adsabs/FOCAL huggingface dataset:
The kinetic energy stored in the CO shell can be estimated as $E_{\rm kin} = 0.5\, M_{\rm shell}\, V^2_{\rm exp}$, where Vexp is the expansion velocity of the shell and Mshell is the total (molecular, atomic, and ionized) shell mass. Adopting an expansion velocity equal to half the velocity interval where the structure is observed, Vexp = 7.0 ± 1.3 km s− 1 , the molecular mass given in Table 1 and the atomic and ionized masses estimated by Cichowolski et al. (2001), 1450 and 3000 M⊙, respectively, we obtain Ekin = (2.5 ± 1.0) × 1049 erg, assuming a 40 per cent error for the masses.. Although Cichowolski et al. (2001) concluded that WR 130 could have alone created the observed structure, it is important to note that they did not take into account the molecular mass present in the shell, which considerably increases the kinetic shell energy. Thus, we can compare now the new value obtained for Ekin with the mechanical energy deposited in the ISM by the wind of the WR star, Ew = (0.7–2.2) × 1050 erg (Cichowolski et al. 2001). We obtain ϵ = Ekin/Ew = 0.007–0.5. The ratio ϵ measures the energy conversion efficiency in the shell, and according to evolutionary models ϵ ≤ 0.2 (Koo & McKee 1992). Thus, not all the possible values of ϵ are compatible with the scenario where the energy injected during the WR phase is enough to create the structure. In this case, the contribution of the energy injected during the O-star phase and/or other massive stars, should be considered. As mentioned in the Introduction, WR 130 is a WNH star, and according to Smith & Conti (2008) its age would be of about 2–3 Myr and its initial mass of at least 60 M⊙. A rough estimation of the energy injected by such a star during its main sequence yields Ew = (2.5–3.5) × 1050 erg (de Jager, Nieuwenhuijzen & van der Hucht 1988), which would be enough to create the observed structure. We have nevertheless looked for the presence of other massive stars in the region. We queried the available catalogues such as the Galactic O-Star Catalog (Maíz Apellániz et al. 2013), the Early-Type Emission-Line Stars Catalogue (Wackerling 1970), the Catalogue of Be stars (Jaschek & Egret 1982), the H-alpha Stars in the Northern Milky Way Catalogue (Kohoutek & Wehmeyer 1997), and the Catalog of Galactic OB Stars (Reed 2003), for early-type and emission stars. No stars were found in any catalogue. The only massive star located nearby is, as mentioned by Cichowolski et al. (2001), an OB star, which has an uncertain spectral type and no distance estimate (Stock, Nassau & Stephenson 1960). It is located in projection not in the centre of the structure but on to the shell (there is a second OB star mentioned by Cichowolski et al. 2001 but its location is actually outside the structure, see fig. 1 of Cichowolski et al. 2001). Although we cannot completely rule out the possibility that the OB star may be playing a role in creating the shell structure, we think that the action of WR 130 is sufficient and most likely dominant in the region.
Citation: Cichowolski et al. (2001)
Citation function: Background; Background
We introduce our target object, MC27/L1521F (e.g., Mizuno et al. 1994; Onishi et al. 1996, 1998, 1999, 2002; Codella et al. 1997), which is one of the densest cores among nearby low-mass star-forming regions, and it contains a very low-luminosity (Lint  0.07 L⊙) protostar (Bourke et al. 2006; Terebey et al. 2009). Earlier studies based on single-dish observations showed both the gas temperature derived from molecular line observations (e.g., Codella et al. 1997; Tatematsu et al. 2004) and the dust temperature obtained from multiband dust continuum observations (e.g., Kirk et al. 2007; Sadavoy et al. 2018) are as cold as ∼10 K, indicating that most of the gas and dust contents at the line of site are in the cold environment. The high-deuterium fractionation estimated by the N2D+/N2H+ ratio also supported the cold and evolved nature of the core (Crapsi et al. 2004, 2005). On the other hand, submillimeter single-dish observations detected CO (J = 6–5, 7–6) lines, which trace the warm (∼30–70 K) and dense (∼105 cm−3) component at the center of the core (Shinnaga et al. 2009). Although the filling factor of this warm gas relative to the entire core is quite small, these facts demonstrated that multiple temperature mediums are coexisting within the core. Tokuda et al. (2014) (hereafter, Paper I), and Tokuda et al. (2016; hereafter, Paper II) observed this core with ALMA and demonstrated the dynamical nature in this system. We found a few starless high-density cores, one of which has a very high density of ∼107 cm−3 (MMS-2), within a region of several hundred astronomical units around a very low-luminosity protostar (MMS-1) detected by Spitzer (Bourke et al. 2006; Terebey et al. 2009). The molecular line observation showed several cores with arc-like structures, possibly due to the dynamical gas interaction. Similar arc-like structures have also been reproduced by hydrodynamical simulations both with and without a magnetic field (Matsumoto et al. 2015b, 2017), including the different mechanisms. These complex velocity/spatial structures indicate that in MC27/L1521F the turbulence may play an essential role in undergoing fragmentation in the central part of the cloud core, which is different from the classic scenarios of fragmentation in massive disks (Larson 1978; Boss 2002; Machida et al. 2008). More recently, Tokuda et al. (2017; hereafter, Paper III) found that the central very low-luminosity protostar has a dynamical mass of ∼0.2 M⊙ and the associated disk is extremely compact with the disk radius of ∼10 au with an indication of detachment nature from the surrounding dense environment. Paper III mainly focused on gas/dust distributions of the central protostar (MMS-1) seen in the 0.87 mm continuum and 12CO (J = 3–2) observations to determine its evolutionary stage. In this paper, we investigate the properties of the surrounding gas around the central protostar to better understand the dynamical nature of this system by using the high-resolution (∼02) 12CO (J = 3–2) observations as well as 13CO (J =2–1) and C18O (J = 2–1) observations with a moderate angular resolution, ∼1″.
Citation: Crapsi et al.; 2005
Citation function: Motivation
Figure 9 demonstrates that the environment plays an important role in shaping the buildup of the passive population. The mild redshift dependence in the field ratios suggests that newly quenched galaxies are being added in both the bright end and the faint end of the population at similar fractions. Indeed, the number density of the bright and faint galaxies in the field have both grown by a factor of ∼4 from the highest redshift bin (z ∼ 1.15) to the lowest redshift bin (z ∼ 0.15). Note that the split magnitude between the bright and faint galaxies (





