adsabs/FOCAL huggingface dataset:
In this work, we study the merger and post-merger evolution of near equal-mass BH–NS binaries. Before turning to the properties of the accretion discs formed in such mergers, we first provide a very brief overview of their formation. We do this by considering the fiducial system TNT.chit.0.35. In order to illustrate the disc formation process, we begin by summarizing the dynamical formation of the disc in Fig. 1, which reports the comoving magnetic energy density b2, the rest-mass density ρ, the electron fraction Ye, and the local fluid temperature T. The different rows correspond to meridional (top panels) and equatorial (bottom panels) views of the accretion disc around the BH, while the different columns correspond to different times after the merger. The general dynamics of this process have been studied extensively in purely hydrodynamical simulations (Etienne et al. 2009; Kyutoku et al. 2011; Foucart et al. 2012). In order for a massive disc to form during and after merger, tidal disruption has to occur outside of the innermost stable circular orbit (ISCO) of the BH (Shibata & Taniguchi 2011; Pannarale et al. 2011b). Starting from the left-hand panel, we can see that shortly after tidal disruption, an initial accretion disc begins to form around the BH. Originating from the cold NS matter, the initial disc is very neutron rich (Ye  0.05), but already reaches temperatures $T \lesssim 10\, \rm MeV$. The disc quickly grows in mass and size due to fall-back accretion from the tidal arm (middle column), begins to circularize and a steady accretion flow develops over time. As expected, this happens on the dynamical time-scales of the discs, which are proportional to the disc mass $M_{\rm disk}^b$, so that the lightest discs circularize first. Initially, the pure neutron matter is far out of beta-equilibrium under these conditions and will rapidly re-equilibrate via beta decay of neutrons, leading to an increasing protonization especially of the low-density parts of the disc. At the same time, the magnetic-field strength is increasing throughout the disc, exceeding $10^{14}\, \rm G$ locally. More details on the magnetic-field evolution will be given in Section 3.3. Finally, after more than $50\, \rm ms$ past merger, the disc has settled into an initial quasi-equilibrium, consisting of a very neutron-rich disc, probing rest-mass densities ${\lesssim}10^{11}\, \rm g\, cm^{-3}$. A disc formed by this process will then set the initial conditions for the long-term evolution in terms of the accretion flow and mass ejection (Fernández et al. 2015, 2017).
Citation: Foucart et al. 2012
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Local dwarf galaxies were the focus of large Herschel and Spitzer surveys (e.g., The Dwarf Galaxy Survey, DGS; Madden et al. 2006). Studies on both resolved and integrated-galaxy scales have highlighted some distinctively unique observational signatures of star-forming low-metallicity dwarf galaxies. A non-linear relation of the dust-to-gas mass (D/G) with metallicity is observed, with extremely low dust masses observed for the lowest metallicity galaxies (Z ≤ 0.1 Z⊙; Herrera-Camus et al. 2012; Fisher et al. 2014; Rémy-Ruyer et al. 2015; Galliano et al. 2018, 2021; Cigan et al. 2021). Furthermore, the hard radiation fields in star-forming dwarf galaxies, along with their lower dust abundance, result in extended ionized gas regions prominent on global galaxy scales (Hunter et al. 2011; Cormier et al. 2015, 2019). The consequence is often a largely photodissociated molecular phase, existing in clumps which are difficult to observe with the usual molecular gas tracer, CO (1-0) (Cormier et al. 2014; Hunt et al. 2015; Accurso et al. 2017b), beckoning the presence of a CO-dark molecular gas phase (Grenier et al. 2005; Röllig et al. 2006; Wolfire et al. 2010; Glover & Clark 2012; Bolatto et al. 2013; Accurso et al. 2017a; Madden et al. 2020). Other emission lines, however, such as the far-infrared [C ii]λl58 µm line, are strikingly enhanced on global scales in dwarf galaxies (e.g., Cormier et al. 2015, 2019; Cigan et al. 2016; Lebouteiller et al. 2017; Jameson et al. 2018), making the [C ii]λl58 µm line a potential tool for tracing star formation activity (Malhotra et al. 2001; Papadopoulos et al. 2007; Pineda et al. 2014; De Looze et al. 2014; Olsen et al. 2015; Herrera-Camus et al. 2015, Herrera-Camus et al. 2018; Carniani et al. 2018; Matthee et al. 2019; Izumi et al. 2021; Fujimoto et al. 2021) and a tracer of the total H2 in galaxies, near and far (Poglitsch et al. 1995; Wolfire et al. 2010; Pineda et al. 2013; Nordon & Sternberg 2016; Fahrion et al. 2017; 
Accurso et al. 2017b; Zanella et al. 2018; Madden et al. 2020; Schaerer et al. 2020; Tacconi et al. 2020).
