SMA OBSERVER CENTER
 
2018B A-ranked projects with tracks in the queue or complete
Project IDP.I.# TracksTitle (hover for abstract)
2018B-A002Shih-Ping Lai1
Pilot mosaic polarization observations towards W51 and Orion BN/KLMagnetic fields are believed to play a crucial role in star formation. The large FOV and the stable instrumental polarization of SMA present an advantage for large-scale mosaic polarization observations, providing measurements of magnetic fields in various physical scales. Also, combining the SMA mosaic maps the the JCMT data will provide a more complete view of magnetic field that cannot be seen with a single pointing SMA or even ALMA observations. Our previous tests of SMA suggest that SMA is capable to do polarization mosaic mapping. This project aims to make mosaic polarization observations in Orion BN/KL and W51. W51 has been observed in 2017, and here we resubmit the Orion part of the proposal. With the proposed SMA mosaic and JCMT polarization maps, the topics of (1) B-field structures from clouds to cores, (2) outflow and B-field interaction, (3) dispersion of B-field orientation, and (4) the origins of the depolarization effects will be better studied in the W51 and Orion BN/KL massive star-forming regions.
2018B-A004Sheng-Yuan Liu1
The Excitation and Variation of A Newly Discovered Methanol Maser in the Massive YSO S255~IR (copied from 2017B-A017)Observations of cosmic masers are of great importace for investigating the physical properties and kinematics of associated astronomical objects as well as for better understanding the maser excitation mechanisms. As an example, observational and theoretical investigations have shown that there are two classes of methanol masers, with the Class II methanol masers being regarded as an effective signpost of high-mass star formation. We have recently made the discovery with ALMA of a new methanol maser, most likely being Class II, toward the massive young stellar object S255IR- NIRS3/SMA1. The varying maser activities are most likley connected to observed Class II 6.7 GHz maser flare and the YSO luminosity burst seen in the near infrared back in 2015. To further investigate the excitation and variability of this newly discovery methanol maser, we request observations in the extended configuration at 345 GHz for S255IR-SMA1. By utilizing the dual receiver operation with the wideband SWARM correlator, we will be able to observe a particular series of methanol transitions, including the newly found maser and other possible quasi-thermal lines. This will enable us to trace the time variability of the maser activity as well as to diagnose its excitation mechanism.
2018B-A006Wei-Hao Wang5
SMA Pilot STUDIES: Imaging the Brightest SCUBA-2 450 micron SourcesWe propose SMA 345 GHz continuum imaging of five bright submillimeter galaxies (SMGs) selected from our extremely deep JCMT SCUBA-2 450 um survey (STUDIES). Current studies of SMGs are limited by the single-dish confusion at 850 um and longer wavebands. ALMA unbiased surveys are not limited by confusion, but the sample sizes are limited by its small primary beam. To overcome these, we conduct extremely deep 450 um imaging with SCUBA-2, to detect a large sample of faint SMGs. In the mean time, we are relying on deep radio (3 GHz) and mid-IR (24 um) images to identify the counterparts to the 450 um sources. However, the effectiveness of this radio/mid-IR identification is unknown. A small ALMA sample of 450 um sources suggested that the radio/mid-IR method may be problematic. To further investigate this, and to pin down the counterparts to SCUBA-2 450 um sources, we plan to use the SMA to image them at 345 GHz. This will help to understand the nature of the 450 um selected SMGs, and to demonstrate that the radio/mid-IR identification can indeed be trusted. In this semester, we propose a pilot program to image the brightest five 450 um SMGs from our SCUBA-2 survey. We will expand the sample size and push the studies to fainter flux limits in future semesters. This will help to build the science case for wSMA and ALMA imaging of even larger and fainter samples.
