CLAXSON universe

What are X-rays?

• A type of light invisible to our eyes

• Electrons emitted by radioactive substances

• Ultrasounds for medical images

• Lightning produced in storms

Why do we need satellites to observe astronomical objects that emit X-rays?

• A satellite can reach closer to the astronomical object

• To avoid interferences with the X-rays in hospitals

• X-rays cannot penetrate the Earth's atmosphere

• X-rays detectors work better under low gravity conditions

Which of these astronomical objects DO NOT emit X-rays?

• The Sun

• The Moon

• Supernovae

• Comets

An X-ray binary is a system composed of:

• A star and a black hole

• A star and a white dwarf

• A star and a neutron star

• A star and a planet

What is the central engine of an AGN?

• A neutron star

• A supermassive black hole

• A star like our Sun

• A Big Bang

AGNs are brighter in:

• Optical

• Infrared

• At all frequencies equally

• X-rays

What kind of spectrum (=intensity of light at different X-ray « colors ») is expect for AGNs?

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In which frequencies are Stars brighter?

• X-rays

• Ultraviolet

• Optical and Infrared

• Equally bright in all of them

Most stars have a pretty constant luminosity. How will be their light curve?

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We expect to see X-ray binaries:

• Only close (in the sky) to the Milky Way

• Far from the Milky Way

• In the center of a black hole

• Either close (in the sky) to the Milky Way or to another galaxy