adsabs/FOCAL huggingface dataset:
The difference in the early-type fractions of star-forming and quenched satellites may be taken to indicate that quenching is associated with structural changes in the galaxies, that is, changes affecting their underlying mass distribution, such as substantial growth of stellar mass in the bulge (or inner disk) components. It is well established that quenched galaxies have radial surface brightness profiles that are steeper than those of star-forming galaxies and are well described by high Sérsic indices (e.g., Kormendy et al. 2009 and references therein), reflecting high central mass densities (e.g., Fang et al. 2013 and references therein). Also, since the pioneering work of Mihos & Hernquist (1994), inward flows of gaseous material have long been recognized to take place during galaxy mergers and through disk instabilities. Such inward gas flows are likely to contribute to the growth of stellar mass in galactic bulges (see, e.g., Courteau et al. 1996; MacArthur et al. 2003; Immeli et al. 2004; our own work, i.e., Carollo et al. 1997, 1998, 2001, 2007 and Carollo 1999, 2004; the comprehensive review by Kormendy & Kennicutt 2004 and references therein; Bournaud et al. 2011, and many others). This idea has been further developed in more recent theoretical studies (e.g., Dekel & Burkert 2014) and is suggested to be observed at high redshifts (e.g., Genzel et al. 2006; Cameron et al. 2011) and, at least for low-mass bulges, certainly observed in the local universe, where small bulges show signs of “rejuvenation” of their stellar populations, with up to 10%–30% of their total mass consistent with having formed in the past few gigayears (Thomas & Davies 2006; Carollo et al. 2007). If mergers and disk instabilities were directly or indirectly connected with galactic quenching, it would not be implausible to draw a connection between quenching and the growth of bulges. Establishing the direction of causality in any such change would remain, however, very difficult. Quenching could be directly linked to the growth of the bulge (e.g., Martig et al. 2013; Genzel et al. 2014), or the quenching process itself could be associated with bulge growth, or the prominence of the bulge could be linked to a third property (e.g., galactic mass or the presence of an AGN) that itself controls the quenching of star formation.
Citation: Carollo et al. 1997
Citation function: Background
Large-scale molecular outflows are also commonly associated with the earliest stages in the formation of massive (B- and O-type) stars. However, bipolar outflows observed in high-mass star-forming regions tend to be less collimated than those observed in low-mass regions (e.g., Arce et al. 2007). Recent radio observations have established that very young massive protostars are also commonly associated with compact free–free emission, being the signpost of mass ejected near the protostar (e.g., Moscadelli et al. 2016; Purser et al. 2016, 2021; Rosero et al. 2016, 2019; Sanna et al. 2018; Obonyo et al. 2019). However, it is not yet clear whether this emission traces the bases of jets as well collimated as those observed in low-mass star-forming regions. To date, we know of only a handful of highly collimated jets from massive protostars extending over tens of thousands of au (e.g., Cep A HW 2: Curiel et al. 2006; HH 80–81: Rodríguez-Kamenetzky et al. 2017; IRAS 16547−4247: Rodríguez et al. 2005; G035.02+0.35: Sanna et al. 2019b; IRAS 16562−3959: Guzmán et al. 2010; G016.59−0.05: Moscadelli et al. 2019), and, although evidence exists for magnetic fields playing an important role in their collimation (e.g., Carrasco-González et al. 2010; Surcis et al. 2014; Sanna et al. 2015; Maud et al. 2019), it is not yet clear whether collimation takes place at small distances from massive protostars. One possibility is that different mechanisms could be at work to produce jets around massive protostars, as they are expected to accrete at higher rates from much larger, massive and turbulent disks than those around low-mass protostars (e.g., Carrasco-González et al. 2012; Sanna et al. 2019a; Añez-López et al. 2020). Under these conditions, it could be very difficult to form strong and well-structured helical magnetic fields capable of highly collimate jets at au scales. Indeed, wide-angle or even spherical winds are also commonly found in high-mass star-forming regions (e.g., Torrelles et al. 1997, 2001, 2011; Moscadelli et al. 2007). Interestingly, it has been proposed that initially poorly collimated winds could be externally collimated at large (≳10–100 au) distances from the protostar by strong ambient medium pressure (e.g., Carrasco-González et al. 2015) or by a large-scale ordered magnetic field (e.g., Albertazzi et al. 2014). Therefore, there is the possibility that mass ejection from massive protostars could be mostly isotropic at au scales, and, under favorable conditions, it might become collimated at larger distances from the driving source.