2018B-A009Kuiyun Huang3
New Insights in Short GRBs We aim to search for submm afterglow associated with short GRBs for characterizing of the explosion physics of short GRBs based on our experiences on long-GRBs. By multi-frequency analysis including submm data taken by SMA and ALMA, we have demonstrated that afterglow follow-up in submm band is crucial to decode complex radiation components and to derive explosion parameters. With our initial studies with SMA and ALMA, we focus on nearby (z<~0.3) short GRBs that forward shock components could be detected with SMA. Short GRB science is timely; because it shares the common compact object merger model with gravitational wave sources that LIGO already detected three events. One of them showed clear association of short GRBs. Based on 11 years statistics, Swift has been detecting ~10 events per year. To respond to triggers from gravitational wave instruments (LIGO, Virogo) and Swift/BAT, we request two half-tracks with rapid observations to identify submm afterglow for three events, and an additional four half-tracks for one event to perform the afterglow monitoring. Therefore, we require three tracks in total.
2018B-A014Sheng-Yuan Liu2
The Interplay between Magnetic Fields and Stellar Feedback in the Sequential Massive Star Forming Complex G9.62+0.19Filamentary structures exist in most massive as well as diffuse molecular clouds with sizes from a few parsecs to tens of parsecs and are threaded with magnetic fields (B-fields). The prevailing B-fields are dynamically important in regulating the gas flow and accretion and consequently the formation of dense cores and stars in filamentary clouds.Meanwhile, stellar feedback from massive stars can also exert strongly influences to their surrounding medium and regulate the subsequent star formation. How do the B-field respond to stellar feedback and gauge the star formation? The G9.62+0.19 clump/filament is an ideal target to study the interplay between B-field and stellar feedback in a sequential high-mass star formation. We propose to observe the 850 um polarized continuum emission toward the G9.62 complex with the SMA. Utilizing SMA's modestly large field of view and high angular resolution and combining with JCMT SCUBA POL2 observational data, we will probe the magnetic field over the entire dense filament and nvestigate the magnetic field morphology and estimate the field strengths in and around the dense filament in G9.62.
2018B-H004Jonathan Williams4
A Search for Water and Complex Organics around an Outbursting StarWe have found a remarkably rich molecular spectrum in the disk around an outbursting FU Ori object. This provides a special opportunity to study the composition of the evaporating ices in a planet forming region. We propose to carry out a line survey using the wide bandwidth of the SMA to search for water and complex organics.
2018B-H005Jonathan Williams6
Resolved Observations of Nearby Debris DisksWe will image known debris disks to measure the radius of the emitting dust. A recent result has found a correlation between debris disk radius and stellar mass that suggests planetesimal formation may be enhanced at the CO snowline. With more resolved observations to measure the dispersion in the relation, we can assess the likelihood of this interpretation.
2018B-S011Charlie Qi3
Close-up Imaging of Comet 46P/WirtanenCompositional structure of cometary nuclei, which holds unique information about the formation and evolution of our own planetary system, is one of the least understood properties of comets. The nucleus structure can be revealed through velocity-resolved spectral time series of the mm emission lines, obtained simultaneously with multi-species observations as the cometary body rotates. The 2018 December apparition of comet 46P/Wirtanen provides an excellent opportunity for SMA to observe a Jupiter-Family Comet at very close geocentric distance (0.08 AU). We propose to use the SMA to map small scale spatio-kinematic differences in emission of primary volatiles in the near-nucleus cometary coma with the compact configuration (a linear scale of about 300 km), in order to investigate the chemical heterogeneity in the nucleus. These observations form an integral part of the observation campaign to characterise 46P in support of future rendezvous mission design.
2018B-S015Anaelle Maury8
Evidence of magnetic braking in Class 0 protostars : towards a statistical viewThe Class 0 phase represents a pivotal stage in star formation during which the angular momentum problem is generally solved through the fragmentation of the core in a multiple system or the formation of a protostellar disk. However, magnetic braking might redistribute the angular momentum in the infalling envelope, hence regulating the formation of multiple systems and circumstellar disks within individual envelopes. Whether or not magnetic fields actually play a dominant role to shape the angular momentum transport in protostellar envelopes still has to be investigated statistically from an observational perspective. We have carried out a polarization survey of 12 low-mass Class 0 protostars with SMA at 345 GHz. In Galametz, Maury, Girart et al. (submitted to A&A) we show that we detect the 345GHz polarized dust emission in each protostar of our sample. Moreover, we find clues of a very interesting correlation between the misalignment of the B-field with respect to the rotation axis at envelope scale and the formation of both large disks and multiple systems within the protostellar envelope. The sources in our sample showing the most misaligned envelope-scale B-field also have on average larger rotational energy and larger small-scale multiplicity. Here, we ask to perform similar observations of the polarized dust continuum emission at envelope scales towards a second sample of low-mass protostars, so as to increase the sample of our study, and test wether results from our pilot study holds as a statistically significant result. If our first results are confirmed, we will have shown for the first time a correlation between the properties of the native magnetic fields and the multiplicity, disk properties and envelope kinematics of low-mass Class~0 protostars.
