Magnetic field structure in the diffuse neutral ISM: a joint analysis of Zeeman splitting and filamentary HI emission

Marta Nowotka (Stanford)

The 21 cm line of neutral hydrogen offers two complementary probes of interstellar magnetic fields: Zeeman splitting, which measures the line-of-sight magnetic field strength, and the morphology of HI emission filaments, which traces the magnetic field orientation on the sky. I present a study combining these two tracers to investigate the three-dimensional structure of the magnetic field in the diffuse neutral interstellar medium. I also share new Zeeman measurements in HI absorption from FAST and discuss future opportunities to expand the Zeeman sample.

State of Cosmological Measurements from CHIME

Tristan Pinsonneault-Marotte (Stanford)

The Canadian Hydrogen Intensity Mapping Experiment (CHIME) has been observing the entire northern sky from the DRAO every day, for over 6 years. Designed to measure the redshifted 21 cm line of neutral Hydrogen and map the large-scale structure between 0.8 < z < 2.5, CHIME  uses interferometry and a large field-of-view over a broad, finely-sampled band to achieve a very rapid mapping speed. These unique characteristics also make it well-suited to other science cases such as pulsar monitoring, transient searches, and galactic science — areas where it has had a significant impact. In this talk I will focus on cosmological measurements from CHIME, which finds itself at the cutting edge of 21 cm cosmology. The main challenge facing the field is the difficulty of separating the faint signal from overwhelmingly bright radio foregrounds — a task complicated by the presence of RFI and instrumental calibration. Despite these issues, the CHIME team has already published detections of 21 cm emission in cross-correlation with galaxy redshfit surveys and the Lyman-alpha forest, the first of their kind. Analysis effort is now focused on producing a detection of the power spectrum on small scales from CHIME data alone. In parallel, a search for high-redshift neutral Hydrogen absorber systems is ongoing using an enhanced frequency resolution stream of the data. Finally, future avenues for cross-correlation are also under study, in particular with lensing of the CMB.

What has CHIME Accomplished?

Mark Halpern (UBC)

We could not have built CHIME without the help we received from people at the DRAO. I would like to share with you a description of what you have helped to create, a unique instrument exploring several quite different astronomical puzzles. I will try to explain to a non-specialist CHIME’s progress in mapping neutral hydrogen to track the expansion history of the Universe, finding and studying Fast Radio Bursts across cosmic distances, and measuring signals from all of the Galactic Pulsars visible from Canada at daily or weekly cadence. For each topic I will describe the puzzle we are trying to solve, explain how the properties of this very strange telescope we have built make it be so well suited to that particular puzzle, share some of what we have learned so far and describe what the future holds.

Here be DRAGONS: Revealing the three-dimensional structure of the local Galactic magnetic field

Rebecca Booth (U Calgary)

Like the Sun and the Earth, our Galaxy has a magnetic field. Earth’s field shields us from the solar wind, while the Sun’s field protects the Solar System from cosmic rays. The Galactic magnetic field is also essential: it influences star formation and supports the structure of the Galactic disk. However, measuring this field is challenging as magnetic fields are not emission sources that can be observed with a telescope. Instead, we observe the Galactic magnetic field indirectly by measuring Faraday rotation, the change in polarisation angle that occurs when a linearly polarised wave passes through a region containing a magnetic field and free electrons. My research uses DRAGONS, the recent broadband radio polarisation survey observed with the ‘DVA-2’ 15-m telescope at the DRAO. With the highest resolution Faraday rotation measurements of the Northern sky ever obtained, DRAGONS offers an unprecedented opportunity to study the three-dimensional structure of the Galactic magnetic field with a high degree of detail. I will present a new model that explains the main features of the magnetic field within 1 kpc of the Sun, including a reversal in the direction of the field between the Local and Sagittarius arms. It is impossible to fit the data without this reversal. Though the cause of the reversal is unknown, I will suggest a few possible origins. By deepening our understanding of the geometry of the local Galactic magnetic field, this model is an important step toward solving the puzzle of how magnetic fields form, evolve, and influence our Galaxy.

A Candidate Planet Orbiting our Closest Solar Type Neighbor or Have we found the Host Planet of the Moon Pandora

Chas Beichman (NASA Exoplanet Science Institute)

Coronagraphic observations at 15 microns with the MIRI instrument on the James Webb Space Telescope (JWST) revealed a candidate gas giant planet orbiting the nearby star Alpha Centauri A. With a semi-major axis of 1.5-2.5 au and an eccentricity of 0.4, the candidate is heated by Alpha Cen to an effective temperature of 225K. It has a radius of ~1 RJup and a mass less than 150 Earth masses, or roughly the size and mass of Saturn. I will discuss the challenges of observing the 3rd brightest star in the sky with JWST and reducing the data in the presence of a bright companion star, Alpha Cen B. I will also put the existence of such a planet in the context of the formation and evolution of planets in close binary systems.

DRAGONS

Anna Ordog (UBCO/DRAO)

TBD