The X-ray dust scattered rings of the black hole low mass binary V404 Cyg

Abstract

We report on the first detection of X-ray dust scattered rings from the Galactic low mass X-ray binary V404 Cyg. The observation of the system with Swift/XRT on June 30 2015 revealed the presence of five concentric ring-like structures centred at the position of V404 Cyg. Follow-up Swift/XRT observations allowed a time-dependent study of the X-ray rings. Assuming that these are the result of small-angle, single X-ray scattering by dust grains along the line of sight, we find that their angular size scales as $\theta \propto \sqrt{t}$ in agreement with theoretical predictions. The dust grains are concentrated in five dust layers located at about 2.12, 2.05, 1.63, 1.50 and 1.18 kpc from the observer. These coincide roughly with locations of enhanced extinction as determined by infrared photometry. Assuming that the grain size distribution is described by a generalized Mathis-Rumpl-Nordsieck model, we find that the power-law index of the most distant cloud is $q\sim 4.4$, while $q\sim 3.5-3.7$ in all other clouds. We constrain at a $3\sigma$ level the maximum grain size of the intermediate dust layers in the range $0.16-0.20\mu$m and set a lower limit of $\sim 0.2\mu$m in the other clouds. Hints of an exponential cutoff at the angular intensity profile of the outermost X-ray ring suggest that the smallest grains have sizes $0.01\mu \mathrm{m}\le {\alpha }_{\min }\lesssim 0.03\mu$m. Based on the relative ratios of dust column densities we find the highest dust concentration at $\sim 1.6$ kpc. Our results indicate a gradient in the dust properties within 1 kpc from V404 Cyg.

17 pages, 13 figures, accepted by MNRAS

References in corpus (4)

• The old nuclear star cluster in the Milky Way: dynamics, mass, statistical parallax, and black hole mass
• A 3D extinction map of the Northern Galactic Plane based on IPHAS photometry
• The X-ray Halo of GX5-1
• Dust-scattered X-ray halos around two Swift gamma-ray bursts: GRB 061019 and GRB 070129

Cited by in corpus (20)

• GRB 221009A: Discovery of an Exceptionally Rare Nearby and Energetic Gamma-Ray Burst
• Living on a Flare: Relativistic Reflection in V404 Cyg Observed by NuSTAR During its Summer 2015 Outburst
• The 2015 Decay of the Black Hole X-ray Binary V404 Cygni: Robust Disk-Jet Coupling and a Sharp Transition into Quiescence
• Swift observations of V404 Cyg during the 2015 outburst: X-ray outflows from super-Eddington accretion
• The obscured X-ray binaries V404 Cyg, Cyg X-3, V4641 Sgr, and GRS 1915+105
• The reverberation lag in the low mass X-ray binary H1743-322
• A Joint Chandra and Swift View of the 2015 X-Ray Dust Scattering Echo of V404 Cygni
• SWIFT view of the 2015 outburst of GS 2023+338 (V404 Cyg): complex evolution of spectral and temporal characteristics
• Accreting, highly magnetized neutron stars at the Eddington limit: A study of the 2016 outburst of SMC X-3
• Probing the Interstellar Dust towards the Galactic Centre: Dust Scattering Halo around AX J1745.6-2901
• Interstellar dust along the line of sight of GX 3+1
• Behind the dust curtain: the spectacular case of GRB 160623A
• The nova-like nebular optical spectrum of V404 Cygni at the beginning of the 2015 outburst decay
• Dust-scattering rings of GRB 221009A as seen by the Neil Gehrels Swift satellite: can we count them all?
• The effect of X-ray dust-scattering on a bright burst from the magnetar 1E 1547.0-5408
• Swift UVOT observations of the 2015 outburst of V404 Cygni
• Exploring the Interstellar Medium Using an Asymmetric X-ray Dust Scattering Halo
• Interstellar absorption and dust scattering
• The X-ray variable sky as seen by MAXI: the future of dust echo tomography with bright Galactic X-ray bursts
• Discovery of annular X-ray emission centered on MAXI J1421-613: Dust-scattering X-rays?