We present 1.05 mm ALMA observations of the deeply embedded high-mass protocluster G11.92-0.61, designed to search for low-mass cores within the accretion reservoir of the massive protostars. Our ALMA mosaic, which covers an extent of ~0.7 pc at sub-arcsecond (~1400 au) resolution, reveals a rich population of 16 new millimetre continuum sources surrounding the three previously-known millimetre cores. Most of the new sources are located in the outer reaches of the accretion reservoir: the median projected separation from the central, massive (proto)star MM1 is ~0.17 pc. The derived physical properties of the new millimetre continuum sources are consistent with those of low-mass prestellar and protostellar cores in nearby star-forming regions: the median mass, radius, and density of the new sources are 1.3 Msun, 1600 au, and n(H2)~10^7 cm^-3. At least three of the low-mass cores in G11.92-0.61 drive molecular outflows, traced by high-velocity 12CO(3-2) (observed with the SMA) and/or by H2CO and CH3OH emission (observed with ALMA). This finding, combined with the known outflow/accretion activity of MM1, indicates that high- and low-mass stars are forming (accreting) simultaneously within this protocluster. Our ALMA results are consistent with the predictions of competitive-accretion-type models in which high-mass stars form along with their surrounding clusters.
We report observations with the Atacama Large Millimetre Array (ALMA) of six submillimetre galaxies (SMGs) within 3 arcmin of the Distant Red Core (DRC) at $z=4.0$, a site of intense cluster-scale star formation, first reported by Oteo et al. (2018). We find new members of DRC in three SMG fields; in two fields, the SMGs are shown to lie along the line of sight towards DRC; one SMG is spurious. Although at first sight this rate of association is consistent with earlier predictions, associations with the bright SMGs are rarer than expected, which suggests caution when interpreting continuum ove…
We study the core mass function (CMF) of the massive protocluster G286.21+0.17 with the Atacama Large Millimeter/submillimeter Array via 1.3~mm continuum emission at a resolution of 1.0\arcsec\ (2500~au). We have mapped a field of 5.3\arcmin$\times$5.3\arcmin\ centered on the protocluster clump. We measure the CMF in the central region, exploring various core detection algorithms, which give source numbers ranging from 60 to 125, depending on parameter selection. We estimate completeness corrections due to imperfect flux recovery and core identification via artificial core insertion experiment…
We exploit ALMA 870um observations to measure the star-formation rates (SFRs) of eight X-ray detected Active Galactic Nuclei (AGNs) in a z~3.1 protocluster, four of which reside in extended Ly-alpha haloes (often termed Ly-alpha blobs: LABs). Three of the AGNs are detected by ALMA and have implied SFRs of ~220-410~M_sun/yr; the non detection of the other five AGNs places SFR upper limits of <210 M_sun/yr. The mean SFR of the protocluster AGNs (~110-210 M_sun/yr) is consistent (within a factor of ~0.7-2.3) with that found for co-eval AGNs in the field, implying that galaxy growth is not signifi…
We study the gas kinematics and dynamics of the massive protocluster G286.21+0.17 with the Atacama Large Millimeter/submillimeter Array using spectral lines of $C^{18}O$(2-1), $N_2D^+$(3-2), $DCO^+$(3-2) and $DCN$(3-2). On the parsec clump scale, $C^{18}O$ emission appears highly filamentary around the systemic velocity. $N_2D^+$ and $DCO^+$ are more closely associated with the dust continuum. $DCN$ is strongly concentrated towards the protocluster center, where no or only weak detection is seen for $N_2D^+$ and $DCO^+$, possibly due to this region being at a relatively evolved evolutionary st…
The ALMA Survey of Star Formation and Evolution in Massive Protoclusters with Blue Profiles (ASSEMBLE): Core Growth, Cluster Contraction, and Primordial Mass Segregation