Citation: Rodríguez-Kamenetzky et al. 2017
Citation function: Motivation; Motivation
Since the expected number density of high-z massive quiescent galaxies is low, large fields with deep photometric coverage are required to identify these systems and reliably assess their SEDs. For this reason, we exploited the 2 deg2 COSMOS field. Sources with Ktot  22.5 were extracted from the catalogue of McCracken et al. (2010), limiting the selection to those satisfying the observed-frame BzK colour criterion for passive systems (Daddi et al. 2004). Targets formally classified as star-forming BzK (sBzK) with a signal-to-noise ratio S/N  5 in the B and z bands were retained since these photometric candidates are degenerate with quiescent galaxies becoming fainter in these bands with increasing redshift and decreasing mass. Photometric redshifts specifically calibrated for high-z QGs were derived with EAZY (Brammer et al. 2008) as in Onodera et al. (2012) and Strazzullo et al. (2015). This calibration was based on the sample of 34 spectroscopically confirmed passive galaxies at 1.3  zspec  2.1 observed with VLT/VIMOS that later appeared in Gobat et al. (2017) and the sample of 18 passive galaxies at 1.4  zspec  1.9 of Onodera et al. (2012) observed with Subaru/MOIRCS. The calibrated zphot were used to select galaxies within 2.5 ≤ zphot ≤ 3.5 and to remove objects with UVJ rest-frame colours inconsistent with passive evolution (Pozzetti & Mannucci 2000; Labbé et al. 2005; Williams et al. 2009). SED fitting was performed using FAST (Kriek et al. 2009), allowing for constant and delayed exponentially declining SFHs. Optical dust attenuation was left free to vary up to AV = 5 mag assuming a Calzetti et al. (2000) attenuation law. Fits were repeated by adopting purely quiescent templates only. All passive UVJ candidates whose SED fits to optical-NIR photometry could not reject dusty star-forming solutions at high confidence were further discarded. Contamination from dusty star-forming galaxies was further minimised by removing objects with Spitzer/MIPS 24 μm S/N ≥ 4 detections in the Le Floc’h et al. (2009) catalogue, except for galaxies with high-confidence passive SEDs, which are indicative of mid-infrared (MIR) emission caused by a central dusty AGN torus. This selection provided a total of 174 passive candidates with UVJ-quiescent colours (47 of which were pBzK in the original selection, plus 67 and 60 uncertain sBzK with and without significant MIPS detections, respectively). The maximum required magnitude to obtain HST/G141 spectra with sufficient S/N in order to secure spectroscopic confirmation within one to two orbits was assessed by simulating their grism spectra based on their best-fitting SED templates. This yielded a magnitude cut of HAB  22, which narrowed the sample down to 23 objects. A total of 10 galaxies were targeted for HST WFC3/IR G141 near-IR observations: 9 randomly drawn galaxies with HAB  22 (M⋆ > 1.1 × 1011 M⊙) plus 1 robust candidate with HAB = 22.9 (M⋆ = 8 × 1010 M⊙) selected to be the highest-z candidate based on its high-confidence passive SED. More details about the selection are available in Lustig et al. (2021).
Citation: Pozzetti & Mannucci 2000
Citation function: Background
Also as noted in Mason et al. (2008), He/O, and to a lesser degree Ne/O, ratios show a downward slope with respect to Fe/C. This cannot by explained by variations of solar wind composition between fast and slow streams. The relative abundances of C and O are similar between slow and fast wind, and since the Fe, He, and Ne are more abundant in the slow than the fast solar wind, this would lead to a positive correlation (von Steiger et al. 2000). However, it is possible that the variations along the power-law slopes are, at least partially, due to a solar cycle effect on the solar wind composition, with the He/O ratios and Ne/O ratios varying throughout the solar cycle (see Desai et al. 2006; Mason et al. 2008). In order to investigate solar cycle phase dependencies in the abundance ratios, the right column of Figure 3 illustrates the ratios by solar cycle phase. To define the phase, the smoothed sunspot number was normalized to the maximum for each solar cycle and broken up into times when the normalized sunspot number was less than 1/3 (solar minimum, blue triangles), greater than 2/3 (solar maximum, red diamonds), or in between (ascending/descending phase, green rectangles). As would be expected from the Fe/O ratio in Figure 1, all of the times the Fe/C ratios were greater than approximately 0.3 occurred during solar maximum. However, the ratios during solar minimum and the declining/ascending phase are very similar. While the solar maximum Fe/C ratios extend to much higher values than for CIRs during either solar minimum or the declining/ascending phases, some of the solar maximum CIRs are also observed to have Fe/C ratios well within the range of values observed for the other phases. This seems to suggest that the process(es) that is/are energizing Fe preferential to C can be more efficient during solar maximum, but the process(es) does/do not require all CIR-associated Fe/C ratios during solar maximum to be necessarily elevated above that during the other phases. An example of this is the Fe/O enhancement during the declining phase (Figure 1).
