adsabs/FOCAL huggingface dataset:
Both Nel (2016) and Zhao et al. (2018) report that these parallel mean free paths are smaller during periods of high solar activity and larger during solar minima, with the opposite being true for the resulting perpendicular mean free paths. Zhao et al. (2018) also show that such solar cycle dependences would not be fully accounted for if only the solar cycle changes in the HMF were taken into consideration. These mean free paths also display complicated spatial dependences if turbulence quantities beyond 1 au, yielded by various turbulence transport models (see, e.g., Oughton et al. 2011; Usmanov et al. 2016; Wiengarten et al. 2016; Zank et al. 2017), taking into account observed latitudinal variations of turbulence quantities in the heliosphere (Forsyth et al. 1996; Bavassono et al. 2000a, 2000b; Erdös & Balogh 2005), were used as inputs for the turbulence quantities (e.g., Engelbrecht & Burger 2013a, 2015b; Chhiber et al. 2017; Moloto et al. 2018). Furthermore, mean free paths such as those discussed have, when used in conjunction with turbulence-reduced drift coefficients (see, e.g., Minnie et al. 2007b; Engelbrecht et al. 2017) in 3D stochastic modulation codes, led to computed galactic intensities in reasonable agreement with spacecraft observations at Earth (see, e.g., Engelbrecht & Burger 2013a, 2013b; Qin & Shen 2017) and even for several different solar minima (Moloto et al. 2018). The necessity of taking cosmic-ray drift effects into account, combined with the complicated spatial dependences and the fact that none of the diffusion coefficients described above display a P1 rigidity dependence, implies that a convection–diffusion or force-field approach would not be ideal to describe long-term modulation, and that the assumptions implicit to the effective diffusion coefficient used in these formulations are unrealistic. This latter point would call into question any conclusions drawn as to historic solar parameters from quantities such as the modulation potential.
Citation: Engelbrecht & Burger 2013a
Citation function: Similarities
Rather than AGN feedback, it is possible that the effects we are seeing are from a different process coeval or prior to the onset of AGN accretion. Several works have pointed out that AGN activity coincides with a recent starburst, with the AGN having significant accretion events at least ∼200 Myr after the starburst has occurred (Davies et al. 2007; Wild et al. 2007; Wild, Heckman & Charlot 2010; Yesuf et al. 2014) giving the neutral material time to propagate out to the impact parameters probed by COS-AGN (Heckman et al. 2017). With a sample of QSO sightlines probing the CGM around 17 low-redshift starburst and post-starburst galaxies, Heckman et al. (2017) have observed a similar signature of enhanced EWs of Ly α, Si iii, and C iv (the latter of which is not measured in our control sample) relative to a control-matched sample (matched in stellar mass and impact parameter). In the range of impact parameters and stellar masses probed by COS-AGN, the strength of our enhanced EW signature is consistent with the values probed by Heckman et al. (2017). However, the results of Heckman et al. (2017) show strong offsets in the kinematics of the gas from the host galaxy (≈100 km s−1; see fig. 5 from Heckman et al. 2017), whereas the COS-AGN sightlines do not (bottom panel of Fig. 6). Assuming that the AGN activity was triggered by the starburst, a minimum delay time of 200 Myr could allow for any starburst-driven winds to dissipate and kinematic offsets to no longer be present at the impact parameters of the COS-AGN sample. Although this starburst picture provides a possible explanation of our observations, we caution that starbursts are not the only astrophysical event linked to AGN accretion activity. For example, mergers that trigger the AGN (Ellison et al. 2011, 2013; Satyapal et al. 2014; Silverman et al. 2014; Goulding et al. 2018) could potentially affect the surrounding CGM gas. Past and future work focusing on the CGM of galaxy mergers can further test this result (Johnson et al. 2014; Hani et al. 2017; Bordoloi et al. in preparation).
