We report the X-ray population study in the giant molecular cloud Sagittarius B2 ( Sgr B2 ) .
More than a dozen of X-ray cloud members ( and candidates ) are discovered with Chandra .
Two bright X-ray sources are located near Sgr B2 Main , the most copious complex of the ultra compact HII sources .
The X-ray spectra are fitted with a thin thermal plasma model of 5–10 keV temperature .
The intrinsic luminosity after correcting the absorption of \sim 5 \times 10 ^ { 23 } ~ { } H~ { } cm ^ { -2 } is \sim 10 ^ { 33 } erg s ^ { -1 } .
Although these two X-ray sources are attributable to young stellar objects ( YSOs ) in the same HII complex , they are in sharp contrast ; one at the center of the HII complex exhibits strong K-shell transition lines of iron , while the other near the east has only weak lines .
The other HII complexes , Sgr B2 North and South , also show hard and highly absorbed X-ray emissions due possibly to the star formation activity .

The composite X-ray spectrum of the other cloud member X-ray sources is fitted with a thin thermal plasma of \sim 10-keV temperature with the hydrogen column density ( N _ { H } ) of 1.3 \times 10 ^ { 23 } ~ { } H~ { } cm ^ { -2 } , and the individual X-ray luminosity of a few times of 10 ^ { 31 - 32 } erg s ^ { -1 } .
These are likely to be a single or cluster of YSO ( s ) , but neither radio nor infrared counterpart is found .
An alternative scenario of isolated white dwarfs powered by the Bondi-Hoyle accretion from the dense cloud gas is also discussed .
The X-ray spectra exhibit an additional 6.4-keV line of neutral or low-ionization irons , which indicates that the environment gas is concentrated near at the sources .