adsabs/FOCAL huggingface dataset:
Many studies indicate a much more complicated star formation history (SFH; e.g., Pagel & Tautvaišvienė 1998; Carrera et al. 2008; Harris & Zaritsky 2009; Rubele et al. 2012; Meschin et al. 2014; Palma et al. 2015; Perren et al. 2017) or AMR for star clusters (e.g., Olszewski et al. 1991; Hill et al. 2000; Dirsch et al. 2000; Rich et al. 2001; Leonardi & Rose 2003; Kerber et al. 2007) in the LMC than in the SMC. Early studies of the cluster AMR in the LMC (e.g., the spectroscopic study of Olszewski et al. 1991) revealed a mysterious gap in the star cluster formation between 10 and 3 Gyr ago (with the sole exception of cluster ESO121-3 and very recently also KMHK1592, as reported by Piatti 2022), which follows the initial formation of old, metal-poor globular clusters, and precedes more recent active formation of intermediate-age clusters. This so-called “age gap”, which is simultaneously a metallicity gap, was later reported also by other authors (e.g., Harris & Zaritsky 2009; Sharma et al. 2010; Kerber et al. 2007, and references therein), even though it has not been fully confirmed when only the field stars are considered. For example, Piatti & Geisler (2013) reported that no clear age gap in the field star formation is observed in their study of fields in the LMC main body, based on Washington photometry. Furthermore, based on their spectroscopic analysis of four fields to the north of the LMC bar, Carrera et al. (2008) maintain that the disk and cluster AMR are similar. However, unlike clusters, there is no age gap in the field population. On the contrary, Harris & Zaritsky (2009) claim that such a gap is evident in the field population of the bar, mostly omitted in previous studies. Also Meschin et al. (2014), using optical photometry, identified two main star-forming epochs with a period characterized by a lower activity in between; however, in their work that interval of time was shorter and lasted from ∼8 up to ∼4 Gyr ago. All the aforementioned authors agree that star formation in the LMC is continuing to this day.
Citation: Piatti 2022
Citation function: Differences
The first direct proof of the existence of magnetic fields in large-scale extragalactic environments, i.e., galaxy clusters, dates back to the 1970s with the discovery of extended, diffuse, central synchrotron sources called radio halos (see, e.g., Feretti et al. 2012 for a review). Later, indirect evidence of the existence of intracluster magnetic fields has been given by several statistical studies on the effect of the Faraday rotation on the radio signal from background galaxies or galaxies embedded in galaxy clusters (Lawler & Dennison 1982; Vallée et al. 1986; Clarke et al. 2001; Johnston-Hollitt 2003; Clarke 2004; Johnston-Hollitt & Ekers 2004). On scales up to a few Mpc from the nearest galaxy cluster, possibly along filaments, only a few diffuse synchrotron sources have been reported (Harris et al. 1993; Bagchi et al. 2002; Kronberg et al. 2007; Giovannini et al. 2013, 2015). Magnetic fields with strengths on the order of 10-15 G in voids might be indicated by γ-ray observations (see Neronov & Vovk 2010; Tavecchio et al. 2010; Takahashi et al. 2012, 2013; but see Broderick et al. 2014a,b for alternative possibilities). Nevertheless, up to now, a robust confirmed detection of magnetic fields on scales that are much larger than clusters is not available. Stasyszyn et al. (2010) and Akahori et al. (2014a) investigated the possibility of statistically measuring Faraday rotation from intergalactic magnetic fields with present observations, showing that only the Square Kilometre Array (SKA) and its pathfinders are likely to succeed in this respect. By comparing the observations with single-scale magnetic field simulations, Pshirkov et al. (2015) infer an upper limit of 1.2 nG for extragalactic large-scale magnetic fields, while the Planck Collaboration XIX (2016) derived a more stringent upper limit for primordial large-scale magnetic fields of B 0.67 nG from the analysis of the Cosmic Microwave Background (CMB) power spectra and the effect on the ionization history (but see also Takahashi et al. 2005; Ichiki et al. 2006).
Citation: Giovannini et al. 2013
Citation function: Background
Citation: Clarke 2004
Citation function: Background
On the other hand, PT has experienced many developments in recent years (Matsubara 2008a; Baumann et al. 2012; Carlson et al. 2013), in part because it can be useful to analytically understand different effects in the power spectrum and correlation function for the dark matter clustering. These effects can be confirmed or refuted, and further explored with simulations to ultimately understand the outcomes of present and future galaxy surveys, such as eBOSS (Zhao 2016), DESI (Aghamousa et al. 2016), EUCLID (Amendola et al. 2013), and LSST (LSST Dark Energy Science Collaboration 2012). Two approaches have been used to study PT: the Eulerian standard PT (SPT) and Lagrangian PT (LPT), which both have advantages and drawbacks, but they are complementary in the end (Tassev 2014). The nonlinear PT for MG was developed initially in (Koyama et al. 2009), and has been further studied in several other works (Taruya et al. 2014a,b; Brax & Valageas 2013; Bellini & Zumalacarregui 2015; Taruya 2016; Bose & Koyama 2016, 2017; Barrow & Mota 2003; Akrami et al. 2013; Fasiello & Vlah 2017; Aviles & Cervantes-Cota 2017; Hirano et al. 2018; Bose et al. 2018; Bose & Taruya 2018; Aviles et al. 2018). The LPT for dark matter fluctuations in MG was developed in Aviles & Cervantes-Cota (2017), and further studies for biased tracers in Aviles et al. (2018). The PT for MG has the advantage that it allows us to understand the role that these physical parameters play in the