X-rays from the Power Sources of the Cepheus A Star-Forming Region

TL;DR

This study used Chandra and Spitzer observations to resolve multiple X-ray sources in Cepheus A, revealing their properties and potential origins, and providing new insights into the star-forming region's energetic processes.

Contribution

The paper presents the first resolved X-ray sources in Cepheus A and analyzes their properties, offering new understanding of the region's energetic phenomena and star formation activity.

Findings

At least 3 X-ray sources identified in Cepheus A.

Sources have high X-ray luminosities and hard spectra.

HW2 is not detected, contrary to previous assumptions.

Abstract

We report an observation of X-ray emission from the exciting region of Cepheus A with the Chandra/ACIS instrument. What had been an unresolved X-ray source comprising the putative power sources is now resolved into at least 3 point-like sources, each with similar X-ray properties and differing radio and submillimeter properties. The sources are HW9, HW3c, and a new source that is undetected at other wavelengths "h10." They each have inferred X-ray luminosities >= 10^31 erg s^-1 with hard spectra, T >= 10^7 K, and high low-energy absorption equivalent to tens to as much as a hundred magnitudes of visual absorption. The star usually assumed to be the most massive and energetic, HW2, is not detected with an upper limit about 7 times lower than the detections. The X-rays may arise via thermal bremsstrahlung in diffuse emission regions associated with a gyrosynchrotron source for the radio emission, or they could arise from powerful stellar winds. We also analyzed the Spitzer/IRAC mid-IR observation from this star-formation region and present the X-ray results and mid-IR classifications of the nearby stars. HH 168 is not as underluminous in X-rays as previously reported.