Figure 3.
Line-of-sight velocities
(left panels) and velocity dispersions (right
panels) of the gas comprising the nebulae (in
units of km/s).
that in these two different types of objects
we see two fundamentally different mechanisms of producing ionized gas on galaxywide scales. However, the mere fact that the
gas is distributed over the entire galaxy does
not imply that the gas is outflowing.
The second piece of the puzzle is the kinematic measurements (Figure 3). The Doppler
effect allows us to determine the average
line-of-sight velocity of the gas at every spatial element in the field-of-view. If the outflow is completely isotropic, then the average radial velocity at any point is in fact zero;
thus, our measurements critically rely on the
intrinsic anisotropy of quasar winds.
Fortunately, such anisotropies seem to be
common. Indeed, in Figure 3 we see in both
SDSS J0319-0058 and SDSS J1040+4745 that
one side predominantly shows blue-shifted
emission, while the other side is mostly redshifted. This means that the gas on one side
is moving towards us (and away from the
galaxy, which is in the center of each image);
the gas on the other side is moving away
from us (and the galaxy).
12
GeminiFocus
Our interpretation of the GMOS
observations is that we have finally observed the long-sought
evidence of radiation-pressuredriven quasar winds. We are conducting further analysis of our
dataset to construct kinematic
models of quasar outflows and
determine their energetics. This
will allow us to estimate the effects of such winds on galaxy
evolution. Furthermore, this semester we are obtaining new
Gemini observations of a comparison sample of unobscured
quasars to determine the effects
of quasar orientation, and perhaps evolutionary stage on the
observed properties of the outflows. We are grateful for the opportunity to
use world-class Gemini data to reveal the critical details of the process of quasar feedback.
References:
The first of the papers describing these results
will be published in the Monthly Notices of the
Royal Astronomical Society.
Kauffmann, G., et al., Monthly Notices of the Royal
Astronomical Society, 346: 1055, 2003
Stoughton, C., et al., The Astronomical Journal,
123: 485, 2002
York, D. G., et al., The Astronomical Journal, 120:
1579, 2002
Guilin Liu is a postdoctoral researcher at the
Department of Physics and Astronomy at Johns
Hopkins University in Baltimore, Maryland. He
can be reached at: [email protected]
Nadia Zakamska is an assistant professor at the
same department. Her e-mail address is:
[email protected]
December2012