Vela X-1: Flares & Off States. West Orange High School Manthan Kothari, Lucy Zipf, Neil Savalia, Brian Meise, Krish Pillai. IN TODAY’S PRESENTATION, WE WILL:. Discuss how we chose our project. Describe the Vela X-1 system.
Vela X-1: Flares & Off States
West Orange High School
Manthan Kothari, Lucy Zipf, Neil Savalia, Brian Meise, Krish Pillai
Discusses flaring behavior of Vela X-1 for 20-40 keV X-Ray energy range based on data from the INTEGRAL (International Gamma-Ray Astrophysics Laboratory, Launched in 2002) satellite.
We look at X-Rays in the 1-10 keV range from the Exosat (European Space Agency X-Ray Observatory, finished its mission in 1986). So, we decided to compare Vela X-1’s flaring behavior in this energy range versus Kreykenbohm’s findings.
1. Compact Object
Literature support: Kretschmar, 2004, Charles and Seward, 1995, Kreykenbohm, 2008.
2. Companion OB Star
63,000 times that of the sun.
21 times that of the sun.
Literature support: Kaper, 1997, Kretschmar, 2004.
--Using values for the orbital speed and the orbital period (from literature), we found the orbital radius of HD77581 to be 2.6x109 m and the orbital radius of the neutron star to be 3.45x1010 m.
~50 solar radii (~1.7RHD77581).
Literature support: Quaintrall et al., 2003, Van Paradijs et al., 1976. Kretschmar et al.,2004, Willems et al., 2005.
the soft x-rays increase
Kreykenbohm’s Flare Models
The Lucy Situation
Do light curves in the 1-10 keV range exhibit flaring and off-state behaviors?
If these behaviors are present, do they have the same characteristics as in the 20-40 keV range?
If they’re present but with different characteristics, what model(s) might account for the difference?
Average cts/sec ~ 40 cts/sec +/- 0.03 cts/sec
Rise Time = ~2500 secs.
Flare Time = ~5000 secs.
Therefore, this is a LONG FLARE.
Pre-Rise Time: 40 cts/sec +/- .447cts/sec
This indicates spectral softening.
Average cts/sec ~ 38 cts/sec +/- 0.031 cts/sec
Rise Time = ~1000 secs.
Flare Time = ~3000 secs.
Therefore, this is a SHORT FLARE.
25 cts/sec +/- .35 cts/sec
This does not indicate Spectral Softening
Hardness plot fluctuates for an off-state which is consistent with Kreykenbohm’s results.
(1) supports the flare models but
(2) is inconsistent with hardness plot
results found bytheKreykenbohm study