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A new, faint population of X-ray transients

Bauer, Franz E. ; Treister, Ezequiel ; Schawinski, Kevin ; Schulze, Steve ; Luo, Bin ; Alexander, David M. ; Brandt, William N. ; Comastri, Andrea ; Forster, Francisco and Gilli, Roberto , et al. (2017) In Monthly Notices of the Royal Astronomical Society 467(4). p.4841-4857
Abstract

We report on the detection of a remarkable new fast high-energy transient found in the Chandra Deep Field-South, robustly associated with a faint (mR = 27.5mag, zph ~2.2) host in the CANDELS survey. The X-ray event is comprised of 115+12 -11 net 0.3-7.0 keV counts, with a light curve characterized by an ~100 s rise time, a peak 0.3-10 keV flux of ~5 × 10-12 erg s-1 cm-2 and a power-law decay time slope of -1.53 ± 0.27. The average spectral slope is Γ = 1.43+0.23 -0.13, with no clear spectral variations. The X-ray and multiwavelength properties effectively rule out the vast majority of previously observed highenergy transients. A few theoretical possibilities... (More)

We report on the detection of a remarkable new fast high-energy transient found in the Chandra Deep Field-South, robustly associated with a faint (mR = 27.5mag, zph ~2.2) host in the CANDELS survey. The X-ray event is comprised of 115+12 -11 net 0.3-7.0 keV counts, with a light curve characterized by an ~100 s rise time, a peak 0.3-10 keV flux of ~5 × 10-12 erg s-1 cm-2 and a power-law decay time slope of -1.53 ± 0.27. The average spectral slope is Γ = 1.43+0.23 -0.13, with no clear spectral variations. The X-ray and multiwavelength properties effectively rule out the vast majority of previously observed highenergy transients. A few theoretical possibilities remain: an 'orphan' X-ray afterglow from an off-axis short-duration gamma-ray burst (GRB) with weak optical emission, a low-luminosity GRB at high redshift with no prompt emission below ~20 keV rest frame, or a highly beamed tidal disruption event (TDE) involving an intermediate-mass black hole and a white dwarf with little variability. However, none of the above scenarios can completely explain all observed properties. Although large uncertainties exist, the implied rate of such events is comparable to those of orphan and low-luminosity GRBs as well as rare TDEs, implying the discovery of an untapped regime for a known transient class, or a new type of variable phenomena whose nature remains to be determined.

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organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
Galaxies: active, Gamma-ray burst: general, X-rays: bursts, X-rays: general
in
Monthly Notices of the Royal Astronomical Society
volume
467
issue
4
pages
17 pages
publisher
Oxford University Press
external identifiers
  • scopus:85029540482
ISSN
0035-8711
DOI
10.1093/mnras/stx417
language
English
LU publication?
yes
additional info
Publisher Copyright: © 2017 The Authors.
id
d1186674-d8c5-42c2-8565-6a307e64b2c5
date added to LUP
2022-03-31 12:40:44
date last changed
2024-04-13 14:07:33
@article{d1186674-d8c5-42c2-8565-6a307e64b2c5,
  abstract     = {{<p>We report on the detection of a remarkable new fast high-energy transient found in the Chandra Deep Field-South, robustly associated with a faint (m<sub>R</sub> = 27.5mag, z<sub>ph</sub> ~2.2) host in the CANDELS survey. The X-ray event is comprised of 115+12 -11 net 0.3-7.0 keV counts, with a light curve characterized by an ~100 s rise time, a peak 0.3-10 keV flux of ~5 × 10<sup>-12</sup> erg s<sup>-1</sup> cm<sup>-2</sup> and a power-law decay time slope of -1.53 ± 0.27. The average spectral slope is Γ = 1.43<sup>+0.23</sup> <sub>-0.13</sub>, with no clear spectral variations. The X-ray and multiwavelength properties effectively rule out the vast majority of previously observed highenergy transients. A few theoretical possibilities remain: an 'orphan' X-ray afterglow from an off-axis short-duration gamma-ray burst (GRB) with weak optical emission, a low-luminosity GRB at high redshift with no prompt emission below ~20 keV rest frame, or a highly beamed tidal disruption event (TDE) involving an intermediate-mass black hole and a white dwarf with little variability. However, none of the above scenarios can completely explain all observed properties. Although large uncertainties exist, the implied rate of such events is comparable to those of orphan and low-luminosity GRBs as well as rare TDEs, implying the discovery of an untapped regime for a known transient class, or a new type of variable phenomena whose nature remains to be determined.</p>}},
  author       = {{Bauer, Franz E. and Treister, Ezequiel and Schawinski, Kevin and Schulze, Steve and Luo, Bin and Alexander, David M. and Brandt, William N. and Comastri, Andrea and Forster, Francisco and Gilli, Roberto and Kann, David Alexander and Maeda, Keiichi and Nomoto, Ken'ichi and Paolillo, Maurizio and Ranalli, Piero and Schneider, Donald P. and Shemmer, Ohad and Tanaka, Masaomi and Tolstov, Alexey and Tominaga, Nozomu and Tozzi, Paolo and Vignali, Cristian and Wang, Junxian and Xue, Yongquan and Yang, Guang}},
  issn         = {{0035-8711}},
  keywords     = {{Galaxies: active; Gamma-ray burst: general; X-rays: bursts; X-rays: general}},
  language     = {{eng}},
  month        = {{06}},
  number       = {{4}},
  pages        = {{4841--4857}},
  publisher    = {{Oxford University Press}},
  series       = {{Monthly Notices of the Royal Astronomical Society}},
  title        = {{A new, faint population of X-ray transients}},
  url          = {{http://dx.doi.org/10.1093/mnras/stx417}},
  doi          = {{10.1093/mnras/stx417}},
  volume       = {{467}},
  year         = {{2017}},
}