Monitoring the transient MAXI J1348-630 with the Neil Gehrels Swift observatory
ATel #12477; Tiziana Bassi (INAF/IASF Palermo, Univ di Palermo, IRAP), Melania Del Santo (INAF/IASF Palermo), Antonino D'Ai (INAF/IASF Palermo), Sara Motta (Oxford University), Alessio Marino (INAF/IASF Palermo, Univ di Palermo, IRAP), Alberto Segreto (INAF/IASF Palermo)
on 6 Feb 2019; 13:26 UT
Credential Certification: Melania Del Santo (melania@ifc.inaf.it)
Subjects: X-ray, Transient
Swift is performing a continuous monitoring of the new X-ray transient MAXI J1348-630 (ATel #12434, GCN #23795, #23796) discovered by MAXI/GSC (ATel #12425) in 2019 January 26.
Multi-wavelengths observations have been performed by several telescopes (Atel #12430, #12439, #12441, #12448, #12456). Based on the spectral-timing features, the source has been proposed as Black Hole transient (Atel #12447).
We have analysed the ToO Swift/XRT observations performed on February 3 (ObsID 00011107002) and February 5 (ObsID 00011107003) for 870 s and 430 s exposure time, respectively.
We fitted the WT pile-up corrected spectra with an absorbed Comptonisation model (SIMPL, Steiner et al., 2009, PASP, 121,1279S) convolved with a disc black body model (chi2_red=1.01 (d.o.f. 464) and chi2_red= 0.97 (d.o.f. 323), respectively).
We obtained a spectral photon index of Gamma=1.68 +0.05/-0.10 and an inner disc temperature kT_in=0.42 +0.07/-0.05 keV from the first spectrum and Gamma=2.25 +0.24/-0.30 and kT_in=0.56 +0.07/-0.09 keV from the second.
We estimated an unabsorbed flux in 2-10 keV energy band of 5E-08 ergs/cm^2/s on February 3 and of 9E-08 ergs/cm^2/s on February 5. Moreover, the flux of the disc component increased of a factor of 3.
These results suggest that the source is undergoing hard-to-soft state transition, in agreement with the softening observed in MAXI and INTEGRAL data (Atel #12469, #12471).
We thank the Neil Gehrels Swift Team for making these observations possible, the duty scientists as well as the science planners.
