2010/01/30 by T. J. Turner, L. Miller, J. N. Reeves +4 · 10 citations
Physics and Astronomy · #Accretion (finance) #Astronomy and Astrophysical Research #Astrophysical Phenomena and Observations #Emission spectrum #Flux (metallurgy) #Galaxies: Formation, Evolution, Phenomena #Galaxy #Line (geometry) #Monte Carlo method #Spectral line #astro-ph.CO #astro-ph.HE
paper · pdf · doi:10.1088/0004-637x/712/1/209
published in The Astrophysical Journal 712(1), 209-217 (IOP Publishing) · 18 pages, accepted for publication by ApJ
arxiv created 2010/01/30 · openalex publication_date 2010/02/25 · arxiv updated 2015/05/18 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/05
A Suzaku X-ray observation of NGC 4051 taken during 2005 November reveals line emission at 5.44 keV in the rest frame of the galaxy which does not have an obvious origin in known rest-frame atomic transitions. The improvement to the fit statistic when this line is accounted for establishes its reality at >99.9% confidence: we have also verified that the line is detected in the three X-ray Imaging Spectrometer units independently. Comparison between the data and Monte Carlo simulations shows that the probability of the line being a statistical fluctuation is p < 3.3 × 10 −4 . Consideration of three independent line detections in Suzaku data taken at different epochs yields a probability p < 3 × 10 −11 and thus conclusively demonstrates that it cannot be a statistical fluctuation in the data. The new line and a strong component of Fe Kα emission from neutral material are prominent when the source flux is low, during 2005. Spectra from 2008 show evidence for a line consistent with having the same flux and energy as that observed during 2005, but inconsistent with having a constant equivalent width against the observed continuum. The stability of the line flux and energy suggests that it may not arise in transient hotspots, as has been suggested for similar lines in other sources, but could arise from a special location in the reprocessor, such as the inner edge of the accretion disk. Alternatively, the line energy may be explained by spallation of Fe into Cr, as discussed in a companion paper.