Modeling the Local Bubble
D. P. Cox;
LNP, 1998, 506, 121
ABSTRACT:Modeling the Local Bubble is one of those activities fraught with danger.
It is very easy to be too naive, to fail to consider
the dependence of the model on assumptions about the nearby ambient state,
or the likelihood of such a structure.
It is similarly easy to become so
caught up in the details of the vicinity that it is unclear where to begin a
necessarily idealized modeling effort.
And finally, it is important to remember
that the data we have may in some cases be lying to us, and that we have not yet
learned to read their facial expressions quite carefully enough.
That said,
I've tried in this paper to be helpful to those who may wish to take the risks.
I surveyed the very most basic stories that the data seem to tell, and
pointed out the standard coincidences that may be telling us a lot about what is
happening, but may turn out once again to have been just coincidences.
I've
described 5 distinct conceptions that in one flavor or another pretty well survey
the collection of mental images that have so far been carried by those
who've attempted models.
One may be right, or something entirely different
may be more appropriate.
It's at least vital to realize that a conception
comes first, followed by a simplified model of details.
I've also included a
long list of questions directed at observers.
Some have partial answers,
some one wouldn't know today quite how to approach.
But it is a list that
students of the soft x-ray background, interstellar absorption lines,
possible instrumentation, and the heliosphere may wish to review from time to
time, just to see whether they can figure out how to be more helpful.
There is
another list for modelers, things the models must address,
however-so-flimsily if necessary, because there are strong observational constraints
(and stronger ones coming) on what can and cannot be present in the local
ISM.
To that I've added a few remarks concerning x-ray emission coming from
beyond the Local Bubble, and another few on how x-ray emission from within the
solar system might be contaminating what we see.
That last bit is new,
exciting, and possibly wrong, but it is an example of the ongoing wariness I
believe one has to take toward the facts in the case.
By the way, Dieter, it
really was a great meeting.
CODE: cox98