2018B-S017Jane Huang4
A pilot wideband chemical survey of Class I protostellar disksThe chemistry of (Class II) protoplanetary disks has been studied extensively with millimeter/sub-millimeter interferometry in order to examine how processes in evolved disks set the composition of exoplanets. However, recent interferometric disk observations suggest that planet formation could already be well underway during the (intermediate) Class I stage of young stellar objects, when their disks are still embedded in envelopes. Consequently, spatially resolved molecular observations of disks still in the Class I stage are key to developing a complete picture of how the composition of planets is ultimately determined. We propose a pilot wideband chemical survey of Class I disks in Taurus, focusing on (1) probing the gas-phase abundances of carbon-, oxygen-, and nitrogen- bearing species and (2) examining chemical differentiation of the disk and envelope with a variety of molecular tracers. The results of the survey will also be compared to our ALMA and SMA Class II disk datasets to examine the chemical evolution of disks.
2018B-S018Hau-Yu Baobab Liu2
Millimeter Flux Variability/Stability of FU Orionis Objects and EXorsOur team has analyzed 40 tracks of SMA observations towards 29 young stellar objects which present accretion outbursts, namely the FUor, EXor, and FUor-like objects. Their >1 mm emission appears to have significant contribution from the hot (>300 K) inner disk (HID) of only a few AU scales. Only a few of these sources happened to be observed at the same frequencies and similar uv-coverage for multiple times, separated by from few months to a few years. We report tentative evidence of 1.33 mm flux variability from three of them: V2494 Cyg, V2495 Cyg, and AR 6A. We suspect that millimeter flux variability may not be uncommon among these outburst YSOs, however, was not being monitored by observatories with reasonably good absolute flux calibration. The flux variability may be related to the chaotic evolution of the HID, altered by their very massive and time varying accretion. We hereby take the initiative to monitor bright and compact sources which are available for the summer semester, and will follow-up the winter term sources in the next deadline.
2018B-S026Sigurd Jensen1
Quantifying water deuteration toward the densely clustered Serpens SMM1 source.Understanding the evolution of water during star formation, from the molecular cloud down to the circumstellar disk, is a central goal of astrochemistry. The amount of deuterated relative to non-deuterated water (HDO/H2O) traces the physical and chemical evolution of water because H2O is predominantly formed in the molecular cloud while deuterated isotopologues form later in the core phase. As a consequence, the D/H ratio of water should differ between isolated and densely clustered protostars since formation time-scales are likely dependent on physical properties of the local environment. To test this hypothesis, we propose to measure the HDO/H2O ratio toward the Serpens SMM1 region. This region is currently forming a dense cluster with at least 5 individual sources and is thus an ideal region over which to observe the HDO/H2O ratio in a dense environment. Comparing the results with recent observations toward isolated cores we will infer how the local cloud environment influences the water deuteration and test the proposed scenario for water formation.
2018B-S031Luca Matrŕ6
REsolved ALMA and SMA Observations of Nearby Stars (REASONS): a legacy population study of the formation location of planetesimal belts (part 3)Locating planetesimal belts is fundamental to understand their formation and evolution. We propose REASONS (REsolved ALMA and SMA Observations of Nearby Stars) to measure the radius and geometry for 26 nearby planetesimal belts, 10 of which with the SMA, completing the mm-flux-limited sample from the SONS JCMT Legacy Survey. We will confirm our newly discovered tentative correlation between belt radius and stellar luminosity, which already suggests a link to the CO snow line location in progenitor protoplanetary disks. If confirmed at high significance through REASONS, this would provide strong evidence for a common belt formation mechanism. By putting together the complete resolved sample of all mm-bright debris disks observed with the SMA and ALMA, we will also provide a crucial test of the population synthesis models that fit the observed population of IR excesses. This community effort will provide a legacy of all mm-bright resolved debris disks, fundamental for our understanding of the formation and evolution of planetesimal belts, including our own.
