Session D03: AMO Frontiers in Astrophysics

Live

Atom interferometry and atomic clocks continue to make impressive gains in sensitivity and time precision. With this in mind, I will discuss the potential science reach and technical feasibility of gravitational wave detectors based on precision atomic sensors. I will describe a new type of atom interferometry based on narrow-line optical transitions that combines inertial sensitivity with features from the best atomic clocks, allowing for increased immunity to technical noise and systematic errors. This technique is central to the Mid-band Atomic Gravitational wave Interferometric Sensor (MAGIS) proposal, which is targeted to detect gravitational waves in a frequency band complementary to existing detectors (0.03 Hz – 10 Hz), the optimal frequency range to support multi-messenger astronomy. I will also discuss MAGIS-100, a 100-meter tall atomic sensor now being constructed at Fermilab that will serve as a prototype of such a gravitational wave detector, and that will be sensitive to proposed ultra-light dark matter (scalar and vector couplings) at unprecedented levels.   

Live

Dark matter is the dominant matter in the universe, yet its nature and origin remain unknown. Determining the distribution of dark matter in the Milky Way Galaxy is crucial to grounding searches for the particles comprising dark matter. Measurements of the Galactic dark matter content currently rely on model assumptions to infer the forces acting upon stars from the distribution of observed velocities. Here, we propose to apply the radial velocity method honed for exoplanet astronomy, to measure the change in the velocity of stars over time. This direct measure of the acceleration of stars would provide a direct probe of the local gravitational potential. We present a realistic strategy to observe the differential accelerations of stars in our Galactic neighborhood with next-generation telescopes, and numerical simulations of the expected sensitivity of such a program.   

Live

Laser frequency combs were originally developed as the clockwork, or gears, of a new generation of optical clocks that presently operate with uncertainty at the 19-th digit. However, this diverse technology has shown itself to be equally valuable for a much wider range of applications. In astronomy, frequency combs function as an ideal calibration source for precision radial-velocity spectroscopy aimed at finding and studying earth-mass habitable exoplanets. In this talk, I will highlight the science and technology of the near infrared laser frequency comb technology that we built as the primary calibrator for the Habitable Zone Planet Finder (HPF). Fiber-integrated electro-optic modulators and broadband supercontinuum generation in nanophotonic waveguides provide a 30 GHz frequency comb spanning 700 to 1600 nm. The comb has been continuously operated for nearly two years and is used nightly with the HPF for astronomical spectroscopy, enabling on-sky stellar radial velocity uncertainty of 1.5 m/s. This precision is unparalleled for such near-infrared technology and has led to confirmation and orbital characterization of exoplanets around nearby M-dwarfs. We have also been employing a laser frequency comb to calibrate a near-infrared heterodyne radiometer with resolving power of 2,000,000. As a first application we observed a selection of iron lines in the solar spectrum near 1560 nm, achieving absolute frequency instability on measurements of single lines at better than 20 MHz in 20 seconds of averaging. Such high-resolution spectroscopy is being explored as a means to disentangle the spectroscopic signatures of surface activity from the center of mass motion of stars.