Citation: Cormier et al. 2015
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Citation: Cormier et al. 2015
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While spatially extended optical jets and bipolar CO molecular outflows have been observed in numerous Class 0/I protostars (e.g. Reipurth & Bally 2001; Bally 2016, and references therein), near-infrared high-resolution spectroscopy and spectroimaging observations in the past two decades have made it possible to study the kinematics of the outflowing gas and physical properties at the base of the jet within a few hundred au of the driving source in Class 0/I protostars (e.g. Davis et al. 2001, 2003, 2011; Nisini et al. 2005, 2016; Caratti o Garatti et al. 2006; Takami et al. 2006; Antoniucci et al. 2008, 2011, 2017; Garcia Lopez et al. 2008, 2013). These microjets are bright in [Fe ii] forbidden and H2 rovibrational emission lines, hence showing the presence of forbidden emission-line (FEL) regions and molecular hydrogen emission-line (MHEL) regions in low-mass Class 0/I protostars. While multiple low- and high-velocity components are observed in both MHELs and FELs, the higher velocity gas is slightly further offset from the driving source than the slower gas, and the kinematics of the H2 emission differs from [Fe ii] emission, revealing complicated kinematic structures. Evidence of H2 emission from cavity walls is also seen in some protostars, suggesting the presence of a wide-angled wind. Strong emission in the well-known accretion diagnostics of Paschen and Brackett hydrogen recombination lines is observed in protostars, with the ratio of the accretion luminosity to bolometric luminosity spanning from ∼0.1 to ∼1. The mass accretion and loss rates for Class 0/I low-mass protostars span the range of 10−6–10−8 M⊙ yr−1, and the derived jet efficiencies (ratio between mass ejection and accretion rates) range between ∼1 per cent and 10 per cent (e.g. Davis et al. 2001, 2003, 2011; Nisini et al. 2005, 2016; Caratti o Garatti et al. 2006; Takami et al. 2006; Antoniucci et al. 2008, 2011, 2017; Garcia Lopez et al. 2008, 2013). These measurements are within the range predicted by the magnetohydrodynamic jet launching models (e.g. Frank et al. 2014).
Citation: Nisini et al. 2005
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Citation: Antoniucci et al.; 2017
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Citation: Antoniucci et al.; 2017
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Citation: Nisini et al. 2005
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The band-limited nature of repeaters makes it essential to have high-resolution simultaneous observations with a large bandwidth that can help detect variations in the spectrotemporal and even polarimetric structures of the bursts at different frequencies. The study of these contemporaneous frequency-dependent variations, as well as long-term changes with time, are paramount in investigating the origins of FRBs. FRB 20121102A was one of the first repeaters to be coherently corrected for dispersion, allowing unprecedented high-time-resolution studies, revealing drifting bursts and an unusually high rotation measure (RM; Gajjar et al. 2018; Michilli et al. 2018; Hessels et al. 2019). Subsequent observations have shown a considerable decrease in the RM value with time (Hilmarsson et al. 2021). This variation is similar to what has been observed for Galactic center magnetar PSR J1745-2900 (Desvignes et al. 2018). On the other hand, FRB 20180916B has a nominal RM and has shown a gradual variation in RM value over the two year timescale (Pleunis et al. 2021). These variations may be due to changes in the viewing geometry or the result of drastic variations in the circumburst environment facilitating magnetoionic disparities. Interestingly, both of these FRBs show a flat polarization position angle (PPA) that can be indicative of emissions at higher altitudes due to relativistic shock (Beloborodov 2017; Metzger et al. 2019). Contrarily, observation of microstructures challenges this idea, as in the case of FRB 20180916B, where such structures have been seen down to 2–3 μs (Nimmo et al. 2020) at 1700 MHz, hinting at emission much closer to the magnetosphere. Studying the evolution of such structures with frequency will aid in constraining the emission region and help to understand the local environment. Another aspect of repeater burst morphology that remains a mystery is the “sad trombone” effect, which describes a linear decrease in burst features with frequency and has been observed for FRB 20121102A and other repeaters; it will be interesting to undertake a comparative study of this behavior between frequencies.
