adsabs/FOCAL huggingface dataset:
In this study, the 272 eV suprathermal electron pitch-angle distributions (PADs) measured by ACE are used. The electron PADs are obtained from the Solar Wind Electron Proton Alpha Monitor (SWEPAM) with angular and time resolutions of 9° and 64 s respectively (McComas et al. 1998). Here we examined 16 s average magnetic field, 64 s average plasma, 1 h average O7+/O6+ ratio, and mean Fe charge state ⟨Fe⟩ data from 1998 to 2008 measured by ACE and identified 272 ICMEs in total. The ICMEs were identified by the following process: (1) We take the events in previous ICME lists of Jian et al. (2006), Chi et al. (2016), and Richardson & Cane (2004)1 as candidate ICMEs. (2) Some lists also report short-duration ( 10 h) structures as ICMEs. As the origin of these smaller-scale ICMEs and flux ropes are still debated (Feng et al. 2007; Rouillard et al. 2011; Janvier et al. 2014; Feng & Wang 2015; Wang et al. 2019), we excluded them from this study. (3) The high Fe charge states (⟨Fe⟩ ≥ 12) and abnormally high O7+/O6+ ratio (≥1) are the result of flare-related heating in the corona (Lepri & Zurbuchen 2004; Reinard 2005), and therefore they are independently reliable ICME indicators (Feng & Wang 2015). If the candidate ICMEs have high Fe charge states and/or abnormally high O7+/O6+ ratio, they are identified as ICMEs. (4) If the candidate ICMEs have no high Fe charge states and abnormally high O7+/O6+ ratio, we look for the following five characteristics: declining speed (apparent expansion), increasing total magnetic magnitude and helium abundance (He/P > 0.06) (Richardson & Cane 2004), and decreasing proton temperatures and proton densities. If the candidate ICMEs have three or more of the above characteristics they are identified as ICMEs. Given that magnetic flux ropes are special field topologies characterized by bundles of helical magnetic-field lines collectively spiraling around a common axis, the essential observational properties of magnetic flux ropes should be enhanced magnetic field strength and smooth rotations (Feng et al. 2008, 2010), namely, measured enhanced magnetic field strength, the center-enhanced magnetic components, and bipolar curve magnetic components. Therefore, if an ICME was found to have enhanced magnetic field strength, both center-enhanced and bipolar field components, it was identified as MC. Among the 272 ICMEs, 101 (37.1%) events were identified as MCs. All 272 ICMEs are listed in Table A.1. The second and third columns show the start and end times, the fourth column gives the duration of the ICMEs, and the fifth column provides the types of ICMEs (MC or nonMC).
Citation: Feng & Wang 2015
Citation function: Uses; Uses
Complementary to studies using the integrated emission and angular power spectrum of DM annihilation from a population of Galactic subhalos, in this paper we present a novel strategy using one-point photon statistics to search for the annihilation signature. Our technique takes advantage of the information in the entire population of sources, including both those that are resolved and those that are faint and unresolved. The concept of leveraging the one-point photon-count distribution to search for DM has previously been studied in Dodelson et al. (2009) and Feyereisen et al. (2015) in the context of emission from extragalactic sources and in Lee et al. (2009) and Koushiappas et al. (2010) with application to Galactic subhalos. We introduce a method to search for signatures of DM annihilation from a Galactic subhalo population using the non-Poissonian template fitting (NPTF) framework (Malyshev & Hogg 2011; Lee et al. 2015, 2016; Mishra-Sharma et al. 2017), which has previously been applied to characterize unresolved point sources in the inner Galaxy (Lee et al. 2016; Linden et al. 2016; Leane & Slatyer 2019, 2020a, 2020b; Chang et al. 2020; Buschmann et al. 2020) and at high latitudes (Zechlin et al. 2016; Lisanti et al. 2016; Zechlin et al. 2018). Using simulations, we