2018B-S039Michael Johnson6
Polarimetric VLBI with the Event Horizon TelescopeWe propose 1.3mm polarimetric VLBI observations of SgrA*, the 4 million solar mass black hole at the Galactic Center, and M87, the giant elliptical galaxy with a black hole mass of 6.4 billion solar masses. Our previous 1.3 mm VLBI observations have detected Schwarzschild radius scale structures in both of these objects, time variable structure in SgrA*, and ordered magnetic fields near SgrA*. We propose to make full polarimetric VLBI observations of SgrA* and M87 to place limits on intrinsic emission mechanisms and magnetic field structure near black holes on Schwarzschild radius scales. Interleaved observations of AGN targets will provide crucial calibration information and will produce the highest resolution studies of jet collimation and outflow. Our observations will be accompanied by complementary 3mm observations with the GMVA+ALMA together with a simultaneous multi-wavelength campaign extending from near-infrared through TeV energies. These observations will connect the smallest objects predicted by general relativity to galactic scale outflows that impact large scale structure in the Universe.
2018B-S059Maria Jesus Jimenez-Donaire4
Searching for Embedded Super Star Clusters in M82Super star clusters (SSCs) are young stellar clusters of extraordinary luminosity and compactness, which are expected to be a dominant mode of star formation in starburst-type environments. Because they are extremely small in size, deeply embedded and have short lifetimes, many aspects about their formation and evolution in different galactic environments remain poorly constrained. We will use the Submillimeter Array to observe the nuclear region of the very nearby (3.6 Mpc) starburst galaxy M82, to confirm the existence and measure the gas and dust content of candidate SSCs suggested by previous VLA imaging. If confirmed, these observations will constitute a major advance for this field, allowing us to test current cluster formation models, estimate the timescales for their formation, and evaluate the likely impact of different types of feedback for the first time. These observations carry a unique legacy value for the SMA, by producing the first sub- arcsecond, sub-mm thermal dust image of one of the brightest and most famous galaxies in the sky.

2018B B-ranked tracks with successful observations:
Project IDP.I.# TracksTitle (hover for abstract)
2018B-S046Dana Anderson10
An Exploration of Nitrogen Gas Content in Protoplanetary DisksThe lifetime of gas in circumstellar disks is a key quantity for understanding disk evolution and planet formation. Because the main component of the gas, H2, is not emissive under most disk conditions, indirect tracers are used to measure the amount of gas in disks. Conventional tracers, (sub)mm dust and CO, may be insufficient on their own due to uncertainties involved in relating their measurements to the total disk gas mass. Recent observational evidence suggests that the CO/H2 ratio may not be constant over time. We propose to investigate additional tracers that will track the nitrogen content of the gas, specifically the N2/CO ratio. Previous observations revealed enhanced N2H+/CO flux ratios in two mature, ~5-11 Myr-old, disks relative to a sample of brighter, gas-rich disks. This may indicate selective removal of CO from the gas phase over time while N2 remains. Here we propose to further investigate this idea through determination of the N2/CO ratio in a sample of disks including different environments, sizes, spectral line fluxes, and binary or multi systems. With the SMA we can simultaneously observe all chemical species required to meet our science goals allowing for efficient observations of several sources. The results of these observations would be used to plan future surveys aimed at more complete analysis of the gas content of disks as they evolve.