screening features of dark matter statistics. We here study some of these effects through screening mechanisms by examining them at second- and third-order perturbation levels using PT for some MG models. To this end, we build on the LPT formalism developed in Aviles & Cervantes-Cota (2017), which was initially posited for MG theories in the Jordan frame, in order to apply it to theories in the Einstein frame. Because of the direct coupling of the scalar field and the dark matter in the Klein–Gordon equation, the equations that govern the screening can differ substantially from those in Jordan-frame MG theories. In general, screening effects depend on the type of nonlinearities that are introduced in the Lagrangian density. We present a detailed analysis of screening features and identify the theoretical roots of their origin. Our results show that screenings possess peculiar features that depend on the scalar field effective mass and couplings, and that may in particular cases cause anti-screening effects in the power spectrum, such as in the symmetron model. We perform this analysis by separating the growth functions into screening and non-screened parts. We note, however, that we do not compare the perturbative approach with a fully nonlinear simulation. We refer to (Koyama et al. 2009), for instance, for investigations like this at the level of the power spectrum.
Citation: Aviles et al. (2018)
Citation function: Extends
Citation: Aviles et al. 2018
Citation function: Uses; Extends
The Λ cold dark matter (CDM) model has had tremendous success in providing a cosmogony that links the state of the very high redshift Universe as inferred from cosmic microwave background observations and big bang nucleosynthesis considerations, with the observed large-scale distribution of galaxies and its evolution at later times. In this paradigm, the observed structures grew due to gravitational amplification of initially small perturbations, perhaps seeded by inflation (Guth 1981), with most of the gravitating mass in the form of ‘dark matter’, an as of yet unknown type of matter that apart from gravitationally, interacts only very weakly if at all with baryonic matter and radiation, see e.g. Frenk & White (2012) for a recent review. Observations on smaller, sub galactic scales, have proven more problematic for ΛCDM, with suggestions that the low abundance (e.g. Klypin et al. 1999; Moore et al. 1999) and shallow density profiles (e.g Gilmore et al. 2007; de Vega & Sanchez 2010) inferred for haloes hosting Milky Way satellites are inconsistent with the numerous substructures with cuspy density profiles that form in Milky Way-like CDM haloes. Indeed the substructures in the haloes of the Aquarius project (Springel et al. 2008) and the GHALO project (Stadel et al. 2009) may be difficult to reconcile with those inferred to host Milky Way satellites. Even if many of the smaller DM substructures may not have a sufficiently deep potential well to form stars after reionization (e.g Efstathiou 1992; Benson et al. 2002) and so may well be dark, some of the more massive ones are probably too big to be affected (Okamoto, Gao & Theuns 2008) and would hence appear to be ‘too big to fail’ (Boylan-Kolchin, Bullock & Kaplinghat 2011, 2012). However, the jury on this is still out: the Milky Way's halo may simply be of lower mass than those of the Aquarius haloes and hence have fewer massive satellites (Wang et al. 2012). The status of the density profiles of the satellite's haloes – cored versus cuspy – is similarly unresolved. Strigari, Frenk & White (2010) claim that the stellar dynamics observations of the satellites do not imply cores at all and hence may be consistent with CDM cusps. But even if the satellites had cored profile, this might result from the action of baryonic feedback processes (Governato et al. 2012; Pontzen & Governato 2012), and hence still be consistent with CDM.
Citation: Klypin et al. 1999
Citation function: Compare/Contrast; Compare/Contrast
The energy in the inner crust is largely influenced by the properties of the neutron gas and, therefore, the EoS of neutron matter of the different calculations plays an essential role. The NV calculation (Negele & Vautherin 1973) is based on a local energy density functional that closely reproduces the Siemens-Pandharipande EoS of neutron matter (Siemens & Pandharipande 1971) in the low-density regime. The Moskow calculation (Baldo et al. 2007) employs a semi-microscopic energy density functional obtained by combining the phenomenological functional of Fayans et al. (2000) inside the nuclear cluster with a microscopic part calculated in the Brueckner theory with the Argonne v18 potential (Wiringa et al. 1995) to describe the neutron environment in the low-density regime (Baldo et al. 2004). The BBP calculation (Baym et al. 1971a,b) gives the EoS based on the Brueckner calculations for pure neutron matter of Siemens (Siemens & Pandharipande 1971). The LS-Ska (Lattimer & Swesty 1991; Lattimer 2015) and DH-SLy4 (Douchin & Haensel 2001) EoSs were constructed using the Skyrme effective nuclear forces Ska and SLy4, respectively. The SLy4 Skyrme force (Chabanat et al. 1998) was parametrized, among other constraints, to be consistent with the microscopic variational calculation of neutron matter of Wiringa et al. (1988) above the nuclear saturation density. The Shen-TM1 EoS (Shen et al. 1998b,a; Sumiyoshi 2015) was computed using the relativistic mean field parameter set TM1 for the nuclear interaction. The calculations of LS (Lattimer & Swesty 1991; Lattimer 2015) and Shen et al. (Shen et al. 1998b,a; Sumiyoshi 2015) are the two EoS tables in more widespread use for astrophysical simulations. The BSk21 EoS (Pearson et al. 2012; Fantina et al. 2013; Potekhin et al. 2013; Goriely et al. 2010) is based on a Skyrme force with the parameters accurately fitted to the known nuclear masses and constrained, among various physical conditions, to the neutron matter EoS derived within modern many-body approaches which include the contribution of three-body forces.
