energiaspektri

Energiaspektri, commonly called the energy spectrum, is a description of how a system's energy is distributed across different energies. It applies to photons, particles, or the total energy content of a source, and it can be represented as a differential distribution over energy or as an integrated, cumulative quantity. The spectrum reflects the physical processes that generate or transport energy.

Mathematically, the differential energy spectrum is often written as dN/dE, the number of particles with energy in [E, E+dE], or as dF/dE for energy flux, with units depending on context. Spectra can be continuous, as from thermal emitters, or discrete, as in atomic or molecular transition lines. In radiative contexts, the spectral energy distribution (SED) expresses energy emitted per unit area per unit time per unit energy.

Characteristic shapes reveal physics. A blackbody emits a Planck spectrum, determined by temperature. Non-thermal processes, such as synchrotron emission or shock-accelerated particles, yield power-law spectra, often plotted on log-log scales. In particle astrophysics and cosmic rays, the energy spectrum is typically a broken power law with changes in slope reflecting different acceleration or propagation regimes.

Measuring energiaspektri employs spectroscopy for photons, calorimetry or magnetic spectrometers for charged particles, and time-of-flight or semiconductor detectors. Data are often presented as log-log plots to emphasize features across many orders of magnitude.

Applications include diagnosing emission mechanisms, estimating energy budgets in stars and galaxies, understanding particle acceleration, and characterizing detector response in experimental physics.