2018B-S028Elizabeth Cooke9
The nature of the ULIRG population in massive clusters at z=1-1.5We propose to measure the continuum and CO line fluxes for the SCUBA-2-selected star-forming galaxies at the center of three massive clusters at z~1. In our highly-successful pilot study of the cluster XCSJ2215 at z=1.46 we resolved four SCUBA-2 sources into fourteen separate continuum sources, five of which revealed CO emission which confirmed their cluster membership. With the same level of multiplicity we therefore expect to observe a statistically significant sample of >80 U/LIRGs across seven clusters (including four southern clusters to be observed with ALMA) to efficiently survey the detailed kinematic, gas and dust properties of this population. Our goal is to compare the properties of a statistically-robust sample (sufficient to split into 2-3 subsets in terms of redshift and environment) of dust-selected ULIRGs in these systems to similarly-luminous examples in the field from previous studies and to also relate them to their wider cluster environment to constrain the down-sizing of the star-forming population from z~1-2 and the build-up of the passive galaxy population within clusters.
2018B-A015Yun-Hsin Hsu4
Determination of the HyLIRG Fraction among Herschel Bright SourcesHyperluminous infrared galaxies (HyLIRGs) are the most rare and extreme sort among submillimeter galaxies, and represent the most violent galaxy formation events in the universe. HyLIRGs are great laboratories for testing hydrodynamic simulations, and probing their nature can shed light on important questions about galaxy formation. Unfortunately, Due to the rareness of these sources and the difficulties of distinguishing them from lensed sources, the sample size of HyLIRGs is very limited, and the fraction of HyLIRG and lensed objects among Herschel bright sources are unknown. We propose new SMA observations to address these problems. Using the H-ATLAS samples selected by González-Nuevo et al. (2012), we can expand the sample size of HyLIRGs. Our observations aim to detect the dust continuum. These Herschel selected sources have large position uncertainties, and SMA will allow us to obtain their accurate positions and optical and submillimeter morphologies. This will help to determine their nature (lensed or intrinsically luminous) and the HyLIRG fraction. This will lead to a systematic survey to determine the HyLIRG fraction among Herschel bright sources.
2018B-A012Cheng Cheng2
Exploring molecular gas content in low mass galaxiesWe propose 10 hours SMA observations to detect the CO ($J= 2-1$) emissions from 10 low redshift ($z \sim 0.02$) low mass ($M_*/M_{\odot} < 10^{9}$) H-ATLAS selected galaxies. All the 10 galaxies have 3$\sigma$ detection at 160$\mu$m, the SED coverage from UV to FIR and high S/N optical spectra. Our previous CO surveys as well as the other survey project have built a good coverage of the main sequence galaxies with stellar mass $M_*/M_{\odot} > 10^{9}$. However, we still lack of the CO survey that focus on the low mass galaxies, which is critically important in understanding the early stage of the galaxy formation. The CO observation we are proposing will help us to understand the star formation efficiency and the connection between the dust and gas the low mass galaxies.

Current or completed Large Scale Programs spanning ALL semesters:
Project IDP.I.# TracksTitle (hover for abstract)
2012B-S097Qizhou Zhang3
Star Formation in the Central Molecular ZoneThe inner 500 pc of our Galaxy, known as the central molecular zone (CMZ), is a star-forming environment with very extreme physical properties. Despite its large reservoir of dense gas that could form massive stars and clusters similar to the starbursts seen in galaxies, CMZ has a star formation rate a factor of 10 lower than the Schmidt-Kennicutt law. Because of the heavy extinction in the optical and infrared wavelengths, however, existing observations may miss a deeply embedded protostellar population. To investigate this scenario, we conducted a mini-survey with the SMA towards a sample of dense clouds with highest star formation potential, i.e. surface density >10^24 cm^-2 in CMZ at 280 GHz. The data reveal that most of them present compact dust continuum peaks possibly from protostellar cores. Are these peaks associated with embedded protostars? How do they compare with normal molecular cores in the Galactic disk? To address these questions, we propose to observe them in the 230 GHz band, to test protostellar nature of these objects via abundant molecular lines in this band. The SMA data will be supplemented with continuum and NH3 lines datasets obtained from the VLA. This is a pilot program to a large scale SMA project that images a significant area of the CMZ to census a population of deeply embedded protostellar objects. A lack of current star formation in the CMZ challenges a well established star formation (Schmidt-Kennicutt) law. The SMA observations play a unique role in solving this puzzle by probing young stellar populations that are possibly hidden from optical and IR observations due to heavy extinction, as well as radio continuum observations due to a lack of HII regions.
