NICER observation of Be/X-ray binary pulsar XTE J1946+274 during its 2024 outburst

Manoj Mandal; Gaurava K. Jaisawal; Sabyasachi  Pal; Keith C. Gendreau; Sebastien Guillot; Andrea Sanna; Mason Ng; Katja Pottschmidt

NICER observation of Be/X-ray binary pulsar XTE J1946+274 during its 2024 outburst

Manoj Mandal
, Gaurava K. Jaisawal
, Sabyasachi Pal
, Keith C. Gendreau
, Sebastien Guillot
, Andrea Sanna
, Mason Ng
, Katja Pottschmidt

Midnapore City College
NASA Goddard Space Flight Center
CNRS
University of Cagliari
Massachusetts Institute of Technology

Research output: Other contribution › Net publication - Internet publication › Research

Abstract

The transient Be/X-ray binary pulsar XTE J1946+274 recently went into an X-ray outburst as reported by MAXI/GSC (ATel #16717). After inactivity of a few years since 2021 (ATel #14936), the source is detected in the X-rays by SVOM/ECLAIRs and Einstein Probe WXT (ATel #16719, #16723) and in the optical by KAIT and SVOM/C-GFT (ATel #16720, #16722) in July 2024. The X-ray flux from the source was seen to increase by MAXI/GSC (2−20 keV) from 0.78 mCrab (MJD 60505) to a peak value of ~24 mCrab (close to MJD 60512). Monitoring by MAXI/GSC and Swift/BAT indicates the source may have crossed the peak of the outburst and entered into a decline phase.

NICER observed the source on 2024-07-24 (MJD 60515) with a total exposure of ~6.7 ks, recording an average count rate of roughly 17 c/s in the 0.5−10 keV energy band. The barycentric-corrected light curve shows X-ray pulsations at a period of 15.76±0.01 s. The pulse profile shows a double-peak feature with a pulsed fraction of nearly 30%.

The NICER spectra (0.7−10 keV) can be modelled with an absorbed power-law model. The best-fit results provide a photon index of 0.65±0.01 and a hydrogen column density of (1.20±0.02) × 1022 cm-2. The absorbed source flux is (2.30±0.03) × 10-10 ergs cm-2 s-1 in the 0.7−10 keV energy band. The corresponding luminosity is estimated to be ~2 × 1036 erg/s assuming a source distance of 8.7 kpc. All reported uncertainties have 90% confidence limits.

We thank the NICER team for making the ToO observation possible. NICER will keep monitoring the source in the following days.

NICER is a 0.2−12 keV X-ray telescope operating on the International Space Station. The NICER mission and portions of the NICER science team activities are funded by NASA.

The latest X-ray monitoring light curves can be found on the following pages:

Swift/BAT: https://swift.gsfc.nasa.gov/results/transients/weak/XTEJ1946p274/

MAXI: http://maxi.riken.jp/star_data/J1945+273/J1945+273.html

Fermi/GBM: https://gammaray.nsstc.nasa.gov/gbm/science/pulsars/lightcurves/xtej1946.html

BeXRB monitor page: http://integral.esac.esa.int/bexrbmonitor/Plots/sim_plot_XTEJ1946+274.html

Original language	English
Publication date	30 Jul 2024
Publication status	Published - 30 Jul 2024

Series	The Astronomer's telegram
Number	ATel #16744

Keywords

X-ray
Neutron Star
Star
Transient
Pulsar

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@misc{7b20c4e2c07147f291e0bb48bf219cf4,

title = "NICER observation of Be/X-ray binary pulsar XTE J1946+274 during its 2024 outburst",

