adsabs/FOCAL huggingface dataset:
Currently, there is an extensive data base of observations of magnetic activity on the main-sequence stars (see e.g. reviews by Donati & Landstreet 2009; Reiners 2012). Cool stars with outer convective envelope are of particular interests because they are Sun-like. It is believed that the magnetic activity on the solar-like stars results from large-scale dynamo processes driven by turbulent convection and rotation (Brandenburg & Subramanian 2005). Observations (e.g. Böhm-Vitense 2007; Donati & Landstreet 2009; Katsova et al. 2010; Saar 2011; Katsova, Livshits & Mishenina 2013; Marsden et al. 2014; Vidotto et al. 2014), as well as the 2D mean-field models of the angular momentum balance (Ruediger 1989; Kitchatinov & Rüdiger 1999; Kitchatinov 2013) and the 3D numerical simulations (Miesch & Toomre 2009; Hotta & Yokoyama 2011; Guerrero et al. 2013b; Brun et al. 2014; Käpylä, Käpylä & Brandenburg 2014) show that parameters of the differential rotation and convection, e.g. the typical size and turnover time of convective flows, depend on the general stellar parameters, such as mass, age, the spectral class and the rotation rate. The mass of a star and its Rossby number, which is the ratio of the period of rotation and a typical turnover time of convection, are likely the most important parameters governing the stellar dynamo (Donati & Landstreet 2009; Morin et al. 2013). The diagram 3 in the paper by Donati & Landstreet (2009) shows an increase of the magnetic activity with decrease of the Rossby number and the mass of a star. These parameters determine the topology of the large-scale magnetic field, as well. It is found that the axisymmetric solar-type dynamo can operate in stars with mass about 1 M⊙, and with periods of rotation longer than 10 d. Observations, also show pieces of evidence that solar analogues with period of rotation smaller than 10 d, may have the substantial non-axisymmetric components of the large-scale magnetic field (Donati & Landstreet 2009; Folsom et al. 2014).
Citation: Brun et al. 2014
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Even though the understanding of high-mass star formation has made tremendous progress over the past decade (Beuther et al. 2007; Zinnecker & Yorke 2007; Klessen 2011; Tan et al. 2014), the initial conditions are still poorly constrained. It is known, that stars predominantly form in clusters (Lada & Lada 2003), which is especially true for high-mass stars (e.g., de Wit et al. 2005; Gvaramadze et al. 2012). On observational grounds, the first evolutionary stage of such clusters spawning future high-mass stars might in general be termed pre-protocluster cores (Evans et al. 2002). Their appearance and morphology can be different depending on the environment. Objects of this sort have been found in several (sub-)millimeter surveys (e.g., Klein et al. 2005; Beuther & Sridharan 2007). Also the ISO satellite mission has resulted in a list of such objects revealed by far-infrared observations at 170 μm within the ISO Serendipity Survey (ISOSS, Bogun et al. 1996). For these clumps, cold dust and gas temperatures have been established in follow-up investigations (Krause et al. 2003, 2004). The most prominent variety of young massive clumps are the infrared dark clouds (IRDCs). They were discovered as dark silhouettes against the galactic background at 8 and 15 μm with the Midcourse Space Experiment (MSX, Egan et al. 1998) and ISO (Perault et al. 1996). ISO, MSX, the Spitzer Space telescope, and further (sub-)millimeter observations have helped for studying these objects in detail (e.g., Simon