars (QSO2s) are AGN seen through a significant amount of
dust and gas that obscures the central supermassive black hole and the broad line region. Despite this, recent mid-infrared spectra of the central 0.5-1.1 kpc of five QSO2s at z~0.1, obtained with the MRS module of JWST/MIRI, revealed 9.7, 18, and 23 micron silicate features in emission in two of them. This indicates that the high angular resolution of JWST/MIRI now allows us to peer into their
nuclear region, exposing some of the directly illuminated dusty clouds that produce silicate emission. To test this, we fitted the
nuclear mid-infrared spectrum of the QSO2 with the strongest silicate features, J1010, with two different sets of
torus models implemented in an updated version of the
Bayesian tool BayesClumpy. These are the CLUMPY and the CAT3D-WIND models. The CAT3D-WIND model is preferred by the observations based on the marginal likelihood and fit residuals, although the two
torus models successfully reproduce the spectrum by means of intermediate covering factors ($\rm C_T=0.45\pm^{0.26}_{0.18}$ and $\rm C_T=0.66\pm^{0.16}_{0.17}$ for the CLUMPY and CAT3D-WIND models) and low inclinations ($\rm i=50^\circ\pm^{8^\circ}_{9^\circ}$ and $\rm i=13^\circ\pm^{7^\circ}_{6^\circ}$). Indeed, four of the five QSO2s with JWST/MIRI observations, including J1010, are in the blowout or ”forbidden” region of the Eddington ratio-column density diagram, indicating that they are actively clearing gas and
dust from their
nuclear regions, leading to reduced covering factors. This is in contrast with Seyfert 2
galaxies observed with JWST, which are in the ”permitted” regions of the diagram and show 9.7 micron silicate features in absorption. This supports a scenario where the more luminous the AGN and the higher their Eddington ratio, the lower the
torus covering factor, driven by radiation pressure on dusty gas.
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All authors C. Ramos Almeida, A. Asensio Ramos, C. Westerdorp Plaza, I. García-Bernete, E. Lopez-Rodriguez, S. Hönig, A. Audibert, S. García-Burillo, M. Pereira-Santaella, F. Donnan, A. Alonso-Herrero, O. González-Martín, N. Levenson, D. Rigopoulou, C. Tadhunter, G. Speranza
Solar and Stellar Astrophysics
Stranger Things: A Grid-based Survey of Strange Modes in Post-Main Sequence Models
D. Tarczay-Nehéz, L. Molnár and M. Joyce
We present a systematic survey of strange mode pulsations in Cepheids using MESA and for the linear stability analysis, MESA RSP. Our model grid spans $2-15\,M_\odot$ in mass and [Fe/H] $= -0.95$-$0.17$ ($Z = 0.0015$-$0.0200$) in
metallicity, with four convective overshoot prescriptions. Strange modes were identified in a relatively small fraction ($5-12.5$ %) of models, occurring at $n_\mathrm{pg} = 5-9$, with $n_\mathrm{pg} = 6$-$7$ as the most frequent radial modes. No unstable solutions were identified beyond $n_\mathrm{pg} = 9$, in contrast to earlier studies reporting strange modes at $n_\mathrm{pg} = 10-12$. We quantified the duration of the instability crossing phase ($\tau_\mathrm{IS}$), the strange mode phase ($\tau_\mathrm{s}$), and their ratio $\mathcal{P}_\mathrm{s} = \tau_\mathrm{s} / \tau_\mathrm{IS}$. Toward higher masses, both $\tau_\mathrm{IS}$ and $\tau_\mathrm{s}$ decrease, yet their ratio shows no systematic trend with mass in models that include convective core overshoot. The absolute timescales for strange modes remain short, typically $\tau_\mathrm{s} \sim 10^{4.5}$-$10^{6}$ years, while $\tau_\mathrm{IS}$ is often an order of magnitude shorter, implying that these
stars may spend a larger fraction of their life in the strange mode phase than in the instability strip itself. The extended duration of the strange mode phase may enhance the detectability of strange mode pulsators, provided that observational precision is sufficient to capture their low-amplitude variability. The predicted periods ($0.6-6.3$ days) are well covered by a single $27-$day TESS sector, making strange mode pulsators potentially detectable with current space-based photometry, although blending with nearby sources may pose challenges.
