Balloon borne instruments detected 511keV photons coming from the direction of the centre of our galaxy?

Question

1keV=10^3eV. What is the wavelength os such photons? In what part of the electromagnetic spectrum do they originate?

Answer 1

from e = hν, i can calculate the frequency, ν (greek letter "nu").

h = 6.6261 x 10 e-34 joule seconds (kg m²/s).

also,

1eV = 1.602 x 10e-19 joules (kg m²/s²)

so,

[511 x 10e3] x [1.602 x 10e-19] = 8.186 x 10e-14 kg m²/s²

ν = e / h
= [8.186 x 10e-14 kg m²/s²] / [6.6261 x 10e-34 kg m²/s]
=1.235 x 10e20 Hz (1/s)

from this i can calculate wavelength, λ = c / ν

λ = [2.998 x 10e17 nm/s] / [1.235 x 10e20 1/s]
= 2.427 x 10e-3 nm

this is in the gamma-ray region of the spectrum.

Answer 2

511 keV is very common. It is the energy of the gamma ray emitted when an electron is destroyed (as in electron-positron collision). The wavelength is inversely proportional to energy. The relation is:

e = c * h / L

where

c = speed of light (2.997 E+8 m/sec)
h = Planck's constant (6.626E-34 joule*sec)
e = Photon energy
L = Wavelength

also: 1 eV = 1.602E-19 joule

In answer to your question:

L = 2.42E-12 m