- Dr. José Cernicharo - Instituto de Física Fundamental, Spain;
- Dr. Kate Pattle - University College London, UK - "Interstellar magnetic fields and other applications of dust polarimetry";
- Dr. Paul Ho - Academia Sinica Institute of Astronomy and Astrophysics, Taiwan - "Role of LLAMA in Submillimeter Wavelength Astronomy in the next decades";
- Dr. Stan Kurtz - Instituto de Radioastronomía y Astrofísica, Mexico - "Observing the Interstellar Medium with LLAMA";
- Dr. Douglas Johnstone - National Research Council, Canada - "Submillimetre Wavelength Monitoring of Protostellar Accretion Variability and Radio Flaring";
- Dr. Thibault Cavalie - Laboratoire d'Astrophysique de Bordeaux, France - "Millimeter observations of atmospheric chemistry and dynamics in the Solar System";
- Dr. Kazumasa Iwai - Nagoya University, Japan - "Single-dish observation of the Sun at millimeter/submillimeter range";
- Dr. Sheperd Doeleman - Harvard University, ngEHT Global Collaboration, EUA - "The next-generation Event Horizon Telescope: From still images to black hole cinema".
Abstracts - Invited Speakers
Interstellar magnetic fields and other applications of dust polarimetry
Dr. Kate Pattle - University College London, UK
In this talk I will discuss the power of dust polarization observations for probing the role of magnetic fields in star formation and interstellar medium evolution, and the importance of polarimetry for constraining dust properties. I will discuss observational results from existing single-dish facilities such as the JCMT and SOFIA, and interferometers such as ALMA and the SMA. I will consider the opportunities and difficulties of extracting quantitative measurements of magnetic field properties from polarization observations, and the increasing importance of comparisons between simulations and observations. Finally, I will consider how LLAMA can fit in to the exciting future of dust polarization observations, and how it will contribute to our understanding of the physics of the interstellar medium.
Role of LLAMA in Submillimeter Wavelength Astronomy in the next decades
Dr. Paul Ho - Academia Sinica Institute of Astronomy and Astrophysics, Taiwan
Submillimeter wavelength astronomy has made great progress in the last two decades, especially with the advent of interferometers like the SMA, NOEMA, and ALMA. These instruments have brought great discoveries on the fine structures of a variety of astrophysical phenomena including star and planet formation, external galaxies, and the early universe. The latest EHT results on the shadow of supermassive black holes came from the connection of these interferometers to large single dish millimeter/submillimeter telescopes to form a global VLBI telescope. LLAMA will participate also in EHT experiments. It will also be an enormous asset for studying large scale structures. The last decade has seen the development of large format cameras with thousands of pixels in the focal plane. The SCUBA-2 instrument on the JCMT is essentially equivalent to the development of CCD cameras for optical astronomy. The ability to do wide-field imaging has applications for studying magnetic fields on the large scales, surveying for rare phenomena on large fields of the sky, and obtaining large scale structures such as molecular clouds in our own galaxy or entire maps of nearby galaxies. The ability to have a large amount of observing time in the submillimeter wavelengths will also be important for studying transient phenomena. The ASIAA has made good progress in the development of submillimeter wavelength astronomy. Our work in building the SMA, ALMA, GLT, and the operation of JCMT, can provide support for the LLAMA project.
Single-dish observation of the Sun at millimeter/submillimeter range
Dr. Kazumasa Iwai - Nagoya University, Japan
Solar observation at millimeter/submillimeter rang can measure the chromosphere, an upper layer of the solar atmosphere which has been poorly understood yet. The absolute brightness temperature distribution and its spatial and time variations can be measured by a single dish observation that can be used to understand the atmospheric structures and possible heating mechanisms of the chromosphere. Therefore, the solar observation with LLAMA has a big advantage to investigate the chromospheric sciences. There are some difficulties to observe the Sun at these wavelength range. The strong radio emission should be attenuated in the receiver system to avoid the saturation. The absolute calibration of the brightness temperature requires accurate estimations of the antenna characteristics. In this talk, solar physics challenges that can be established by LLAMA and possible synergy with ALMA are summarized. The methodologies of solar observation and calibration at millimeter/submillimeter range are also summarized.
