Optical and near-infrared observations of the SPT2349-56 proto-cluster core at z = 4.3
K. M. Rotermund, S. C. Chapman, K. A. Phadke, R. Hill, E. Pass, M. Aravena, M. L. N. Ashby, A. Babul, M. Béthermin, R. Canning, C. de Breuck, C. Dong, A. H. Gon… 展开作者
K. M. Rotermund, S. C. Chapman, K. A. Phadke, R. Hill, E. Pass, M. Aravena, M. L. N. Ashby, A. Babul, M. Béthermin, R. Canning, C. de Breuck, C. Dong, A. H. Gonzalez, C. C. Hayward, S. Jarugula, D. P. Marrone, D. Narayanan, C. Reuter, D. Scott, J. S. Spilker, J. D. Vieira, G. Wang, A. Weiss
We present Gemini-S and {\it Spitzer}-IRAC optical-through-near-IR observations in the field of the SPT2349-56 proto-cluster at $z=4.3$. We detect optical/IR counterparts for only nine of the 14 submillimetre galaxies (SMGs) previously identified by ALMA in the core of SPT2349-56. In addition, we detect four $z\sim4$ Lyman-break galaxies (LBGs) in the 30 arcsec diameter region surrounding this proto-cluster core. Three of the four LBGs are new systems, while one appears to be a counterpart of one of the nine observed SMGs. We identify a candidate brightest cluster galaxy (BCG) with a stellar mass of $(3.2^{+2.5}_{-1.4})\times10^{11}\,{\rm M}_{\odot}$. The stellar masses of the eight other SMGs place them on, above, and below the main sequence of star formation at $z\approx4.5$. The cumulative stellar mass for the SPT2349-56 core is at least $(11.5\pm2.9)\times10^{11}\,{\rm M}_{\odot}$, a sizeable fraction of the stellar mass in local BCGs, and close to the universal baryon fraction (0.16) relative to the virial mass of the core ($10^{13}\,{\rm M}_{\odot}$). As all 14 of these SMGs are destined to quickly merge, we conclude that the proto-cluster core has already developed a significant stellar mass at this early stage, comparable to $z=1$ BCGs. Importantly, we also find that the SPT2349-56 core structure would be difficult to uncover in optical surveys, with none of the ALMA sources being easily identifiable or constrained through $g,r,$ and $i$ colour-selection in deep optical surveys and only a modest overdensity of LBGs over the extended core structure. SPT2349-56 therefore represents a truly dust-obscured phase of a massive cluster core under formation.
A sample of 1.3 mm continuum cores in the Dragon infrared dark cloud (also known as G28.37+0.07 or G28.34+0.06) is analyzed statistically. Based on their association with molecular outflows, the sample is divided into protostellar and starless cores. Statistical tests suggest that the protostellar cores are more massive than the starless cores, even after temperature and opacity biases are accounted for. We suggest that the mass difference indicates core mass growth since their formation. The mass growth implies that massive star formation may not have to start with massive prestellar cores, d…
We used data from WISE, IRAS, and Herschel in conjuction with our previous observations with SABOCA and LABOCA, and constructed the far-IR to submillimetre spectral energy distributions (SEDs) of dense cores in the filamentary Seahorse infrared dark cloud (IRDC) G304.74+01.32. For the 12 analysed cores, which include two IR dark cores (no WISE counterpart), nine IR bright cores, and one HII region, the mean dust temperature of the cold (warm) component, the mass, luminosity, H$_2$ number density, and surface density were derived to be $13.3\pm1.4$ K ($47.0\pm5.0$ K), $113\pm29$ M$_{\odot}$, $1…
The physical processes behind the transfer of mass from parsec-scale clumps to massive-star-forming cores remain elusive. We investigate the relation between the clump morphology and the mass fraction that ends up in its most massive core (MMC) as a function of infrared brightness, i.e. a clump evolutionary tracer. Using ALMA 12 m and ACA we surveyed 6 infrared-dark hubs in 2.9mm continuum at $\sim$3" resolution. To put our sample into context, we also re-analysed published ALMA data from a sample of 29 high mass-surface density ATLASGAL sources. We characterise the size, mass, morphology, and…
Environment is one of the primary drivers of galaxy evolution; via multiple mechanisms, it can control the critical process of transforming galaxies from star forming to quiescent, commonly termed "quenching". Despite its importance, however, we still do not have a clear view of how environmentally-driven quenching proceeds even in the most extreme environments: galaxy clusters and their progenitor proto-clusters. Recent advances in infrared capabilities have enabled transformative progress not only in the identification of these structures but in detailed analyses of quiescence, obscured star…
We present the first mid-infrared (MIR) detections of HNC and H13CN in the interstellar medium, and numerous, resolved HCN rovibrational transitions. Our observations span 12.8 to 22.9 micron towards the hot core Orion IRc2, obtained with the Echelon-Cross-Echelle Spectrograph aboard the Stratospheric Observatory for Infrared Astronomy (SOFIA). Exceptional, ~5 km/s, resolution distinguishes individual rovibrational transitions of the HNC and HCN P, Q, and R branches; and the H13CN R branch. This allows direct measurement of the species' excitation temperatures, column densities, and relative a…
We have performed a 5-8 $μ$m spectral line survey of the hot molecular core associated with the massive protostar AFGL 2591, using the Echelon-Cross-Echelle Spectrograph (EXES) on the Stratospheric Observatory for Infrared Astronomy (SOFIA). We have supplemented these data with a ground based study in the atmospheric M band around 4.5 $μ$m using the iSHELL instrument on the Infrared Telescope Facility (IRTF), and the full N band window from 8-13 $μ$m using the Texas Echelon Cross Echelle Spectrograph (TEXES) on the IRTF. Here we present the first detection of ro-vibrational transitions of CS i…