show that the NPTF can constrain DM annihilation from a population of subhalos in the face of astrophysical background emission. We find that using photon statistics to look for collective emission from a subhalo population can be especially promising when a large number of individual subhalo candidates are identified in point-source catalogs. This establishes a method complementary to the established ones based on characterizing individual resolved point sources as subhalo candidates, as well as those based on using the measured 0-point (overall flux) and two-point (angular power spectrum) statistics to characterize a subhalo population. Moreover, note that our methodology is completely independent of assumptions about, e.g., the location of stellar overdensities, so we are less sensitive to certain uncertainties which can bias dwarf galaxy constraints such as those in modeling tracer populations. Thus, this framework provides an important comparison for the dwarf galaxy analyses as well.
Citation: Mishra-Sharma et al. 2017
Citation function: Uses
Citation: Lee et al.; 2016; Lee et al. 2016
Citation function: Uses; Motivation
By radio continuum surveys of interstellar space and direct in situ measurements in the solar system, it is well established that for many scenarios the background magnetic fields are spatially varying. However, the above research about parallel and perpendicular diffusion only explored the uniform mean magnetic field. One can show that the spatially varying background magnetic fields lead to the adiabatic focusing effect of charged energetic particle transport and introduces correction to the particle diffusion coefficients (see, e.g., Roelof 1969; Earl 1976; Kunstmann 1979; Beeck & Wibberenz 1986; Bieber & Burger 1990; Kóta 2000; Schlickeiser & Shalchi 2008; Shalchi 2009b, 2011; Litvinenko 2012a, 2012b; Shalchi & Danos 2013; Wang & Qin 2016; Wang et al. 2017b). To explore the influence of adiabatic focusing on particle transport, the perturbation method is frequently used (see, e.g., Beeck & Wibberenz 1986; Bieber & Burger 1990; Schlickeiser & Shalchi 2008; Schlickeiser & Jenko 2010; Litvinenko & Schlickeiser 2013; He & Schlickeiser 2014). To use the perturbation method, since the anisotropic distribution function is an implicit function, by using the iteration method, one can find that the anisotropic distribution function becomes an infinite series of the spatial and temporal derivatives of the isotropic distribution function. Therefore, the governing equation of the isotropic distribution function derived from the Fokker–Planck equation contains infinite terms because of the infinite series of the anisotropic distribution function. By using the truncating method to neglect the higher-order derivative terms, the approximate correction formulas of parallel or perpendicular diffusion coefficients were obtained (see, e.g., Schlickeiser & Shalchi 2008; Schlickeiser & Jenko 2010; He & Schlickeiser 2014). However, the higher-order derivative terms probably also make the correction to the parallel and perpendicular diffusion much like the lower-order derivative ones do. The magnitude of the correction from higher-order derivative term might not necessarily be a higher-order small quantity than the magnitude of the lower-order derivative terms. Therefore, the correction obtained by the previous authors is likely to contain significant errors. In this paper, by considering the higher-order derivative terms, we derive the parallel and perpendicular diffusion coefficients and obtain the correction formulas coming from all order derivative terms by using the improved perturbation method (He & Schlickeiser 2014) and the iteration operation. And for the weak adiabatic focusing limit we evaluate the correction to the parallel diffusion coefficient and compare it with the correction obtained in the previous papers.
Citation: Schlickeiser & Jenko 2010
Citation function: Background
Citation: Schlickeiser & Jenko 2010