Observing the Interstellar Medium with LLAMA
Dr. Stan Kurtz - Instituto de Radioastronomía y Astrofísica, Mexico
The interstellar medium may span a wider range of topics and physical phenomena than any other branch of astronomy. Already nearly a half-century ago, Spitzer's classical text includes topics ranging from molecular, atomic, and ionized clouds, to magnetic fields, dust grains, cosmic rays, and shocks and explosive motions of HII regions and supernova remnants. More modern treatments include topics such as star formation, stellar winds and feedback mechanisms, turbulence, and astrochemistry, among others. In this talk, I will touch on only a few of these many topics, concentrating in particular on those very few where I have some experience, and also a few where I think the LLAMA telescope is well-positioned to make some valuable contributions. Many phenomena of the interstellar medium require higher angular resolution than a single-dish telescope can provide; this is especially true of my own area of research, that of high-mass star formation. Nevertheless, by shrewd use of observational probes, and by careful selection of the phenomena to study, I hope to show in this talk that single-dish telescopes such as LLAMA have a great deal to offer to studies of the interstellar medium.
Submillimetre Wavelength Monitoring of Protostellar Accretion Variability and Radio Flaring
Dr. Doug Johnstone - Herzberg Astronomy and Astrophysics Research Centre; National Research Council,Canada
The James Clerk Maxwell Telescope has been monitoring eight nearby low-mass star-forming regions in the Gould Belt at submillimetre wavelengths for six years to search for and quantify the time dependent brightness variability of the resident deeply embedded protostars. Secular variability is common among these protostars, greater than 25% of the sample show measurable long-term brightness changes and 10% show burst behaviour lasting months to years. We interpret this secular variability as reflecting changes in the mass accretion rate from the disk to the protostar, as predicted by theoretical models of (proto)stellar assembly. For a subset of our sample we have contemporaneous mid-IR light-curves which allow additional constraints on the conditions responsible for the brightness variations, confirming that the submillimetre variability is driven by changes in the dust temperature profile of the envelope. Most recently we have combined, for one source, single dish and interferometric monitoring, which has allowed us to unambiguously recover a time lag in the variability at larger angular scales and use the results to confirm the envelope structure surrounding the embedded protostar. Finally, a dedicated search for radio flares emitted by protostars and pre-main sequence stars in these regions has uncovered a single event from the TTauri star JW566. Time domain submillimetre observing is still in its infancy, and I will close with a discussion of future opportunities, especially with LLAMA, along with the importance of ever-improving submillimetre calibration techniques.
Millimeter observations of atmospheric chemistry and dynamics in the Solar System
Dr. Thibault Cavalie - Laboratoire d'Astrophysique de Bordeaux, France
Millimeter spectroscopy is a fantastic tool to expand our understanding of fundamental questions regarding the formation and evolution of the Solar System. Spectral signatures observed at the very high spectral resolution offered by heterodyne spectroscopy can reveal both the composition and dynamics of the probed atmospheres. In this talk, I will present a selection of results that address the key questions of the composition and dynamics of atmospheres in the Solar System. These results have been obtained with ground-based and orbiting telescopes (Herschel, IRAM-30m, JCMT) as well as interferometers (ALMA, Plateau de Bure, SMA) operating in the (sub-)millimeter range. In a focus on giant planet atmospheres, I will show that millimeter observations are sensitive to deep composition and can therefore constrain formation models. The spectral lines observed in this wavelength range can also result from external sources contaminating planetary atmospheres. The interactions that exist between the giant planets and their environment can therefore be better understood. Finally, the very high spectral resolution enabled by heterodyne spectroscopy is a unique tool to probe atmospheric dynamics by measuring winds. After reviewing recent results relevant to this field, I will attempt to show how LLAMA can contribute with its foreseen instrumentation.
The next-generation Event Horizon Telescope: From still images to black hole cinema
Dr. Sheperd Doeleman - Harvard University, ngEHT Global Collaboration, USA
Einstein's theories predict that a distant observer should see a ring of light encircling a black hole, which forms when radiation emitted by infalling hot gas is lensed by the extreme gravity near the event horizon. The Event Horizon Telescope (EHT) has used the Very Long Baseline Interferometry technique to image two supermassive black holes: M87 and SgrA*. These results have tested GR at the 10-15% level near the horizon and opened the door to precision studies of black holes. To advance these efforts, the next-generation EHT (ngEHT) project will quadruple bandwidths, increase observing frequency, and double the number of dishes in the global VLBI array. One of the most notable differences between the EHT and ngEHT, is the inclusion of new telescopes at new geographical sites to dramatically improve the range of interferometric baselines. These enhancements will allow us to capture the dynamics of black holes through real-time and time-lapse video. I will describe prior results, and the path to realizing the ngEHT.