Citation: Heckman et al. (2017)
Citation function: Similarities
Citation: Heckman et al. (2017)
Citation function: Background; Similarities
The largest fragment in this cluster, (525) Adelaide, is the only asteroid with some physical characterisation available. Masiero et al. (2014) analysed WISE/NEOWISE infrared observations and reported Adelaide’s size D = 9.33 ± 0.24 km and geometric albedo pV = 0.22 ± 0.05. These results assume an absolute magnitude H = 12.4 mag in the visible band. More up-to-date absolute magnitude determinations across all standard databases (such as MPC, JPL, or AstDyS) indicate a slightly smaller value of absolute magnitude: H ≃ 12.1. The difference of about 0.3 magnitude is a characteristic scatter in this parameter reported by Pravec et al. (2012), who also noted that near H ≃ 12 mag the systematic offset of the database-reported values should be small (becoming as large as − 0.5 mag for smaller objects). It is therefore possible that the true size of (525) Adelaide is slightly larger, its geometric albedo slightly higher, or a combination of both. The answer will be found when photometrically calibrated data of this asteroid are taken. Luckily, this issue is not critical for our analysis. With a safe margin we can assume Adelaide’s size to be between 9 and 11.5 km, and the geometric albedo between 0.22 and 0.29. This albedo range closely matches the characteristic value in the Flora family region of the inner main belt. Nesvorný et al. (2015) identified (525) Adelaide as a member in the Flora family despite the proper inclination value of its orbit being at the high end of the Flora family members. Nevertheless, whether Adelaide is a fragment from the Flora-family formation event, which took part more than 1 Gyr ago (e.g. Vokrouhlický et al. 2017b), is again not a crucial issue for our study. The confirmation of this albedo value also comes from broad-band photometry of (525) Adelaide taken by the Sloan Digital Sky Survey (SDSS) project. Considering the methodology in Parker et al. (2008), we used the SDSS-based observations to infer its colour indexes a* = 0.108 and i − z = −0.08. Given the information in Fig. 3 of Parker et al. (2008) we concluded that these values are characteristic of S-complex asteroids. This is a prevalent spectral type in the Flora zone, and the characteristic albedo values of these objects very closely match those given for (525) Adelaide.
Citation: Pravec et al. (2012)
Citation function: Compare/Contrast; Compare/Contrast; Uses
By comparing our results with the numerical studies of Wyper et al. (2017, 2018), we propose a compound eruption model of circular-ribbon flares consisting of two sets of successively formed ribbons and eruptions of multiple filaments in a fan-spine-type magnetic configuration. A simple schematic picture is shown in Figure 6. First, the null-point reconnection between the outermost flux of the filament F1 (blue curves) and the ambient open field occurs (panel (a)), which transfers partial flux of F1 to the closed field under the far side of the dome and to the open field exterior to the near side of the dome (dashed cyan lines in panel (a)). Meanwhile, the circular ribbon CR1 and inner ribbon IR1 (orange curves) are generated due to the flow of reconnection-accelerated particles from the null along the fan plane and the spine field into the lower atmosphere. The null-point reconnection is likely of the breakout nature (Antiochos et al. 1999; Wyper et al. 2017, 2018). Then, the F1 undergoes the slipping magnetic reconnection along the QSL binding the F1, which induces the far flux of F1 reaching the null point (panel (b)). The continuous null-point reconnection causes the sequential opening of F1, and thus leads to the significant shifts of the brightenings of CR1 and IR1 (orange regions in panel (b)). In the first episode, partial flux is transferred from under the separatrix dome via the null-point reconnection, which effectively alleviates the constraint of the nearby filament F2 (green curves). Later on, the stability of F2 is disrupted and the second episode of the flare is initiated. The continuous null-point reconnection between F2 and open field is at work and generates the sequential brightenings of CR2 and IR2 (panels (c)–(d)), similar to the evolution of the first episode. Meanwhile, the blowout jet is formed at the same time as filament material below the separatrix is ejected along field lines outside the separatrix.