2013A-S079Michael Dunham3
(p)MASSES: (pilot) Mass Assembly of Stellar Systems and their Evolution with the SMAStars are assembled in molecular clouds through the gravitational collapse of dense cores of gas and dust. The final masses of stars are set during the protostellar stage by the complex interaction of many interrelated physical processes, including the underlying core mass function, core and disk fragmentation, the formation and evolution of protostellar disks, and mass-loss through direct ejection of jets and entrainment of surrounding material in molecular outflows. Several key questions related to the growth of stars and origins of the stellar initial mass function (IMF) are yet to be answered, including: (1) When, where, and how do cores and disks fragment into multiple systems? (2) What role do disks play in the transfer of mass from cores to stars? (3) To what extent do outflows regulate the protostellar mass accretion process? To answer these questions, we propose to conduct a 230 and 345 GHz, continuum and molecular line emission survey of a large sample of protostars in the nearby Perseus molecular cloud. Here we submit a small, pilot study of 4 targets in order to determine necessary sensitivities, verify our technical setup, and demonstrate the validity of our observations in answering the key science questions motivating this program.
2013B-S091Eric Keto61
CMZWe propose to exploit the SMA's unique combination of large primary beam, high angular resolution, and large instantaneous bandwidth to conduct the first sub-pc scale survey of the largest reservoir of dense gas in our Galaxy -- the central molecular zone (CMZ), the inner 500 pc of the Milky Way. This survey of the mm continuum and spectral line transitions will provide: (i) a complete census of the most massive and dense cloud cores; (ii) the location, strength and nature of strong shocks; (iii) the relationship of star formation to environmental conditions such as density, shocks, and large-scale flows. The high angular resolution of the SMA is necessary to find the highest density gas and image the distribution of shocks within individual star- forming clouds. The survey seeks to address fundamental open questions about the CMZ. What are the environmental conditions that lead to the formation of the most massive stars ($>$100 \Msun)? How do mass and energy flows shape the CMZ, regulate star formation, and control the activity of the central supermassive black hole? This survey will not only address immediate science goals but also provide a resource for future studies. Insofar as the CMZ resembles the central regions of other barred spiral galaxies, starburst galaxies in a quiescent phase, and the highly dense and energetic environment expected in galaxies in the early universe, this data set can be used as our nearest proxy for these environments.
2014A-S093Michael Dunham55
MASSES: Mass Assembly of Stellar Systems and their Evolution with the SMAStars are assembled in molecular clouds through the gravitational collapse of dense cores of gas and dust. The final masses of stars are set during the protostellar stage by the complex interaction of many interrelated physical processes, including the mass infall rate, core and disk fragmentation, ejection from multiple systems, the formation and evolution of protostellar disks, and mass-loss through jets and outflows. Several key questions related to the growth of stars and origins of the stellar initial mass function (IMF) are yet to be answered, including: (1) When, where, and how do cores and disks fragment into multiple systems? (2) What role do disks play in the transfer of mass from cores to stars? (3) To what extent do outflows regulate the protostellar mass accretion process? To answer these questions, we propose to conduct a 230 and 345 GHz, continuum and molecular line emission survey of all 73 protostars in the nearby Perseus molecular cloud. Our program will enable significant progress in answering all three of these questions and ultimately determining how stars are assembled from the surrounding dense gas.
