2014A&A...567A..77F


C.D.S. - SIMBAD4 rel 1.7 - 2020.07.03CEST21:03:12

2014A&A...567A..77F - Astronomy and Astrophysics, volume 567A, 77-77 (2014/7-1)

Hiccup accretion in the swinging pulsar IGR J18245-2452.

FERRIGNO C., BOZZO E., PAPITTO A., REA N., PAVAN L., CAMPANA S., WIERINGA M., FILIPOVIC M., FALANGA M. and STELLA L.

Abstract (from CDS):

The source IGRJ18245-2452 is the fifteenth discovered accreting millisecond X-ray pulsar and the first neutron star to show direct evidence of a transition between accretion- and rotation-powered emission states. These swings provided the strongest confirmation to date of the pulsar recycling scenario. During the two XMM-Newton observations that were carried out while the source was in outburst in April 2013, IGRJ18245-2452 displayed a unique and peculiar X-ray variability. In this work, we report on a detailed analysis of the XMM-Newton data and focus on the timing and spectral variability of the source. In the 0.4-11keV energy band, IGRJ18245-2452 continuously switched between lower and higher intensity states, with typical variations in flux by factor of ∼100 on time scales as short as a few seconds. These variations in the source intensity were sometimes accompanied by dramatic spectral hardening, during which the X-ray power-law photon index varied from Γ=1.7 to Γ=0.9. The pulse profiles extracted at different count-rates, hardnesses, and energies also showed a complex variability. These phenomena were never observed in accreting millisecond X-ray pulsars, at least not on such a short time-scale. Fast variability was also found in the 5.5 and 9GHz ATCA radio observations that were carried out for about 6h during the outburst. We interpret the variability observed from IGRJ18245-2452 in terms of a hiccup accretion phase, during which the accretion of material from the inner boundary of the Keplerian disk is reduced by the onset of centrifugal inhibition of accretion, possibly causing the launch of outflows. Changes across accretion and propeller regimes have been long predicted and reproduced by magnetohydrodynamic simulations of accreting millisecond X-ray pulsars, but have never observed to produce as extreme a variability as that shown by IGRJ18245-2452.

Abstract Copyright:

Journal keyword(s): X-rays: binaries - pulsars: individual: IGR J18245-2452 - stars: neutron

Simbad objects: 12

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Number of rows : 12

N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2020
#notes
1 PSR J1023+0038 LXB 10 23 47.6840307966 +00 38 41.006983532     17.31     GV 308 0
2 XSS J12270-4859 LXB 12 27 58.7475950389 -48 53 42.826034125           ~ 205 0
3 NAME Gal Center reg 17 45 40.04 -29 00 28.1           ~ 11533 0
4 [HAC2010] NGC 6440 X-2 LXB 17 48 52.76 -20 21 24.0           ~ 63 0
5 V* V4580 Sgr LXB 18 08 27.54 -36 58 44.3   16.81 16.51     ~ 870 0
6 V* V5511 Sgr LXB 18 13 39.03 -33 46 22.3   18.61 18.33 18.05   ~ 175 0
7 QSO J1820-2528 QSO 18 20 57.84869182 -25 28 12.5836842   18.56       ~ 79 0
8 IGR J18245-2452 LXB 18 24 32.50 -24 52 07.8           ~ 172 0
9 M 28 GlC 18 24 32.89 -24 52 11.4           ~ 662 0
10 X Aql X-1 LXB 19 11 16.0572031521 +00 35 05.876658556           ~ 1011 1
11 ICRF J193925.0-634245 Sy2 19 39 25.02671 -63 42 45.6255   18.87 18.37 17.64   ~ 953 1
12 PSR J2229+26 Psr 22 29 50.8864 +26 43 57.785           ~ 83 1

    Equat.    Gal    SGal    Ecl

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2020.07.03-21:03:12

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