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High Energy Astrophysical Phenomena · Cross-listed from nucl-th
Thermoelectric coefficients of two-flavor quark matter from the Kubo formalism
Harutyun Gabuzyan, Arus Harutyunyan and Armen Sedrakian
The hot
quark matter created in heavy-ion collision experiments can exhibit strong temperature and chemical-potential gradients, which in turn can generate electric fields through thermoelectric effects. In this work, we investigate two relevant thermoelectric coefficients – the thermopower (Seebeck coefficient) and the Thomson coefficient – of two-
flavor quark matter using the Kubo formalism and the Nambu–Jona-Lasinio model as an effective description of dense, finite-temperature QCD. The required two-point
equilibrium correlation functions are evaluated using the Matsubara formalism of thermal field theory, applying a 1/Nc expansion to the relevant multi-loop Feynman diagrams. We employ previously derived
quark spectral functions obtained from one–
meson-exchange diagrams above the Mott transition temperature. Our numerical results show that both thermoelectric coefficients increase approximately linearly with temperature and decrease with increasing chemical potential. We also estimate the magnitude of the electric fields that can be generated in heavy-ion collisions by thermal gradients via the Seebeck effect.
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Earth and Planetary Astrophysics
Stellar chemistry and planet size: insights from GALAH DR4
N. Sussholz, S. Zucker, R. Helled et al. (+1 more)
The well-known correlation between
stellar metallicity and
planet occurrence is strongest for
giant planets, but weaker for smaller
planets, suggesting that detailed elemental patterns beyond [Fe/H] may be relevant. Using abundances from the fourth data release of the GALAH spectroscopic survey, we analyzed 104 host
stars with 141 confirmed transiting
planets. We divide
planets at 2.6 Earth radii, the theoretical threshold radius above which
planets are unlikely to be pure-water worlds. We find that large-
planet hosts are enriched by approximately 0.2 dex in iron and show a possible excess of highly volatile elements (C, N, O), though these measurements are affected by observational limitations, whereas small-
planet hosts exhibit an enhanced contribution of the classical rock-forming elements (Mg, Si, Ca, Ti) relative to iron, corresponding to a modest [Rock/Fe] offset of 0.06 dex, which is statistically significant, with a p value of 10^{-4}. These offsets remain significant for alternative radius cuts. A matched control sample of non-
planet-host
stars shows only weak and mostly statistically insignificant similar trends, confirming that the stronger chemical signatures are linked to the planetary characteristics. As our study relies on transiting
planets, it mainly probes short-period systems (periods shorter than 100 days). These results refine the
planet-
metallicity relation, highlighting the role of the relative balance between iron, volatiles, and rock-forming elements in
planet formation.
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All authors N. Sussholz, S. Zucker, R. Helled, D. Bashi
Solar and Stellar Astrophysics
Radio, X-ray, and EUV signatures of internal and external reconnection of an erupting flux rope
Jana Kašparová, Jaroslav Dudík, Marian Karlický et al. (+5 more)
We analyse imaging (EUV, X-ray) and spectral (
radio, X-ray) data obtained by ground based and space instruments on board space missions both on Earth (
Fermi, Hinode,
Solar Dynamics Observatory) and
solar orbit (
Solar Orbiter, STEREO-A), which provide a multi-directional view on the same event. The combination of EUV and X-ray images and X-ray spectra allowed us to identify hot loops in the vicinity of the filament before its eruption. We interpreted their interaction with the rising filament as a signature of an arcade-to-rope reconnection geometry. The subsequent EUV brightening within the filament revealed helical structure of the erupting rope. We explained co-temporal
radio slowly positively drifting bursts as a result of beam acceleration within the
magnetic rope and propagation along the helical structure. Corresponding X-ray spectra were consistent with a thermal origin. The filament rising was accompanied by co-temporal normal and reverse drift type III
radio bursts. We interpreted them as a signature of a reconnection event and estimated electron density at the reconnection site. Further untwisting of the helical structure led to formation of a quasi-circular EUV structure seen from Earth and STEREO-A. Its occurrence was co-temporal with a unique tangle of
radio U- and inverse U-bursts. We proposed that several accelerated beams propagate within that complex structure and generate the burst tangle. During the start of the
flare hard X-ray emission was concentrated near the filament leg only suggesting predominant propagation of the beams towards its rooting. We collected multi-wavelength observations indicating interaction of the erupting
magnetic flux rope with the overlying arcade and internal
magnetic reconnection inside the rising flux rope.
