ADDITIONAL OBSERVATIONS AND ANALYSIS OF THE LYMAN-ALPHA ABSORPTION-LINES TOWARD THE QSO PAIR Q0107-025A,B

We present further analysis and discussion of the properties of the ab sorption lines in the QSO pair Q0107-025A,B (z(em) = 0.956, 0.952; ang ular separation 1.'29) based upon spectroscopy obtained with the Faint Object Spectrograph (FOS) of the Hubble Space Telescope (HST). We als o present observations of the pair at shorter wavelengths taken with t he HST Goddard High Resolution Spectrograph lower-solution grating, as well as Multiple Mirror Telescope spectra obtained with the intent of looking for metal-line counterparts to the Lyman-alpha absorption sys tems. The most interesting feature revealed by the GHRS spectra is a w eak Lyman limit system with a redshift of z(LLS) = 0.3997. The Lyman l imit system itself is seen only in Q0107-025B, but corresponding Ly al pha lines can be seen in the FOS spectra of both Q0107-025A and B indi cating that lower column density gas extends out to greater distances than higher column density gas. From a sample of 5 sigma lines with W- 0 > 0.32 Angstrom detected in the FOS spectra, we count five systems ( including a probable system) common to both spectra with velocity diff erences less than 150 km s(-1) and six systems that are not in common to both spectra in the redshift range 0.48 < z < 0.89. From the presen ce of common absorption, we obtain lower limits on the radius of the a bsorbers of 140-160 h(-1) kpc [h = H-0/(100 km s(-1) Mpc(-1)) q(0) = 0 .5]. Using a simple maximum-likelihood analysis, we estimate a charact eristic radius of 505 h(-1) kpc assuming spherical absorbers, with con fidence lower and upper limits of 345 < R < 1520 h(-1) kpc. For diskli ke absorbers, we derive a most probable radius of 715 h(-1) kpc and 95 % confidence limits of 470 < R < 2310 h(-1) kpc. We also present a new statistical technique to test the relative likelihood of three geomet ric models. In particular, we consider spherical absorbers, with and w ithout a distribution in size, as well as filamentary and disklike abs orbers. Spherical absorbers with uniform radius can be ruled out since they cannot simultaneously reproduce the large equivalent width coinc idences and anticoincidences observed. The model that best reproduce t he equivalent width distribution of the observed coincident and antico incident systems corresponds to randomly inclined disks with character istic radius 915 h(-1) kpc and 95% confidence interval 560 < R < 1270 h(-1) kpc. Our results are in agreement with recent cosmological simul ations that produce Ly alpha forest absorbers in the form of filaments and sheets with coherence lengths as great as 1 Mpc.