abstract = "The transient Be/X-ray binary pulsar XTE J1946+274 recently went into an X-ray outburst as reported by MAXI/GSC (ATel \#16717). After inactivity of a few years since 2021 (ATel \#14936), the source is detected in the X-rays by SVOM/ECLAIRs and Einstein Probe WXT (ATel \#16719, \#16723) and in the optical by KAIT and SVOM/C-GFT (ATel \#16720, \#16722) in July 2024. The X-ray flux from the source was seen to increase by MAXI/GSC (2−20 keV) from 0.78 mCrab (MJD 60505) to a peak value of \textasciitilde{}24 mCrab (close to MJD 60512). Monitoring by MAXI/GSC and Swift/BAT indicates the source may have crossed the peak of the outburst and entered into a decline phase. NICER observed the source on 2024-07-24 (MJD 60515) with a total exposure of \textasciitilde{}6.7 ks, recording an average count rate of roughly 17 c/s in the 0.5−10 keV energy band. The barycentric-corrected light curve shows X-ray pulsations at a period of 15.76±0.01 s. The pulse profile shows a double-peak feature with a pulsed fraction of nearly 30\%. The NICER spectra (0.7−10 keV) can be modelled with an absorbed power-law model. The best-fit results provide a photon index of 0.65±0.01 and a hydrogen column density of (1.20±0.02) {\texttimes} 1022 cm-2. The absorbed source flux is (2.30±0.03) {\texttimes} 10-10 ergs cm-2 s-1 in the 0.7−10 keV energy band. The corresponding luminosity is estimated to be \textasciitilde{}2 {\texttimes} 1036 erg/s assuming a source distance of 8.7 kpc. All reported uncertainties have 90\% confidence limits. We thank the NICER team for making the ToO observation possible. NICER will keep monitoring the source in the following days. NICER is a 0.2−12 keV X-ray telescope operating on the International Space Station. The NICER mission and portions of the NICER science team activities are funded by NASA. The latest X-ray monitoring light curves can be found on the following pages: Swift/BAT: https://swift.gsfc.nasa.gov/results/transients/weak/XTEJ1946p274/ MAXI: http://maxi.riken.jp/star\_data/J1945+273/J1945+273.html Fermi/GBM: https://gammaray.nsstc.nasa.gov/gbm/science/pulsars/lightcurves/xtej1946.html BeXRB monitor page: http://integral.esac.esa.int/bexrbmonitor/Plots/sim\_plot\_XTEJ1946+274.html ",

keywords = "X-ray, Neutron Star, Star, Transient, Pulsar",

author = "Manoj Mandal and Jaisawal, \{Gaurava K.\} and Sabyasachi Pal and Gendreau, \{Keith C.\} and Sebastien Guillot and Andrea Sanna and Mason Ng and Katja Pottschmidt",

year = "2024",

month = jul,

day = "30",

language = "English",

series = "The Astronomer's telegram",

publisher = "R. Rutledge",

number = "ATel \#16744",

type = "Other",

}

TY - ICOMM

T1 - NICER observation of Be/X-ray binary pulsar XTE J1946+274 during its 2024 outburst

AU - Mandal, Manoj

AU - Jaisawal, Gaurava K.

AU - Pal , Sabyasachi

AU - Gendreau, Keith C.

