Code for Early Bright Hot - Updated
There is a code to follow when reading astronomy news stories. This is a follow up to the earlier post on this topic, to supersede it rather than describe changes. The main difference: hot can depend on the telescope.
'early' means it has an extreme red shift which is assumed to have an extreme velocity and so then it is also at an extreme distance. Billions of light years away means that many years ago.
These are incorrect assumptions. Red shifts from galaxies are different than from quasars. A galaxy red shift is proportional to the intergalactic hydrogen atoms in the light path so intervening clouds anywhere in the path increase the shift. Quasar red shifts come from hydrogen ions zooming toward the core and indicate nothing about the quasar distance or velocity.
'brighter' means the red shift indicates an extreme (wrong) distance for this object but the conclusion is the observed brightness is wrong. This 'brighter' can refer to any part of the spectrum from radio to infrared to light to X-ray.
'hot' depends on the telescope. With Chandra:
'hot' means there are X-rays. Those from intergalactic space are assumed to come from an extremely hot gas; while those from a galactic core are assumed from material around a black hole. Each is wrong because X-rays are part of synchrotron radiation implying there are electric and magnetic fields in action. The assumption for 'hot' is this hot gas behaves like a blackbody so its high temperature results in blackbody radiation in the X-ray band.
For a black hole a proposed accretion disk is assumed to have that blackbody temperature for X-rays.
With the Spitzer or WISE telescopes, 'hot' is stronger in the infrared.
Images of the M87 core in radio or in infrared show the same donut, generated by the plasmoid and its synchrotron radiation. Technically this heat is electrical not thermal.
A few hours later I added this comment:
I should have included a definition:
Black-body radiation is the thermal electromagnetic radiation within or surrounding a body in thermodynamic equilibrium with its environment, emitted by a black body (an idealized opaque, non-reflective body).
A hot gas or plasma is not a blackbody so its temperature cannot be measured this way. These assumed temperatures are invalid.
Hit back to go to previous page in history.
Here is the list of topics in this Cosmology Topic Group .
Ctrl + for zoom in; Ctrl - for zoom out ; Ctrl 0 for no zoom;
triple-tap for zoom to fit; pinch for zoom change; pinched for no zoom