) roughly corresponds to 





.24

24
This M/L conversion is derived using a range of SSP models, assuming zf = 0.5−4.0 and Z = Z⊙.
 The mild redshift dependence in the field ratios is therefore consistent with previous studies on the stellar mass function of passive galaxies in the field, which have seen significant growth in both the high-mass end and low-mass end from z ∼ 1 to z ∼ 0 (e.g., Muzzin et al. 2013b; Tomczak et al. 2014). The growth is commonly attributed to various mass-quenching processes internal to the galaxies, such as energetic feedback from supernovae and stellar winds for low-mass galaxies (e.g., Dekel & Silk 1986; Hopkins et al. 2014) and ejective feedback from AGNs for more massive galaxies (e.g., Bower et al. 2006; Terrazas et al. 2016). Given that the field ratios do not evolve strongly with redshift, it is evident that the strong redshift dependence of the cluster ratios is a result of the high-density environment and that preferentially low (or moderate) mass galaxies are quenched by the environment. Additionally, the difference between the cluster and field ratios suggests that the quenching effects induced by the environment are clearer at low redshifts. This is consistent with the mostly mass-independent environmental quenching scenario established at low redshift (e.g., Peng et al. 2010). Because the LF of star-forming galaxies is steeper at the faint end, a population of environmentally quenched galaxies would have a relatively high faint-to-luminous ratio. Recent studies of infalling galaxies in local groups and clusters have demonstrated that the ram pressure stripping of the cold gas in the galaxies when it passes through the ICM is the dominant mechanism (e.g., Boselli et al. 2016; Fillingham et al. 2016; Fossati et al. 2018), although strangulation may also play a significant role (for galaxies with 