Citation: Desai et al. 2006
Citation function: Uses
The circumgalactic medium (CGM) is the interface between cold flows from the intergalactic medium on to a galaxy, and hosts hot halo gas and material ejected from galaxies (for reviews, see Putman, Peek & Joung 2012; Tumlinson, Peeples & Werk 2017). With various processes in galaxy evolution consuming (e.g. star formation) and removing (e.g. winds) gas, the CGM is shaped by the processes internal to the galaxy. Early progress in the study of the CGM came from connecting the absorption lines in quasar (QSO) spectra with galaxies imaged in the foreground, tracing the extent and properties of the CGM gas as a function of the host galaxy’s properties (e.g. Bergeron 1986; Bowen, Blades & Pettini 1995; Lanzetta et al. 1995; Adelberger et al. 2005; Chen et al. 2010; Steidel et al. 2010; Bordoloi et al. 2011; Prochaska et al. 2011; Turner et al. 2014). Building on these foundations, our understanding of the CGM has been significantly improved through the surveys with the Hubble Space Telescope (HST) Cosmic Origins Spectrograph (COS; Green et al. 2012). The first of several surveys of the CGM surrounding low-redshift galaxies was the COS-Halos survey (Tumlinson et al. 2013) which targetted the CGM around 44 ∼L⋆ galaxies, demonstrating that the properties of the CGM differ depending on whether the central galaxy is passive or star forming [defined using a specific star formation rate cut of specific star formation rate (sSFR) $\rm {=10^{-11} yr^{-1}}$; Tumlinson et al. 2011; Werk et al. 2013; Borthakur et al. 2016]. The COS-Halos team found a distinct lack of O vi around passive galaxies, while H i was found at the same strength around all galaxies (Tumlinson et al. 2011; Thom et al. 2012). Additionally, connections have been made between the CGM and properties of the host galaxy, including increased H i content of the CGM with larger interstellar medium (ISM) gas masses (COS-GASS; Borthakur et al. 2015), the presence of extended gas reservoirs around galaxies of all stellar mass (COS-Dwarfs; Bordoloi et al. 2014b), and enhanced metal content around starbursting hosts (COS-Burst; Borthakur et al. 2013; Heckman et al. 2017).
Citation: Steidel et al. 2010
Citation function: Background
DSFGs in the z > 5 tail are thought to be rare, but their level of rarity is subject to debate (e.g., Béthermin et al. 2015, 2017; Asboth et al. 2016; Ivison et al. 2016; see also Simpson et al. 2014, 2020; Dudzevičiūtė et al. 2020). A significant challenge in determining the space density of such sources is the difficulty in finding them in the first place. Given their distance, classical techniques combining optical and radio identifications have been largely unsuccessful due to the faintess or lack of detection at these wavelengths, commonly leading to misidentifications given the significant positional uncertainties of the classical sub/millimeter single-dish surveys in which they are the most easily seen (e.g., Chapman et al. 2005; Cowie et al. 2009, and references therein). Also, due to the strong negative K correction at sub/millimeter wavelengths (e.g., Blain et al. 2002), it remained challenging to pick out the most distant DSFGs among the much more numerous specimens at z  3.5. Over the past decade, many of these challenges were overcome through new observational capabilities and selection techniques, such as direct identifications based on interferometric observations of the dust continuum emission (e.g., Younger et al. 2007; Smolčić et al. 2012; Simpson et al. 2014, 2015; Brisbin et al. 2017; Stach et al. 2018; see also earlier works by, e.g., Downes et al. 1999; Dannerbauer et al. 2002), redshift identifications through targeted molecular line scans (e.g., Weiß et al. 2009; Riechers 2011), and target selection based on sub/millimeter colors or flux limits (e.g., Cox et al. 2011; Riechers et al. 2013, 2017; Dowell et al. 2014; Vieira et al. 2010; Weiß et al. 2013 ). Nevertheless, all of the current studies only provide incomplete censuses of the z > 5 DSFG population due to biases in the selection, limited sensitivity in the parent sub/millimeter surveys, and incomplete redshift confirmations of existing samples.
Citation: Chapman et al. 2005
Citation function: Compare/Contrast