et al. 2006; Hennemann et al. 2008; Vasyunina et al. 2009; Ragan et al. 2009; Peretto & Fuller 2009). Because IRDCs can only be seen in absorption against a strong infrared background, their location is mainly within the disk toward the inner quadrants of our Milky Way, whereas ISOSS sources are more widely distributed. In fact, the Milky Way midplane had to be avoided for ISOSS because of saturation. IRDCs can have masses up to several thousand solar masses, and the more massive ones are explicitly thought to be progenitors of star clusters (e.g., Wyrowski 2008; Rathborne et al. 2010; Henning et al. 2010; Ragan et al. 2012a). On average the ISOSS sources have masses less than 500 M⊙ (Hennemann et al. 2008). While their masses often are somewhat lower than for large high-contrast IRDCs, the general characteristics such as low temperature and low turbulent linewidth are similar to IRDCs. Therefore, ISOSS sources are also considered to be early evolutionary stages of intermediate- to high-mass star formation in more isolated regions. Consequently, the better characterization of such clumps (ISOSS and IRDCs) is an important step toward understanding the initial conditions of high-mass star formation.
Citation: Egan et al. 1998
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X-rays emerging from active galactic nuclei (AGNs) are the result of an inverse-Compton process occurring in the proximity of the central black hole (BH), where optical-UV photons arising from the accretion disc are inverse-Compton scattered by hot electrons in an optically thin, compact corona (e.g. Haardt & Maraschi 1991, 1993; Haardt et al. 1994, for details on the two-phase model). Such a Comptonisation mechanism accounts for the power-law-like shape of the X-ray primary continuum emission and the high-energy roll-over observed in various nearby AGNs (e.g. Nicastro et al. 2000; Perola et al. 2002; De Rosa et al. 2002; Molina et al. 2009, 2013; Malizia et al. 2014; Ricci et al. 2018). Broadband X-ray spectral investigations are of primary importance in studying AGN Comptonisation properties. Indeed, as extensively discussed in the literature (e.g. Ghisellini 2013) both the photon index (Γ) and high-energy cut-off (Ec) of the X-ray primary emission depend on the intrinsic properties of the Comptonising medium, namely its temperature, optical depth, and geometry. Therefore, the interplay between coronal parameters and the AGN X-ray spectral shape has been the object of several investigations, especially with observatories capable of detecting hard X-rays. Dadina (2007), using BeppoSAX data, collected and studied the photon index and Ec of a sample of AGNs (see also Perola et al. 2002, for previous results), while similar works were performed on INTEGRAL data (e.g. Bassani et al. 2006; Molina et al. 2009; Malizia et al. 2014), and, in the context of the BAT AGN Spectroscopic Survey, by Ricci et al. (2018). Subsequently, NuSTAR (Harrison et al. 2013), thanks to its unprecedented effective area above 10 keV, greatly helped in studying the exponential cut-offs of the nuclear continuum in several AGNs (see e.g. Fabian et al. 2015, 2017; Tortosa et al. 2018a). These space missions gave rise to a substantial corpus of high-energy cut-off and photon index measurements.
Citation: Molina et al. 2009; Molina et al. 2009
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Lastly, we model the evolution of the ejecta discussed in Section 2.2 into circumstellar profiles discussed in Section 2.3. We use our cosmic-ray hydrodynamics code, hereafter called ChN to model the evolution of the ejecta to an age of 