We present new continuum and molecular line data from the ALMA Three-millimeter Observations of Massive Star-forming regions (ATOMS) survey for the two protoclusters, G12.42+0.50 and G19.88-0.53. The 3 mm continuum maps reveal seven cores in each of the two globally contracting protoclusters. These cores satisfy the radius-mass relation and the surface mass density criteria for high-mass star formation. Similar to their natal clumps, the virial analysis of the cores suggests that they are undergoing gravitational collapse ($\rm α_{vir} << 2$). The clump to core scale fragmentation is investiga…
The ALMA EGO-10 Survey of Massive Protoclusters: Correlation of 1.3 mm Continuum Source Clustering with Evolutionary State
Scottish Universities Physics Alliance (SUPA), School of Physics and Astronomy, University of St Andrews（圣安德鲁斯大学物理与天文学学院）；National Radio Astronomy Observatory（国家射电天文台）；INAF-IAPS（意大利国家天体物理研究所天体物理与行星科学研究所）；University of Arizona Department of Astronomy and Steward Observatory（亚利桑那大学天文学系和斯图尔德天文台）；Department of Astronomy, University of Texas at Austin（德克萨斯大学奥斯汀分校天文学系）
We present a detailed study of the massive star-forming region G35.2-0.74N with ALMA 1.3 mm multi-configuration observations. At 0.2" (440 au) resolution, the continuum emission reveals several dense cores along a filamentary structure, consistent with previous ALMA 0.85 mm observations. At 0.03" (66 au) resolution, we detect 22 compact sources, most of which are associated with the filament. Four of the sources are associated with compact centimeter continuum emission, and two of these are associated with H30α recombination line emission. The H30α line kinematics show ordered motion of the io…
A multiwavelength analysis of star formation associated with the extended green object, G19.88-0.53 is presented in this paper. With multiple detected radio and millimetre components, G19.88-0.53 unveils as harbouring a protocluster rather than a single massive young stellar object. We detect an ionized thermal jet using the upgraded Giant Meterwave Radio Telescope, India, which is found to be associated with a massive, dense and hot ALMA 2.7 mm core driving a bipolar CO outflow. Near-infrared spectroscopy with UKIRT-UIST shows the presence of multiple shock-excited H2 lines concurrent with th…
JWST reveals extended stellar disks for ALMA-bright dusty star-forming galaxies in the Spiderweb protocluster
Purple Mountain Observatory, Chinese Academy of Sciences（中国科学院紫金山天文台）；University of Science and Technology of China（中国科学技术大学）；Instituto de Astrofísica de Canarias (IAC)（加那利天体物理研究所）；Universidad de La Laguna（拉各拉纳大学）；National Astronomical Observatory of Japan（日本国立天文台）；Graduate University for Advanced Studies (SOKENDAI)（综合研究大学院大学）；Shanghai Jiao Tong University（上海交通大学）；INAF–Osservatorio Astronomico di Capodimonte（意大利国家天体物理研究所卡波迪蒙特天文台）
We present the results of continuum and 12CO(3-2) and CH3OH(7-6) line observations of IRAS16547-4247 made with the Atacama Large Millimeter/submillimeter Array (ALMA) at an angular resolution of ~0.5". The 12CO(3-2) emission shows two high-velocity outflows whose driving sources are located within the dust continuum peak. The alignment of these outflows do not coincide with that of the wide-angle, large scale, bipolar outflow detected with APEX in previous studies. The CH3OH(7-6) line emission traces an hourglass structure associated with the cavity walls created by the outflow lobes. Taking i…
With the aim of understanding the role of outflows in star formation, we performed a statistical study of the physical parameters of outflows in eleven massive protoclusters associated with ultra-compact HII regions. A total of 106 outflow lobes are identified in these protoclusters using the ALMA CO (3-2), HCN (4-3) and HCO+ (4-3) line observations. Although the position angles of outflow lobes do not differ in these three tracers, HCN and HCO+ tend to detect lower terminal velocity of the identified outflows compared to CO. The majority of the outflows in our targets are young with typical d…
Fragmentation of massive dense molecular clouds is the starting point in the formation of rich clusters and massive stars. Theory and numerical simulations indicate that the population of the fragments (number, mass, diameter, separation) resulting from the gravitational collapse of such clumps is probably regulated by the balance between the magnetic field and the other competitors of self-gravity, in particular turbulence and protostellar feedback. We have observed 11 massive, dense and young star-forming clumps with the Atacama Large Millimeter Array (ALMA) in the thermal dust continuum emi…
