Gravitational-Wave Astronomy Ophiuchu Op h s Ophiuchus S pe Su perc rcluster er Supercluster Hercules err Supercluster Capricornus Void 270° LIGO 2015-2 01 6 Coro C o ona a Borealis Bor Bo Corona Vo V oid d Void Microscopium Vo d Void Pavo vo nd d Pavo-Indus Supe S perclus c ter Supercluster A4 403 0 8 4038 ced 180° A 36 627 7 3627 Ce t r Centaurus W Wall Scu S c ptor Sculptor Vo V d Void Sc S c pto ptor p Sculptor W Wall Phoe hoe x Phoenix S Su perclus pe rc st r Supercluster C Co Coma W Wall C e t r Centaurus S Superc u t r Supercluster C o Coma S Supe perclust r p Supercluster Virg Virgo V Supe Su S p rc s er pe Supercluster LI GO 2010 Hydra H yd S upe p rc rclust l t r Supercluster 0° Perseus-Pisces P rseus-Pi e s-Pi ce Supercluster Supercluster Fornax Void Columba C Void Canis Majorr Void 90° Leo Le o S Superc perc st r p Supercluster 100 million light-years Columba Columba Supe S up rcluster Supercluster COSMIC REACH For its first eight years of operation, LIGO could "hear" gravitational waves from neutron star mergers out to about 70 million light-years (yellow sphere), and black hole mergers as "loud" as GW150914 out to about 1.9 billion light-years (not shown) - but it found nothing. Once Advanced LIGO came online in 2015, with significant improvements made to its dectectors' sensitivity, the reach quadrupled (red sphere), upping the volume accessible to LIGO by roughly a factor of 40. 30 S E P T E M B E R 2 0 1 7 * SK Y & TELESCOPE LE A H TISCIO N E / S&T; SO U RCES: R IC H A R D POWE LL , M A R T Y N OV E T A L . 2 016 , PH YSICAL RE VIE W LE T TERS Ad n va