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All authors Jana Kašparová, Jaroslav Dudík, Marian Karlický, Alena Zemanová, Paolo Massa, Samuel Krucker, Frédéric Schuller, Ján Rybák
High Energy Astrophysical Phenomena
A Statistical Analysis of Fluence and Energy Distributions of Non-repeating Fast Radio Bursts Detected by CHIME
Nurimangul Nurmamat, Yong-Feng Huang, Xiao-Fei Dong et al. (+6 more)
Fast
Radio Bursts (FRBs) are energetic
radio bursts that typically last for milliseconds. They are mostly of extragalactic origin, but the progenitors, trigger mechanisms and radiation processes are still largely unknown. Here we present a comprehensive analysis on 415 non-repeating FRBs detected by CHIME, applying manual filtering to ensure sample completeness. It is found that the distribution of fluence can be approximated by a three-segment power-law function, with the power-law indices being $-3.76 \pm 1.61$, $0.20 \pm 0.68$ and $2.06 \pm 0.90$ in the low, middle, and high fluence segments, respectively. Both the total dispersion measure (\text{DM}) and the extragalactic \text{DM} follow a smoothly broken power-law distribution, with characteristic break DM values of $\sim 703$ pc $\rm cm^{-3}$ and $\sim 639$ pc $\rm cm^{-3}$, respectively. The
redshifts are estimated from the extragalactic \text{DM} by using the Macquart relation, which are found to peak at $ z \sim 0.6$. The isotropic energy release ($E_{\text{iso}}$) is also derived for each burst. Two-Gaussian components are revealed in the distribution of $E_{\text{iso}}$, with the major population narrowly clustered at $\sim 2.3 \times 10^{40} {\rm erg}$. The minor population have a characteristic energy of $\sim 1.6 \times 10^{39}$ erg and span approximately one order of magnitude. The distribution hints a near-uniform energy release mechanism for the dominant population as expected from some catastrophic channels, whereas the lower-energy component (potentially including repeat-capable sources) may reflect a broader diversity in FRB origins, emission mechanisms and evolutionary stages.
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All authors Nurimangul Nurmamat, Yong-Feng Huang, Xiao-Fei Dong, Chen-Ran Hu, Orkash Amat, Ze-Cheng Zou, Abdusattar Kurban, Jin-Jun Geng, Chen Deng
Earth and Planetary Astrophysics
Quantification of abundance uncertainties in chemical models of exoplanet atmospheres
Marcelino Agundez
Chemical models are routinely used to predict the atmospheric composition of
exoplanets and compare it with the composition retrieved from observations, but little is known about the reliability of the calculated composition. We carried out a sensitivity analysis to quantify the uncertainties in the abundances calculated by a state-of-the-art chemical atmosphere model of the widely observed
planets WASP-33b, HD209458b, HD189733b, WASP-39b, GJ436b, and GJ1214b. We found that the abundance uncertainties in the observable atmosphere are relatively small, below one order of magnitude and in many cases below a factor of two, where vertical mixing is a comparable or even larger source of uncertainty than (photo)chemical kinetics. In general,
planets with a composition close to chemical
equilibrium have smaller abundance uncertainties than
planets whose composition is dominated by photochemistry. Some molecules, such as H2O, CO, CO2, and SiO, show low abundance uncertainties, while others such as HCN, SO2, PH3, and TiO have more uncertain abundances. We identified several critical albeit poorly constrained processes involving S-, P-, Si-, and Ti-bearing species whose better characterization should lead to a global improvement in the accuracy of models. Some of these key processes are the three-body association reactions S + H2, Si + O, NH + N, and N2H2 + H; the chemical reactions S + OH –> SO + H, NS + NH2 –> H2S + N2, P + PH –> P2 + H, and N + NH3 –> N2H + H2; and the photodissociation of molecules such as P2, PH2, SiS, CH, and TiO.
