Abstract
Recent works have discovered two fast (≈10 ks) extragalactic X-ray transients in the Chandra Deep Field-South (CDF-S XT1 and XT2). These findings suggest that a large population of similar extragalactic transients might exist in archival X-ray observations. We develop a method that can effectively detect such transients in a single Chandra exposure, and systematically apply it to Chandra surveys of CDF-S, CDF-N, DEEP2, UDS, COSMOS, and E-CDF-S, totaling 19 Ms of exposure. We find 13 transient candidates, including CDF-S XT1 and XT2. With the aid of available excellent multiwavelength observations, we identify the physical nature of all these candidates. Aside from CDF-S XT1 and XT2, the other 11 sources are all stellar objects, and all of them have z-band magnitudes brighter than 20. We estimate an event rate of {59+77-38} for CDF-S XT-like transients with 0.5-7 keV peak fluxes log Fpeak -12.6 (erg cm-2 s-1). This event rate translates to {15+20-10} transients existing among Chandra archival observations at Galactic latitudes |b| > 20°, which can be probed in future work. Future missions such as Athena and the Einstein Probe with large grasps (effective area × field of view) are needed to discover a large sample (∼thousands) of fast extragalactic X-ray transients.
| Original language | English (US) |
|---|---|
| Pages (from-to) | 4721-4736 |
| Number of pages | 16 |
| Journal | Monthly Notices of the Royal Astronomical Society |
| Volume | 487 |
| Issue number | 4 |
| DOIs | |
| State | Published - Jun 25 2019 |
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All Science Journal Classification (ASJC) codes
- Astronomy and Astrophysics
- Space and Planetary Science
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Searching for fast extragalactic X-ray transients in Chandra surveys. / Yang, G.; Brandt, W. N.; Zhu, S. F.; Bauer, F. E.; Luo, B.; Xue, Y. Q.; Zheng, X. C.
In: Monthly Notices of the Royal Astronomical Society, Vol. 487, No. 4, 25.06.2019, p. 4721-4736.Research output: Contribution to journal › Article
TY - JOUR
T1 - Searching for fast extragalactic X-ray transients in Chandra surveys
AU - Yang, G.
AU - Brandt, W. N.
AU - Zhu, S. F.
AU - Bauer, F. E.
AU - Luo, B.
AU - Xue, Y. Q.
AU - Zheng, X. C.
PY - 2019/6/25
Y1 - 2019/6/25
N2 - Recent works have discovered two fast (≈10 ks) extragalactic X-ray transients in the Chandra Deep Field-South (CDF-S XT1 and XT2). These findings suggest that a large population of similar extragalactic transients might exist in archival X-ray observations. We develop a method that can effectively detect such transients in a single Chandra exposure, and systematically apply it to Chandra surveys of CDF-S, CDF-N, DEEP2, UDS, COSMOS, and E-CDF-S, totaling 19 Ms of exposure. We find 13 transient candidates, including CDF-S XT1 and XT2. With the aid of available excellent multiwavelength observations, we identify the physical nature of all these candidates. Aside from CDF-S XT1 and XT2, the other 11 sources are all stellar objects, and all of them have z-band magnitudes brighter than 20. We estimate an event rate of {59+77-38} for CDF-S XT-like transients with 0.5-7 keV peak fluxes log Fpeak -12.6 (erg cm-2 s-1). This event rate translates to {15+20-10} transients existing among Chandra archival observations at Galactic latitudes |b| > 20°, which can be probed in future work. Future missions such as Athena and the Einstein Probe with large grasps (effective area × field of view) are needed to discover a large sample (∼thousands) of fast extragalactic X-ray transients.
AB - Recent works have discovered two fast (≈10 ks) extragalactic X-ray transients in the Chandra Deep Field-South (CDF-S XT1 and XT2). These findings suggest that a large population of similar extragalactic transients might exist in archival X-ray observations. We develop a method that can effectively detect such transients in a single Chandra exposure, and systematically apply it to Chandra surveys of CDF-S, CDF-N, DEEP2, UDS, COSMOS, and E-CDF-S, totaling 19 Ms of exposure. We find 13 transient candidates, including CDF-S XT1 and XT2. With the aid of available excellent multiwavelength observations, we identify the physical nature of all these candidates. Aside from CDF-S XT1 and XT2, the other 11 sources are all stellar objects, and all of them have z-band magnitudes brighter than 20. We estimate an event rate of {59+77-38} for CDF-S XT-like transients with 0.5-7 keV peak fluxes log Fpeak -12.6 (erg cm-2 s-1). This event rate translates to {15+20-10} transients existing among Chandra archival observations at Galactic latitudes |b| > 20°, which can be probed in future work. Future missions such as Athena and the Einstein Probe with large grasps (effective area × field of view) are needed to discover a large sample (∼thousands) of fast extragalactic X-ray transients.
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U2 - 10.1093/mnras/stz1605
DO - 10.1093/mnras/stz1605
M3 - Article
AN - SCOPUS:85070063076
VL - 487
SP - 4721
EP - 4736
JO - Monthly Notices of the Royal Astronomical Society: Letters
JF - Monthly Notices of the Royal Astronomical Society: Letters
SN - 1745-3925
IS - 4
ER -