Citation function: Background
Gravitational-wave astronomy has recently become a reality with the first detection of gravitational waves (GW hereafter) by the Laser Interferometer Gravitational-Wave Observatory (LIGO) and Virgo ground-based interferemeters. To date, eleven events have been reported by the LIGO and Virgo detectors (Abbott 2018), and this number will quickly increase to tens of events in the coming years. Some of these events may correspond to gravitationally lensed events with magnification factors ranging from a few tens to a few hundreds (Dai et al. 2017; Ng et al. 2018; Li et al. 2018a; Smith et al. 2018a,b; Broadhurst et al. 2019). Recent works have studied lensing effects in the existing LIGO/Virgo O1 and O2 events (Hannuksela et al. 2019; Broadhurst et al. 2019), while Smith et al. (2018c) searched for candidate galaxy cluster lenses for the GW170814 event. The most likely lenses for such events would be massive galaxies or galaxy clusters (Ng et al. 2018; Dai et al. 2017; Smith et al. 2018b; Broadhurst et al. 2019). On the other extreme of the lens mass regime, compact objects with masses of a few hundreds to a few tens M⊙ can also act as lenses (Lai et al. 2018). In this case, the geometric optics limit is not valid since the Schwarszchild radius of the lens is comparable to the wavelength of the wave. For these relatively low masses, the lensing effect has a modest impact on the average magnification, but it can introduce a frequency dependence on the magnification (see for instance, Jung & Shin 2019; Lai et al. 2018). An even smaller mass regime was considered in Christian et al. (2018) where the authors find that lenses with a mass as low as 30 M⊙ could be detected with current experiments. They also consider future, higher-sensitivity experiments and show how they can push the limit to even smaller masses of order 1 M⊙. These conclusions are, however, obtained assuming isolated microlenses and without accounting for the effect of the macromodel, or other nearby microlenses. In the small mass regime, microlenses such as neutron stars have been also considered as scattering sources of GWs, and it is found that a GW can be focussed at a focal point near the neutron star surface (Halder et al. 2019; Stratton & Dolan 2019).
Citation: Broadhurst et al. 2019
Citation function: Background
Citation: Broadhurst et al. 2019
Citation function: Background
‘Blind’ searches through H i surveys performed by large aperture single-dish telescopes provide chances to uncover more H i absorption systems. Although such surveys usually utilize the non-tracking, drift scan observing strategy, with integration time for each individual source is limited, the collecting areas of the participating telescopes can still achieve considerable sensitivities. Allison, Sadler & Meekin (2014) identified four H i absorbers, including one previously unknown source, with the archival data of the H i Parkes All-Sky Survey (H i PASS; see Barnes et al. 2001), while Darling et al. (2011), Wu et al. (2015), as well as Song et al. (in preparation) have made attempts to perform ‘blind’ searches for absorption features using part of Arecibo Legacy Fast Arecibo L-Band Feed Array (ALFA) Survey (ALFALFA; see Giovanelli et al. 2005; Haynes et al. 2018) data, respectively, with 10 sources identified in total, including 3 samples remained undetected by other instruments so far, i.e., UGC 00613, CGCG 049-033, and PGC 070403, thus proving the feasibility of searching for new H i absorbers with massive blind sky surveys. Compared with radio interferometers, large single-dish telescopes such as Arecibo can provide better sensitivities and usually higher spectral resolution, which are all crucial to reveal the characteristics of extragalactic H i lines. And although the spatial resolution for such instruments are quite limited compared with interferometers, the chance of having two or more H i absorbing systems lying within the beamwidth with similar redshift is quite low, thus making confusions in source identification unlikely to happen. However, it should be noted that due to temporal variations in spectral baseline commonly seen during drift scans, follow-up observations are needed for reliable characterization of the newly identified absorbers, especially for the weak ones. Also, interferometric mappings are usually required to discern possible fine structures within each absorbing system.