Citation: Antiochos et al. 1999
Citation function: Uses
In order to separate the role of different physical mechanisms in galaxy evolution, a number of studies have constrained stellar-to-halo mass (SHM) relations and ratios as a function of time using the abundance matching technique (e.g. Behroozi, Conroy & Wechsler 2010a; Moster et al. 2010; Behroozi, Conroy & Wechsler 2010b), the conditional luminosity function technique proposed by Yang, Mo & Van Den Bosch (2003), the halo occupation distribution (HOD) formalism (e.g. Berlind & Weinberg 2002; Kravtsov et al. 2004; Moster et al. 2010), and by combining the HOD, N-body simulations, galaxy clustering, and galaxy–galaxy lensing techniques (e.g. Leauthaud et al. 2012; Coupon et al. 2015). Distinguishing the properties of central galaxies from those of satellite galaxies in studies based only on the distribution of luminosity or stellar mass is challenging (e.g. George et al. 2011). By combining several observables and techniques (e.g. HOD, galaxy–galaxy lensing, and galaxy clustering) one can probe a global SHM relation for central galaxies and satellite galaxies (e.g. Leauthaud et al. 2012; Coupon et al. 2015). Coupon et al. (2015), for example, used multiwavelength data of ∼60 000 galaxies with spectroscopic redshifts in the Canada France Hawaii Telescope Lensing Survey (CFHTLenS) and Vimos Public Extragalactic Redshift Survey (VIPERS) field to constrain the relationship between central/satellite mass and halo mass, characterizing the contributions from central and satellite galaxies in the SHM relation. In this paper, we directly identify the BGGs using their precise redshifts and estimate stellar masses using the broad-band spectral energy distribution (SED) fitting technique (Ilbert et al. 2010) as used by Coupon et al. (2015). We utilize the advantages of the X-ray selection of galaxy groups and a wealth of multiwavelength, high signal-to-noise ratio observations such as the UltraVISTA survey in the COSMOS field (Laigle, Capak & Scoville 2016) to investigate the SHM relation for the central galaxies over 9 billion years. We aim to quantify the intrinsic (lognormal) scatter in stellar mass at fixed redshift in observations and compare them to the recently implemented semi-analytic model (SAM) by Henriques et al. (2015).
Citation: Leauthaud et al. 2012
Citation function: Background
Citation: Leauthaud et al. 2012
Citation function: Background; Background
The choice of κ has some bearing on the value of Mej as calculated in Eq. (2). Although taken as a constant in various model light curves, the actual optical opacity varies with time (e.g. Chugai 2000; Nagy 2018), but tests have shown that that a constant opacity can be a reasonable assumption at early times (see Mazzali et al. 2000; Taddia et al. 2018). SN 2019bkc is a H/He-deficient SN, so to select an appropriate value for κ, we search the literature literature and consider only SNe of this type. For SNe Ia, where the large abundance of Fe-group elements is a source of significant opacity, Cappellaro et al. (1997) used κ = 0.15 cm2 g−1, while Arnett (1982) used κ = 0.08 cm2 g−1. The light curve of the broad lined SNe Ic 1997ef was modelled in Mazzali et al. (2000) using the same code as Cappellaro et al. (1997), this time a lower constant opacity of 0.08 cm2 g−1 was used owing to the lower Fe abundance in this SN type. The average opacity of model CC-SNe light curves was investigated by Nagy (2018), where it was found that κ = 0.1 cm2 g−1 was suitable for their H/He-deficient models. Taddia et al. (2018) demonstrated that fitting the light curves of H-deficient CC-SNe with a simple analytical model and a constant opacity κ = 0.07 cm2 g−1 returned physical parameters consistent with more complex hydrodynamic light curve models. Prentice et al. (2019) also found that using κ = 0.07 cm2 g−1 gave comparable ejecta masses to both photospheric phase and nebular phase spectroscopic modelling of H-deficient CC-SNe, with the exception of some gamma-ray burst SNe. From Sect. 5 we find that the outer ejecta is not rich in Fe-group elements, and there is no indication of helium. From the early-nebular spectra in Sect. 4.2 we see no indication of strong Fe II or Fe III line emission, demonstrating that the ejecta is poor in Fe-group elements relative to normal SNe Ia and is more like H/He-deficient CC-SNe. This justifies the use of κ = 0.07 cm2 g−1, but to show the range of possible Mej, we consider the range 0.07–0.1 cm2 g−1.