t


SNR


=
400


 yr. ChN is a Lagrangian hydrodynamics code that includes a prescription for diffusive shock acceleration (DSA; Ellison et al. 2007; Lee et al. 2012). We have modified the code to include the effects of DSA on non-equilibrium ionization (Patnaude et al. 2009, 2010) and have coupled the code to SN ejecta models (Lee et al. 2014; Patnaude et al. 2015). We have also included radiative losses via forbidden line cooling (Lee et al. 2015). This effect will be important in the evolution of the SN shock with a nearby CSM shell, or if we choose to model the radiative shock that could form in the ejecta during early SN evolution (Nymark et al. 2006). However, we begin our simulations at an age of 5 yr, and over the lifetime of the simulation the shocks remain adiabatic, so we do not consider the radiative shock model presented in our previous work here. Since ChN couples nonlinear particle acceleration to the SNR shock dynamics, we are able to reproduce the broadband thermal and nonthermal emission (Ellison et al. 2010, 2012; Castro et al. 2012; Slane et al. 2014; Lee et al. 2013). The diffusive shock acceleration process is an integral part of ChN, and some injection of thermal particles into the acceleration process is always assumed. Here we set the injection parameter to the test particle limit, though we note that the interaction of a strong shock with a massive CSM shell or cloud will lead to enhanced particle acceleration (e.g., Ellison et al. 2012; Lee et al. 2014), and the differing CSM configurations, combined with the differing ejecta profiles and compositions, may result in differences in the broadband nonthermal emission. The study of nonthermal emission in evolving SNe is sufficiently broad that we defer its study to future papers.
Citation: Lee et al. 2014
Citation function: Uses
In addition to being useful laboratories for studying the evolution of galaxies in dense environments, galaxy clusters can be effective gravitational lenses (for a review, see Kneib & Natarajan 2011). Gravitational lensing is the deflection of light by intervening mass, that can produce highly magnified and distorted images of background galaxies. The large mass and solid angle covered by highly concentrated galaxy clusters make them ideal gravitational lenses, which can be used as ‘cosmic telescopes’ to observe very distant galaxies (e.g. Richard et al. 2009). The amplification of sources through gravitational lensing has been extremely effective in observing faint, distant sources across the electromagnetic spectrum, including continuum and spectral line emission in the radio domain (e.g. Carilli & Walter 2013, and references therein). While molecular gas has been studied across the Universe up to z ∼ 1 and beyond, H i emission remains undetected through lensing, with two searches for galaxy–galaxy lensed H i sources at z ∼ 0.4 (Hunt, Pisano & Edel 2016; Blecher et al. 2019). Gravitational lensing conserves surface brightness while increasing the solid angle of the source, boosting the observed flux. This amplification μ can facilitate the detection of unresolved lensed sources, which maximises their detection probability, and reduces the integration time needed for a given source by μ2. Next-generation cm-wavelength interferometers are now sensitive enough to observe the higher redshift H i Universe, and the detection of gravitationally lensed H i is probable in new surveys (Deane, Obreschkow & Heywood 2015). The detection of lensed H i behind intermediate-redshift galaxy clusters will provide a deep cosmic view of H i emission in galaxies, pre-SKA era, within a fraction of the observation time of unlensed detections. Successful lensed H i detections, along with readily detected CO emission lines, will constrain the H i/H2 ratio at these redshifts, an important parameter in understanding galaxy evolution over cosmic time (Obreschkow & Rawlings 2009).
Citation: Richard et al. 2009
Citation function: Uses
The present Universe is full of galaxies that come in various shapes and sizes with different mass, luminosity, colour, star formation rate (SFR), metallicity, and H i content. Understanding the galaxy properties and their evolution is an important goal of cosmology. The modern galaxy surveys, 2dF Galaxy Redshift Survey (2dFGRS; Colless et al. 2001) and Sloan Digital Sky Survey (SDSS; Strauss et al. 2002) reveal that the galaxies are distributed in the cosmic web (Bond, Kofman & Pogosyan 1996), which is an interconnected web-like network comprising of different types of environments such as filaments, sheets, knots, and voids. The galaxy properties vary across the different environments in the cosmic web. For example, the well-known density–morphology relation reveals that the ellipticals are preferably found inside the dense groups and clusters, whereas the spirals are intermittently distributed in the fields (Hubble 1936; Zwicky 1968; Oemler 1974; Dressler 1980; Goto et al. 2003). These findings are further supported by other studies with two-point correlation function (Willmer, da Costa & Pellegrini 1998; Brown, Webstar & Boyle 2000; Zehavi et al. 2005), genus statistics (Hoyle et al. 2002; Park et al. 2005), and filamentarity (Pandey & Bharadwaj 2005, 2006) of the galaxy distribution. It is now well known that many other galaxy properties are strongly sensitive to their environment (Davis & Geller 1976; Guzzo et al. 1997; Zehavi et al. 2002; Blanton et al. 2003; Einasto et al. 2003a; Hogg et al. 2003; Kauffmann et al. 2004; Mouhcine, Baldry & Bamford 2007; Koyama et al. 2013). The formation and evolution of galaxies are known to be driven by accretion, tidal interaction, merger, and various other secular processes. These physical processes are largely determined by the environment of the galaxies. The environment thus play a central role in the formation and evolution of galaxies and the study of the environmental dependence of the galaxy properties provides crucial inputs to the theories of galaxy formation and evolution.
Citation: Dressler 1980
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We recall that the velocity anisotropy profile is given by a combination of the radial and tangential velocity dispersion:

(15)

\begin{equation}
\beta _{\rm ani}(r)\equiv 1-\frac{\bar{v_{\theta }^2}(r)}{\bar{v_r^2}(r)}\,.
\end{equation}

