Results are reported from the first survey of X-ray emission from galaxies in pairs .
The sample consists of fifty-two pairs of galaxies from the Catalog of Paired Galaxies ( CPG ) Karachentsev ( 1972 ) whose coordinates overlap ROSAT Position Sensitive Proportional Counter ( PSPC ) pointed observations .
The mean observed log l _ { x } for early-type pairs is 41.35 \pm 0.21 while the mean log l _ { x } predicted using the l _ { x } -l _ { b } relationship for isolated early-type galaxies is 42.10 \pm 0.19 .
With 95 % confidence , the galaxies in pairs are underluminous in the X-ray , compared to isolated galaxies , for the same l _ { b } .
A significant fraction of the mixed pair sample also appear similarly underluminous .
A spatial analysis shows that the X-ray emission from pairs of both types typically has an extent of \sim 10 - 50 kpc , much smaller than group intergalactic medium and thus likely originates from the galaxies .
CPG 564 , the most X-ray luminous early-type pair , 4.7 \times 10 ^ { 42 } ergs sec ^ { -1 } , is an exception .
The extent of it ’ s X-ray emission , > 169 kpc , and HWHM , \sim 80 kpc , is comparable to that expected from an intergalactic medium .
The sample shows only a weak correlation , \sim 81 % confidence , between l _ { x } and l _ { b } , presumably due to variations in gas content within the galaxies .
No correlation between l _ { x } and the pair velocity difference ( \Delta v ) , separation \Delta r , or far-infrared luminosity ( l _ { fir } ) is found though the detection rate is low , 22 % .