adsabs/FOCAL huggingface dataset:
The Large Binocular Telescope (LBT) consists of two 8.4Â m aperture optical telescopes on a single ALT-AZ mount installed on Mount Graham in southeastern Arizona (at an elevation of 3192Â m) and operated by an international collaboration among institutions in the United States, Italy, and Germany (Hill et al. 2014; Veillet et al. 2014). Both telescopes are equipped with deformable secondary mirrors which are driven with the LBT's adaptive optics (AO) system to correct atmospheric turbulence at 1Â kHz (Esposito et al. 2010; Bailey et al. 2014). Each deformable mirror uses 672 actuators that routinely correct 400 modes and provide Strehl ratios exceeding 80%, 95%, and 99% at 1.6âÎ¼m, 3.8âÎ¼m, and 10âÎ¼m, respectively (Esposito et al. 2012; Skemer et al. 2014). The LBTI is an interferometric instrument designed to coherently combine the beams from the two 8.4Â m primary mirrors of the LBT for high-angular resolution imaging at infrared wavelengths (1.5â13âÎ¼m; Hinz et al. 2012). It is developed and operated by the University of Arizona and based on the heritage of the Bracewell Infrared Nulling Cryostat on the MMT Hinz et al. (2000). The overall LBTI system architecture and performance will be presented in full detail in a forthcoming publication (P. M. Hinz et al., in preparation). In brief, the LBTI consists of a universal beam combiner (UBC) located at the bent center Gregorian focal station and a cryogenic Nulling Infrared Camera (NIC). The UBC provides a combined focal plane for the two LBT apertures while the precise overlapping of the beams is done in the NIC cryostat. Nulling interferometry, a technique proposed 36Â yr ago to image extra-solar planets (Bracewell 1978), is used to suppress the stellar light and improve the dynamic range of the observations. The basic principle is to combine the beams in phase opposition in order to strongly reduce the on-axis stellar light while transmitting the flux of off-axis sources located at angular spacings which are odd multiples of 0.5Î»/B (where B = 14.4Â m is the distance between the telescope centers and Î» is the wavelength of observation). Beam combination is done in the pupil plane on a 50/50 beamsplitter which can be translated to equalize the pathlengths between the two sides of the interferometer. One output of the interferometer is reflected on a short-pass dichroic and focused on the Nulling Optimized Mid-Infrared Camera (NOMIC) (Hoffmann et al. 2014). NOMIC uses a 1024 Ã 1024 Raytheon Aquarius detector split into two columns of eight contiguous channels. The optics provides a field of view (FOV) of 12Â arcsec with a plate-scale of 0.018Â arcsec. Tip/tilt and phase variations between the LBT apertures are measured using a fast-readout (1âHz) K-band PICNIC detector (PHASECam) which receives the near-infrared light from both outputs of the interferometer. Closed-loop correction uses a fast pathlength corrector installed in the UBC (see more details in DefrÃ¨re et al. 2014).
Citation: Skemer et al. 2014
Citation function: Background
This paper is the fourth in a series. In our first work (Merlin et al. 2018) we presented an accurate and conservative technique to single out passive galaxies at high redshift by means of spectral energy distribution (SED) fitting with a probabilistic approach. We selected 30 z > 3 candidates in the GOODS-S field. Passive galaxy candidates, while being relatively easy to select from photometric surveys once the technique is established, need to be confirmed by other means. This is usually achieved through spectroscopic observations. However, spectroscopy becomes particularly difficult and time consuming at z > 3, where only few candidates have been confirmed so far (Glazebrook et al. 2017; Schreiber et al. 2018a; Tanaka et al. 2019; Valentino et al. 2020; Forrest et al. 2020a,b; Saracco et al. 2020; D’Eugenio et al. 2020). In our second work (Santini et al. 2019, S19 hereafter), we used a complementary approach and looked for evidence of the lack of star formation as seen in the sub-millimetre regime to confirm the passive classification of the high-z candidates selected in GOODS-S. At that time, we could confirm 35% of the targets on an individual basis adopting conservative assumptions, and we validated the sample as a whole in a statistical sense. In our third work (Merlin et al. 2019, M19 hereafter), we extended the search for passive galaxies to the entire CANDELS sample and selected 102 z > 3 candidates over the five fields. In the present work, we first confirm the passive nature of these candidates, adopting the method presented in S19 and taking advantage of the richer ALMA archive, which includes observations that were still proprietary at the time of our previous work. We then analyse the emergence and mass growth of this peculiar class of galaxies by means of two powerful statistical tools: the stellar mass function (SMF) and the stellar mass density (SMD). Very few studies so far have pushed the analysis of the SMF of passive galaxies at z > 3 (Muzzin et al. 2013; Davidzon et al. 2017; Ichikawa & Matsuoka 2017; Girelli et al. 2019) because of the difficulty in assembling statistically meaningful samples of candidates at such high redshift.
