Evidence for massive warm-hot circumgalactic medium around NGC 3221
  We report a 3.4$\sigma$ detection of the warm-hot, massive, extended
circumgalactic medium (CGM) around an L$^\star$ star-forming spiral galaxy NGC
3221, using deep Suzaku observations. The temperature of the gas is $10^{6.1}$
K, comparable to that of the Milky Way CGM. The spatial extent of the gas is at
least $150$ kpc. For a $\beta$-model of density profile with solar abundance,
the central emission measure is EM = $3\pm 1 \times 10^{-5}$ cm$^{-6}$ kpc and
the central electron density is $n_{eo} = 4\pm 1 \times10^{-4}$ cm$^{-3}$, with
a slope of $\beta = 0.56$. We investigate a range of $\beta$ values, and find
that the details of the density profile do not change our results
significantly. The mass of the warm-hot gas, assuming a metallicity of
$\frac{1}{3}$ Z$_\odot$ is $16 \pm 3 \times 10^{10}$ M$_\odot$, being the most
massive baryon component of NGC 3221. The baryon fraction is $f_b$ = 0.120
$\pm$ 0.036 (statistical) $^{+0.104}_{-0.048}$ (systematic), consistent with
the cosmological mean value, closing the baryon budget of this galaxy. We also
investigated the missing metals problem in conjunction with the missing baryons
problem and conclude that metals are likely to be preferentially expelled from
the galaxy. Ours is the first detection of an extended warm-hot CGM around an
external L$^\star$ star-forming spiral galaxy, where the CGM likely accounts
for the missing galactic baryons.