ALMA 870$μ$m continuum imaging has uncovered a population of blends of multiple dusty star-forming galaxies (DSFGs) in sources originally detected with the Herschel Space Observatory. However, their pairwise separations are much smaller that what is found by ALMA follow-up of other single-dish surveys or expected from theoretical simulations. Using ALMA and VLA, we have targeted three of these systems to confirm whether the multiple 870$μ$m continuum sources lie at the same redshift, successfully detecting $^{12}$CO($J = 3$-2) and $^{12}$CO($J = 1$-0) lines and being able to confirm that in th…
A Possible Protocluster of Galaxies Serendipitously Discovered in the Field of an Intermediate-Redshift Post-starburst Galaxy
Texas A&M University（德州农工大学）；University of Pittsburgh（匹兹堡大学）；Rochester Institute of Technology（罗切斯特理工学院）；Princeton University（普林斯顿大学）；University of Colorado, Boulder（科罗拉多大学博尔德分校）
High-mass stars shape the interstellar medium in galaxies, and yet, largely because the initial conditions are poorly constrained, we do not know how they form. One possibility is that high-mass stars and star clusters form at the junction of filamentary networks, referred to as 'hubs'. In this letter we present the complex anatomy of a protocluster hub within an Infrared Dark Cloud (IRDC), G035.39-00.33, believed to be in an early phase of its evolution. We use high-angular resolution ($\{θ_{\rm maj}, θ_{\rm min}\}=\{1.4{\rm arcsec}, 0.8{\rm arcsec}\}\sim\{0.02{\rm pc}, 0.01{\rm pc}\}$) and h…
Probing Star-Forming Properties via ALMA Observations of Massive Protocluster IRAS 15596-5301
Kunming University of Science and Technology（昆明理工大学）；Chuxiong Normal University（楚雄师范学院）；Shanghai Astronomical Observatory, Chinese Academy of Sciences（中国科学院上海天文台）；Instituto de Radioastronomía y Astrofísica, Universidad Nacional Autónoma de México（墨西哥国立自治大学无线电天文学与天体物理研究所）；Yunnan University（云南大学）；Anqing Normal University（安庆师范大学）；Peking University（北京大学）
We report the results of $1^{\prime}.5 \times3^{\prime}$ mapping at 1.1~mm with the Atacama Large Millimeter/submillimeter Array (ALMA) toward the central region of the $z=3.09$ SSA22 protocluster. By combining our source catalog with archival spectroscopic redshifts, we find that eight submillimeter galaxies (SMGs) with flux densities, $S_{\rm 1.1~mm}=0.7-6.4$~mJy ($L_{\rm IR}\sim10^{12.1}-10^{13.1}L_\odot$) are at $z=3.08-3.10$. Not only are these SMGs members of the protocluster but they in fact reside within the node at the junction of the 50 Mpc-scale filamentary three-dimensional structu…
We investigate gas contents of star-forming galaxies associated with protocluster 4C23.56 at z = 2.49 by using the redshifted CO(3-2) and 1.1 mm dust continuum with the Atacama Large Millimeter/submillimeter Array. The observations unveil seven CO detections out of 22 targeted H$α$ emitters (HAEs) and four out of 19 in 1.1 mm dust continuum. They have high stellar mass ($M_{\star}>4\times 10^{10}$ $M_{\odot}$) and exhibit a specific star-formation rate typical of main-sequence star forming galaxies at $z\sim2.5$. Different gas mass estimators from CO(3-2) and 1.1 mm yield consistent values for…
We report the results of ongoing monitoring of the 6.7 GHz CH$_3$OH masers associated with G188.95+0.89. In these observations five features are periodically varying and at least two exhibit evidence of velocity drifts. It is not clear the cause of these velocity drifts. The spectra have varied significantly since detection in 1991. The 11.45 km s$^1$ feature has decreased exponentially from 2003. Complementary ALMA 1.3 mm continuum and line observational results are also presented. Eight continuum cores (MM1 - MM8) were detected in G188.95+0.89. We derived the masses of the detected cores. G1…
