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Abstract
Following the recent report of enhanced activity from Sgr A* (ATeLs #12768, #13007, #13023), we report measurements derived from INTEGRAL observations.
Sgr A* is not detected by the imaging pipeline in the combined images covering the Galactic Center region performed from 2019-08-15 15:10:48 to 2019-08-16 08:20:18. We derive a flux upper limit by forcing the IBIS/ISGRI spectral extraction at the source location. Assuming a power-law spectrum with index -2 (ATeL #13023) and exploiting an exposure of 36 ks, the 3 sigma upper limit is 4e-11 erg/s/cm^2 in the 30-50 keV energy band, which corresponds to 1e-10 erg/s/cm^2 in the 5-16 keV band. The JEM-X 3 sigma upper limit is 1e-10 erg/cm2/s (6.5 mCrab) in the 3-10 keV band and 1.5e-10 erg/cm2/s (13.5 mCrab) in the 10-25 keV for 10 ks on-source time.
In the same observation, we could detect with IBIS/ISGRI at a significance of about 7 sigma, the accreting millisecond pulsar SAX J1808.4-3658, recently reported to be in outburst (ATeL #12964,, #13001, #13022). We performed spectral extraction of IBIS/ISGRI data only, as the source is outside the JEM-X field of view. The power-law index is 2.6-0.8+1.2, while the 30-50 keV flux of SAX J1808.4-3658 is 9.3±2.4 × 1e-11 erg/s/cm^2, which corresponds to about 18±5 mCrab (uncertainties at 90% c.l.).
Sgr A* is not detected by the imaging pipeline in the combined images covering the Galactic Center region performed from 2019-08-15 15:10:48 to 2019-08-16 08:20:18. We derive a flux upper limit by forcing the IBIS/ISGRI spectral extraction at the source location. Assuming a power-law spectrum with index -2 (ATeL #13023) and exploiting an exposure of 36 ks, the 3 sigma upper limit is 4e-11 erg/s/cm^2 in the 30-50 keV energy band, which corresponds to 1e-10 erg/s/cm^2 in the 5-16 keV band. The JEM-X 3 sigma upper limit is 1e-10 erg/cm2/s (6.5 mCrab) in the 3-10 keV band and 1.5e-10 erg/cm2/s (13.5 mCrab) in the 10-25 keV for 10 ks on-source time.
In the same observation, we could detect with IBIS/ISGRI at a significance of about 7 sigma, the accreting millisecond pulsar SAX J1808.4-3658, recently reported to be in outburst (ATeL #12964,, #13001, #13022). We performed spectral extraction of IBIS/ISGRI data only, as the source is outside the JEM-X field of view. The power-law index is 2.6-0.8+1.2, while the 30-50 keV flux of SAX J1808.4-3658 is 9.3±2.4 × 1e-11 erg/s/cm^2, which corresponds to about 18±5 mCrab (uncertainties at 90% c.l.).
Original language | English |
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Publication date | 16 Aug 2019 |
Publication status | Published - 16 Aug 2019 |
Series | The Astronomer's telegram |
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Number | ATel #13035 |
Keywords
- X-ray
- Gamma ray
- Neutron star
- Pulsar
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JEM-X: The JEM-X X-ray monitor on INTEGRAL
Brandt, S. (PI), Chenevez, J. (Project Participant), Westergaard, N. J. S. (Project Participant), Oxborrow, C. A. (Project Participant), Budtz-Jørgensen, C. (Project Participant), Lund, N. (Project Participant), Rasmussen, I. L. (Project Participant) & Villa, G. P. (Project Participant)
17/10/2002 → …
Project: Research