ALMA-IMF. VIII. Combination of Interferometric Continuum Images with Single-dish Surveys and Structural Analysis of Six Protoclusters
Abstract: We present the combination of ALMA-IMF and single-dish continuum images from the MUSTANG-2 Galactic Plane Survey (MGPS90) at 3 mm and the Bolocam Galactic Plane Survey (BGPS) at 1 mm. Six and 10 out of the 15 ALMA-IMF fields are combined with MGPS90 and BGPS, respectively. The combination is made via the feathering technique. We used the dendrogram algorithm throughout the combined images, and performed further analysis in the six fields with the combination in both bands (G012.80, W43-MM1, … Show more
Search citation statements
Paper Sections
Citation Types
Year Published
Publication Types
Relationship
Authors
Journals
Cited by 3 publications
References 75 publications
One of the central questions in astrophysics is the origin of the initial mass function (IMF). It is intrinsically linked to the processes from which it originates, and hence its connection with the core mass function (CMF) must be elucidated. We aim to measure the CMF in the evolved W33-Main star-forming protocluster to compare it with CMF recently obtained in other Galactic star-forming regions, including the ones that are part of the ALMA-IMF program. We used observations from the ALMA-IMF large programme: sim 2$' 2'$ maps of emission from the continuum and selected lines at 1.3 mm and 3 mm observed by the ALMA 12m only antennas. Our angular resolution was typically 1$''$, that is, sim 2400 au at a distance of 2.4 kpc. The lines we analysed are CO (2--1), SiO (5--4), N$_2$H$^+$ (1--0), H41alpha as well as He41alpha blended with C41alpha . We built a census of dense cores in the region, and we measured the associated CMF based on a core-dependent temperature value. We confirmed the evolved' status of W33-Main by identifiying three H II regions within the field, and to a lesser extent based on the number and extension of N$_2$H$^+$ filaments. We produced a filtered core catalogue of 94 candidates that we refined to take into account the contamination of the continuum by free-free and line emission, obtaining 80 cores with masses that range from 0.03 to 13.2 $M_ odot $. We fitted the resulting high-mass end of the CMF with a single power law of the form N(log(M)) propto M$^ alpha $, obtaining $ $, which is slightly steeper but consistent with the Salpeter index. We categorised our cores as prestellar and protostellar, mostly based on outflow activity and hot core nature. We found the prestellar CMF to be steeper than a Salpeter-like distribution, and the protostellar CMF to be slightly top heavy. We found a higher proportion of cores within the H II regions and their surroundings than in the rest of the field. We also found that the cores' masses were rather low (maximum mass of sim 13 $M_ odot$). We find that star formation in W33-Main could be compatible with a clump-fed' scenario of star formation in an evolved cloud characterised by stellar feedback in the form of H II regions, and under the influence of massive stars outside the field. Our results differ from those found in less evolved young star-forming regions in the ALMA-IMF program. Further investigations are needed to elucidate the evolution of late CMFs towards the IMF over statistically significant samples.
One of the central questions in astrophysics is the origin of the initial mass function (IMF). It is intrinsically linked to the processes from which it originates, and hence its connection with the core mass function (CMF) must be elucidated. We aim to measure the CMF in the evolved W33-Main star-forming protocluster to compare it with CMF recently obtained in other Galactic star-forming regions, including the ones that are part of the ALMA-IMF program. We used observations from the ALMA-IMF large programme: sim 2$' 2'$ maps of emission from the continuum and selected lines at 1.3 mm and 3 mm observed by the ALMA 12m only antennas. Our angular resolution was typically 1$''$, that is, sim 2400 au at a distance of 2.4 kpc. The lines we analysed are CO (2--1), SiO (5--4), N$_2$H$^+$ (1--0), H41alpha as well as He41alpha blended with C41alpha . We built a census of dense cores in the region, and we measured the associated CMF based on a core-dependent temperature value. We confirmed the evolved' status of W33-Main by identifiying three H II regions within the field, and to a lesser extent based on the number and extension of N$_2$H$^+$ filaments. We produced a filtered core catalogue of 94 candidates that we refined to take into account the contamination of the continuum by free-free and line emission, obtaining 80 cores with masses that range from 0.03 to 13.2 $M_ odot $. We fitted the resulting high-mass end of the CMF with a single power law of the form N(log(M)) propto M$^ alpha $, obtaining $ $, which is slightly steeper but consistent with the Salpeter index. We categorised our cores as prestellar and protostellar, mostly based on outflow activity and hot core nature. We found the prestellar CMF to be steeper than a Salpeter-like distribution, and the protostellar CMF to be slightly top heavy. We found a higher proportion of cores within the H II regions and their surroundings than in the rest of the field. We also found that the cores' masses were rather low (maximum mass of sim 13 $M_ odot$). We find that star formation in W33-Main could be compatible with a clump-fed' scenario of star formation in an evolved cloud characterised by stellar feedback in the form of H II regions, and under the influence of massive stars outside the field. Our results differ from those found in less evolved young star-forming regions in the ALMA-IMF program. Further investigations are needed to elucidate the evolution of late CMFs towards the IMF over statistically significant samples.
