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.