Supernova remnant RCW103 is not exactly a new discovery. In fact, it was found over 25 years ago, the survivor of an explosion that took place in the early days of the Roman empire, though visible only in southern skies. And as you would expect, the area in question looks to be fairly standard issue for a supernova aftermath: a rapidly spinning neutron star and a surrounding bubble of material ejected by the explosion.
But look again, as an Italian team using the European Space Agency’s XMM-Newton x-ray satellite has done, and you spot some anomalies. The scientists, based at the Istituto Nazionale di Astrofisica (INAF) in Milan, find that emissions from the central source of the explosion repeat on a cycle of 6.7 hours, far longer than would be expected from such a neutron star. Another oddity is that the spectral properties found in these observations differ from another set of data made just five years ago with the same XMM-Newton equipment.
So what we have is an object embedded in a supernova remnant that acts more like a multimillion year old neutron star than one that is no more than two millennia old. “RCW 103 is an enigma,” said Giovanni Bignami, director of France’s Centre d’Etude Spatiale des Rayonnements (Toulouse), and co-author of a paper on the find. “We simply don’t have a conclusive answer to what is causing the long X-ray cycles. When we do figure this out, we’re going to learn a lot more about supernovae, neutron stars and their evolution.”
Possible explanations include a magnetar, or magnetized neutron star, whose magnetic field lines slow the object’s rotation, perhaps influenced in this case by a debris disk. Or we could be looking at a binary system, one in which a normal star somehow stayed bound to the object created by the supernova explosion. In either case, anomalies remain that may tell us much about how neutron stars evolve, especially since this system is a million times younger than other x-ray binary systems with low-mass companions.
The paper is De Luca, Caraveo, Mereghetti et al., “A long-period, violently-variable X-ray source in a young Supernova Remnant,” which ran in Science Express on July 6, 2006, with abstract available here.
Astrophysics, abstract
astro-ph/0607173
From: Andrea De Luca [view email]
Date: Mon, 10 Jul 2006 11:46:10 GMT (463kb)
A long-period, violently-variable X-ray source in a young SNR
Authors: A. De Luca, P.A. Caraveo, S. Mereghetti, A. Tiengo, G.F. Bignami
Comments: Accepted for publication in Science. Published online via Science Express on 2006, July 6. 17 pages, 7 figures
Observations with the Newton X-ray Multimirror Mission (XMM) show a strong periodic modulation at 6.67+/-0.03 hours of the X-ray source at the centre of the 2,000-year-old supernova remnant RCW 103. No fast pulsations are visible. If genetically tied to the supernova remnant, the source could either be an X-ray binary, comprising a compact object and a low-mass star in an eccentric orbit, or an isolated neutron star. In the latter case, its age-period combination would point to a peculiar magnetar, dramatically slowed-down, possibly by a supernova debris disc. Both scenarios require non-standard assumptions on the formation and evolution of compact objects in supernova explosions.
http://arxiv.org/abs/astro-ph/0607173
A magnetar hybrid found?
http://www.nasa.gov/centers/goddard/news/topstory/2008/magnetar_hybrid.html
Deep infrared observations of the puzzling central X-ray source in RCW103
Authors: A. De Luca, R. P. Mignani, S. Zaggia, G. Beccari, S. Mereghetti, P. A. Caraveo, G. F. Bignami
(Submitted on 19 Mar 2008)
Abstract: 1E 161348-5055 (1E 1613) is a point-like, soft X-ray source originally identified as a radio-quiet, isolated neutron star, shining at the center of the 2000 yr old supernova remnant RCW103. 1E 1613 features a puzzling 6.67 hour periodicity as well as a dramatic variability over a time scale of few years. Such a temporal behavior, coupled to the young age and to the lack of an obvious optical counterpart, makes 1E 1613 a unique source among all compact objects associated to SNRs.
It could either be the first low-mass X-ray binary system discovered inside a SNR, or a peculiar isolated magnetar with an extremely slow spin period. Analysis of archival IR observations, performed in 2001 with the VLT/ISAAC instrument, and in 2002 with the NICMOS camera onboard HST unveils a very crowded field. A few sources are positionally consistent with the refined X-ray error region that we derived from the analysis of 13 Chandra observations. To shed light on the nature of 1E 1613, we have performed deep IR observations of the field with the NACO instrument at the ESO/VLT, searching for variability. We find no compelling reasons to associate any of the candidates to 1E 1613. On one side, within the frame of the binary system model for the X-ray source, it is very unlikely that one of the candidates be a low-mass companion star to 1E 1613. On the other side, if the X-ray source is an isolated magnetar surrounded by a fallback disc, we cannot exclude that the IR counterpart be hidden among the candidates.
If none of the potential counterparts is linked to the X-ray source, 1E 1613 would remain undetected in the IR down to Ks>22.1. Such an upper limit is consistent only with an extremely low-mass star (an M6-M8 dwarf) at the position of 1E 1613, and makes rather problematic the interpretation of 1E 1613 as an accreting binary system.
Comments: 26 pages, 5 figures. Accepted for publication in ApJ
Subjects: Astrophysics (astro-ph)
Cite as: arXiv:0803.2885v1 [astro-ph]
Submission history
From: Andrea De Luca [view email]
[v1] Wed, 19 Mar 2008 20:28:36 GMT (222kb)
http://arxiv.org/abs/0803.2885
Strange Ring Found Circling Dead Star
NASA Science News for May 29, 2008
NASA’s Spitzer Space Telescope has found a bizarre ring of material around the magnetic remains of a star that blasted itself to smithereens. Although rings and spheres of material are common in the universe, this one is not quite like any ring astronomers have seen before.
FULL STORY at:
http://science.nasa.gov/headlines/y2008/29may_magnetar.htm?list1094208