Discovery and monitoring of the likely IR counterpart   of SGR 1806–20 during the 2004 <i>γ</i>-ray burst-active state

Israel, G. L.; Covino, S.; Mignani, Roberto; Stella, L.; Marconi, G.; Testa, V.; Mereghetti, S.; Campana, S.; Rea, N.; Götz, D.; Perna, Rosalba; Curto, G. Lo

doi:10.1051/0004-6361:200500138

Cited by 55 publications

(52 citation statements)

References 24 publications

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“…It connects rather well with the low energy (< 10 keV) spectrum [32], and the intensity and spectral hardness are correlated with the degree of bursting activity of the source [31,8] and with the flux of the recently discovered IR counterpart of the source [17]. Our group is continuosly monitoring the hard X-ray flux of SGR 1806-20, and the long term light curve of the source is shown in This behaviour can be interpreted, as an increase of the twist angle in the magnetar magnetic field, which in turn increases the burst emission rate and the multiple resonant cyclotron scattering, which produces harder spectra, as predicted by [46].…”

Section: Discovery Of the Persistent Emissionmentioning

confidence: 68%

Unveiling soft gamma-ray repeaters with INTEGRAL

Götz

Mereghetti

Hurley

2007

Isolated Neutron Stars: From the Surface to the Interior

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Thanks to INTEGRAL's long exposures of the Galactic Plane, the two brightest Soft Gamma-Ray Repeaters, SGR 1806-20 and SGR 1900+14, have been monitored and studied in detail for the first time at hard-X/soft gamma rays.This has produced a wealth of new scientific results, which we will review here. Since SGR 1806-20 was particularly active during the last two years, more than 300 short bursts have been observed with INTEGRAL and their characteristics have been studied with unprecedented sensitivity in the 15-200 keV range. A hardness-intensity anticorrelation within the bursts has been discovered and the overall Number-Intensity distribution of the bursts has been determined. In addition, a particularly active state, during which 100 bursts were emitted in 10 minutes, has been observed on October 5 2004, indicating that the source activity was rapidly increasing. This eventually led to the Giant Flare of December 27th 2004, for which a possible soft gamma-ray (>80 keV) early afterglow has been detected.

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Section: Discovery Of the Persistent Emissionmentioning

confidence: 68%

Unveiling soft gamma-ray repeaters with INTEGRAL

Götz

Mereghetti

Hurley

2007

Isolated Neutron Stars: From the Surface to the Interior

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“…In the IR, magnetars have a peculiar flux distribution which flattens with respect to the extrapolation of the X-ray spectra, see e.g. Israel et al (2005). This flattening could be due either to the contribution of emission from a fallback disk, or to a turnover in the magnetospheric emission from the magnetar.…”

Section: Introductionmentioning

confidence: 99%

Deep VLT infrared observations of X-ray dim isolated neutron stars

Curto

Mignani

Perna

et al. 2007

A&A

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Context. X-ray observations have unveiled the existence of a family of radio-quiet Isolated Neutron Stars whose X-ray emission is purely thermal, hence dubbed X-ray Dim Isolated Neutron Stars (XDINSs). While optical observations have allowed to relate the thermal emission to the neutron star cooling and to build the neutron star surface thermal map, IR observations are critical to pinpoint a spectral turnover produced by a so far unseen magnetospheric component, or by the presence of a fallback disk. The detection of such a turnover can provide further evidence of a link between this class of isolated neutron stars and the magnetars, which show a distinctive spectral flattening in the IR. Aims. We present the deepest IR observations ever of five XDINSs, which we use to constrain a spectral turnover in the IR and the presence of a fallback disk. Methods. We have used archived VLT observations of these neutron stars performed with the ISAAC instrument in the H-band (1.65 µm) and the available fallback disk models. Results. For none of our targets it was possible to identify the IR counterpart down to limiting magnitudes H ∼ 21.5 − 22.9. Although these limits are the deepest ever obtained for neutron stars of this class, they are not deep enough to rule out the existence and the nature of a possible spectral flattening in the IR. We also derive, by using disk models, the upper limits on the mass inflow rate in a fallback disk. We find the existence of a putative fallback disk consistent (although not confirmed) with our observations.

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“…There are abundant infrared and optical photons within Cl * 1806-20 (see Balman et al 2003;Israel et al 2005;Kosugi et al 2005;Rea et al 2005), and cosmic microwave background photons are everywhere. These both can be seed photons for leptonic cosmic-rays to produce γ-ray emission through IC.…”

Section: -20/clmentioning

confidence: 99%

STUDYING THE SGR 1806-20/Cl* 1806-20 REGION USING THE FERMI LARGE AREA TELESCOPE

Yeung

Kong

Tam

et al. 2016

ApJ

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The region around SGR 1806-20 and its host stellar cluster Cl * 1806-20 is a potentially important site of particle acceleration. The soft γ-ray repeater and Cl * 1806-20, which also contains several very massive stars including a luminous blue variable hypergiant LBV 1806-20, are capable of depositing a large amount of energy to the surroundings. Using the data taken with the Fermi Large Area Telescope (LAT), we identified an extended LAT source to the southwest of Cl * 1806-20. The centroid of the 1-50 GeV emission is consistent with that of HESS J1808-204 (until now unidentified). The LAT spectrum is best-fit by a broken power law with the break energy =  E 297 15 MeV b . The index above E b is 2.60±0.04 and is consistent with the flux and spectral index above 100 GeV for HESS J1808-204, suggesting an association between the two sources. Meanwhile, the interacting supernova remnant SNR G9.7-0.0 is also a potential contributor to the LAT flux. A tentative flux enhancement at the MeV band during a 45 day interval (2011 January 21-March 7) is also reported. We discuss possible origins of the extended LAT source in the context of both leptonic and hadronic scenarios.

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Discovery and monitoring of the likely IR counterpart of SGR 1806–20 during the 2004 γ-ray burst-active state

Cited by 55 publications

References 24 publications

Unveiling soft gamma-ray repeaters with INTEGRAL

Unveiling soft gamma-ray repeaters with INTEGRAL

Deep VLT infrared observations of X-ray dim isolated neutron stars

STUDYING THE SGR 1806-20/Cl* 1806-20 REGION USING THE FERMI LARGE AREA TELESCOPE

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