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High Energy Astrophysical Phenomena
Modeling Particle Acceleration and MWL Emission of a PeVatron Microquasar V4641 Sgr
Anton Dmytriiev, Frans van der Merwe and Markus Böttcher
The Large High Altitude Air Shower Observatory (LHAASO) has recently reported five
Galactic microquasars as Ultra-High-Energy (UHE) $\gamma$-ray emitters (> 100 TeV). Among these sources, the microquasar V4641 Sgr exhibits $\gamma$-ray emission up to $\sim$0.8 PeV, requiring the acceleration of particles to multi-PeV energies, as well as the hardest UHE spectrum. The mechanisms behind particle acceleration to such energies are not well understood. Furthermore, the limited multi-wavelength (MWL) information on this source appears contradictory, further complicating interpretation and suggesting that V4641 Sgr may represent a particularly unusual case. In this work, we present a detailed physical model of V4641 Sgr that combines first-principles simulations of
stochastic (turbulent) particle acceleration with MWL emission modeling. We adopt a leptonic scenario in which electrons are accelerated via the second-order
Fermi process driven by relativistic strong
turbulence ($\delta B/B \sim 1$). The particle energization is simulated using a dedicated Monte Carlo framework STRIPE that incorporates the effects of intermittent energy gains and radiative losses. The resulting accelerated electrons produce UHE $\gamma$-rays through inverse Compton scattering on both the
cosmic microwave background (CMB) and the interstellar radiation fields (ISRF). Our model is capable of reproducing key observational characteristics of the system, including particle acceleration to energies of tens of PeV, as well as the TeV-PeV $\gamma$-ray spectrum and the hard spectral index measured by LHAASO. Nonetheless, several aspects remain unresolved, highlighting the need for deeper observational coverage and further theoretical refinement.
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Solar and Stellar Astrophysics
The near-Sun Heliospheric Current Sheet, fluid and kinetic properties
Naïs Fargette, Jonathan P. Eastwood, Tai D. Phan et al. (+2 more)
The heliospheric current sheet (HCS) is an important large-scale structure of the heliosphere, and, for the first time, the Parker
Solar Probe (PSP) mission enables us to study its properties statistically close to the Sun. We visually identify the 39 HCS crossings measured by PSP below 50~\Rs~during encounters 6 to 21, and investigate the occurrence and properties of
magnetic reconnection, the behavior of the spectral properties of the turbulent energy cascade, and the occurrence of kinetic instabilities at the HCS. We find that 82% of HCS crossings present signatures of reconnection jets, showing that the HCS is continuously reconnecting close to the Sun. The proportion of inward/outward jets depends on heliocentric distance, and the main HCS reconnection X-line has a higher probability of being located close to the Alfvén surface. We also observe a radial asymmetry in jet acceleration, where inward jets do not reach the local Alfvén speed, contrary to outward jets. We find that
turbulence levels are enhanced in the ion kinetic range, consistent with the triggering of an inverse cascade by
magnetic reconnection. Finally, we highlight the ubiquity of
magnetic hole trains in the high $\beta$ environment of the HCS, showing that the mirror mode instability plays a key role in regulating the ion temperature anisotropy in HCS reconnection. Our findings shed new light on the properties of
magnetic reconnection in the high $\beta$
plasma environment of the HCS, its interplay with the turbulent cascade and the role of the mirror mode instability.
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All authors Naïs Fargette, Jonathan P. Eastwood, Tai D. Phan, Lorenzo Matteini, Luca Franci
Cosmology and Nongalactic Astrophysics
Updates on dipolar anisotropy in local measurements of the Hubble constant from Cosmicflows-4
Vincenzo Salzano, J. Beltrán Jiménez, Dario Bettoni et al. (+2 more)
We investigate the angular anisotropy of the Hubble constant using the Cosmicflows-4 catalogue, with particular emphasis on three issues often treated only implicitly in the literature: the statistical formulation of the Hubble–Lemaître relation, the internal consistency of the working sample, and the role of peculiar-velocity corrections. Rather than working in luminosity-distance space, we adopt a logarithmic formulation based directly on distance
moduli, thereby preserving the Gaussian error properties of the measured quantities. We first subject the catalogue to internal consistency tests, including the depth dependence of $\langle \log H_0 \rangle$ and the behaviour of residual skewness and kurtosis across radial shells, and use these diagnostics to define conservative subsamples minimally affected by selection effects, namely $\mu \in [31,36]$ and $z \in [0.03,0.06]$. Within these ranges, we reconstruct angular maps of $\log H_0$ and fit them with a spherical-harmonic expansion up to octupole order. We find a statistically significant anisotropic signal in the uncorrected CF4 data, dominated by a dipole and favoured over a monopole-only model by
Bayesian evidence. However, when peculiar-velocity-corrected data are used, the anisotropy amplitude is strongly reduced, especially at lower depths, while only a weaker residual signal survives at larger distances. We also test for a monotonic radial
evolution of the dipole, as expected in some differential-expansion scenarios, but find no robust evidence for such a trend. These results indicate that the anisotropy is driven primarily by local velocity flows and catalogue/survey structure, rather than by a large-scale breakdown of isotropic expansion. Finally, we show that although such anisotropy may affect local determinations of $H_0$, its impact on the global Hubble tension is likely limited.