AU - Guillot, Sebastien

AU - Sanna, Andrea

AU - Ng, Mason

AU - Pottschmidt, Katja

PY - 2024/7/30

Y1 - 2024/7/30

N2 - The transient Be/X-ray binary pulsar XTE J1946+274 recently went into an X-ray outburst as reported by MAXI/GSC (ATel #16717). After inactivity of a few years since 2021 (ATel #14936), the source is detected in the X-rays by SVOM/ECLAIRs and Einstein Probe WXT (ATel #16719, #16723) and in the optical by KAIT and SVOM/C-GFT (ATel #16720, #16722) in July 2024. The X-ray flux from the source was seen to increase by MAXI/GSC (2−20 keV) from 0.78 mCrab (MJD 60505) to a peak value of ~24 mCrab (close to MJD 60512). Monitoring by MAXI/GSC and Swift/BAT indicates the source may have crossed the peak of the outburst and entered into a decline phase. NICER observed the source on 2024-07-24 (MJD 60515) with a total exposure of ~6.7 ks, recording an average count rate of roughly 17 c/s in the 0.5−10 keV energy band. The barycentric-corrected light curve shows X-ray pulsations at a period of 15.76±0.01 s. The pulse profile shows a double-peak feature with a pulsed fraction of nearly 30%. The NICER spectra (0.7−10 keV) can be modelled with an absorbed power-law model. The best-fit results provide a photon index of 0.65±0.01 and a hydrogen column density of (1.20±0.02) × 1022 cm-2. The absorbed source flux is (2.30±0.03) × 10-10 ergs cm-2 s-1 in the 0.7−10 keV energy band. The corresponding luminosity is estimated to be ~2 × 1036 erg/s assuming a source distance of 8.7 kpc. All reported uncertainties have 90% confidence limits. We thank the NICER team for making the ToO observation possible. NICER will keep monitoring the source in the following days. NICER is a 0.2−12 keV X-ray telescope operating on the International Space Station. The NICER mission and portions of the NICER science team activities are funded by NASA. The latest X-ray monitoring light curves can be found on the following pages: Swift/BAT: https://swift.gsfc.nasa.gov/results/transients/weak/XTEJ1946p274/ MAXI: http://maxi.riken.jp/star_data/J1945+273/J1945+273.html Fermi/GBM: https://gammaray.nsstc.nasa.gov/gbm/science/pulsars/lightcurves/xtej1946.html BeXRB monitor page: http://integral.esac.esa.int/bexrbmonitor/Plots/sim_plot_XTEJ1946+274.html

AB - The transient Be/X-ray binary pulsar XTE J1946+274 recently went into an X-ray outburst as reported by MAXI/GSC (ATel #16717). After inactivity of a few years since 2021 (ATel #14936), the source is detected in the X-rays by SVOM/ECLAIRs and Einstein Probe WXT (ATel #16719, #16723) and in the optical by KAIT and SVOM/C-GFT (ATel #16720, #16722) in July 2024. The X-ray flux from the source was seen to increase by MAXI/GSC (2−20 keV) from 0.78 mCrab (MJD 60505) to a peak value of ~24 mCrab (close to MJD 60512). Monitoring by MAXI/GSC and Swift/BAT indicates the source may have crossed the peak of the outburst and entered into a decline phase. NICER observed the source on 2024-07-24 (MJD 60515) with a total exposure of ~6.7 ks, recording an average count rate of roughly 17 c/s in the 0.5−10 keV energy band. The barycentric-corrected light curve shows X-ray pulsations at a period of 15.76±0.01 s. The pulse profile shows a double-peak feature with a pulsed fraction of nearly 30%. The NICER spectra (0.7−10 keV) can be modelled with an absorbed power-law model. The best-fit results provide a photon index of 0.65±0.01 and a hydrogen column density of (1.20±0.02) × 1022 cm-2. The absorbed source flux is (2.30±0.03) × 10-10 ergs cm-2 s-1 in the 0.7−10 keV energy band. The corresponding luminosity is estimated to be ~2 × 1036 erg/s assuming a source distance of 8.7 kpc. All reported uncertainties have 90% confidence limits. We thank the NICER team for making the ToO observation possible. NICER will keep monitoring the source in the following days. NICER is a 0.2−12 keV X-ray telescope operating on the International Space Station. The NICER mission and portions of the NICER science team activities are funded by NASA. The latest X-ray monitoring light curves can be found on the following pages: Swift/BAT: https://swift.gsfc.nasa.gov/results/transients/weak/XTEJ1946p274/ MAXI: http://maxi.riken.jp/star_data/J1945+273/J1945+273.html Fermi/GBM: https://gammaray.nsstc.nasa.gov/gbm/science/pulsars/lightcurves/xtej1946.html BeXRB monitor page: http://integral.esac.esa.int/bexrbmonitor/Plots/sim_plot_XTEJ1946+274.html

KW - X-ray

KW - Neutron Star

KW - Star

KW - Transient

KW - Pulsar

M3 - Net publication - Internet publication

T3 - The Astronomer's telegram

ER -

NICER observation of Be/X-ray binary pulsar XTE J1946+274 during its 2024 outburst

Abstract

Keywords

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