Citation: Santini et al. 2019
Citation function: Background; Background
Before leaving this section, in Fig. 8 we display the spatial dependence of the self-consistent neutron and proton density profiles for the optimal solutions in spherical WS cells with average baryon densities nb = 0.0475 fm-3, 0.065 fm-3, and 0.076 fm-3. It is observed that in denser matter the size of the WS cell decreases, as we discussed previously, and that the amount of free neutrons in the gas increases, as expected. It can be seen that the nuclear surface is progressively washed out with increasing average baryon density as the nucleon distributions become more uniform. At high nb the density profile inside the WS cell extends towards the edge of the cell, pointing out that the WS approximation may be close to its limits of validity (Negele & Vautherin 1973; Chamel et al. 2007; Baldo et al. 2007; Pastore et al. 2011; Gögelein & Müther 2007; Newton & Stone 2009). Although the proton number Z is similar for the three average baryon densities of Fig. 8, the local distribution of the protons is very different in the three cases. In Fig. 8c the proton density profile extends more than 3 fm farther from the origin than in Fig. 8a, while the central value of the proton density has decreased by more than a factor 2, hinting at the fact that the neutrons have a strong drag effect on the protons. Figure 9 presents the nucleon density profiles obtained for cylindrical and planar geometries at the same average density nb = 0.076 fm-3 as in Fig. 8c. From Figs. 8c (droplets),  9a (rods), and 9b (slabs) we see that the size of the WS cells decreases with decreasing dimensionality, i.e. Rc,droplet>Rc,rod>Rc,slab. At high average densities near the crust-core transition, nucleons inside the WS cell can arrange themselves in such a way that the region of higher density is concentrated at the edge of the cell, leaving the uniform region of lower density in the inner part of the cell. This distribution of nucleons corresponds to the cylindrical tube and spherical bubble configurations. In Figs. 9c and d, we plot the neutron and proton density profiles of the optimal solution for tubes and bubbles at nb = 0.076 fm-3. At equal average density, the size of the cells containing tubes and bubbles is larger than the size of the cells accommodating rods and droplets, respectively, as can be appreciated by comparing Fig. 9a for rods with Fig. 9c for tubes, and Fig. 8c for droplets with Fig. 9d for bubbles. As a consequence of this fact and of the effectively larger value of the integration factors 2πr and 4πr2 when the densities are accumulated near the edge of the cell, the total number of nucleons and the atomic number in the tube and bubble cells is about 1.5−2 times larger than in their rod and droplet counterparts. The proton fraction xp = Z/A is, however, practically the same for all geometries.
Citation: Gögelein & Müther 2007
Citation function: Background
Citation: Chamel et al. 2007
Citation function: Uses
Recent theoretical models clearly demonstrate the role of expanding H I shells for the formation of molecular clouds (e.g., Hennebelle et al. 2008; Heitsch et al. 2009; Inoue & Inutsuka 2009). In particular, these models highlight the importance of multiple compressions for the formation of magnetized filamentary molecular clouds (e.g., Inutsuka et al. 2015; Iwasaki et al. 2019). The typical timescale of such compressions is estimated in the Galactic disk to be on average ~1 Myr (McKee & Ostriker 1977; Inutsuka et al. 2015). Thus, the formation of molecular clouds may last from a few million years to ~10 Myr or more (see, e.g., Kobayashi et al. 2017). These successive compressions may continuously alter the density, velocity, and magnetic field structures of the clouds, and also have a strong impact on the formation of new generations of filaments and consequently that of stars. While the first generation of stars form and impact their (local) surroundings (through outflow, jets, winds, and ionizing radiation), new cold matter is continuously assembled replenishing the sites of star formation (i.e., filaments and hubs). This matter replenishment may be channeled from within the cloud itself through molecular filaments toward dense ridge-like main filaments (Schneider et al. 2010; Palmeirim et al. 2013) or toward hubs (Myers 2009; Peretto et al. 2013, 2014; Treviño-Morales et al. 2019). Matter can also be brought into the system (the cloud) by a new event of external collision (e.g., Fukui et al. 2018b). Arzoumanian et al. (2018) identified, in position-velocity (PV) diagrams, extended structures with mean line-of-sight (LOS) velocities offset with respect to, and connected to the velocity of, a filament. They suggested a multi-interaction scenario where sheet-like extended structures interact, in space and time, with a star-forming filament, and are responsible for its compression or disruption. Arzoumanian et al. (2018) also identified a bent velocity structure in the PV space. They showed that such a V- or Λ-shaped velocity structure can result from the filament formation process by shock compression as proposed by the theoretical model of Inoue et al. (2018). In this model, a filament is formed due to convergence of a flow of matter generated by the bending of the ambient magnetic field structure induced by an interstellar shock compression (see also Inoue & Fukui 2013; Vaidya et al. 2013). This velocity structure has also been observed toward another filament, the Musca filament (Bonne et al. 2020). More recently, in a theoretical study, Abe et al. (2021) proposed a classification of filament formation mechanisms resulting from the variation in the relative importance between the shock velocity, the turbulence, and the magnetic field strength (see also the theoretical study by Chen et al. 2020a).