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All authors Vincenzo Salzano, J. Beltrán Jiménez, Dario Bettoni, Philippe Brax, Aurélien Valade
High Energy Astrophysical Phenomena · Cross-listed from hep-ph
Properties of Stable Massive Quark Stars in Holography
Kazem Bitaghsir Fadafan, Jesús Cruz Rojas and Jonas Mager
We study a
holographic D3/D7 system, whose dilaton profile has been phenomenologically adjusted in the infrared. The model is used to describe a deconfined yet massive
quark phase of QCD at finite density, concluding that the equation of state of such a phase can be stiff enough to support exotic dense
stars as massive as 2
solar masses. Nucleons are modeled phenomenologically using the Hebeler-et.al EFT
baryon phases. For the stiff phenomenological
baryon phases the transition to the
quark phase is weakly first order allowing for stable
quark cores. We also find that
holographic baryons, modeled as wrapped D5-branes, provide unrealistic pressures (in the homogeneous approximation) and have to be discarded. We compute the mass vs. radius relation and
tidal deformability for these hybrid
stars. Contrary to a large number of other
holographic models, this
holographic model indicates that
quark matter could be present at the core of heavy compact
stars and may be used to explore the phenomenology of such objects.
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Astrophysics of Galaxies
Evolution and Mass Dependence of UV-to-near-IR Color Gradients up to z=2.5 from HST+JWST
Marco Martorano, Arjen van der Wel, Andrea Gebek et al. (+7 more)
We present the
redshift evolution of radial color gradients (in rest-frame ${\textit{U}} - {\textit{V}}$ and ${\textit{V}} - {\textit{J}}$) for
galaxies in the range $0.5<$ z $<2.5$ and investigate their origin and dependence on
stellar mass. We select $\sim 10,200$
galaxies with
stellar masses $M_\star>10^{9.5}~{\text{M}}_\odot$ from publicly available JWST/NIRCam-selected catalogs. Using 2D Sérsic profile fits to account for PSF broadening, we perform spatially resolved SED fitting on HST and JWST/NIRCam photometry retrieving accurate rest-frame ${\textit{U}} - {\textit{V}}$ and ${\textit{V}} - {\textit{J}}$ color gradients within 2$R_\text{e, F444W}$.
Star-forming
galaxies generally exhibit negative ${\textit{V}} - {\textit{J}}$ color gradients that are strongly mass and
redshift dependent. For massive
star-forming
galaxies ($M_\star>10^{10.5}~{\text{M}}_\odot$) at $z>1.5$ ${\textit{V}} - {\textit{J}}$ colors are $\approx 0.5$ mag redder within the effective radius than outside, on average. We find that, at all
redshifts and across the entire
stellar mass range, ${\textit{V}} - {\textit{J}}$ gradients strongly correlate with global attenuation ($A_V$), suggesting that they predominantly trace
dust attenuation gradients. Edge-on
galaxies are redder and have stronger gradients at all $z$, although the correlation weakens at higher $z$. The ${\textit{U}} - {\textit{V}}$ and ${\textit{V}} - {\textit{J}}$ color gradients in the quiescent
galaxy population, in contrast, are weakly negative (from $\approx -0.1$ to $\approx- 0.2$ mag), though significant, and show little or no dependence on
stellar mass,
redshift or axis ratio. The implication is that quiescent
galaxies must be largely transparent, with low $A_V$, and color gradients mostly attributable to
stellar population gradients.
