Results from DROXO IV. EXTraS discovery of an X-ray flare from the Class I protostar candidate ISO-Oph 85

• Published in: arXiv.org 2015-12
• Main Authors: Pizzocaro, Daniele, Stelzer, Beate, Paladini, Roberta, Tiengo, Andrea, Lisini, Gianni, Novara, Giovanni, Vianello, Giacomo, Belfiore, Andrea, Marelli, Martino, Salvetti, David, Pillitteri, Ignazio, Sciortino, Salvatore, D'Agostino, Daniele, Haberl, Frank, Watson, Mike, Wilms, Joern, Salvaterra, Ruben, De Luca, Andrea
• Format: Article
• Language: English
• Subjects: Archives & records; Emission analysis; Light curve; Luminosity; Mathematical models; Photometry; Protostars; Star & galaxy formation; Star formation; Thermal analysis; X ray sources; XMM (spacecraft)
• ISSN: 2331-8422
• DOI: 10.48550/arxiv.1510.06286

X-ray emission from Young Stellar Objects (YSOs) is crucial to understand star formation. A very limited amount of X-ray results is available for the protostellar (ClassI) phase. A systematic search of transient X-ray phenomena combined with a careful evaluation of the evolutionary stage offer a widely unexplored window to our understanding of YSOs X-ray properties. Within the EXTraS project, a search for transients and variability in the whole XMM-Newton archive, we discover transient X-ray emission consistent with ISO-Oph 85, a strongly embedded YSO in the rho Ophiuchi region, not detected in previous time-averaged X-ray studies. We extract an X-ray light curve for the flare and determine its spectral parameters from XMM-Newton/EPIC (European Photon Imaging Camera) data using quantile analysis. The X-ray flare (\(2500\,s\)), the only one detected in the XMM-Newton archive for ISO-Oph 85, has a luminosity of \(LogL_X[erg/s]=31.1\) and a spectrum consistent with a highly-absorbed one-component thermal model (\(N_H=1.0^{+1.2}_{-0.5}10^{23}\,cm^{-2}\), \(kT=1.15^{+2.35}_{-0.65}\,keV)\). We set an upper limit of \(LogL_X[erg/s]