gc_psr.abs.tex to appear in ApJ
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\title{Finding Radio Pulsars in and Beyond the Galactic Center}
\author{James M. Cordes \& T. Joseph W. Lazio}
\affil{Dept. of Astronomy and NAIC, Cornell University, Ithaca, NY  14853-6801
	USA; cordes@spacenet.tn.cornell.edu; lazio@spacenet.tn.cornell.edu}

\begin{abstract}
Radio-wave scattering is enhanced dramatically for Galactic center
sources in a region with radius $\gtrsim 15$~arc~min.  Using
scattering from Sgr~A${}^*$ and other sources, we show that pulse
broadening for pulsars in the Galactic center is {\em at least\/}
$6.3\,\nu^{-4}$~seconds ($\nu$ = radio frequency in GHz) and is most
likely 50--200 times larger because the relevant scattering screen
appears to be within the Galactic center region itself.  Pulsars
beyond---but viewed through---the Galactic center suffer even greater
pulse broadening and are angularly broadened by up to $\sim 2$~{\em
arc~min}.  Periodicity searches at radio frequencies are likely to
find only long period pulsars and, then, only if optimized by using
frequencies $\gtrsim 7$~GHz and by testing for small numbers of
harmonics in the power spectrum.  The optimal frequency is $\nu \sim
7.3\,{\rm GHz} (\Delta_{0.1}P\sqrt{\alpha})^{-1/4}$ where
$\Delta_{0.1}$ is the distance of the scattering region from
Sgr~A${}^*$ in units of 0.1~kpc, P is the period (seconds), and
$\alpha$ is the spectral index.  A search for compact sources using
aperture synthesis may be far more successful than searches for
periodicities because the angular broadening is not so large as to
desensitize the survey.  We estimate that the number of {\em
detectable\/} pulsars in the Galactic center may range from $\le 1$
to~100, with the larger values resulting from recent, vigorous
starbursts.  Such pulsars provide unique opportunities for probing the
ionized gas, gravitational potential, and stellar population near
Sgr~A${}^*$.
\end{abstract}

\keywords{scattering --- pulsars: general --- Galaxy: center}
 
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