Deep upper limit on the optical emission during a hard X-ray burst from the magnetar SGR J1935+2154

Abstract

In September 2021 the magnetar SGR J1935+2154 entered a stage of burst/flaring activity in the hard X-ray band. On September 10, 2021 we observed SGR J1935+2154 with the fiber-fed fast optical photon counter IFI+Iqueye, mounted at the 1.22 m Galileo telescope in Asiago. During one of the IFI+Iqueye observing windows a hard X-ray burst was detected with the Fermi Gamma-ray Burst Monitor. We performed a search for any significant increase in the count rate on the 1-s, 10-ms and 1-ms binned IFI+Iqueye light curves around the time of the Fermi burst. No significant peak was detected with a significance above 3$\sigma$ in an interval of $\pm$90 s around the burst. Correcting for interstellar extinction ($A_V\simeq 5.8$ mag), the IFI+Iqueye upper limits to any possible optical burst from SGR J1935+2154 are $V=10.1$ mag, $V=7.2$ mag and $V=5.8$ mag for the 1-s, 10-ms and 1-ms binned light curves, respectively. The corresponding extinction corrected upper limits to the fluence (specific fluence) are $3.1\times 10^{-10}$ erg cm${}^{-2}$ (0.35 Jy s), $4.2\times 10^{-11}$ erg cm${}^{-2}$ (4.8 Jy $\cdot$ 10 ms), and $1.6\times 10^{-11}$ erg cm${}^{-2}$ (17.9 Jy ms), orders of magnitude deeper than any previous simultaneous optical limit on a magnetar burst. The IFI+Iqueye measurement can also place a more stringent constraint to the spectral index of the optical to hard X-ray fluence of SGR J1935+2154, implying a spectrum steeper than ${\nu }^{0.64}$. Fast optical timing observations of bursts associated with radio emission have then the potential to yield a detection.

arXiv comment8 pages, 4 figures, accepted for publication in The Astrophysical Journal Letters

References in corpus (36)

• The NumPy array: a structure for efficient numerical computation
• The Astropy Project: Building an inclusive, open-science project and status of the v2.0 core package
• A 3D Dust Map Based on Gaia, Pan-STARRS 1 and 2MASS
• Magnetars
• astroquery: An Astronomical Web-Querying Package in Python
• A fast radio burst associated with a Galactic magnetar
• A bright millisecond-duration radio burst from a Galactic magnetar
• Gamma-Ray Observations of a Giant Flare from The Magnetar SGR 1806-20
• Magnetars: the physics behind observations
• Empirical extinction coefficients for the GALEX, SDSS, 2MASS and WISE passbands
• The Giant Flare of 1998 August 27 from SGR 1900+14: II. Radiative Mechanism and Physical Constraints on the Source
• INTEGRAL discovery of a burst with associated radio emission from the magnetar SGR 1935+2154
• Explosive reconnection in magnetars
• Magnetars: Properties, Origin and Evolution
• Blast Waves from Magnetar Flares and Fast Radio Bursts
• A peculiar hard X-ray counterpart of a Galactic fast radio burst
• The discovery, monitoring and environment of SGR J1935+2154
• No pulsed radio emission during a bursting phase of a Galactic magnetar
• A Swift gaze into the 2006 March 29th burst forest of SGR 1900+14
• X-ray Bursts from the Transient Magnetar Candidate XTE J1810-197
• X-ray and radio observations of the magnetar SGR J1935+2154 during its 2014, 2015, and 2016 outbursts
• The lowest frequency Fast Radio Bursts: Sardinia Radio Telescope detection of the periodic FRB 180916 at 328 MHz
• Burst properties of the most recurring transient magnetar SGR J1935+2154
• Revisiting the distance, environment and supernova properties of SNR G57.2+0.8 that hosts SGR 1935+2154
• The X-ray reactivation of the radio bursting magnetar SGR 1935+2154
• Multiwavelength observations of Fast Radio Bursts
• Radiative transfer simulations of magnetar flare beaming
• Three-Dimensional Simulations of Magnetar-Powered Superluminous Supernovae
• Intensity Interferometry with Aqueye+ and Iqueye in Asiago
• The impulsive phase of magnetar giant flares: assessing linear tearing as the trigger mechanism
• On the spectrum and polarization of magnetar flare emission
• Aqueye+: a new ultrafast single photon counter for optical high time resolution astrophysics
• Identification of the infrared counterpart of SGR 1935+2154 with the Hubble Space Telescope
• Constraining the X-ray - Infrared spectral index of second-timescale flares from SGR1935+2154 with Palomar Gattini-IR
• On the polarization properties of magnetar giant flare pulsating tails
• Searching for radio pulsation from SGR 1935+2154 with the Parkes Ultra-Wideband Low receiver

Cited by in corpus (1)

• Simultaneous and panchromatic observations of the Fast Radio Burst FRB 20180916B