The ALMA-IMF Large Program imaged a total noncontiguous area of 53pc2, covering 15 extreme, nearby protoclusters of the Milky Way. They were selected to span relevant early protocluster evolutionary stages. Our 1.3mm and 3mm observations provide continuum images that are homogeneously sensitive to point-like cores with masses of 0.2 and 0.6Msun, respectively, with a matched spatial resolution of 2000au. We also detect lines that probe the protocluster structure, kinematics, chemistry, and feedback over scales from clouds to filaments to cores. We classify ALMA-IMF protoclusters as Young, Inter…
Tracking Protostellar Variability in Massive Protoclusters with ALMA: I. Insights from QUARKS and MaMMOtH
Shanghai Astronomical Observatory, Chinese Academy of Sciences（中国科学院上海天文台）；School of Astronomy and Space Sciences, University of Chinese Academy of Sciences（中国科学院大学天文与空间科学学院）；State Key Laboratory of Radio Astronomy and Technology, Shanghai Astronomical Observatory, Chinese Academy of Sciences（中国科学院上海天文台射电天文学与技术国家重点实验室）；Institute of Astronomy and Astrophysics, Academia Sinica（中央研究院天文及天文物理研究所）；NRC Herzberg Astronomy and Astrophysics（加拿国家研究委员会赫茨伯格天体物理学研究所）；Department of Physics and Astronomy, University of Victoria（维多利亚大学物理与天文系）；Kavli Institute for Astronomy and Astrophysics, Peking University（北京大学卡尔·萨根天文与天体物理研究所）；Department of Astronomy, Peking University（北京大学天文系）
Massive dense clumps in the Large Magellanic Cloud can be an important laboratory to explore the formation of populous clusters. We report multiscale ALMA observations of the N159W-North clump, which is the most CO-intense region in the galaxy. High-resolution CO isotope and 1.3 mm continuum observations with an angular resolution of $\sim$0."25($\sim$0.07 pc) revealed more than five protostellar sources with CO outflows within the main ridge clump. One of the thermal continuum sources, MMS-2, shows especially massive/dense nature whose total H$_2$ mass and peak column density are $\sim$10$^{4…
We report interferometric imaging of [CII] and OH emission toward the center of the galaxy protocluster associated with the z=5.3 submillimeter galaxy (SMG) AzTEC-3, using the Atacama Large (sub)Millimeter Array (ALMA). We detect strong [CII], OH, and rest-frame 157.7 um continuum emission toward the SMG. The [CII] emission is distributed over a scale of 3.9 kpc, implying a dynamical mass of 9.7 x 10^10 Msun, and a star formation rate (SFR) surface density of Sigma_SFR = 530 Msun/yr/kpc2. This suggests that AzTEC-3 forms stars at Sigma_SFR approaching the Eddington limit for radiation pressure…
We present results from a deep 2'x3' (comoving scale of 3.7 Mpc x 5.5 Mpc at z=3) survey at 1.1 mm taken with the Atacama Large Millimeter/submillimeter Array (ALMA) in the SSA22 field. We observe the core region of a z = 3.09 protocluster, achieving a typical rms sensitivity of 60 micro-Jy/beam at a spatial resolution of 0".7. We detect 18 robust ALMA sources at a signal-to-noise ratio (SNR) > 5. Comparison between the ALMA map and a 1.1 mm map taken with the AzTEC camera on the Atacama Submillimeter Telescope Experiment (ASTE) indicates that three submillimeter sources discovered by the AzTE…
A nine-member protostellar system forming via filament fragmentation in the high mass protocluster NGC 6334-43
Scottish Universities Physics Alliance (SUPA), School of Physics and Astronomy, University of St Andrews（圣安德鲁斯大学物理与天文学学院）；National Radio Astronomy Observatory（国家射电天文台）；Massachusetts Institute of Technology（麻省理工学院）；Aberystwyth University（阿伯里斯特威斯大学）
We present a study of outflows at extremely early stages of high-mass star formation obtained from the ALMA Survey of 70 $μ\rm m$ dark High-mass clumps in Early Stages (ASHES). Twelve massive 3.6$-$70 $μ\rm m$ dark prestellar clump candidates were observed with the Atacama Large Millimeter/submillimeter Array (ALMA) in Band 6. Forty-three outflows are identified toward 41 out of 301 dense cores using the CO and SiO emission lines, yielding a detection rate of 14%. We discover 6 episodic molecular outflows associated with low- to high-mass cores, indicating that episodic outflows (and therefore…
The stellar initial mass function (IMF) is fundamental for many areas of astrophysics, but its origin remains poorly understood. It may be inherited from the core mass function (CMF) or arise as a result of more chaotic, competitive accretion. Dense, gravitationally bound cores are seen in molecular clouds and some observations have suggested that the CMF is similar in shape to the IMF, though translated to higher masses by a factor of $\sim3$. Here we measure the CMF in 28 dense clumps within 3.5 kpc that are likely to be central regions of massive protoclusters, observed via $1.3\:{\rm{mm}}$…
