light curves these light curves were taken by the swift gamma-ray burst explorer & rossi x-ray...
TRANSCRIPT
Light Curves• These light curves were taken by the Swift Gamma-Ray Burst Explorer & Rossi X-Ray Timing Explorer
• Each graph plots the counts of x-rays with a particular energy per second over the duration of the event
• Before the outburst, the flux from the system was consistently 1/100th of the peak
• ‘Hard’ x-rays are higher energy than ‘soft’ x-rays
• As we will see in the next slide, we care about the ratio of the hard flux (E > 5 keV) to the soft flux (E <5keV)
•This ratio is called the hardnessLight curves of the outburst taken from Krimm et al.
Current Interpretation•The outburst decay rate was consistent with an x-ray burst transient•The spectra1 showed what Krimm et al. interpreted as an iron line at 6.72 ± .58 keV•Observations have found have found very low flux at quiescence•This suggests that the companion star is of low mass
Hardness vs. Flux (Intensity), taken from Krimm et al.
• Two possibilities for a LMXRB – a black hole or a neutron star•Neutron star x-ray hardness/intensity curves either trace a distinct Z shape (so-called ‘Z Sources’) or lack the observed hard/high flux• The transitions from hard to soft-intermediate are thought to be faster with neutron stars
1The paper did not include individual spectrum
• Swift J1539.2-6227 shares many traits with confirmed BH outbursts• Rapid rise of hard X rays followed by a
soft flux about 8 days later is very similar to confirmed BH GRO J155-40• Temporary hardening in the middle of
the outburst very similar to XTE J1859+266• PL index, disk fraction, and rms power
all correlate with X-ray hardness in a way that is indicative of a black hole (see figure)
• In addition to these shared traits, no pulsations were observed during the recorded outburst
Further Evidence for Candidacy
Hardness vs. key features from Krimm et al.
• Mass from the companion star falls onto the compact object until an outburst occurs• The properties of the outburst can help identify the compact object• The outburst of Swift J1539.2-6227 shows several features of a BH, but no high-energy radio jet was observed
• This is a problem because these jets are an integral part of BHs• Due to the power of a BH’s magnetic field, you would not expect to see a BH without seeing a jet in every wavelength!• Without a jet in the radio we can’t define of Swift J1539.2-6227 as a BH
Jet of M87’s Supermassive BH
Could Swift J1539.2-6227 be a neutron star or an anomalous nova? (most likely not)
An Unresolved Issue
Detecting High Energy Radio Jets
Proving this anomaly is indeed a BH.
Typical radio images from a BH.
1) Material rotates around BH, some of which is Ionized.
2) Ionized Material causes moving charges, which in-turn creates a B-field which in this case twists causing streams of jets that can be observed by ground-based radio observatories.
Very Large Array
Reason why H. A. Krimm et al. did not have radio data.• Lack of observation time needed to confirm that this is a
BH.• However there is really sufficient evidence to deduce
that it most probably is a BH without radio data.