; see, e.g., Fillingham et al. 2015; Peng et al. 2015).
Citation: Tomczak et al. 2014
Citation function: Similarities
Specific examples of IR/maser flare correlations include the 22-GHz H2O and 6.7-GHz methanol masers associated with the ucH ii region G025.65+1.05 (Stecklum et al. 2017; Sobolev et al. 2019). The H2O maser variability in this object may be correlated with IR K-band variability in a source approximately 1500 au from the maser position (Sobolev et al. 2019). To be precise, the H2O emission appears to exhibit an anticorrelation, with bright 22-GHz episodes corresponding to times of low K band (most observations centred on 2.20 μm wavelength) flux density. This is to be expected for typical 22-GHz masers in star-forming regions, where computational models, for example Gray et al. (2016), show that strong IR emission from dust tends to destroy the 22-GHz inversion, probably by inhibiting the loss of population from the lower maser level (Strelnitskii 1981; Sobolev & Gray 2012). The 6.7-GHz methanol masers in this source have been described as showing a moderate flux rise at the time of a 22-GHz H2O maser flare (Sugiyama et al. 2017). A radiative mechanism is not the only explanation for H2O flaring in G025.65+1.05. VLBI observations identify the flaring object with a single compact spot of maser emission (Burns et al. 2020). An image from spectral channels in the blue-shifted wing of this spot shows a double structure, leading to an interpretation as a possible line-of-sight overlap of two masing objects. Preliminary modelling results for spatial overlap (Gray 2018) indicate that this mechanism can produce flares of significantly higher variability index than is typical of radiative pumping mechanisms, and the overlap interpretation therefore becomes more likely if the source is at the further of the two possible distances (2.7 and 12.5 kpc) mentioned in Burns et al. (2020). Another possible example of this overlap mechanism is a very high brightness H2O flare from Orion KL (Shimoikura et al. 2005). The 22-GHz maser emission of G025.65+1.05 has been monitored by a combination of the Simeiz, Torun, and Hartebeesthoek telescopes since 2000 (Vol’vach et al. 2019). Observations were approximately monthly for early data, but on an almost daily basis since a giant flare in 2017–2018. During the period 2000–2019, it has flared strongly (peak flux density >2000 Jy) three times: the peak flux density of each flare shows an increasing trend, while the flare duration and inter-flare interval have decreased. The shortest, brightest, and most recent flare (2017–2018) showed a double-peaked light curve, with rising sections well approximated by exponentials with characteristic times of approximately 10 d. The exponential shape, backed by evidence from polarization and spectral width, has led Vol’vach et al. (2019) to conclude that the flaring maser is unsaturated. The continuum flux at 870 μm has generally been rising towards G025.65+1.05 since 2008, but the data are very sparse compared to the maser observations, including an interval of 8 yr with no data (Vol’vach et al. 2019).
Citation: Sugiyama et al. 2017
Citation function: Background
With the introduction of the first integral-field spectrographs (IFS, see e.g. Bacon et al. 1995), it became feasible to perform such observations in a spatially resolved manner and for larger samples of galaxies. The SAURON survey (Bacon et al. 2001; de Zeeuw et al. 2002) was one of the first projects to make extensive use of this technology. Based on their representative sample of 72 nearby early-type galaxies, the project investigated stellar and gaseous kinematics (Emsellem et al. 2004; Sarzi et al. 2006; Falcón-Barroso et al. 2006; Ganda et al. 2006) and stellar population properties (Peletier et al. 2007; Kuntschner et al. 2010), and distinguished between fast and slow rotating early-type galaxies (Emsellem et al. 2007). Subsequently, the ATLAS3D project (Cappellari et al. 2011) continued this endeavour by further investigating kinematic properties, for instance the global specific angular momentum (Emsellem et al. 2011), based on a volume complete sample of 260 early-type galaxies. The CALIFA survey (Sánchez et al. 2012) advanced these previous studies towards a morphologically unbiased sample of 667 galaxies. In addition, it provides a unique combination of a large spatial coverage of a few effective radii and high spatial sampling (see also García-Benito et al. 2015). Other surveys observe even larger samples: while the SAMI survey (Croom et al. 2012; Bryant et al. 2015) includes ∼3000 galaxies across different environments, MaNGA (Bundy et al. 2015) will contain approximately 10 000 nearby galaxies. Most recently, these projects are being complemented by IFS studies of local galaxies in unprecedented spatial resolution (e.g. MUSE, Bacon et al. 2010). For instance, the TIMER project (Gadotti et al. 2019) analyses the central structures of 24 barred local disc galaxies in order to study the formation histories of these structures and infer constraints on the related secular evolution processes. Fornax3D (Sarzi et al. 2018; Iodice et al. 2019) investigates mostly early-type galaxies in the Fornax cluster environment, spatially covering galaxies up to four effective radii. The PHANGS survey (Leroy et al., in prep.)1 aims to connect the physics of gas and star formation with the large-scale galactic structure by complementing IFS data from MUSE with interferometric data from ALMA.
Citation: Emsellem et al. 2007
Citation function: Background; Background
A large 





 survey in nearby spiral galaxies and (U)LIRGs performed by Gao & Solomon (2004a, 2004b) revealed a tight linear correlation between the infrared (IR) and the HCN luminosities for normal star-forming galaxies and starbursts. This linearity seemingly extends down to the scale of Galactic massive cores in the Milky Way and holds over a total range of luminosity of about eight orders of magnitude (Wu et al. 2005). These results imply that the dense molecular gas (i.e., 