Citation: Pleunis et al. 2021
Citation function: Differences
The above qualitative theoretical reasoning raises the question about why would Swift J1834.9−0846 be the only magnetar so far powering a wind nebula, given that previous searches around individual magnetars have returned no sign of extended emission attributable to wind nebulae (e.g., Viganò et al. 2014). With only one observed so far, it is difficult to draw any firm conclusions. Nevertheless, Swift J1834.9−0846 has some interesting characteristics that are not shared with the entire magnetar population. First, the environment of Swift J1834.9−0846 is extremely crowded, with a Fermi GeV source, an H.E.S.S. TeV source, an SNR, a GMC, and an OH maser in its vicinity (Frail et al. 2013; H.E.S.S. Collaboration et al. 2015). The relationship between all these sources is unclear. However, it is tempting to speculate that environmental effects from such a rich field could be playing a role in the production of this wind nebula (e.g., triggering of pair cascade by external gamma rays from a nearby source; Shukre & Radhakrishnan 1982; Istomin and Sob’yanin 2011). Second, the Swift J1834.9−0846 X-ray luminosity in quiescence is 





 erg s−1. Only five other magnetars (SGR 0418+5729, SGR 1745−2900, XTE J1810−197, Swift J1822.3−1606, 3XMM J185246.6+003317)20

20

http://www.physics.mcgill.ca/ pulsar/magnetar/main.html

 have luminosities ≲1032 erg s−1. Among these five, three have the smallest surface B fields measured (SGR 0418+5729, Swift J1822.3−1606, 3XMM J185246.6+003317; 





 G), and only one source, SGR 1745−2900, has a rotational energy loss rate 





 similar to Swift J1834.9−0846, while the rest have 





 at least an order of magnitude lower. Hence, from an observational point of view, it seems that the combination of very weak X-ray luminosity, a magnetar-like B-field strength, and a somewhat large 





 (properties that are only shared by the Galactic center magnetar SGR 1745−2900) may favor wind nebula production. Another possibility is that the Swift J1834.9−0846 magnetar/nebula system is an older analog to the Kes 75 system, where the central pulsar evolves into a magnetar while preserving its originial PWN.
Citation: Frail et al. 2013
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Citation: Istomin and Sob’yanin 2011
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The populous blue LMC cluster NGC 1866 is already known to host an exceptionally rich sample of more than 20 Cepheids (Musella et al. 2006; Welch & Stetson 1993). One of these was identified by Musella et al. (2006) in a preliminary analysis of the proprietary BVI Very Large Telescope (VLT) data. It is unquestionable that such a unique sample of Cepheids – likely all members of the cluster and at the same distance, chemical composition and age – would constitute a milestone in our understanding of the Cepheid pulsational scenario. Indeed, it offers an unprecedented opportunity to investigate both empirical and theoretical estimates of the luminosity and colour of the pulsating structures and their relation with the observed periods. For this reason, many authors have studied the NGC 1866 Cepheids (Welch 1991; Welch & Stetson 1993; Gieren, Richtler & Hilker 1994; Walker 1995; Gieren et al. 2000; Storm et al. 2005; Testa et al. 2007) in both the optical and near-infrared bands, and have tested different methods to calibrate the PL relations in different filters. In Brocato et al. (2004), we already discussed the sample of the 23 known Cepheids in NGC 1866, concluding that unfortunately only 4–6 Cepheids had light curves accurate enough to allow a meaningful determination of their luminosities and colours. On the basis of such a tantalizing situation, we took advantage of assigned observing time at the ESO VLT to perform an accurate photometric investigation of