Citation: Nagy (2018)
Citation function: Background; Uses
Citation: Nagy 2018
Citation function: Uses
The stellar initial mass function (IMF) of stars (i.e., the distribution of the masses of stars at their birth) is of fundamental importance in astrophysics. The IMF controls the efficiency of star formation in molecular clouds (Dib et al. 2011, 2013; Hony et al. 2015), the radiative and mechanical feedback from stars into the large-scale interstellar medium (Dib et al. 2006, 2021; Martizzi et al. 2016; Silich & Tenorio-Tagle 2017), and the dynamical and chemical evolution of galaxies (Côté et al. 2016). Significant efforts have been devoted to the determination of the shape of the IMF in a variety of environments, including the Galactic field (Salpeter 1955; Bochanski et al. 2010; Rybizki & Just 2015; Mor et al. 2019; Sollima 2019), the Galactic bulge (Zoccali et al. 2000; Wegg et al. 2017), and globular clusters (GCs; Da Costa & Freeman 1976; De Marchi & Paresce 1997; Covino & Ortolani 1997; Marconi et al. 1998; Paresce & De Marchi 2000; Sollima et al. 2007; Balbinot et al. 2009; Sollima & Baumgardt 2017; Cadelano et al. 2020), as well as in many young open clusters and associations (Dib 2014; Weisz et al. 2015; Maia et al. 2016; Dib et al. 2017; Jose et al. 2017; Madaan et al. 2020; Bisht et al. 2021; Damian et al. 2021; Elsanhoury et al. 2022). The existence of IMF variations in clusters has significant consequences for the galaxy-wide IMF and for galactic evolution (Dib & Basu 2018; Dib 2022). In the galactic ecosystem, GCs stand out as relics of early star formation with ages that span the range ≈11 Gyr to ≈13.2 Gyr (Salaris et al. 1997; VandenBerg et al. 2013; Pfeffer et al. 2018; Usher et al. 2019; Oliveira et al. 2020), and it is well established that GCs in the Milky Way and in the Magellanic clouds harbor two or more stellar populations (D’Antona & Caloi 2008; Milone et al. 2010; Sbordone et al. 2011; Gratton et al. 2012; Cummings et al. 2014; Piotto et al. 2015; Lee 2015; Oldham & Auger 2016; Mucciarelli et al. 2016; Massari et al. 2016; Dalessandro et al. 2016; Bowman et al. 2017; Carretta & Bragaglia 2018; Latour et al. 2019; Gilligan et al. 2020; Dondoglio et al. 2021; Jang et al. 2021; D’Antona et al. 2022; Kapse et al. 2022).
