As a multi-wavelength mission, with a flexible Target of Opportunity programme, Swift has also made many
discoveries in fields other than GRBs.
Some highlights are given below.
- Dust haloes in V404 Cyg
V404 Cyg is a Low Mass X-ray Binary system, which most recently went into outburst on 15th June 2015 and continued to flare intermittently in gamma-rays and X-rays for several weeks. The X-ray source eventually faded sufficiently for Swift to observe V404 Cyg in the 2-dimensional Photon Counting mode, at which point we discovered expanding rings (or haloes), caused by dust scattering along the line of sight. See this page for more details.
- Tidal Disruption Events
On 28th March 2011, Swift triggered on a new gamma-ray source. This source flared in gamma-rays repeatedly over the next
couple of days, showing that it was not a typical GRB. This appears to have been the discovery of the onset of a
tidal disruption event, whereby a powerful jet was formed when a star fell into a massive black hole at the centre of a
et al. (2011) and Burrows et
al. (2011) for more details. The figure below shows the X-ray light-curve, with the zero time corresponding
to the initial trigger at 12:57:45 UT on 28th March.
- Galaxies - nearby and active
Swift has observed many nearby galaxies, including Andromeda (also known as M31); the false-colour image below was created from hundreds of individual pointings, detecting more than 20,000 UV sources. UV data can be used to study star-forming regions and dust, among other things.
An all-sky hard X-ray survey is being performed by the Swift BAT (22-month
catalogue), with the majority of detected sources being AGN. Fabian et
al. (2009) used this sample of hard X-ray selected AGN to provide evidence for a
coupling of the radiation from AGN and the surrounding gas.
- Supernovae and their shock breakouts
More than 100 SNe have now been observed by Swift, detected not only in the optical/UV, but also in X-rays, allowing classification and the investigation of different light-curve shapes.
The figure below shows Swift UVOT Optical and UV (left and middle) and XRT (right) images of SN 2006X.
While observing SN 2007uy in the galaxy NGC 2770, Swift detected a new, bright X-ray
transient in the same galaxy, lasting just a few hundred
seconds - see figure below; this object was found to be associated with another supernova, SN
2008D. Astronomers had long thought that the shock breakout produced when a
supernova is formed should produce bright X-ray emission with a duration of a
few minutes - but this was the first time the event had actually been observed.
See Soderberg et
al. (2008) for more information.
- Large amplitude variability in nova X-ray light-curves
In 2006, the recurrent nova RS Oph went into outburst. Swift began a
detailed monitoring campaign, which revealed astonishing variability in the
soft X-ray emission at the start of the so-called "supersoft phase". The
details of the RS Oph data are presented by Osborne et
al. (2011). Although RS Oph was the first nova to be followed in such
detail by Swift, it has not been the last, and other novae have shown similar
large amplitude variations, including KT Eri, V458 Vul and V2491 Cyg.
Soft Gamma-Ray Repeaters (SGRs) are a type of magnetar - an object powered
by a very strong magnetic field. SGRs sometimes produce a series of short
gamma-ray/X-ray flares, events which can and do trigger Swift; Swift has
also detected previously unknown SGRs. However, much more
rarely, an SGR can emit a giant flare, with an energy about a thousand times
higher than these "normal" bursts. Swift detected such a flare from SGR
1806-20 on 27th December 2004, only about a month after launch, which is the
topic of Palmer et
See also the webpage on Gamma-Ray Bursts in the Swift
Era for more on magnetar research with Swift.