Citation: Myers 2009
Citation function: Background; Background
The above finds an explanation within the context of the two-phases formation scenario of ETGs (Oser et al. 2010). According to this scenario, in the early (z ≳ 2) dissipative phase driven by wet major mergers (e.g. Hopkins et al. 2008) and/or violent disc instability (e.g. Barro et al. 2013; Dekel & Burkert 2014; Zolotov et al. 2015; Tacchella et al. 2016), the proto-ellipticals are compact objects that form stars in situ in a very intense regime until this process is stopped abruptly by gas shock heated in massive haloes, and/or rapid gas exhaustion and Supernova/AGN feedback. As the compact quiescent galaxy ages and reddens (red nugget), during the second non-dissipative phase (z ≲ 1−2), more mass is assembled by the accretion of ex situ stars through merging with other galaxies, which are also mostly quiescent. Dry minor or intermediate mergers contribute little to the mass growth but promote substantial size growth (the accreted stars tend to be deposited mostly in the external regions), making spheroidal galaxies less compact and likely also less concentrated (Bezanson et al. 2009; Naab, Johansson & Ostriker 2009; Oser et al. 2010; Trujillo, Ferreras & de La Rosa 2011; Bluck et al. 2012; Johansson, Naab & Ostriker 2012; Hilz, Naab & Ostriker 2013; Shankar et al. 2013; van Dokkum et al. 2015; Wellons et al. 2016; Faisst et al. 2017; Furlong et al. 2017; Hill et al. 2017; Genel et al. 2018, among others). Dry mergers can also be major, though they are less frequent and relevant only to the most massive galaxies (e.g. Bundy et al. 2009; López-Sanjuan et al. 2012; Rodríguez-Puebla et al. 2017). These mergers increase substantially the mass, while the size increases approximately proportional to the mass increase (e.g. Nipoti, Londrillo & Ciotti 2003; Johansson et al. 2012; Nipoti et al. 2012; Hilz et al. 2013) in a such way that the shift in the mass–size relation is small, affecting in a lesser degree the compactness and concentration of the merged galaxies. Although the second phase of ETG formation, driven by dry mergers, is a reliable explanation for the growth in size and the puffing-up of massive ETGs, there is still an intense debate as to whether or not this mechanism is enough to describe observational inferences (e.g. López-Sanjuan et al. 2012; Newman et al. 2012; Nipoti et al. 2012; Sonnenfeld, Nipoti & Treu 2014; Man, Zirm & Toft 2016; Frigo & Balcells 2017, see for a discussion Zanisi et al. 2021 and more references therein). An alternative or complementary mechanism suggested for the apparent strong growth in size of massive ETGs is quasar feedback, which removes huge amounts of cold gas from the central regions, inducing an expansion of the stellar distribution (Fan et al. 2008, but see Trujillo et al. 2011).