Citation: Marconi et al. 1998
Citation function: Background; Background
With a mass of Mb = 37.1 ± 5.6 M⊕ and a radius of Rb = 7.50 ± 0.44 R⊕, K2-280 b joins the group of sub-Saturns planets – defined as planets having radii between 4 and 8 R⊕ (Petigura et al. 2017) – whose masses and radii have been measured. The basic physical parameters of a sample of 23 sub-Saturns with densities measured with a precision better than 50 per cent have been presented and discussed by Petigura et al. (2017). We here extend this sample by adding K2-280 b alongside 6 additional sub-Saturns that have densities measured with a precision better than 50 per cent, as described below. WASP-156 b (Demangeon et al. 2018), an ∼0.5 $\mathrm{R_\mathrm{Jup}}$ planet with a Jupiter-like density was discovered by the ground-based SuperWASP transit survey (Pollacco et al. 2006; Smith & WASP Consortium 2014). Kepler-1656 b, a dense sub-Saturn with a high eccentricity of e = 0.84 transiting a relatively bright (V = 11.6 mag) solar-type star, was recently reported by Brady et al. (2018). Three sub-Saturns were discovered and characterized by the KESPRINT consortium, two of them in K2 campaign 3 (K2-60 b, Eigmüller et al. 2017) and campaign 14 (HD 89345 b, aka K2-234 b, Van Eylen et al. 2018; Yu et al. 2018b), and HD 219666 b (Esposito et al. 2019) in TESS Sector 1. One sub-Saturn, GJ 3470 b (Bonfils et al. 2012), orbiting an M1.5 dwarf was not included by Petigura et al. (2017), but we add it to the current sample, adopting the parameters from Awiphan et al. (2016). All of these new sub-Saturns, including K2-280 b, reside in apparently single systems. Fig. 6 shows the mass–radius and mass–density diagrams for this extended sample of 30 planets. Sub-Saturns found to be in multiplanet systems are marked with green filled circles, whereas those in single systems are marked with blue filled circles. The position of K2-280 b is indicated with a red-rimmed circle. Sub-Saturns whose density has been measured with a precision slightly worse than 50 per cent are marked with green and blue open circles. All the remaining transiting planets with measured radii and masses are marked with open grey circles.12 According to the Fortney, Marley & Barnes (2007)’s models – also shown in the mass–radius diagram (Fig. 6, upper panel) – K2-280 b has a core of about 10–25 M⊕, accounting for ∼25–65 per cent of its total mass.
Citation: Demangeon et al. 2018
Citation function: Background; Background
At quasi-perpendicular shocks, the average shock structure is dominated by a foot of reflected ions, which is upstream of the shock ramp where the major thermalization and deceleration occurs. Non-stationarity in the form of rippling of the surface or steepened whistler waves (Moullard et al. 2006; Lobzin et al. 2007) is an intrinsic feature of the shock, but this is generally manifest as minor perturbations on top of an otherwise stationary shock ramp. Simulations have predicted that if the fraction of ions reflected by the shock front becomes sufficiently high, the quasi-perpendicular shock can become periodically reforming on timescales of the ion gyroperiod. Various theories have been suggested for such non-stationarity, including self-reformation where a new shock ramp grows at the edge of the foot (Biskamp & Welter 1972a; Lembège & Dawson 1987), whistler-induced reformation (Biskamp & Welter 1972b; Scholer & Burgess 2007), kinetic instabilities such as the Buneman and modified two-stream instability (e.g., Cargill & Papadopoulos 1988; Matsukiyo & Scholer 2003, 2006b; Scholer et al. 2003; Scholer & Burgess 2007; Matsumoto et al. 2013), and gradient catastrophe of nonlinear whistler waves due to steepening (Krasnoselskikh et al. 2002). However, it has not been until recently that such non-stationarity has been confirmed with in situ spacecraft observations. In a survey of Cassini shock crossings at Saturn, Sulaiman et al. (2015) found evidence of a periodically reforming shock, pulsating at a period near 0.3 of the ion gyroperiod in the unperturbed upstream medium. This period agrees with the time taken for a specularly reflected proton to gyrate across the foot and return to the main shock ramp. Sulaiman et al. (2015) also report that these periodic non-stationary shocks are primarily found in the very high Mach number regime, which gives evidence for a relation between Mach number and reformation. The main processes behind the non-stationary behavior of these very high Mach number shocks, such as the details of the ion- and electron-scale processes acting within the shock transition, remain elusive.