) as traced by the 





 line, rather than the total molecular gas, is the direct fuel for star formation. High-resolution simulation of dense clouds found that the HCN luminosity is related to mass of dense gas of ≳104 cm−3 (Onus et al. 2018). In addition, Spitzer studies of Galactic molecular clouds also show evidence that star formation is restricted to the dense cores of GMCs (e.g., Evans 2008; Lada et al. 2010). The critical density ncrit40

40
The critical density of rotational level j is defined as 





, where 





 is the Einstein coefficient for spontaneous emission, 





 in units of s−1, and 





 is the collision rate coefficient that depends on the gas temperature, in units of cm3 s−1. All critical densities in this work are calculated on the assumption of Tkin = 100 K and optically thin conditions. The critical densities will decrease if the lines are optically thick.
 of rotational transitions is proportional to μ2ν3 (for optically thin lines at frequency ν; μ is the dipole moment of the molecule); therefore, molecules with high dipole moment are expected to trace high-density molecular gas (e.g., μHCN ∼ 2.98 D, 





 D, and μCS ∼ 1.96 D vs. μCO ∼ 0.11 D; see Schöier et al. 2005). Subsequently, a number of studies have explored the link between molecular lines of dense gas (e.g., HCN, HCO+, and CS) and IR luminosities in different populations of galaxies (e.g., Gao et al. 2007; Papadopoulos 2007; Baan et al. 2008; Liu & Gao 2010; Wu et al. 2010; Wang et al. 2011; García-Burillo et al. 2012; Zhang et al. 2014; Chen et al. 2015; Usero et al. 2015; Liu et al. 2016).
Citation: Lada et al. 2010
Citation function: Uses
From the excitation maps as shown in Fig. 9, we determine the maximum distance of AGN-ionized regions (RENLR, max) with respect to the AGN location that we can cover with our depth and area. To suppress the impact of noise on misclassification close to the borders of the demarcation lines, we require that at least six surrounding unbinned spaxels share the same AGN-ionization classification or the classification is present in the spatially binned data with its intrinsically higher S/N. We need to exclude the LINER and the intermediate BPT regions, because those are not necessarily associated with AGN photoionization and can originate from post-AGN stars (e.g., Binette et al. 1994; Singh et al. 2013), shocked gas from stellar winds (e.g., Ho et al. 2016; López-Cobá et al. 2019), or the diffuse ionized gas inbetween star forming regions (e.g., Lacerda et al. 2018; Levy et al. 2019). We define the maximum ENLR size, RENLR, max, as the maximum projected distance of a robust AGN region to the AGN location detectable within the IFU FoV at the observational depth. In general, the maximum ENLR extent can be biased due to surface brightness dimming and observational depth. This is not a concern for the large FoV of MUSE and the narrow redshift distribution of the CARS sample. Nevertheless, we also determine two additional ENLR radii, RENLR, 15 and RENLR, 16, corresponding to the ENLR size out to a surface brightness limit of Σ15 = 10−15 erg s−1cm−2 arcsec−2(1 + z)−4 (e.g Liu et al. 2013b, 2014; Hainline et al. 2013, 2014), or Σ16 = 10−16 erg s−1cm−2 arcsec−2(1 + z)−4 (Chen et al. 2019b), respectively. All these measurements are listed in Table 5. The ENLR size can become unresolved for the CARS targets, in particular, at high intrinsic ENLR surface brightnesses. For such nondetections we set the upper limits for the ENLR size to be the angular size of the binned spaxels. The error on the sizes are generally driven by the spatial resolution of a given observations, so that we assume the error on all sizes to be the FWHM of seeing for each observation as reported in Table 2.
Citation: Levy et al. 2019
Citation function: Uses; Uses