Citation: Lattimer & Swesty 1991
Citation function: Background; Background
Citation: Lattimer & Swesty 1991
Citation function: Background; Background
As illustrated in this paper, the variation of spectral line intensity induced by GSA varies among different spectral lines. Thus, such influence could be precisely analysed if multispectral lines for the same element is achievable. In addition, the alignment on the ground state is transferred to the levels of atoms on the excited states through absorption process, as illustrated in Section 3 and 4. The intensity of the ultraviolet-pumped fluorescence lines, which are derived from successive decays to different levels of atoms and applied to the modelling of reflection nebulae (Sellgren 1984, 1986), are dependent on the initial upper levels, and thus is influenced by GSA through the scattering process. The influence of collision is neglected in this paper, which applies to most diffuse ISM and IGM. Collisionsreduce the alignment efficiency (see Hawkins 1955). The collision effect can become important in the case of higher density medium where the collision rate $\tau _c^{-1}$ (either inelastic collision rate or Van der Waals collision rate) dominates over optical pumping rate $B_{lu}\bar{J}^0_0$ (see Yan & Lazarian 2006 for details). The focus of our paper is on the GSA effect that is a saturated state. When the magnetic precession rate is comparable to the optical pumping from the ground state ($2\pi \nu _L\sim B_{lu}\bar{J}^0_0$), the ground-level Hanle effect is applicable (see Landolfi & Landi Degl’Innocenti 1986), which means the magnetic field influence on the spectrum is not limited to the change of direction but also the magnetic field strength. As demonstrated in Yan & Lazarian (2008), the effect becomes saturated when $2\pi \nu _L\rightarrow 10B_{lu}\bar{J}^0_0$. Therefore, we set rHanlewhere $2\pi \nu _L\simeq 10B_{lu}\bar{J}^0_0$ as the boundary between the ground-level Hanle regime and the GSA regime (see Fig. 12a):
(10)
\begin{eqnarray*}
r_{Hanle}=r_\ast \sqrt{\frac{A_{ul}[J_u]}{1.76(B/{\mu }G)(\exp (h\nu /(k_BT))-1)[J_l]}}
\end{eqnarray*}
We calculate the boundary rHanle for C ii λ1037 Å in the presence of stars with different effective temperature Teff and radius r* for the magnetic field with the strength range from μG to mG in Fig. 12(b). The rHanle increases as the magnetic field becomes weaker and as the effective temperature Teff and radius r* increase. Nevertheless, even in the most optimistic scenario with Teff = 4 × 104K, r* = 10r⊙, B = 1μG (though rarely applies), the boundary rHanle ≃ 180Au = 8.5 × 10−4pc, which is a thousand times smaller than the normal H ii Region which is in pc scale. All the analysis with GSA and their observational implication in this paper is applicable to most of the ISM, except when performing very high resolution spectral analysis on regions very close to the very bright O-type star.
Citation: Yan & Lazarian 2006
Citation function: Background
The focus of this work is to address the proplyd lifetime problem from a modelling perspective using recent developments in both the theory of photoevaporating discs and observations of the star and disc population in the ONC. The most similar study to this work is that of Scally & Clarke (2001), who produced an N-body model of the ONC coupled with theoretical photoevaporative mass-loss rates. The aim was to test the idea put forward by Störzer & Hollenbach (1999) that radial orbits of stars could result in shorter periods of exposure to strong FUV flux close to θ1C, thus increasing the PPD dispersal time-scale. The models demonstrated that such dynamical orbits alone are insufficient to produce significantly extended disc lifetimes. However, since that study a number of developments mean that the problem is due to be revisited. First, thermodynamic calculations of conditions in photodissociation regions (PDRs) have been coupled with self-consistent equations for the thermally driven disc wind (Adams et al. 2004; Facchini et al. 2016; Haworth et al. 2018; Haworth & Clarke 2019). In particular, the recent Fried grid (Haworth et al. 2018) can be interpolated across FUV flux, disc outer radius, and disc mass to calculate an instantaneous mass-loss rate for a given PPD. Secondly, the recent sub-mm survey of disc masses and radii by Eisner et al. (2018, hereafter E18) offers further observational constraints on a successful model of PPD evolution, and the host mass-dependent disc properties permit a test of theoretical predictions. Thirdly, Beccari et al. (2017, see also Jerabkova et al. 2019) recently found evidence of three stellar populations with distinct ages in the ONC. This has multiple consequences for models of a PPD population, most obviously that a subset of discs has evolved for a shorter period than the oldest stars in the region. Additionally, since stars are formed from gas, during the evolution of the cluster prior to the most recent formation event there may have been considerable intracluster extinction of UV photons. Understanding how such a scenario influences the disc population would also represent a test of the hypothesis that discrete epochs of star formation occurred in the ONC.
Citation: Facchini et al. 2016
Citation function: Uses
GRB 100814A is another special event with an early-time shallow decay phase and late-time significant rebrightening in its optical afterglow light curve (Nardini et al. 2014). The power-law (