Emergence of high-mass stars in complex fiber networks (EMERGE)
High-resolution images from Atacama Large Millimetre Array (ALMA) allow for the filamentary structure of the interstellar medium (ISM) to be resolved down to a few thousand astronomical units (au) in star-forming regions located at kiloparsec (kpc) distances. We aim to systematically quantify the impact of the interferometric response and the effects of the short-spacing information during the characterization of the ISM structure using ALMA observations. We created a series of continuum ALMA synthetic observations to test the recovery of the fundamental observational properties of dense cores and filaments (i.e., intensity peak, radial profile, and width) at different spatial scales. We homogeneously compared the results obtained with and without different data combination techniques and using different ALMA arrays and SD telescopes in both simulated data and real observations. Our analysis illustrates the severity of interferometric filtering effects. ALMA-12m-alone observations show significant scale-dependent flux losses that systematically corrupt ($>$ 30<!PCT!> error) all the physical properties inferred in cores and filaments (i.e., column density, mass, and size) well before the maximum recoverable scale of the interferometer. These effects are only partially mitigated by the addition of the ALMA ACA-7m array, although at the expenses of degrading the telescope point-spread-function (PSF). Our results demonstrate that only the addition of the ALMA Total Power(TP) information allows for the true sky emission to be recovered down to a few times the ALMA beamsize with sufficient accuracy ($<$ 10<!PCT!> error). Additional tests show that the emission recovery of cores and filaments at all scales is further improved if the 7m+TP data are replaced by additional maps obtained by a larger SD telescope (e.g., IRAM-30m), even if the latter are noisier than expected. In particular, these observational biases affect partially resolved targets, which becomes especially critical for studies in nearby regions such as Taurus or Orion. Our results demonstrate the need for the use of the state-of-the-art data combination techniques to accurately characterize the complex physical structure of the ISM in the ALMA era.
A crucial aspect in addressing the challenge of measuring the core mass function (CMF), that is pivotal for comprehending the origin of the initial mass function (IMF), lies in constraining the temperatures of the cores. We aim to measure the luminosity, mass, column density and dust temperature of star-forming regions imaged by the ALMA-IMF large program. These fields were chosen to encompass early evolutionary stages of massive protoclusters. High angular resolution mapping is required to capture the properties of protostellar and pre-stellar cores within these regions, and to effectively separate them from larger features, such as dusty filaments. We employed the point process mapping (PPMAP) technique, enabling us to perform spectral energy distribution fitting of far-infrared and submillimeter observations across the 15 ALMA-IMF fields, at an unmatched 2.5$^ prime $ angular resolution. By combining the modified blackbody model with near-infrared data, we derived bolometric luminosity maps. We estimated the errors impacting values of each pixel in the temperature, column density, and luminosity maps. Subsequently, we employed the extraction algorithm getsf on the luminosity maps in order to detect luminosity peaks and measure their associated masses. We obtained high-resolution constraints on the luminosity, dust temperature, and mass of protoclusters, that are in agreement with previously reported measurements made at a coarser angular resolution. We find that the luminosity-to-mass ratio correlates with the evolutionary stage of the studied regions, albeit with intra-region variability. We compiled a PPMAP source catalog of 313 luminosity peaks using getsf on the derived bolometric luminosity maps. The PPMAP source catalog provides constraints on the mass and luminosity of protostars and cores, although one source may encompass several objects. Finally, we compare the estimated luminosity-to-mass ratio of PPMAP sources with evolutionary tracks and discuss the limitations imposed by the 2.5$^ prime $ beam.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
Contact Info
customersupport@researchsolutions.com
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Product
Resources
This site is protected by reCAPTCHA and the Google Privacy Policy and Terms of Service apply.
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.