Due to the lack of observational constraints on this quantity, the first anisotropy profiles discussed in the literature were based on analytical studies aiming at building dynamical models (in spherical symmetry) with self-consistent stellar phase-space distribution functions. Many such models have simple anisotropy profiles that are either constant or change from isotropic near the centre to radial at large radius (e.g. Osipkov 1979; Merritt 1985, see below). More recently, indications of radial anisotropy in the outer regions of DM haloes have been obtained from numerical simulations (e.g. Diemand, Moore & Stadel 2004). In the inner region, a strong anisotropy can be generated by dynamical formation and evolution processes. To better describe these profiles, Baes & van Hese (2007) introduced a technique to construct dynamical models with arbitrary mass density and anisotropy profiles. These three different families of anisotropy profiles are described below and will be explored in Section 5.

The constant anisotropy modelling (e.g. used by Charbonnier et al. 2011) simply reads

(16)

\begin{equation}
\beta _{\rm ani}^{\rm Cst}(r)=\beta _0.
\end{equation}


The Osipkov–Merritt profile (Osipkov 1979; Merritt 1985) is parametrized as

(17)

\begin{equation}
\beta _{\rm ani}^{\rm Osipkov}(r)=\frac{r^2}{r^2+r_a^2},
\end{equation}

with a single free scale parameter ra which locates the transition from βani = 0 in the inner parts (isotropic) to 1 at large radii (full radial anisotropy).
The Baes and van Hese profile (Baes & van Hese 2007) is more general and is written as

(18)

\begin{equation}
\beta _{\rm ani}^{\rm Baes}(r) =\frac{\beta _0 + \beta _\infty (r/r_a)^\eta }{1+(r/r_a)^\eta }\,,
\end{equation}

where the four parameters are the central anisotropy β0, the anisotropy at large radii β∞, and the sharpness of the transition η at the scale radius ra. The Osipkov–Merritt profile is recovered when using β0 = 0, β∞ = 1 and η = 2.
Citation: Diemand, Moore & Stadel 2004
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Ring systems are a ubiquitous feature in planetary systems – all the gas giants in the Solar System have ring systems around them of varying optical depths (see, e.g., Tiscareno 2013; Charnoz et al. 2018), and ring systems have been detected around minor planets (e.g., Chariklo; Braga-Ribas et al. 2014), so it is reasonable that exoplanets and substellar objects host ring systems as well. Long-period eclipsing binary star systems, where one star is surrounded by an extended dark disk-like structure that periodically eclipses the other component, have already been observed, such as EE Cep (Mikolajewski & Graczyk 1999), ϵ Aurigae (Guinan & Dewarf 2002), and TYC 2505-672-1, with a companion period of 69 yr (Lipunov et al. 2016; Rodriguez et al. 2016). A large ring-like structure around a substellar companion was proposed to explain observations from 2007 from the J1407 system (Mamajek et al. 2012). 1SWASP J140747.93-394 542.6 (V1400 Cen; hereafter called “J1407”) is a young, pre-main-sequence star in the Sco-Cen OB association (Mamajek et al. 2012) with spectral type K5 IV(e) Li and is similar in size and mass to the Sun. In 2007, it displayed a complex symmetric dimming pattern of up to ~ 3 magnitudes during a 56 day eclipse. This has been attributed to the transit of a substellar companion (called “J1407 b”) with a mass of 60–100 MJup (Rieder & Kenworthy 2016) surrounded by an exoring system consisting of at least 37 rings and extending out to 0.6 au in radius (Kenworthy & Mamajek 2015). For these rings to show detectable transit signatures, they must be significantly misaligned with respect to the orbital plane of J1407 b (Zanazzi & Lai 2017). This potential ring system would be considerably larger than the ring system of Saturn, which is located within the planet’s tidal disruption radius. The proposed rings around J1407 b would even cover a significant fraction of the companion’s Hill sphere and would not be expected to be stable over gigayear timescales. If the candidate ringed companion is in a bound orbit around the star, this orbit must be moderately eccentric in order for no othereclipses to have been detected to date (Kenworthy et al. 2015), raising the possibility that there might be a second as yet undetected companion in the system that causes the implied orbital eccentricity for J1407 b. Radial velocity measurements are overwhelmed by the chromospheric noise of the star and do not place strong constraints on other substellar companions (Kenworthy et al. 2015). The transit of J1407 suggests that its orbital plane has a high inclination to our line of sight – if there are other planets inside the orbit of J1407 b, their orbits may well be coplanar with J1407 b and there is a high chance that these companions may transit J1407.
Citation: Rieder & Kenworthy 2016
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In order to try to get insights into such systematics, we produced several variants of the ICRF3 S/X band frame by changing the reference epoch of the catalog or alternately by not considering Galactic acceleration in the modeling. Interestingly, the D2 and D3 glide terms for these variants were found to vary by several tens of microarcseconds in the comparison to ICRF2, in line with the level of the systematics observed for those terms. Such findings are not unexpected since Galactic acceleration manifests itself as a dipolar deformation in the source coordinates (e.g., Titov & Lambert 2013). Moving further, and noting that Mignard et al. (2016) mentioned this phenomenon as a possibility for explaining the observed glide between ICRF2 and the Gaia Data Release 1 (Gaia DR1) auxiliary quasar solution, we decided to reproduce an equivalent of ICRF2 by considering only the stretch of data used for ICRF2 (i.e., including only the VLBI sessions up to March 2009 in the solution) and to make a variant that adds Galactic acceleration in the modeling, as implemented for ICRF3. To guarantee the maximum consistency, those two analyses were conducted by employing the same software package as that used for ICRF2, namely CALC-SOLVE (see Fey et al. 2015). Looking at the results, we first observed that our “reproduced” ICRF2 shows similar deformations as the original ICRF2 when compared to ICRF3, hence ruling out the possibility that ICRF2 was in error. Most importantly, the ICRF2 variant that incorporates Galactic acceleration modeling was found to have much reduced glide terms compared to the original or reproduced ICRF2. This is illustrated by the bar chart in Fig. 16 which shows that the D2 term has now vanished while the D3 term has been cut by more than half (down to a value of −39 ± 4 μas) in this variant, hence indicating that the deformations between the two frames, in large part, stem from Galactic acceleration not accounted for in ICRF2. This is somehow not surprising since the data set for ICRF2 already covered 30 years, enough for Galactic acceleration effects to emerge, even though the accuracy of the frame was lower than that of ICRF3.
Citation: Titov & Lambert 2013
Citation function: Similarities
NGC 3557 is a bona fide southern-sky elliptical galaxy (E3) at a distance of 40 Mpc (1″ is 198 pc at this distance7

