occultation of x-rays from scorpius x-1 by small trans-neptunian objects (2006, nature letters)
DESCRIPTION
Occultation of X-Rays from Scorpius X-1 by Small Trans-Neptunian Objects (2006, Nature Letters). Hsiang-Kuang Chang, Sun-Kun King, Jau-Shian Liang, Ping-Shien Wu, Lupin Chun-Che Lin,& Jeng-Lun Chiu1. Kuiper Belt Object. [ Conceptual illustration of KBO detection ]. Optical occultation search: - PowerPoint PPT PresentationTRANSCRIPT
![Page 1: Occultation of X-Rays from Scorpius X-1 by Small Trans-Neptunian Objects (2006, Nature Letters)](https://reader036.vdocuments.mx/reader036/viewer/2022062305/56814cac550346895db9b39d/html5/thumbnails/1.jpg)
Occultation of X-Rays from Scorpius X-1 by Small Trans-Neptunian Objects (2006, Nature Letters)
Hsiang-Kuang Chang, Sun-Kun King, Jau-Shian Liang, Ping-Shien Wu, Lupin Chun-Che Lin,& Jeng-Lun Chiu1
![Page 2: Occultation of X-Rays from Scorpius X-1 by Small Trans-Neptunian Objects (2006, Nature Letters)](https://reader036.vdocuments.mx/reader036/viewer/2022062305/56814cac550346895db9b39d/html5/thumbnails/2.jpg)
Kuiper Belt Object
![Page 3: Occultation of X-Rays from Scorpius X-1 by Small Trans-Neptunian Objects (2006, Nature Letters)](https://reader036.vdocuments.mx/reader036/viewer/2022062305/56814cac550346895db9b39d/html5/thumbnails/3.jpg)
[ Conceptual illustration of KBO detection ]
![Page 4: Occultation of X-Rays from Scorpius X-1 by Small Trans-Neptunian Objects (2006, Nature Letters)](https://reader036.vdocuments.mx/reader036/viewer/2022062305/56814cac550346895db9b39d/html5/thumbnails/4.jpg)
Optical occultation search:
TAOS – CfA, NCU, ASIAA
French – Roques et al. Paris Observatory
Australian – Georgevits et al. UNSW, AAO
Canadian – Kavelaars et al. NRC, McMaster U
(Whipple – CfA, JPL)
No definite detections so far……
![Page 5: Occultation of X-Rays from Scorpius X-1 by Small Trans-Neptunian Objects (2006, Nature Letters)](https://reader036.vdocuments.mx/reader036/viewer/2022062305/56814cac550346895db9b39d/html5/thumbnails/5.jpg)
![Page 6: Occultation of X-Rays from Scorpius X-1 by Small Trans-Neptunian Objects (2006, Nature Letters)](https://reader036.vdocuments.mx/reader036/viewer/2022062305/56814cac550346895db9b39d/html5/thumbnails/6.jpg)
Why X-ray occultation?
faster photometryless diffraction
shorter events smaller bodies better chance to detect
* The background X-ray source needs to be bright enough.
* Sco X-1 is the brightest in the Sky.
* RXTE/PCA has the largest effective area.
* The typical PCA count rate of Sco X-1 is 105 cps. * Detection of msec time-scale occultation is possible.
* The RXTE/PCA data used in this search spans over 7 years from 1996 to 2002. The total exposure is 564.3 ksec.
![Page 7: Occultation of X-Rays from Scorpius X-1 by Small Trans-Neptunian Objects (2006, Nature Letters)](https://reader036.vdocuments.mx/reader036/viewer/2022062305/56814cac550346895db9b39d/html5/thumbnails/7.jpg)
![Page 8: Occultation of X-Rays from Scorpius X-1 by Small Trans-Neptunian Objects (2006, Nature Letters)](https://reader036.vdocuments.mx/reader036/viewer/2022062305/56814cac550346895db9b39d/html5/thumbnails/8.jpg)
![Page 9: Occultation of X-Rays from Scorpius X-1 by Small Trans-Neptunian Objects (2006, Nature Letters)](https://reader036.vdocuments.mx/reader036/viewer/2022062305/56814cac550346895db9b39d/html5/thumbnails/9.jpg)
![Page 10: Occultation of X-Rays from Scorpius X-1 by Small Trans-Neptunian Objects (2006, Nature Letters)](https://reader036.vdocuments.mx/reader036/viewer/2022062305/56814cac550346895db9b39d/html5/thumbnails/10.jpg)
* In the 564-ksec data, 107 events were found.
* What are they? Instrumental? Intrinsic variation of Sco X-1? Objects moving around Sco X-1? Objects in the interstellar space moving across the line of sight? The main belt asteroids?
* Assuming a distance of 43 AU and a circular orbital with a minimum inclination, the corresponding size of these occulting TNOs can be estimated from its speed relative to the RXTE spacecraft at each event epoch.
![Page 11: Occultation of X-Rays from Scorpius X-1 by Small Trans-Neptunian Objects (2006, Nature Letters)](https://reader036.vdocuments.mx/reader036/viewer/2022062305/56814cac550346895db9b39d/html5/thumbnails/11.jpg)
Direct imaging is possible only for larger ones (e.g. Trujillo et al. 2001).
A pains-taking HST observation reports 3 detections (Bernstein et al. 2004).
Models predict a turnover in the power law at small sizes (e.g. Kenyon et al. 2004).
Optical occultation survey may be able to detect objects down to km size (e.g. the Taiwan-America Occultation Survey, TAOS).
![Page 12: Occultation of X-Rays from Scorpius X-1 by Small Trans-Neptunian Objects (2006, Nature Letters)](https://reader036.vdocuments.mx/reader036/viewer/2022062305/56814cac550346895db9b39d/html5/thumbnails/12.jpg)
Summary
> The discovery of X-ray occultation by small TNOs opens up a new window in this field.
> The first result indicates a small turnover radius (less than about 100 meters) in the size distribution of TNOs, or, a second component at small sizes. The total mass in the trans-Neptunian region can be several earth masses, much more than previously thought.
> More detailed analysis and more observations will be very rewarding in deriving the size and spatial distribution of TNOs and in resolving the X-ray emitting region of Sco X-1.