Citation: Barnes et al. 2001
Citation function: Background
Observation of amino acids and their most essential isomers and potential precursors in the interstellar medium (ISM) should be crucial for revealing the chemistry that may have led to life's origin (Ehrenfreund et al. 2001). In particular, the central question of whether glycine (CH2(NH2)C(O)OH) exists or not in the ISM is one of the most pursued targets in astrochemistry. Although several attempts to observe glycine have been reported (Hollis et al. 2003; Cunningham et al. 2007; Jones et al. 2007; Jiménez-Serra et al. 2016, 2020), its detection has never been confirmed (Snyder et al. 2005). Nevertheless, it has been found in the coma of comets 67P/Churyumov–Gerasimenko through in situ mass spectrometry (Altwegg et al. 2016). The presence of glycine in the volatile cometary material thus strongly suggests the existence of a process capable of generating amino acids in cold environments (Bizzocchi et al. 2020). Hence, as a prerequisite step for its astronomical identification, the rotational spectra of glycinamide (CH2 (NH2)C(O)NH2; Alonso et al. 2018; Kisiel et al. 2022) and aminoacetonitrile (CH2(NH2)CN; Kolesniková et al. 2017), which are relevant intermediates in the Strecker synthesis of glycine; hydantoin (CH2C(O)NHC(O)NH; Alonso et al. 2017) and hydantoic acid (C(O)OHCH2NHC(O)NH2; Kolesniková et al. 2019), potential glycine precursors through a different hydrolytic pathway (Ozeki et al. 2017), and the glycine isomer glycolamide (CH2(OH)C(O)NH2); Sanz-Novo et al. 2020) have been recently reported. In addition, Sanz-Novo et al. (2019) very recently carried out a computational study of the potential energy surfaces (PES) corresponding to the formation reactions of several protonated glycine isomers. Surprisingly, the only exothermic process with no net activation barrier led to protonated acetohydroxamic acid [CH3C(O)NH2OH]+. Its formation could therefore be feasible under interstellar conditions. Consequently, the corresponding neutral counterpart, CH3C(O)NHOH, might be a candidate molecule to be searched for in the ISM. Our previous simulations (Sanz-Novo et al. 2019) suggest that this glycine isomer should be searched for in the ISM, eventually, but there is no experimental rotational data available for this molecular system.
Citation: Snyder et al. 2005
Citation function: Motivation; Motivation
Diffusive shock acceleration (DSA), a process entering the category of first-order Fermi acceleration, is the process by which astrophysical shocks accelerate charged particles to relativistic speeds. DSA requires the magnetic field near the shock front to reflect the particle, leading to repeated shock-crossings with the particle gaining energy at each crossing (e.g., Bell 1978; Blandford & Ostriker 1978; Drury 1983). DSA is a self-sustaining process because the presence of high-energy particles triggers instabilities in the magnetic field, which in turn allow the magnetic field to reflect the particles more efficiently (e.g., Bell 1978, 2004). DSA has been explored numerically using the particle-in-cell (PIC) method, as well as the PIC-hybrid method, whereby the ions are treated as particles and the electrons as a fluid. Simulations of this type seem to indicate that although this process is effective in the case of (quasi-)parallel shocks where the magnetic field is aligned with the direction of motion, it becomes ineffective once the angle between the magnetic field and the shock exceeds approximately 50° (Caprioli & Spitkovsky 2014a,2014b, 2014c).
4


