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.
Explore
The TeV sky, in three dimensions
Abdo's Milagro discoveries plotted on the celestial sphere, in Galactic coordinates. The bright ring is the Galactic plane — where nearly all the sources sit. Drag to orbit the sky; it rotates on its own.
3D view loads as it approaches · drag to rotate · scroll to zoom
View the plotted sources as text
- MGRO J2019+37ℓ 75°, b 0.2° · discovery
- MGRO J2031+41ℓ 80.2°, b 1.1° · discovery
- MGRO J1908+06ℓ 40.4°, b -1° · discovery
- Cygnus diffuse regionℓ 74°, b 0° · diffuse
- Crab Nebulaℓ 184.6°, b -5.8° · reference
Discovery · 2008
A pulsar discovered through gamma rays alone
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
Fermi-LAT study · 2015
A lensed blazar with a missing gamma-ray echo
The foreground galaxy lensing PKS 1830−211 creates two images of the distant blazar. Radio measurements predict that a flare in the second image should follow roughly 25 days after the first. In the Fermi-LAT data, however, Abdo and the collaboration found no substantial delayed gamma-ray activity, constraining the gamma-ray flux ratio between the images to greater than six. That mismatch offers a probe of the emitting region, the lens, and possible microlensing.
- Source
- Blazar PKS 1830−211 · z = 2.507
- Lens
- Foreground spiral galaxy
- Expected radio delay
- ~25 days between the images
- Fermi-LAT result
- No substantial delayed gamma-ray flare · flux ratio >6
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. The Fermi-LAT window sits on the high-energy hump.
View the spectrum bands as text
- Radio · 10⁹–10¹¹ Hz
- Infrared · 10¹¹–10¹⁴ Hz
- Optical / ultraviolet · 10¹⁴–10¹⁶ Hz
- X-ray · 10¹⁶–10¹⁹ Hz
- GeV · Fermi-LAT · 10²²–10²⁵·⁴ Hz
- TeV · 10²⁵·⁴–10²⁷ Hz