First observing run of LIGO's Advanced detectors begins

18 September, 2015

The first official 'observing run' (O1) of LIGO's advanced detectors in Hanford WA and Livingston LA began the 18th of September. While this date marks the official start of data collection, both interferometers have been operating in engineering mode collecting data for some weeks already as technicians, scientists, and engineers worked to refine the instrument to prepare it for official data-collection duties.

Our PhD student, Miquel Oliver, was in the Hanford observatory at the time that the observational run began, doing a three month internship.

LIGO's detectors are searching for gravitational waves emanating from the depths of space. Gravitational waves are the evanescent vibrations of space-time generated by some of the most violent explosions and events occurring in the Universe; events like supernovae (exploding stars) and the collision and merger of black holes and neutron stars (the remnants of massive stars after their thermonuclear deaths).

These events are so cataclysmic that when they occur, they cause the very fabric of space itself to vibrate like a drum. The waves of rippling space-time emanate in every direction, traveling at the speed of light, physically distorting everything in their paths. But the farther they travel from their source, the smaller and smaller the ripples become until, by the time they reach the Earth, the spatial distortion caused by the waves is on the order of a billionth the diameter of an atom! This unimaginably small movement is what LIGO’s detectors are designed to sense.

Another notable achievement on this day: LIGO’s advanced detectors are already three times more sensitive than Initial LIGO was by the end of its observational lifetime. Out of the gate, the new and improved LIGO will listen for gravitational waves from as far away as 225 million light years (70 Mpc)1, compared to the 65 million light years (20 Mpc) reachable at the end of LIGO's last search for gravitational waves (which concluded in 2010). Three times the reach in distance translates into 27 times more volume of space accessible to LIGO than before.

This first observing-run will last 3 months, during which time both detectors in Washington and Louisiana will operate in tandem for as many hours per day as they can be kept in ‘lock’ mode (keeping both interferometers locked for very long stretches of time is a challenge, but making sure both instruments are operating with the same precision for the same times is crucial to LIGO’s mission of detecting gravitational waves). As more observing runs occur in the months and years to come, the instruments will be fine-tuned until the detectors achieve 10 times the sensitivity of initial LIGO, listening for gravitational waves generated as far away as 650 million light years (200 Mpc).

In the press: UIB