) temporal index of the early shallow decay is 





, which is inconsistent with expectations from the external shock model. It is argued that the shallow decay phases come from energy injection. Usually, the injection luminosity is assumed as 





 (Nousek et al. 2006; Zhang et al. 2006; Yu & Huang 2013), which may naturally come from the magnetic dipole radiation of a newborn millisecond magnetar (Dai & Lu 1998; Zhang & Mészáros 2001; Dall’Osso et al. 2011). As a result, magnetars have been suggested as the central engines for some GRBs, including both long and short events (Zhang & Mészáros 2001; Troja et al. 2007; Metzger et al. 2011; Bernardini et al. 2012; Rowlinson et al. 2013). In both Dai & Lu (1998) and Dall’Osso et al. (2011), works considering a strongly magnetized neutron star as the central engine of a GRB, the energy injection power is more realistically derived as 





, where T is the spin-down timescale and 





 is the initial luminosity. In particular, while considering the exact form for the energy injection power of a spinning down magnetar due to magnetic dipole radiation, Dall’Osso et al. (2011) found that the luminosity of the X-ray afterglow naturally has a shallow decay phase with a temporal power-law index of 





. Recently, a nearly constant dipole radiation luminosity (





) during the spin-down timescale was favored by observations from GRBs, such as 050801 (de Pasquale et al. 2007), 060729 (Grupe et al. 2007), and 080913 (Greiner et al. 2009). However, some observations of GRB afterglows with rebrightenings or bumps (i.e., 





