1RXS J180408.9-342058: an ultra compact X-ray binary candidate with a transient jet

Abstract

We present a detailed NIR/optical/UV study of the transient low mass X-ray binary 1RXS J180408.9-342058 performed during its 2015 outburst, aimed at determining the nature of its companion star. We obtained three optical spectra at the 2.1 m San Pedro Martir Observatory telescope (Mexico). We performed optical and NIR photometric observations with both the REM telescope and the New Technology Telescope (NTT) in La Silla. We obtained optical and UV observations from the Swift archive. Finally, we performed optical polarimetry of the source by using the EFOSC2 instrument mounted on the NTT. The optical spectrum of the source is almost featureless since the hydrogen and He I emissions lines, typically observed in LMXBs, are not detected. Similarly, carbon and oxygen lines are neither observed. We marginally detect the He II 4686 AA emission line, suggesting the presence of helium in the accretion disc. No significant optical polarisation level was observed. The lack of hydrogen and He I emission lines in the spectrum implies that the companion is likely not a main sequence star. Driven by the tentative detection of the He II 4686 AA emission line, we suggest that the system could harbour a helium white dwarf. If this is the case, 1RXS J180408.9-342058 would be an ultra-compact X-ray binary. By combining an estimate of the mass accretion rate together with evolutionary tracks for a He white dwarf, we obtain a tentative orbital period of ~ 40 min. On the other hand, we also built the NIR-optical-UV spectral energy distribution (SED) of the source at two different epochs. One SED was gathered when the source was in the soft X-ray state, and it is consistent with the presence of a single thermal component. The second SED, obtained when the source was in the hard X-ray state, shows a thermal component together with a tail in the NIR, likely indicating the presence of a (transient) jet.

8 pages, 5 figures, 4 tables. Accepted for publication in Astronomy & Astrophysics (Section 7)

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• Empirical Color Transformations Between SDSS Photometry and Other Photometric Systems
• Black hole-like hysteresis and accretion states in neutron star low mass X-ray binaries
• Stability of helium accretion discs in ultracompact binaries
• Polarimetric and spectroscopic optical observations of the ultra-compact X-ray binary 4U 0614+091

Cited by in corpus (21)

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• Low-Mass X-ray Binaries
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• Jet quenching in the neutron star low-mass X-ray binary 1RXS J180408.9$-$342058
• The evolving jet spectrum of the neutron star X-ray binary Aql X-1 in transitional states during its 2016 outburst
• UltraCompCAT: a comprehensive Catalogue of Ultra-Compact and Short Orbital Period X-ray Binaries
• ALMA observations of 4U 1728-34 and 4U 1820-30: first detection of neutron star X-ray binaries at 300 GHz
• New insights on the puzzling LMXB 1RXS J180408.9-342058: the intermediate state, the clocked type-I X-ray bursts and much more
• The Galactic LMXB Population and the Galactic Centre Region
• Probing jet launching in neutron star X-ray binaries: the variable and polarized jet of SAX J1808.4-3658
• Peering at the outflow mechanisms in the transitional pulsar PSR J1023+0038: simultaneous VLT, XMM-Newton, and Swift high-time resolution observations
• Detection of Millihertz Quasi-Periodic Oscillations in the X-Ray Binary 1RXS J180408.9$-$342058
• Swift and SALT observations of the Multiple Outbursts of MAXI J1957+032
• Testing jet geometries and disk-jet coupling in the neutron star LMXB 4U 0614+091 with the internal shocks model
• Quiescent NIR and optical counterparts to candidate black hole X-ray binaries
• Partially accreted crusts of neutron stars
• Quasi-simultaneous Integral, Swift, And Nustar Observations Of The New X-ray Clocked Burster 1rxsj180408.9-342058
• Near-infrared counterparts of three transient very faint neutron star X-ray binaries
• MAXI J1957+032: an accreting neutron star possibly in a triple system
• On the origin of the near-infrared emission from the neutron-star low-mass X-ray binary GX 9+1
• Optical spectroscopy of 4U 1812-12: an ultra-compact X-ray binary seen through an H II region