4
Notice that most of the studies on DSA including the present one assume shocks are propagating into a homogeneous medium; effects of a nonmonotonous shock are discussed in Hanusch et al. (2019). Most simulations also assume that the pre-shock medium is fully ionized. Simulations for a partially ionized medium (Ohira 2013, 2016) show an increased injection rate, allowing for DSA even in oblique shocks. Also, studies by Kumar & Reville (2021) demonstrate that DSA can be triggered by the shock emitted waves at highly oblique shocks. However, different results were obtained by van Marle et al. (2018), using a combined PIC-MHD approach. This method, which treats the thermal gas as a fluid but nonthermal ions as individual particles, showed that, given a sufficient injection rate, even for magnetic obliquity up to 70°, shocks can accelerate particles through the DSA process. Several factors were believed to contribute to this discrepancy between PIC-MHD and PIC or PIC-hybrid methods:1.Time-period covered by the simulation. The DSA occurring in PIC-MHD simulations is only effective after more than 200 ion-gyrotimes (



ωci−1

) and it takes more than 500 ion-gyrotimes to fully develop whereas published hybrid simulations where limited to scales of the order of 200 ion-gyrotimes. Notice that at the time ∼200 



ωci−1

 both PIC-hybrid and PIC-MHD simulations find similar results, namely that particles are accelerated by the shock-drift acceleration (SDA).2.Effective number of particles per cell. DSA requires an upstream current of CRs in order to develop. Because only a small fraction of the particles that cross the shock is reflected, a large particle population is required to produce sufficient nonthermal particles in the upstream medium.3.Simulation box size. van Marle et al. (2018) showed that the relevant upstream instabilities operate on long wavelengths, larger than the box size of hybrid simulations.
Citation: Caprioli & Spitkovsky 2014a
Citation function: Compare/Contrast
Galactic fountains or infall are the possible origins for the ECs in this sample. Both scenarios present possible explanations and restrictions. The accretion of low metallicity gas from the intergalactic medium may occur through filamentary structures with the gas cooling into clouds (Fernández et al. 2012). Subsequently HVCs may be destroyed or fragmented into smaller clouds by drag forces from the halo and phenomena such as Rayleigh-Taylor and Kelvin-Helmholtz instabilities. Star formation can be triggered by these interactions, within clouds that reach sufficient density (Figs. 9 and 10). However, there is evidence that star formation is possible only within dark-matter encapsulated HVCs such as the Smith Cloud (Smith 1963; Heitsch & Putman 2009; Nichols & Bland-Hawthorn 2009; Joung et al. 2012). Christodoulou et al. (1997) argue that without dark matter, HVCs are unable to reach the mass required to collapse. On the other hand, C 932, C 934, and C 939 are located right above the Local spiral arm (Fig. 11), which would be consistent with the chimney scenario. Schlafly et al. (2015) mapped various bubble-like structures vertically along the range 0.3 to 2.8 kpc, which form the Orion superbubble. The expansion of these substructures powered by massive stellar winds and supernovae triggers star formation in various shells and rings, inputting energy to the superbubble (Lee & Chen 2009). The star formation engine in the Galactic fountain may work in a similar way to the infall scenario, through the interaction of a cloud with the surrounding halo environment. However, high-latitude clusters in this study are located at distances from the disc larger than has been expected for a chimney-like event in recent studies (Melioli et al. 2009). Regardless of the scenario, a possible cloud-cloud interaction may be leading the clouds analysed in Fig. 9 to collapse and triggering not only star formation, but also cluster formation. However, the timescale for cloud-cloud collision in a cloud complex appears to be larger than 1 Gyr (Christodoulou et al. 1997). Therefore, additional studies are required to check the presence of dark-matter in HVCs, estimate the cloud-cloud interaction timescales, and provide more insight into the effect of the halo environment on the HVCs and chimney-like events. That is beyond the purpose of this study.
Citation: Smith 1963
Citation function: Compare/Contrast
As Advanced LIGO and Virgo will upgrade while additional interferometers (KAGRA and LIGO-India) come online in the future, the detection horizon would be several hundred megaparsecs for BNS and BH–NS mergers with the localization accuracy reaching ∼10 deg2 for a network of these 2nd generation GW detectors (Abbott et al. 2018). In contrast, higher localization accuracy would be obtained by networking of 3rd generation GW detectors (Zhao & Wen 2018; Chan et al.2018; Hall & Evans 2019; Maggiore et al. 2020). In these regimes, present and future wide-field-of-view survey projects will be able to cover the sky localization given by GW detections in a few pointings and achieve deep detection depths with relatively short exposure integration times. The detection of GW170817/AT 2017gfo was made in an i-band filter and subsequently confirmed by larger telescopes (Coulter et al. 2017). Similar to this case, we assume that one can use only one filter to make follow-up searches after GW triggers. With quick response times of follow-up observations after GW events, we also assume that the survey telescopes would not miss the peaks of kilonovae in each band. Therefore, by assuming that all GW detectors in each era can operate normally (i.e., the most optimal situation for detector networks of different generations), the detection rates for target-of-opportunity observations for a given X-band limiting magnitude mX,limit can be expressed as
15








N







X


=


∫


0




z


max











ρ










m


X
,
limit




(
z
)


1
+
z






dV
(
z
)


dz



dz
,


where 






z


max




 is the maximum detectable distance and 








ρ










m


X
,
limit




(
z
)


 represents the cosmological event rate densities of the BH–NS mergers that can be triggered by GW detectors and be detected by telescopes in band X. Here, the astronomical magnitude system we adopted is the AB magnitude system, i.e.,






m


ν


=
−
2.5
log
(


F


ν



/

3631

Jy
)


.
Citation: Hall & Evans 2019
Citation function: Compare/Contrast