the cluster field, with the aim of securing suitable data constraining the light curves of all the member Cepheids. Moreover, to get accurate information about radial velocities and chemical abundances of the stars in NGC 1866, we have performed FLAMES@VLT (Fibre Large Array Multi Element Spectrograph mounted on VLT) spectroscopic observations for 30 stars (19 belonging to the cluster and 11 to the LMC field), including three Cepheids (Mucciarelli et al. 2011; Molinaro et al. 2012). Mucciarelli et al. (2011) found that, as far as the chemical composition is concerned, the cluster stars are reasonably homogeneous. Indeed, they appear to share the same abundances within the uncertainties, and this property is independent of the evolutionary status. The average iron abundance is [Fe/H] = −0.43 ± 0.01 dex, with a dispersion σ = 0.04 dex. For the three spectroscopically investigated Cepheids Molinaro et al. (2012), adopting the same procedure used in Mucciarelli et al. (2011), found values fully consistent with the average iron content. Moreover, Molinaro et al. (2012) applied the CORS Baade–Wesselink (BW) method (Ripepi et al. 1997) to a sample of 11 Cepheids, using radial velocities obtained both from our FLAMES investigation and from literature data, and light curves based on a part of the UBVI data used in this paper complemented with K data by Testa et al. (2007). In this way, they obtained a direct estimate of the distance modulus of NGC 1866, μ0 = 18.51 ± 0.03 mag (see Molinaro et al. 2012, for details).
Citation: Storm et al. 2005
Citation function: Motivation; Motivation
Here we demonstrate that, over a fixed time interval, the planar three-body problem can be solved by means of a multilayered deep artificial neural network (ANN; e.g. see LeCun, Bengio & Hinto 2015). These networks are designed for high-quality pattern recognition by mirroring the function of our brains (McCulloch & Pitts 1943; Rosenblatt 1985) and have been successfully applied to a wide variety of pattern recognition problems in science and industry, even mastering the game of Go (Silver et al. 2016). The abundance of real-world applications of ANNs is largely a consequence of two properties: (i) an ANN is capable of closely approximating any continuous function that describes the relationship between an outcome and a set of covariates, known as the universal approximation theorem (Cybenko 1989; Hornik 1991); and (ii) once trained, an ANN has a predictable and a fixed computational burden. Together, these properties lead to the result that an ANN can be trained to provide accurate and practical solutions to Newton’s laws of motion, resulting in major improvements in computational economy (Lee, Sode-Yome & Park 1991) relative to modern technologies. Our proof-of-principle method shows that an ANN can accurately match the results of converged solutions found using the arbitrary precision numerical integrator that, for computationally challenging scenarios, e.g. during multiple close encounters, can offer numerical solutions at a fraction of the time cost and CO2 expense. We demonstrate the importance of training an ANN on converged solutions. This enables the trained ANN to accurately predict particle locations even when a conventional ‘double-precision’ numerical integrator fails dramatically. By training an ANN that can accurately compute particle trajectories during close encounters, our work extends previous work training neural networks on an n-body-type problem (e.g. Quito, Monterola & Saloma 2001; Battaglia et al. 2016). Our findings also add to the growing body of literature that supports machine learning technologies being developed to enrich the assessment of chaotic systems (Pathak et al. 2018; Stinis 2019) and providing alternative approaches to classical numerical solvers more broadly (Hennig, Osborne & Girolami 2015).