Citation: Faisst et al. 2017
Citation function: Background
To highlight the evidence for CO2 in the transmission spectrum, in Fig. 18 we show three atmo model atmospheres: our best-fitting model from the free-chemistry retrieval; a model with all of the same parameters as the best fit, except the CO2 abundance, which is set to zero; and a third model with both CO and CO2 abundances set to zero. The strong absorption feature centred on the 4.5 $\, \mu$m Spitzer channel disappears in the latter two models. With only Spitzer photometry, however, the contribution of CO to the 4.5 $\, \mu$m point complicates the interpretation of the C/O ratio. Theoretical models have found that CO should be the dominant carbon-bearing molecule for hydrogen-dominated atmospheres above 1000 K (e.g. Lodders & Fegley 2002; Heng & Lyons 2016), and CO has been detected at high resolution in hot Jupiter atmospheres (e.g. Snellen et al. 2010). In our equilibrium chemistry retrieval, CO is at least 100× more abundant than CO2 (see Fig. 12). However, at 4.5 $\, \mu$m the CO2 opacity is much stronger and dominates over the CO contribution even though CO has much higher VMR concentrations. In the free-chemistry retrieval, the CO VMR is not constrained by the data – only an upper limit to the CO is found, as very high values affect the mean molecular weight, and the data are consistent with no CO contribution. The lack of a CO feature in the WFC3 data further pushes the free-chemistry retrieval to prefer CO2 over CO. With CO constrained through chemistry in one retrieval and unconstrained in the free case, the C/O ratios obtained are vastly different. In the chemical-equilibrium case, a supersolar C/O is found (see Fig. 13) while in the free case a subsolar C/O ratio is found (Fig. 14). This finding highlights the extreme sensitivity and degeneracies of measuring the C/O ratio with a free-chemistry retrieval model, as all major molecular species have to be well constrained by the data. For a hot Jupiter such as WASP-127b, we consider a scenario with all of the carbon found in CO2 and little to none in CO to be thermochemically implausible, as no obvious non-equilibrium mechanism would deplete CO by many orders of magnitude while enhancing CO2. This situation is unlike CH4, where dynamical mixing and vertical quenching can dramatically enhance CH4 (e.g. Cooper & Showman 2006; Moses et al. 2011; Tsai et al. 2017; Drummond et al. 2018a, b). With only one photometric data point at 4.5 $\, \mu$m, it is currently impossible to fully disentangle the contribution of both CO and CO2 in a model-independent way. Further transmission spectroscopy observations of WASP-127b at high resolution with the JWST will clarify which is the dominant carbon-bearing molecule in WASP-127b’s atmosphere, and allow stronger constraints to be placed on its carbon-to-oxygen ratio.
Citation: Snellen et al. 2010
Citation function: Compare/Contrast; Compare/Contrast
In the last decade, several projects have focused on collecting the deepest images of clusters and groups of galaxies. Among the most recent examples, we can mention the Frontier Fields initiative (Lotz et al. 2017), the Hyper Suprime-Cam Subaru Strategic Program (Aihara et al. 2018a, 2018b, 2019), the Fornax Deep Survey (Iodice et al. 2016), or the upcoming Vera C. Rubin Observatory (Ivezic et al. 2008). In addition, technical development offers a new and barely explored perspective: a panchromatic, more detailed view of the universe through the use of narrowband filter systems, such as those from the J-PLUS and J-PAS surveys (Benitez et al. 2014; Cenarro et al. 2019; Bonoli et al. 2021). In this work we intend to show how the combination of these two characteristics, high-quality data and information at different wavelengths, can provide strong clues on the clusters’ formation and evolution through the analysis of the ICL. It is known that the ICL presents different morphologies, substructures, and ICL fractions depending on the wavelength used (Tang et al. 2018). Whereas the ICL fraction measured in single bands can be useful for establishing qualitative relations (e. g., evolution with redshift or halo mass), a panchromatic view of the ICL can give insights into its stellar populations or the dynamical stage of the cluster (e.g., Jiménez-Teja et al. 2019). With this aim, we use the recently acquired data from the Reionization Lensing Cluster Survey (RELICS; Coe et al. 2019), a Hubble Space Telescope (HST) Treasure program that has observed 41 very massive, strong-lensing clusters in three optical (ACS) and four infrared (WFC3) bands. In this work we present the potential of the RELICS data for ICL purposes, focused on the cluster WHL J013719.8–08284 (WHL0137 hereafter). Future work will apply the CICLE algorithm, which is free of a priori assumptions, extensively to the whole RELICS sample with two main aims: (1) analyze the optical and infrared ICL fractions to extract information about the stellar populations of the diffuse light, and (2) infer the dynamical stage of the clusters.