PNe provide crucial information about the nucleosynthesis and chemical evolution of different elements. It is thought that PNe progenitors do not synthesize O and other α-elements as Ne, S, or Ar and, in principle, they can be considered as probes of the chemical composition of the ISM at the moment of the birth of the progenitors. Therefore, they can be used as tracers of the temporal evolution of the abundance gradients of the Galaxy. However, the recent results by Delgado-Inglada et al. (2015) indicate the production of O in C-rich PNe at near-solar metallicities that can increase the O/H ratio up to 0.3 dex. This result calls into question the suitability of O in PNe as tracer of the ISM composition. Other critical problems in the determination of the abundance gradients from PNe data is the large uncertainties in the distances of these objects (Frew, Parker & Bojičić 2016; Stanghellini & Haywood 2018; García-Rojas 2018; Peña & Flores-Durán 2019), the different range of ages of their progenitors and the radial migration along the lifetime of the progenitors. Most of the determinations of the Galactic O/H gradient based on data of young PNe – with ages between 1 and 4 Gyr – provide slopes which tend to be flatter than our value (Liu et al. 2004; Maciel, Costa & Cavichia 2015; Stanghellini & Haywood 2018; Peña & Flores-Durán 2019), with typical values in the range between −0.019 and −0.048 dex kpc−1 for RG between 0 and 16 kpc. This behaviour has led some authors to propose the steeping of the O gradient with time (e.g. Stanghellini & Haywood 2018). However, other authors as Henry et al. (2004) or Maciel & Costa (2013) claim that the time variation of the O/H gradient may be masked by the aforementioned uncertainties related to the abundance and gradient determination with PNe. As α-elements, Ne, S, and Ar should have abundance gradients similar to that of O/H, but as it has been discussed in Section 4.2, their value may be affected by the ICF scheme used. For Ne and Ar, Peña & Flores-Durán (2019) reported a slope of −0.026 ± 0.014 dex kpc−1 and −0.010 ± 0.006 dex kpc−1, respectively, for a sample of young PNe, which are flatter than our slopes for these elements in H ii regions. Henry et al. (2004) studied a large sample of PNe providing the radial gradients for the different elements studied here but for a sample of objects covering progenitors of a wide range of ages. Those authors reported values of the slope for the gradients of Ne, S, Cl, and Ar abundances fairly similar to ours, from −0.030 to −0.048 dex kpc−1. On the other hand, the results obtained by Stanghellini & Haywood (2018) for their compilation of PNe data from the literature show slopes of Ne and Ar which are somewhat flatter than ours, −0.018 to −0.030 dex kpc−1, respectively. As we can see, the comparison with available data from PNe does not give conclusive evidence of a time variation of the abundance gradients in the Milky Way.
Citation: García-Rojas 2018
Citation function: Background
The Chamaeleon I star-forming region, including CR Cha, was covered in Sectors 11 and 12 of the Transiting Exoplanet Survey Satellite (TESS, Ricker et al. 2015) in 2019. The observations started on 2019 April 22 and were completed on June 19, providing almost uninterrupted broadband optical photometric observations with a 30-min cadence. Details of the TESS data reduction and photometry can be found in Plachy et al. (2021) and Pál et al. (2020). We only summarize the main steps here. Photometry of the source was performed via differential image analysis using the ficonv and fiphot tools of the FITSH package (Pál 2012). This requires a reference frame, which we constructed as a median of 11 individual 64 × 64 subframes obtained close to the middle of the observing sequence. The convolution-based approach used here exploits all of the information in the images by minimizing the difference and simultaneously correct for the various temporal aberrations (e.g., differential velocity aberration, variations in the point spread function, PSF, and pointing jitter corrections). A more detailed description of these methods can be found in Plachy et al. (2021) or Pál et al. (2020). This method is therefore equivalent to an ensemble analysis and requires basically no further post-processing of the light curves such as cotrending or similar types of decorrelartion methods. The photometry process also requires a reference flux to correct for various instrumental and intrinsic differences between the target and the reference frames. For this, we used the median of our SMARTS I-band photometry (see below) taken over the same time period as the TESS data. We obtained aperture photometry in the TESS images using an aperture radius of 2 pixels and a sky annulus between 5 and 10 pixels (the pixel scale is about 20″). We note that we also inspected the most recent TESS observations, obtained between 2021 April 2 and June 24, and those data were reduced with the same procedure.
Citation: Pál 2012
Citation function: Uses
The second ingredient is the probability distribution of stellar mass at given SFR and redshift:
5