Citation: Lee, Sode-Yome & Park 1991
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Citation: Hornik 1991
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The characterization of the dynamics of galaxies just after (4 ≲ z ≲ 6) and within the Epoch of Reionization (z ≳ 6) is still in its infancy as spatially resolved observations targeting emission lines are available only for about ten of sub-mm sources (e.g., Rizzo et al. 2020; Lelli et al. 2021; Rizzo et al. 2021) and a handful of Lyman break galaxies (e.g., Jones et al. 2017; Fujimoto et al. 2021). Instead, the number of marginally resolved observations aiming at inferring the integrated properties of early galaxies has increased in the last five years (Smit et al. 2018; Le Fèvre et al. 2020; Bouwens et al. 2022). In their pioneering work, Smit et al. (2018) used marginally resolved Atacama Large Millimeter/Submillimetre Array (ALMA, Wootten & Thompson 2009) observations of the [C II]-158 μm emission line to show that two star-forming galaxies at z ∼ 7 have smooth velocity gradients and interpreted them as being rotationally supported disks. Similar results are obtained in studies of individual galaxies at z ∼ 6–8 (Bakx et al. 2020; Harikane et al. 2020). However, given the low angular resolution of these data, they can not rule out the possibility that one or more merging [C II]-bright satellites are mimicking the smooth gradient observed in the velocity maps (see discussion in Smit et al. 2018; Simons et al. 2019). Instead, a gradient in the velocity fields of two Lyman break galaxies at z = 6.1 and 7.1, combined with the identification of two compact components, has been interpreted as evidence of mergers (Jones et al. 2017; Hashimoto et al. 2019). Recently, Le Fèvre et al. (2020) and Romano et al. (2021) performed the first systematic morpho-kinematic analysis of a statistically significant sample of z ∼ 4–6 main-sequence galaxies from the ALMA Large Program to INvestigate [C II] at Early times (ALPINE) survey. After combining the morphological and kinematic analysis of the [C II] observations with the rest-frame UV and optical data, Romano et al. (2021) conclude that 23 out of the 75 ALPINE galaxies are merging systems. This large fraction of mergers in the ALPINE sample could imply a significant contribution of major mergers to the mass assembly in the early Universe (Le Fèvre et al. 2020; Romano et al. 2021), confirming previous results based on the count of close-pair galaxies in photometric surveys (Mantha et al. 2018; Duncan et al. 2019). However, due to the sensitivity and angular resolutions of the ALPINE observations, the kinematic characterization and, consequently, the merger fraction may be uncertain.
Citation: Bakx et al. 2020
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Low- and intermediate-mass stars are formed by the gravitational collapse of the parental giant molecular cloud (GMC), followed by the accretion process (Palla 1996). During the accretion phase, material is ejected as well via collimated bipolar jets. However, when a YSO reaches 8 M⊙, the radiative flux becomes so intense (using ϕ = L/4πd2, the ratio between the radiative fluxes of an O5 and a B3 star – masses of ∼40 and ∼8 M⊙, respectively – is ≈250) that it may interrupt the accretion flow. A process that constrains the outcoming radiation field to narrower angles may leave some room for the accretion process to continue in some directions. This seems to be the case for the outflows driven by young stars from a very broad mass range, as previous reported by several authors (Bachiller 1996; Bontemps et al. 1996; Shepherd & Churchwell 1996; Beuther et al. 2002; Wu et al. 2004). Outflows associated with high-mass objects are expected to be more energetic than the outflows observed in lower mass YSOs (Beuther et al. 2005; Zhang et al. 2005; López-Sepulcre et al. 2009), with velocities greater than ∼100 km s−1 (Martí, Rodríguez & Reipurth 1998). Some authors have found evidences that outflows associated with massive stars are scaled up versions of their low-mass counterparts (Vaidya et al. 2011; Codella et al. 2013) while other works have reported that no well-collimated outflows have been found towards MYSOs (Shepherd, Testi & Stark 2003; Sollins et al. 2004). Massive YSO outflows mapped in high-velocity CO lines have collimation factors R = length/width ∼2.05 ± 0.96 as compared to R ∼ 2.81 ± 2.16 for low-mass stars (Wu et al. 2004), indicating a weak tendency that outflows associated with massive stars are less collimated than those from low-mass stars as previously thought (Richer et al. 2000). Besides the degree of collimation, these massive outflows would work removing mass from the plane of the accretion disc, lowering the density on the plane and, therefore, facilitating the accretion flow to reach the stellar core as shown in the recent 3D simulations presented by Krumholz et al. (2009). Although these authors have not included the outflow activity on their simulations, they argue that the presence of outflows would decrease the star formation efficiency from 70 per cent (considering purely radiation effects) to 50 per cent.
Citation: Wu et al. 2004
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Citation: Wu et al. 2004
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Citation: Wu et al. 2004
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