X-Ray and Near-Infrared Studies of the Star-forming Cloud L1448

Abstract

We present the results of X-ray and near-infrared (NIR) observations of L1448, a star-forming region in the Perseus cloud complex using the Chandra X-Ray Observatory and the 4 m telescope at the Kitt Peak National Observatory. We detect 72 X-ray sources in a ~17' × 17' region with a ~68 ks ACIS exposure down to the X-ray flux limit of ~ 10-15 ergs s-1 cm-2 (0.5–8 keV), for which we conduct follow-up NIR imaging observations in a concentric ~11' × 11' region with FLAMINGOS down to m ~ 17 mag. Twelve X-ray sources have NIR or optical counterparts. By plotting X-ray mean energy versus the NIR-to-X-ray flux ratio, the X-ray sources are clearly separated into two groups. The X-ray spectral and temporal features, as well as NIR magnitudes and colors, indicate that one group mainly consists of young stellar objects (YSOs) in the cloud and the other of background extragalactic sources. Ten X-ray-emitting YSO candidates are thus newly identified as low-mass or brown dwarf mass sources from their NIR magnitudes. In addition, a possible X-ray signal is found from a midinfrared protostar, L1448 IRS 3(A). The lack of detection of this source in our deep NIR images indicates that this source has a very steep spectral slope of gtrsim3.2 in the 2–10 μm wavelength range.