We report the discovery of 4 new H$_2$ jets in Mon R1 star-forming region on the images obtained with the 2.5-m telescope of the Caucasian Mountain Observatory of SAI MSU through the filter, centered on the H$_2$ 1-0 S(1) emission line. This discovery confirms the nature of these flows, which existence was previously suspected using archival Spitzer GLIMPSE360 and WISE survey images. Also two infrared reflection nebulae were revealed. On the Herschel PACS survey images we found a small group of far-infrared sources, mostly unknown ones. Among them are the possible exciting objects of these out…
Since the start of ALMA observatory operation, new and important chemistry of infrared cold core was revealed. Molecular transitions at millimeter range are being used to identify and to characterize these sources. We have investigated the 231 GHz ALMA archive observations of the infrared dark cloud region C9, focusing on the brighter source that we called as IRDC-C9 Main. We report the existence of two sub-structures on the continuum map of this source: a compact bright spot with high chemistry diversity that we labelled as core, and a weaker and extended one, that we labelled as tail. In the…
The majority of the ultimate main-sequence mass of a star is assembled in the protostellar phase, where a forming star is embedded in an infalling envelope and encircled by a protoplanetary disk. Studying mass accretion in protostars is thus a key to understanding how stars gain their mass and ultimately how their disks and planets form and evolve. At this early stage, the dense envelope reprocesses most of the luminosity generated by accretion to far-infrared and submillimeter wavelengths. Time-domain photometry at these wavelengths is needed to probe the physics of accretion onto protostars,…
We present near-infrared spectra of three low-luminosity protostars and one background star in the Perseus molecular cloud, acquired using the Infrared Camera (IRC) onboard the \textit{AKARI} space telescope. For the comparison with different star-forming environments, we also present spectra of the massive protostar AFGL 7009S, where the protostellar envelope is heated significantly, and the low-mass protostar RNO 91, which is suspected to be undergoing an episodic burst. We detected ice absorption features of \ch{H2O}, \ch{CO2}, and \ch{CO} at all spectra around the wavelengths of 3.05, 4.27…
Molecular Line Observations of Infrared Dark Clouds II: Physical Conditions
使用偏向于高质量恒星形成区域的源选择，我们使用了大速度梯度（LVG）代码来计算中途空间实验（MSX）8微米红外暗核样本的H2密度和CS柱密度。我们的平均H2密度和CS柱密度分别为1.14 x 10 e6 cm-3和1.21 x 10 e13 cm-2。此外，我们还计算了每个核心的金斯质量和维里质量，以更好地了解它们的引力稳定性。我们发现，根据Ragan等人2006年（论文1）对N2 H + J = 1-0和C18 O J = 1-0的观测计算的核心质量足以发生坍缩，尽管大多数区域可能形成原星系团。我们探索了样本中分子气体的恒星形成特性，并发现了一些多样性，这些多样性将红外暗云的范围从产生大型星团的巨大云扩展到与我们当地的一些对应物（例如巨蛇座，蛇夫座）相似的云。
The 14N/15N ratio in molecules exhibits a large variation in star-forming regions, especially when measured from N2H+ isotopologues. However, there are only a few studies performed at high-angular resolution. We present the first interferometric survey of the 14N/15N ratio in N2H+ obtained with the Atacama Large Millimeter Array towards four infrared-dark clouds harbouring 3~mm continuum cores associated with different physical properties. We detect N15NH+ (1-0) in about 20-40% of the cores, depending on the host cloud. The 14N/15N values measured towards the millimeter continuum cores range f…
We present APEX, infrared and radio continuum observations of the G345.88-1.10 hub filament system which is a newly discovered star-forming cloud that hosts an unusually bright bipolar infrared nebulosity at its centre. At a distance of 2.26$^{+0.30}_{-0.21}$ kpc, G345.88-1.10 exhibits a network of parsec-long converging filaments. At the junction of these filaments lie four infrared-quiet fragments. The densest fragment (with M=210 M$_{\odot}$, R$_{\rm{eff}}=0.14$ pc) sits at the centre of a wide (opening angle of $\sim$ 90$\pm$15$^{o}$) bipolar nebulosity. $^{12}$CO(2-1) observations show th…
Using Scattered Near-Infrared Light to Map Water Ice in Prestellar Cores with SPHEREx
University of California Berkeley（加州大学伯克利分校）；Massachusetts Institute of Technology（麻省理工学院）；Max-Planck-Institut für Extraterrestrische Physik（马克斯·普朗克地外物理学研究所）
We study centimeter continuum emission of eight high- and intermediate-mass protostars that are part of the SOFIA Massive (SOMA) Star Formation Survey, thus building extended spectral energy distributions (SEDs) from the radio to the infrared. We discuss the morphology seen in the centimeter continuum images, which are mostly derived from archival VLA data, and the relation to infrared morphology. We use the SEDs to test new models of high-mass star formation including radiative and disk-wind feedback and associated free-free and dust continuum emission (Tanaka, Tan, & Zhang 2016). We show tha…
Far-infrared/sub-millimetre properties of pre-stellar cores L1521E, L1521F and L1689B as revealed by the Herschel SPIRE instrument -- I. Central positions
We conduct a census of the high-mass protostellar population of the $\sim70,000\:M_\odot$ Infrared Dark Cloud (IRDC) G028.37+00.07, identifying 35 sources based on their $70\:μ$m emission, as reported in the {\it Herschel} Hi-GAL catalog of Molinari et al. (2016). We perform aperture photometry to construct spectral energy distributions (SEDs), which are then fit with the massive protostar models of Zhang & Tan (2018). We find that the sources span a range of isotropic luminosities from $\sim$20 to 4,500$\:L_\odot$. The most luminous sources are predicted to have current protostellar masses of…