dpdlogM⋆(M⋆∣ψ,z)∝M⋆M⋆M⋆,MS(ψ,z)M⋆,MSexp−logM⋆−logM⋆,MSψ,z22σlogM⋆2M⋆≥M⋆,MS(ψ,z),

where M
⋆,MS(ψ, z) is the observed redshift-dependent galaxy main sequence with log-normal scatter 



σlogM⋆≈0.2

 dex (we adopt the determination by Speagle et al. 2014 for an anlytic fit, see their Equation (28)). The main sequence is a relationship between SFR and stellar mass followed by the majority of star-forming galaxies, apart from some outliers located above the average SFR at given stellar mass (see Daddi et al. 2007; Rodighiero et al. 2011, 2015; Sargent et al. 2012; Speagle et al. 2014; Whitaker et al. 2014; Schreiber et al. 2015; Caputi et al. 2017; Bisigello et al. 2018; Boogaard et al. 2018). The expression in Equation (5) holds for an approximately constant SFR history, which is indicated both by in situ galaxy formation scenarios (see Mancuso et al. 2016b; Pantoni et al. 2019; Lapi et al. 2020) and by observations of ETG progenitors (that have on overage slowly rising star formation history with typical duration of ≲1 Gyr; see Papovich et al. 2011; Smit et al. 2012; Moustakas et al. 2013; Steinhardt et al. 2014; Cassará et al. 2016; Citro et al. 2016) and late-type galaxies (that have on the average slowly declining star formation history over a long timescale of several gigayears; e.g., see Chiappini et al. 1997; Courteau et al. 2014; Pezzulli & Fraternali 2016; Grisoni et al. 2017). In this vein, off-main-sequence objects can be simply viewed as galaxies caught in an early evolutionary stage that are still accumulating their stellar mass (which grows almost linearly with time for a constant SFR), and are thus found to be preferentially located above the main sequence or, better, to the left of it. As time goes by and the stellar mass increases, the galaxy moves toward the average main-sequence relationship, around which it will spend most of its lifetime before being quenched due to gas exhaustion or feedback processes.
Citation: Lapi et al. 2020
Citation function: Uses
In this paper, we will use a SAD map of the Large Magellanic Cloud (LMC) to derive the DTD of RR Lyrae stars—pulsating horizontal branch stars with periods between 0.2 and 1 day (Smith 2004). We chose to test the DTD method on RR Lyrae for several reasons. First, the sample size of RR Lyrae in the LMC is quite large (see Section 2.1), allowing us to measure a DTD with high significance. Second, there is strong evidence that RR Lyrae are mostly ancient stars, older than 10 Gyr, given their pulsational properties (Smith 2004; Marconi et al. 2015) and abundance in old globular clusters (Clement et al. 2001; Soszyński et al. 2014, 2016). Measuring an RR Lyrae DTD therefore provides a rigorous test of the DTD method for the recovery of progenitor age distributions as well as measurements of the star formation history of old resolved stellar populations. Lastly, a DTD analysis provides an opportunity to test stellar evolution models of RR Lyrae in a completely new way. While there is consensus on the interpretation of RR Lyrae as ancient stars, the lower limit on their ages has been somewhat unconstrained. For example, the absence of RR Lyrae in the SMC cluster Lindsey 1 (




t
≈
9


 Gyr), compared to their presence in NGC 121 (




t

≈


 10–11 Gyr), is generally cited as evidence of a lower limit of 10 Gyr for the progenitor age of RR Lyrae (Olszewski et al. 1996; Glatt et al. 2008). However, growing evidence of thin-disk RR Lyrae in the Milky Way raises questions about whether this limit might be lower, and whether an intermediate-age progenitor channel can exist (Layden 1995; Zinn et al. 2019; Prudil et al. 2020). Additionally uncertainties may exist in the evolutionary models of RR Lyrae stars themselves: since RR Lyrae are horizontal branch stars, their positions on the color–magnitude diagram depend on an unknown combination of factors (commonly known as the second-parameter phenomenon) such as metallicity, age, mass loss on the red giant branch, stellar rotation, core structure, and chemical abundance (see Fusi Pecci & Bellazzini 1997; Catelan 2009; Dotter 2013, for reviews).
Citation: Clement et al. 2001
Citation function: Motivation; Motivation