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All authors Marco Martorano, Arjen van der Wel, Andrea Gebek, Maarten Baes, Eric F. Bell, Gabriel Brammer, Sharon E. Meidt, Angelos Nersesian, Katherine Whitaker, Stijn Wuyts
High Energy Astrophysical Phenomena
The exotic black hole-neutron star binaries in our Galaxy
Man Ho Chan
It has been suggested that there are $\sim 10^5$ black hole-
neutron star (BH-NS) binaries in our
Galaxy. However, despite the effort of intensive
radio search for decades, none of these binaries has been found to date. These binaries are regarded as a holy grail of astronomy because they can greatly improve our understanding about relativistic systems of compact objects and fundamental physics. In this article, we propose the existence of exotic BH-NS binaries which can open a new way in searching the missing BH-NS binaries in our
Galaxy. By considering the possible dark matter density spikes formed around the
primordial black holes in the BH-NS binaries, we show that extremely high temperature ($\sim 10^6$ K) could be maintained on the surface of the
neutron stars due to effective dark matter capture. This interesting feature can also help reveal the nature of dark matter and possibly further improve the upper limit of dark matter scattering cross section well below $10^{-47}$ cm$^2$.
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Instrumentation and Methods for Astrophysics
High-Precision Amplitude-Modulated Continuous-Wave Lunar Laser Ranging
Slava G. Turyshev
Lunar
laser ranging (LLR) currently delivers mm-class tests of relativistic
gravity and the lunar interior, but further gains are limited by
photon-starved pulsed systems, array-induced pulse broadening, and atmospheric variability. This paper develops the metrology and covariance layer for high-power amplitude-modulated continuous-wave (AM-CW) LLR. The optical link budget and kW-class CW architecture are taken from the companion high-power CW LLR analysis; here the focus is on RF-envelope phase observables, multi-tone ambiguity removal, range and range-rate
estimators, detector requirements, Doppler derotation, and observation-level covariances. For a GHz-class precision tone, \(c/(4\pi f_m)\) =2.38567 cm/rad, so 0.10 mm
photon-limited range precision requires SNR ~ 240. With detected
photon rates appropriate to a 1 kW, 1064 nm transmitter on a 1-2 m class
telescope ranging to 10 cm corner-cube retroreflectors, the T ~ 100 s
photon-statistical range floor is 0.08-0.14 mm in a generic high-power case, 30-60 um in a dedicated AM-CW case, and <30 um in a
photon-rich case. With representative residual atmosphere and instrument allocations, a dedicated station can plausibly reach 0.08 mm absolute range precision under favorable conditions. Range-rate precision below 1 um/s requires several-hundred-second windows, or shorter windows only in
photon-rich operation. Differential LLR between nearby lunar reflectors suppresses common-mode station and atmospheric terms, but it cannot suppress independent
photon noise. Robust design bands are ~45-90 um for the dedicated AM-CW case and ~35-60 um in
photon-rich excellent-seeing operation. The resulting requirements on link SNR, Doppler derotation, detector mode, instrument PSD/Allan stability, oscillator slew, multi-tone nonlinearity, and differential CONOPS are presented.
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Cosmology and Nongalactic Astrophysics
"SNe Ia twins" in the Hubble flow, and the determination of H0
Pilar Ruiz-Lapuente, Antonio Quintana-Estellés, Jonay I. González Hernández et al. (+1 more)
We have applied our approach of using ”SNe Ia twins”in the Hubble flow to obtain distances to SNe Ia at z $>$ 0.015 and derive H$_{0}$. Our results, taking a single step between the low z domain and the Hubble flow, validate the three rung classical method. We find, however, that the full compilation of distances, both in Pantheon+ and in the Carnegie-Chicago Hubble Program (CCHP), contain some inaccurate values in the colors due to an underestimate of reddening by
dust, or due to the adoption of not well–defined light curve declines.This produces odd individual values for H$_{0}$ from single Type Ia SNe (SNe Ia). Our sample of carefully addressed SNe Ia in the Hubble flow contains a dozen
supernovae, for which the distances are determined with high accuracy. Three of these SNe Ia are of the Broad Line subtype and can be compared with SN 1989B in M66, a host
galaxy with a unique convergence of the Cepheid distance determination and the Tip of the Red
Giant Branch
stars (TRGB) determination by the CCHP group. There is, as well, a very good agreement on the distances to NGC 7250 and NGC 5643 between those derived with Cepheids by SH0ES and those derived with the use of J-Asymptotic
Giant Branch
stars(JAGB
stars) by the CCHP, which makes them very good anchors. The sample of 12 SNe Ia gives a value of H$_{0}$ $=$ 72.56 $\pm$ 1.54 (stat) $\pm$ 1.33(sys) km s$^{-1}$ Mpc $^{-1}$,when anchored in Cepheids, and of H$_{0}$ $=$ 72.20 $\pm$ 1.53 (stat) $\pm$ 1.33 (sys) km s$^{-1}$ Mpc $^{-1}$,when anchored in JAGBs by the CCHP.We take a mean of the two values of H$_{0}$ as derived by the Cepheids and by JAGB (from the CCHP) and obtain H$_{0}$ $=$ 72.38 $\pm$ 1.54(stat) $\pm$ 1.33(sys) km s$^{-1}$ Mpc $^{-1}$. Our findings confirm that the Hubble tension is real.