) require that the injection luminosity increases with time (i.e., 





). Additionally, there is a plateau phase in the X-ray band of GRB 100814A between 103 and 105 s (Nardini et al. 2014) indicating continuous energy injection from the central engine during this prolonged period.
Citation: Metzger et al. 2011
Citation function: Background
Outside the TC, the MHD simulation behaves similarly to its HD counterpart, with baroclinicity being the dominant contribution. In terms of balance between left- and right-hand sides of (13), panels A and D show a very good agreement in most of the CZ. Differences are only evident inside the TC in the top layers and slightly near the poles. We attribute these differences to the upper and polar boundary conditions for the magnetic field. The difference observed between panels 12A and D in the top boundary might be due to the radial magnetic field we enforce at the surface. This means that when we have a strong poloidal field located near the surface, it will be forced over a couple grid points by the boundary condition into the radial direction. This is exactly the case of the poloidal field configuration during cycle maximum (see Fig. 3E). This problem might be alleviated in future simulations by introducing more realistic top boundary conditions like that used in Warnecke et al. (2016). The differences between the left- and right-hand sides during cycle minimum (not shown here) are much smaller. It is the radial derivative of the poloidal field present in the second magnetic term of Eq. (13) that is responsible for this “artificial” contribution. There are two other possible sources of error that can explain the minute differences we find in this balance calculation (and in the previous section as well). The first is numerical diffusivity, which we cannot measure directly. The other issue is related with the different numerical methods used to compute derivatives and other composite quantities in the main code during the simulation and a posteriori. During the simulation run, EULAG numerics computes central cell values and fluxes across the cell borders, while the type of analysis that we perform a posteriori assumes values computed in the cell corners using centered finite differences. Differentiation across the poles can also introduce some artifacts. Nevertheless, the very good match obtained in the HD case indicates that these two sources of error are in fact very small, and that the main issue here seems related to the magnetic field boundary conditions. Despite these possible sources of uncertainty, we consider that there is a general good agreement between left- and right-hand sides for most of the CZ.
Citation: Warnecke et al. (2016)
Citation function: Future Work
In analogy to the hydrodynamic case, the nonlinear coherent vortex structure also plays an important role in plasma dynamics and transport processes (Hasegawa & Mima 1978; Shukla et al. 1985; Petviashvili & Pokhotelov 1992; Horton & Hasegawa 1994). These vortices tend to have a long lifetime and are widely observed in space, laboratory, and numerical simulation of plasma (Chmyrev et al. 1988; Burlaga 1990; Volwerk et al. 1996; Stasiewicz et al. 2000; Sundkvist et al. 2005; Alexandrova et al. 2006; Alexandrova 2008; Alexandrova & Saur 2008; Vianello et al. 2010; Servidio et al. 2015). An essential subset of these plasma vortices is known as Alfvén vortices, which can be viewed as the cylindrical analog of the nonlinear Alfvén wave (Petviashvili & Pokhotelov 1992). The Alfvén vortices have an axis that is nearly parallel to the unperturbed magnetic field, along which the shape is generally invariant. Thus, these vortices are quasi-2D structures. The associated perpendicular magnetic fluctuations are linearly related with the perpendicular velocity fluctuations, but their relative amplitudes are not obligatorily equal (as is the case in an Alfvén wave): 





, where ξ is not necessarily equal to 1. In addition, Alfvén vortices do not propagate along 





 in the plasma frame, and they hardly propagate in the perpendicular plane when the axis of the vortex is inclined with respect to 





 that are in contrast with Alfvén wave (Wang et al. 2012). After first being reported in the Earth’s magnetosheath (Alexandrova et al. 2006; Alexandrova 2008), multiscale quasi-bidimensional Alfvén vortices (with 





) have been identified in numerous space environments: in slow solar wind (Perrone et al. 2016; Roberts et al. 2016), in fast solar wind (Lion et al. 2016; Perrone et al. 2017), and in Saturn’s magnetosheath (Alexandrova & Saur 2008). It seems that the intermittent structures in fast solar wind are dominated by Alfvén vortices (Perrone et al. 2017), which agrees with the 2D MHD turbulence model (Zank et al. 2017).
Citation: Alexandrova 2008
Citation function: Background
Citation: Alexandrova 2008
Citation function: Background