Citation: Scholer & Burgess 2007
Citation function: Background; Background
Molecular line ratio diagrams for NGC 4710, NGC 5866 and a variety of other galaxies. Our data for NGC 4710 and NGC 5866 are shown as filled circles and squares, respectively, while our data for the nuclear discs and inner rings are shown in blue and red, respectively (black for the intermediate region). Upper and lower limits are represented by arrows. Other lenticular galaxies are indicated by magenta filled stars (Krips et al. 2010; Crocker et al. 2012), starburst nuclei by dark green filled stars, Seyferts by brown filled stars, spiral arm GMCs by black circles with an X (see Baan et al. 2008; table 3 in Krips et al. 2010 and references therein), NGC 6946 (starburst) GMCs by black circles with a cross (Topal et al. 2014), and M31 GMCs by turquoise circles with an X (Brouillet et al. 2005). The data for NGC 1266 (a lenticular galaxy with a molecular outflow) are shown by magenta squares with a filled star (Alatalo et al. 2011). The green shaded region in panel a indicates the typical range of 12CO(1–0)/HCN(1–0) ratios in starbursts with LFIR > 1011 L⊙ (see table B2 in Baan et al. 2008). The range of R11 ratios in the nuclear disc and inner ring of NGC 5866 (this work) are indicated by respectively the blue and red horizontal lines in panel b, while the typical range in spirals with LFIR  1011 L⊙ (Paglione et al. 2001) is indicated by the pale grey shaded region. In panels a and b, Crocker et al.'s (2012) single-dish observations of NGC 4710 and NGC 5866 are shown as an open black circle and an open black square, respectively (see table 4 of Crocker et al. 2012). The HCN(1–0)/HCO+ ratios for M31 GMCs (Brouillet et al. 2005) are indicated by the turquoise shaded region in panels c and d. The green shaded region in panel d indicates the typical range of 13CO(1–0)/HCO+(1–0) ratios in the disc of M82 (starburst; Tan et al. 2011). The 12CO(1–0)/HCN(1–0) ratios in spirals (Gao & Solomon 2004a) are indicated by the dark grey shaded region in panels a, e and f, respectively. The black solid lines in a number of panels show the 1 : 1 relation and are there to guide the eye. Similarly, the black dashed lines show a ratio of 1 in panels c, d and f.
Citation: Brouillet et al. 2005
Citation function: Uses
The two LSST observing programs are complementary in the SN samples they will provide. The main survey will obtain light curves in six bands and photometric redshifts of about 400,000 photometrically classified SNe Ia that can be used for cosmological distance measurements, with further spectroscopic follow-up of a subsample of their host galaxies. Such a sample will not only provide larger statistics for the study of the Type Ia population in the universe but also be spread across the full 18,000 deg2 LSST main survey footprint, allowing different probes of the large-scale structure of the low-redshift universe. This sample of SNe can be used as a tracer of large-scale structure by directly probing the gravitational potential of structure through inferences of their peculiar velocities (Gordon et al. 2007; Bhattacharya et al. 2011; Howlett et al. 2017), WL of SN brightnesses (Dodelson & Vallinotto 2006; Quartin et al. 2014; Macaulay et al. 2017; Scovacricchi et al. 2017), and the local bulk flow (Riess 2000; Dai et al. 2011; Turnbull et al. 2012; Feindt et al. 2013; Huterer et al. 2015), as well as low-redshift constraints on the isotropy of the universe (Antoniou & Perivolaropoulos 2010; Campanelli et al. 2011; Colin et al. 2011; Cai et al. 2013; Javanmardi et al. 2015). The rapidly sampled Deep Drilling Fields, possibly co-added over short timescales, will yield well-sampled light curves of tens of thousands of SNe to redshifts peaking around z ∼ 0.7 and reaching beyond a redshift of 1.0, limited by the systematics related to the limits of our astrophysical understanding of SN populations and relative photometric calibration. In addition to the usual use of SNe Ia to probe the redshift–distance relation to high redshift, the luminosities will be magnified by lensing from foreground structure, a correlation that can be probed with these data. The ultimate promise of such SN surveys will be linked to the observing strategy employed by the LSST.
Citation: Scovacricchi et al. 2017
Citation function: Motivation; Motivation