Context. To better understand the formation of high-mass stars, it is fundamental to investigate how matter accretes onto young massive stars, how it is ejected, and how all this differs from the low-mass case. The massive protocluster G31.41+0.31 is the ideal target to study all these processes because observations at millimeter and centimeter wavelengths have resolved the emission of the Main core into at least four massive dust continuum sources, named A, B, C, and D, within 1" or 0.018 pc, and have identified signatures of infall and several outflows associated with the core. Aims. We stud…
The ALMA-QUARKS Survey: Properties of Hot Molecular Fragments in the Massive Protocluster IRAS 17233-3606
Yunnan University（云南大学）；Shanghai Astronomical Observatory, Chinese Academy of Sciences（中国科学院上海天文台）；Jet Propulsion Laboratory, California Institute of Technology（加州理工学院喷气推进实验室）；Max Planck Institute for Astronomy（马克斯·普朗克天文学研究所）；Indian Institute of Astrophysics（印度天体物理研究所）
We show the first interferometric maps of the 14N/15N ratio obtained with the Atacama Large Millimeter Array (ALMA) towards the Solar-like forming protocluster OMC-2 FIR4. We observed N2H+, 15NNH+, N15NH+ (1-0), and N2D+ (2-1), from which we derive the isotopic ratios 14N/15N and D/H. The target is one of the closest analogues of the environment in which our Sun may have formed. The ALMA images, having synthesised beam corresponding to ~600 au, show that the emission of the less abundant isotopologues is distributed in several cores of ~10" (i.e. ~0.02~pc or 4000 au) embedded in a more extende…
Sufficiently massive clumps of molecular gas collapse under self-gravity and fragment to spawn a cluster of stars that have a range of masses. We investigate observationally the early stages of formation of a stellar cluster in a massive filamentary infrared dark cloud, G28.34+0.06 P1, in the 1.3mm continuum and spectral line emission using the ALMA. Sensitive continuum data reveal further fragmentation in five dusty cores at a resolution of several 10^3 AU. Spectral line emission from C18O, CH3OH, 13CS, H2CO and N2D+ are detected for the first time toward these dense cores. We found that thre…
Discovery of a Compact Hub-Filament System in G286.21+0.17 with JWST and ALMA: Insights into Protocluster Formation and Competitive Accretion
Peking University（北京大学）；National Astronomical Research Institute of Thailand（泰国国家天文研究所）；Gifu University（岐阜大学）；Indian Institute of Technology Gandhinagar（甘地纳加尔印度理工学院）；Korea Astronomy and Space Science Institute（韩国天文学与宇宙科学研究所）；University of Science and Technology, Korea (UST)（韩国科学技术院）；Jet Propulsion Laboratory, California Institute of Technology（加州理工学院喷气推进实验室）；Nazarbayev University（纳扎尔巴耶夫大学）
The ALMA-QUARKS Survey: Evidence of an Explosive Molecular Outflow in IRAS 15520--5234
S. N. Bose National Centre for Basic Sciences（S. N. 玻色基础科学国家中心）；Instituto Argentino de Radioastronomía (CCT-La Plata, CONICET, UNLP, CICPBA)（阿根廷射电天文研究所）；Shanghai Astronomical Observatory, Chinese Academy of Sciences（中国科学院上海天文台）；Chinese Academy of Sciences South America Center for Astronomy, National Astronomical Observatories, CAS（中国科学院国家天文台南美天文中心）；Departamento de Astronomía, Universidad de Chile（智利大学天文学系）；Jet Propulsion Laboratory, California Institute of Technology（加州理工学院喷气推进实验室）；Max Planck Institute for Astronomy（马克斯·普朗克天体物理学研究所）
Isotopic fractionation is an important tool to investigate the chemical history of our Solar System (SS). In particular, the isotopic fraction of nitrogen (14N/15N) is lower in comets and other pristine SS bodies with respect to the value measured for the protosolar nebula, suggesting a local chemical enrichment of 15N during the SS formation. Therefore, interferometric studies of nitrogen fractionation in SS precursors are imperative for us to obtain clues about our astrochemical origins. In this work, we investigated the variation of the 14N/15N ratio in one of the closest analogues of the e…
