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Old January 24th 17, 06:06 PM posted to sci.astro.research
Martin Brown
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Default Single vs Double hot spots for BH Jets? (e.g. Pictor A)

On 23/01/2017 22:45, wrote:
On Friday, January 20, 2017 at 8:44:02 AM UTC-8, Martin Brown wrote:
On 19/01/2017 03:53,
wrote:
Example object, Pictor A


in particular, the x ray Chandra image:
http://chandra.harvard.edu/photo/201...ctora_xray.jpg

Question 1:

Has anyone proposed any model that describes a mechanism to produce
a single BH jet, or, alternating BH jets (e.g. the jet shoots one
way for a while, then the other way for a while, alternating back
and forth)?


However time of flight considerations could mean that there hasn't yet
been time for the light from the more distant hotspot of two to reach us=


in the case of a source where the jet is almost pointing at us.


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Its sometimes hard to know if your mail client is misbehaving this way.

Thanks and good point, time of flight, as the jets are million light year l=
ong, we would see the jet toward us first, and the jet away from us second,=
with perhaps 2 million years to who knows, 10 million years from jet emerg=
ence to our current view which could be anywhere along that entire evolutio=
n. The thing is, I've seen a lot of pictures, but it's always presented th=
at the hot spot is coming toward us.


The brightest one will be since we get the benefit of it being nearer,
geometrical line of sight into the beam and relativistic beaming. The
near hotspot we are looking directly at the impact shock front of the
relativistic beam into pristine IGM but on the far side we are looking
at the shock front through the backwash of material flowing away.

My point is that there ought to be 50% of these objects where the hot spot =
we observe is the hot spot of the receding jet. I understand beaming and h=
ow we might not observe the receding jet vs the jet coming at us. But, the=
hot spot should be relatively stationary and glowing, so that we see both =
hot spots if there are two to be seen. And if they shut down so, we ought =
to see half of them with the receding hot spot and no observed jet because =
it is receding.


It is fair to point out here that FRII are the most powerful radio
galaxies where the jets are way more potent than the IGM. OTOH FRI radio
galaxies have a puny jet strength compared to the IGM and look more like
terrestrial smoke stacks fighting against wind shear.

3C465 being a canonical nice bright well studied example:
http://www.jb.man.ac.uk/atlas/object/3C465.html

Or for an example 3C83.1 having a really bad hair day:
http://www.jb.man.ac.uk/atlas/object/3C83P1B.html

I don't recall seeing a hot spot without a jet feeding it such that the hot=
spot is supposed to be the receding hot spot, and no jet is observed due t=
o alignment. Is there an image of this out there that anyone knows?


3C16 is the closest I can think of where there is a huge asymmetry
between the brightness of the lobes and hotspots.

http://www.jb.man.ac.uk/atlas/object/3C16.html

You might want to look through the DRAGN catalogue at Jodrell Bank to
get a feel for what variable morphology of radio galaxies looks like:

http://www.jb.man.ac.uk/atlas/alpha.html

I'll also add the links for 3C84 and 3C303 with hotspots seen inside the
radio lobes that I forgot from a previous post:

http://www.jb.man.ac.uk/atlas/object/3C84.html

http://www.jb.man.ac.uk/atlas/object/3C303.html

Historical note for the OP.

Radio sources named Constellation A/B/C etc date from the birth of radio
astronomy and are big, very bright and well studied at many wavelengths
and resolutions.

Radio sources named 3Cnnn are from the third Cambridge catalogue (the
first truly reliable one that didn't overstate the numbers due to
sidelobe problems) and are again bright and amenable to detailed study
by modern instruments. Radio source numbers was a hot topic in the 60's
since it showed up another flaw in the Steady State theory. Namely that
looking back in time the early universe was a much more exciting place
than it is today (not at all good news for Steady State proponents).

--
Regards,
Martin Brown