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All authors Pilar Ruiz-Lapuente, Antonio Quintana-Estellés, Jonay I. González Hernández, Andrea Pastorello
High Energy Astrophysical Phenomena
The first extragalactic ultra-compact X-ray binary : a candidate black hole-white dwarf system
Qian-Qi Ma, Jiachang Zhang, Wei-Min Gu et al. (+3 more)
M31 UCXB-1 is one of the brightest X-ray point sources in the bulge of M31, with a peak X-ray luminosity $ L_{\mathrm{0.5-10 \: keV}} = 2.9^{+0.2}_{-0.2} \times 10^{38} \: \mathrm{erg} \: \mathrm{s}^{-1} $. Both XMM-Newton and Chandra observations have detected an eclipsing signal with a period of about 465 seconds from this source, and we note that the periodic signal is detected exclusively during the source's high-luminosity states. This signal probably originates from its orbital motion, therefore it is an ultra-compact X-ray binary (UCXB) candidate with the highest X-ray luminosity. Our theoretical analyses show that M31 UCXB-1 is in good agreement with the luminosity-orbital period relation ($ L_{\mathrm{2-10 \: keV}}-P_{\mathrm{orb}} $) of the black hole/
neutron star–white
dwarf (BH/NS–WD) UCXB system. Moreover, our spectral analyses indicate that the primary in M31 UCXB-1 is more likely to be a BH rather than an NS. The results show that M31 UCXB-1 is a BH–WD system, with the shortest orbital period, the possibly strongest gravitational wave emission, and the most massive white
dwarf among the known UCXBs.
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All authors Qian-Qi Ma, Jiachang Zhang, Wei-Min Gu, Zhiyuan Li, Shan-Shan Weng, Tong Bao
High Energy Astrophysical Phenomena
Padé Approximants for cosmic Dispersion Measures
Marios Kalomenopoulos and Jiaming Zhuge
Fast
Radio Bursts (FRBs) have become an indispensable tool for studying the “missing
baryons”, the Universe's ionisation properties, as well as the cosmological parameters. This is achieved by analysing the diffuse dispersion measure (${\rm DM}_{\rm diff}$) of FRBs as a function of
redshift. However, the rapidly increasing data size requests more and more computational resources. In this work, we first develop an accelerated method for any
cosmic dispersion measure by deriving an analytical approximation formula for flat, $\Lambda$CDM and $w$CDM universes. Focusing on FRBs, we show that our approximation works well for the ranges $0.01 \leq z \leq 2$, $0.2 \leq \Omega_m \leq 1.0$ and $-3.0 \leq w \leq -0.5$, with relative error to a numerically evaluated ${\rm DM}_{\rm diff}$ always smaller than $3.5 \%$ (in the worst case scenario). This error remains below observationally relevant ${\rm DM}$ scatter and is especially small near the concordance $\Lambda$CDM cosmology. Additionally, we perform a cosmological analysis of simulated FRB data and show that our approximation gives robust and unbiased results, even when applied in regions of parameter space where its relative error becomes larger than $3\%$. Finally, the approximation is more than $15$ ($2$) times faster than the numerical solution of $\Lambda$CDM ($w$CDM), and can reach a timing improvement of a factor of $25$ when used in an MCMC cosmological inference.
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