2017A-S060Garrett "Karto" Keating25
The Millimeter-wave Intensity Mapping Experiment (mmIME)Molecular gas is central to the formation of stars in galaxies, but at high redshift, it has been well-studied in only a handful of the most luminous systems. Recent surveys with ALMA have hinted at a significant population (larger than theoretically expected) of molecular gas-rich (i.e., CO-bright) main sequence-like galaxies at high redshift, although these surveys have been limited in volume. While instruments like ALMA afford incredible sensitivity and resolution for performing studies of individual systems, it is suboptimal for blindly surveying for such objects over the large volumes required to reduce the impact of cosmic variance and sampling biases. We instead propose to use the SMA, whose larger bandwidth and primary beam make it more well-suited for a blind, large volume survey, covering a total area of ~100 sq. arcmin, between 195-203/211-219/227-235 GHz, within four regions within areas that are rich in multi-wavelength data sets. With these observations, we will use direct detection, stacking, and intensity mapping techniques, which will allow us to probe the abundance and physical properties of molecular gas in galaxies in a volume of nearly a million cubic megaparsecs. The proposed measurement will additionally leverage line intensity mapping efforts with both VLA, ACA, and ALMA, enabling cross-correlation between a multitude of line species. Relevant SMA Publications ------------------------- No SMA publications to date, as our first observations were completed in Feb 2016. Analysis of these data is on-going, and we are presently finalizing our results for publication. We expect to submit said publication in September/October 2017. Summary of Relevant Pilot Projects ---------------------------------- Proposal is a large-scale continuation of 2016B-S044, and is the successor to a recently completed intensity mapping experiment with CARMA. This proposal leverages two existing programs: a large-scale campaign with VLA at 1cm, and a recently completed (Cycle 4) 40-hour program with the ACA at 3mm. We also plan to propose for additional time with ACA and VLA, which will require cross- correlation with SMA data to fully enable the science potential of new data with these instruments. This proposal additionally builds off of two separate awards: one archival study focused on searching SMA calibrator fields for blind detections of spectral line emission from high-redshift objects, and one technical study looking at the feasibility of daytime observing with the SMA. The calibrator study, which is being conducting by the PI Keating and M. Fuchs, has made steady progress towards the development of a software pipeline, capable of digesting calibrator data and producing -- from a variety of instrument setups and array configurations -- bandpass, gain, and spectral SEFD/flux correction factors, with the goal of automatically being capable of producing calibrated image cubes for all calibrator observations performed by the SMA. At the time of proposal submission, we estimate that the first version of this pipeline will be ready to deploy in September 2017. The daytime observing project, which is also being led by the PI (with significant help from numerous members of the SMA staff), has also made significant progress in the past 6 months, and early tests seem to indicate that the array may be capable of operating up to 22 hours a day under "normal" weather conditions. One significant factor that was limiting daytime observations -- the degradation of pointing during post-sunrise observations -- has already been solved, allowing for generally good array performance until approximately noon HST (i.e., 18 hours of observations a day). Progress is now underway looking at methods for realtime phase correction and improved bandpass calibration techniques, as well as isolating sources of crosstalk/coupling within the system. We anticipate these efforts to offer improved observing capabilities moving forward toward the proposed observations, although we have estimated our time/sensitivity requirements with what we believe to be feasible at the time of proposal submission.
2017B-S075Jan Forbrich12
SMA Survey of Resolved Dust and Simultaneous CO Observations of GMCs in M31We propose a powerful and unique SMA survey to detect and resolve dust continuum emission in a large population of (~100) Giant Molecular Clouds (GMCs) in the famous Andromeda galaxy M31. As demonstrated in our pilot study, the SMA wideband upgrade is now enabling resolved interferometric dust continuum detections of individual GMCs in M31 at 230 GHz, the first such detections beyond the Magellanic Clouds. Our observations will provide the most robust, dust-derived measurements of the physical properties of GMCs within an external disk galaxy. We also propose to acquire simultaneous observations of 12CO(2-1) and 13CO(2-1) emission to measure the gas content of the GMCs with identical uv coverage. We will combine these measurements to characterize the fundamental physical properties of the GMC population across M31 to a degree only comparable in many key aspects to Milky Way studies. This project will enable much high-impact science including: 1) high-fidelity measurements of the GMC masses and shapes leading to an improved GMC mass function in M31, 2) direct measurements of the infamous CO "X" factor in individual GMCs and its variation across the galaxy, 3) a significantly improved assessment of Larson's scaling relations in M31 GMCs, and 4) a detailed assessment of cloud-scale star formation laws in M31, utilizing extensive existing multi-wavelength data. These results will provide an important calibration for the use of CO observations in deriving basic gas and star formation properties of external galaxies. Additional science goals include an assessment of dust emission vs optical extinction in M31. The survey will provide a unique SMA legacy that will remain unsurpassed for many years, in particular exceeding what can practically be done with ALMA due to the combination of wideband sensitivity and nearby distance of this northern target.