7
For distance derivations, we have assumed a cosmology model with H0 =73 km s−1 Mpc−1, Ωmatter = 0.27, and Ωvacuum = 0.73.
), and a member of a small group of galaxies (Brough et al. 2006). It has been classified as a LINER (e.g., Annibali et al. 2010) and as a flat-spectrum radio galaxy (Healey et al. 2007), with a jet that bends at distances of a few arcmin from the center (Schmitt et al. 2002). Detections of several of the ISM components of this object have been reported in the literature. Dust has been observed both as FIR emission (Pasquale et al. 2009) and as absorption against the central stellar continuum (Lauer et al. 2005). Nuclear optical line emission has been reported from spectroscopy (Veron-Cetty & Veron 1986; Rampazzo et al. 2005) as well as narrowband photometry (Goudfrooij et al. 1994). The MIR spectrum of NGC 3557 is of the most common Class-2 type, which is currently associated with a post-star-formation phase (Vega et al. 2009). Regarding the cold gas component, atomic gas (H i) has been reported as nondetection in several works (Serra & Osterloo 2010), while molecular gas emission has been detected in single-dish observations (Prandoni et al. 2010). NGC 3557 was included in our sample because of its relative proximity and CO(2–1) brightness (as reported by Prandoni et al. 2010), which suggested the possibility to study the molecular structures in detail. Since the object is considered to be in a stage where little current star formation may be happening, it was considered important as a representative of the molecular gas structures to be expected in post-star-formation scenarios. Furthermore, the disk-like nuclear dust distribution seen in the photometry by Lauer et al. (2005) indicated the possible presence of a molecular gas disk, which is a very interesting dynamical structure linked to the presence of organized angular momentum at those spatial scales.
Citation: Veron-Cetty & Veron 1986
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