The general form of the velocity-dependent cross-section is given by $\bar{\sigma }=\sigma _0 (v/c)^n$, where the index n depends on different physical DM processes and c is the velocity of light in space (in natural unit $\bar{\sigma }=\sigma _0 v^n$). In the case of DM with magnetic and/or electric dipole moment, n = +2, −2 are considered. n = 2, 1, 0, −1 are applicable for scattering in presence of Yukawa potential (Buckley & Fox 2010), n = −4 is attributed for millicharged DM (Holdom 1986; Chun, Park & Scopel 2011). In Ref. Dvorkin, Lin & Schutz (2021), the nature of the DM–baryon cross-section is discussed for a wide mass range of DM. Similar investigations are also carried out in Ref. Nadler et al. (2019), Bhoonah et al. (2018), Kovetz et al. (2018), and Mack, Beacom & Bertone (2007). In this work, the DM–baryon interaction cross-section ($\bar{\sigma }$) is parametrized as $\bar{\sigma }=\sigma _0 v^{-4}$ (Muñoz, Kovetz & Ali-Haïmoud 2015; Barkana 2018; Mukhopadhyay et al. 2021). The term σ0 is the DM scalar scattering cross-section with baryons (of the type $\alpha _q \bar{\chi }\chi \bar{q}q$ for dark DM particle χ with coupling αq). It may be mentioned in some earlier works like Bhoonah et al. (2018) and Kovetz et al. (2018), where millicharged DM is considered. But here, we assume a particle DM candidate and adopt value of $\sigma _0 \sim 10^{-41}\,\rm {cm^2}$ consistent with the scalar cross-section bound obtained from ongoing direct DM search experiments [extrapolating the allowed region for 0.1 GeV ≤mχ ≤ 3 GeV from recent experiments like Aprile et al. (2018), Akerib et al. (2017), and Cui et al. (2017)] in the mass range discussed in this work. Several recent investigations on EDGES 21-cm signal also suggest the similar velocity dependence (n = −4) of the cross-section like Muñoz et al. (2015), Mahdawi & Farrar (2018), and Barkana (2018). Moreover, n = −4 is chosen in many DM-related cases, namely, hadronically interacting DM, millicharge DM, the baryon acoustic oscillations (BAO) signal, etc.
Citation: Holdom 1986
Citation function: Uses
The required stellar population mass of ≳104 M⊙ represents a hard limit for the detection of direct star light from z ≳ 7 Pop III star clusters at magnification μ ∼ 1000 in the foreseeable future. As discussed in Section 1, large numbers of Pop III stars can form in atomic cooling haloes that manage to remain chemically pristine, a scenario that likely requires a background Lyman–Werner (LW) radiation field that suppresses molecular hydrogen (H2) formation and, consequently, Pop III star formation in minihaloes. This scenario has been explored predominantly in the context of supermassive star and direct collapse black hole (Bromm & Loeb 2003; Haiman 2013) formation in regions of the Universe with an LW radiation field high enough above the cosmic mean to entirely suppress H2 formation. It thought the onset of efficient H2 cooling is required for star cluster, rather than supermassive star, formation (Regan & Haehnelt 2009), requiring a UV background intensity below J21 ∼ 103 for H2 to form in sufficient abundance but above J21 ∼ 10 to suppress star formation in minihaloes (here, J21 denotes the radiation intensity at the Lyman-limit in units of 10−21 erg s−1 cm−1 Hz−1 sr−1). Explicitly focusing on Pop III star cluster formation, Safranek-Shrader et al. (2012) argued that total stellar masses of 104 M⊙ may be achievable given a low enough LW background intensity, though unaccounted for internal LW feedback may be significant in reducing the star formation efficiency. The inclusion of ionizing radiation further increases the propensity for Pop III galaxies with total stellar masses ≳104 M⊙ (Johnson et al. 2014). Related studies (Regan & Haehnelt 2009; Shang, Bryan & Haiman 2010; Latif et al. 2014; Regan, Johansson & Wise 2014; Visbal, Haiman & Bryan 2014) have routinely found central gravitationally unstable clumps with masses in excess of 104−5 M⊙ and central accretion rates of 0.01–1 M⊙ yr−1 to form in chemically pristine, high-redshift atomic cooling haloes. The results of these studies additionally suggest that fragmentation, if it does occur, happens on small scales (≲1–10 pc) favouring the formation of a compact Pop III stellar cluster. While the limit of ≳104 M⊙ adopted in this work seems marginally achievable for the total stellar mass of a Pop III galaxy, additional cosmological simulations are needed that focus on the possibility and characteristics of a metal-free stellar cluster forming in an atomic cooling halo.
Citation: Haiman 2013
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