Landmark discoveries
The gamma-ray sky, made visible.
A few of the moments that defined the Fermi-LAT era — each one an interactive look at what the highest-energy light in the universe revealed. The signature discovery, the flaring binary PSR B1259−63, lives on the home page.
Discovery · 2008
The first gamma-ray pulsar
In 2008, Fermi-LAT found a pulsar no radio telescope had ever seen — PSR J0007+7303, buried in the supernova remnant CTA 1. It was the first pulsar ever discovered in a blind search of gamma rays alone, and Aous Abdo led the analysis. It proved that a whole hidden population of radio-quiet gamma-ray pulsars was waiting — and hundreds soon followed.
Two beams → two pulses per turn
- Pulsar
- PSR J0007+7303 · 315.9 ms
- Remnant
- CTA 1 supernova remnant
- How found
- Blind search — gamma rays alone
- Why it mattered
- First radio-quiet gamma-ray pulsar
Discovery · Fermi-LAT era
Gravitational lensing in gamma rays
Einstein predicted that gravity bends light. A century later, Fermi-LAT watched a foreground galaxy bend the gamma-ray flares of the distant blazar B0218+357 — the same outburst arriving twice, about 11.5 days apart, along two paths of unequal length. It was the first time gravitational lensing had ever been seen in gamma rays — a milestone of the mission Abdo helped build.
- Source
- Blazar B0218+357
- Lens
- Foreground spiral galaxy
- Two images
- ~0.3″ apart — the most compact known lens
- Time delay
- ~11.5 days between the images
The physics
How a source shines — radio to TeV
Every source in Abdo's catalogs is, underneath, a spectrum — a fingerprint of how it radiates across the electromagnetic spectrum. Blazars show the classic double hump: low-energy synchrotron light, then the same particles boosting photons up into the gamma-ray band that Fermi-LAT opened. Explore it below.
Two humps: relativistic electrons emit low-energy synchrotron light, then boost photons up to gamma rays by inverse Compton scattering. TheFermi-LAT window sits on the high-energy hump.