Citation: Bonoli et al. 2021
Citation function: Background
With the release of Gaia DR2 (Gaia Collaboration et al. 2018; Katz et al. 2019), the proper motions of billions of stars are now available to the astronomical community. Combining with radial velocities from large spectroscopic surveys, like the Sloan Digital Sky Survey (Eisenstein et al. 2011; Blanton et al. 2017), Gaia-ESO survey (Gilmore et al. 2012; Randich et al. 2013), and LAMOST Galactic spectroscopic survey (Deng et al. 2012; Zhao et al. 2012), the wealth of 6D information of billions of stars have challenged and even overthrown many aspects of our understanding of the Milky Way (MW). The discovery of snail shells in the phase-space distribution of MW disk stars (Antoja et al. 2018) has inspired debates about their origin: whether they are generated by the passage of a dwarf galaxy (probably the Sagittarius dwarf galaxy) through the MW disk (Binney & Schönrich 2018) or are the echo of the MW bar buckling (Khoperskov et al. 2019). Meanwhile, major accretion events begin to unveil themselves when the stellar distribution in various energy–momentum spaces (e.g., Myeong et al. 2019) is investigated. These major accretion events injected most of the materials from the progenitor dwarf galaxies into our MW, including globular clusters (GCs). As GCs are one of the oldest objects in our Galaxy, identifying and studying accreted GCs help us trace back the accretion history of our Galaxy. Though details of major accretion events, e.g., the number of accretion events and the GCs associated with each event, are still under debate (e.g., Helmi et al. 2018; Massari et al. 2019; Myeong et al. 2019), it is widely accepted that a substantial number of halo stars and GCs were accreted (e.g., Ostdiek et al. 2019). Along the same line, more and more substructures, e.g., stellar streams, are identified inside the MW (e.g., Malhan et al. 2018; Ibata et al. 2019b). An increasing number of stellar streams are suggested to be related to the debris of (inner-halo) GCs (e.g., Ibata et al. 2019a). Aside from these GC destruction events under the influence of Galactic potential, the dynamical relaxation of GCs (e.g., Weinberg 1994; Vesperini & Heggie 1997) also ejects member stars into the field. It would be of great interest to find such GC-ejected stars in order to estimate the mass loss from GCs to better understand the formation and evolution of our MW. To help achieve this goal, another characteristic of GCs is very helpful.
Citation: Antoja et al. 2018
Citation function: Background; Background
Many studies have been done to understand the dynamics and origin of such systems since the discovery of the first binary asteroid system, Dactyl orbiting around (243) Ida in 1993 (Chapman et al. 1995). Based on the structure of ‘rubble pile’ asteroids (a collection of gravitationally bound boulders with a distribution of size scales and very little tensile strength between them), a model for how they can disrupt due to close flybys of a planet was developed. However, close encounters with the planets proved not to be enough for creation of the current population of binary systems (Margot et al. 2002; Walsh & Richardson 2008). Another model for their formation is by increasing their spin rates due to incident and remitted solar photons, known as the Yarkovsky–O'Keefe–Radzievskii–Paddack (YORP) effect. The YORP effect on contact binary asteroids has been studied (Bottke et al. 2002; Merline et al. 2002; Scheeres 2002; Walsh & Richardson 2006). Using a model with an ellipsoid and a sphere in a planar case, Scheeres (2007) studied fission limits (spin limit to occur a fission) and the stability of that kind of system for different initial conditions. After that, the stability of a binary system was analysed using a two-ellipsoid model (Scheeres 2009). Pravec et al. (2010) made a complete study about formation of asteroid pairs through rotation fission. Jacobson & Scheeres (2011) studied the creation of binaries and other observed near-Earth asteroid (NEA) systems, including doubly synchronous binaries, high-e binaries, ternary systems and contact binaries. That study analysed the dynamics of a binary system just after rotational fission. Using a two-ellipsoid model taking into account mutual gravitational interactions and tidal dissipation, they analysed the dynamics for different mass ratios of the system under a planar assumption. The current work follows from these results, but looks at more likely, non-planar initial configurations. This extension is significant, as non-planar cases must take into account the complete rotational motion (rotation, precession and nutation) of each body. Our results are compared with the results obtained by Jacobson & Scheeres (2011).
Citation: Walsh & Richardson 2008
Citation function: Background
Citation: Scheeres 2002
Citation function: Background