NuSTAROBSERVATION OF A TYPE I X-RAY BURST FROM GRS 1741.9-2853

Abstract

We report on two NuSTAR observations of GRS 1741.9-2853, a faint neutron star low mass X-ray binary burster located 10 ′ away from the Galactic center. NuSTAR detected the source serendipitously as it was emerging from quiescence: its luminosity was 6 × 10 34 erg s −1 on 2013 July 31, and 5 × 10 35 erg s −1 in a second observation on 2013 August 3. A bright, 800-s long, H-triggered mixed H/He thermonuclear Type I burst with mild photospheric radius expansion (PRE) was present during the second observation. Assuming that the luminosity during the PRE was at the Eddington level, a H mass fraction X = 0.7 in the atmosphere, and a neutron star mass M = 1.4M ⊙ , we determine a new lower limit on the distance for this source of 6.3 ± 0.5 kpc. Combining with previous upper limits, this places GRS 1741.9-2853 at a distance of 7 kpc. Energy independent (achromatic) variability is observed during the cooling of the neutron star, which could result from the disturbance of the inner accretion disk by the burst. The large dynamic range of this burst reveals a long power-law decay tail. We also detect, at a 95.6% confidence level (1.7 σ), a narrow absorption line at 5.46 ± 0.10 keV during the PRE phase of the burst, reminiscent of the detection by Waki et al. (1984). We propose that the line, if real, is formed in the wind above the photosphere of the neutron star by a resonant Kα transition from H-like Cr gravitationally redshifted by a factor 1 + z = 1.09, corresponding to a radius range of 29.0 -41.4 km for a mass range of 1.4 -2.0 M ⊙ .

NuSTAR HARD X-RAY SURVEY OF THE GALACTIC CENTER REGION. II. X-RAY POINT SOURCES

“…The source and background counts combination for each interval allows for a well constrained pulsar search. A comprehensive search did not produce a significant signal for any interval, consistent with the null timing search result reported in Barrière et al (2015).…”

“…NuSTAR observed GRS 1741.9-2853 four times, during one of which a Type I burst was fully recorded. A comprehensive paper on these data sets is presented in Barrière et al (2015). These authors were able to place a lower limit of 6.3kpc on the distance to the NS based on the peak flux from the burst assuming the photospheric radius expansion model.…”

“…The NuSTAR observations of bright X-ray flares and bursts in the GC region are presented elsewhere: see Mori et al (2013) for the NuSTAR detection of X-ray pulsations from SGR J1745-29, a transient magnetar (see also Kaspi et al 2014); Barrière et al (2014) for the SgrA * flares; Barrière et al (2015) for Type I X-ray bursts from GRS1741.9-2853, a NS-LMXB; Younes et al (2015) for an outburst from GRO J1744-28, also known as the Bursting Pulsar.…”

A Uniform Search for Thermonuclear Burst Oscillations in the RXTE Legacy Data Set

“…The source was not in outburst again before the end of the RXTE mission. In 2013, Barrière et al (2015) observed GRS 1741.9−2853 with NuSTAR. Unfortunately, the 2.5-ms dead time of NuSTAR hindered TBO detection.…”

XMM-Newton and NuSTAR Simultaneous X-Ray Observations of IGR J11215-5952

“…6), following the approach described by several authors (Bhalerao et al 2015;Lotti et al 2016;Barrière et al 2015). We used the simftest routine in XSPEC with 100000 simulations 6 , fixing the N H to the values reported in Table 3 to speed FIG. 3.-IGR J11215-5952 pulse profiles (period P=187 s; MJD 57432 is the epoch of φ=0) in different energy ranges are shown, as observed simultaneously by XMM-Newton (EPIC pn, left panels) and by NuSTAR (FPMA for clarity, right panels).…”