English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Plus monthly

Global: Zendy Tools annual

Global: Zendy Tools monthly

Global: Zendy Free Plan

We present the results of MAXI monitoring and two NuSTAR observations of therecently discovered faint X-ray transient MAXI J1848-015. Analysis of the MAXIlight-curve shows that the source underwent a rapid flux increase beginning on2020 December 20, followed by a rapid decrease in flux after only $\sim5$ days.NuSTAR observations reveal that the source transitioned from a bright softstate with unabsorbed, bolometric ($0.1$-$100$ keV) flux $F=6.9 \pm 0.1 \times10^{-10}\,\mathrm{erg\,cm^{-2}\,s^{-1}}$, to a low hard state with flux $F=2.85\pm 0.04 \times 10^{-10}\,\mathrm{erg\,cm^{-2}\,s^{-1}}$. Given a distance of$3.3$ kpc, inferred via association of the source with the GLIMPSE-C01 cluster,these fluxes correspond to an Eddington fraction of order $10^{-3}$ for anaccreting neutron star of mass $M=1.4M_\odot$, or even lower for a more massiveaccretor. However, the source spectra exhibit strong relativistic reflectionfeatures, indicating the presence of an accretion disk which extends close tothe accretor, for which we measure a high spin, $a=0.967\pm0.013$. In additionto a change in flux and spectral shape, we find evidence for other changesbetween the soft and hard states, including moderate disk truncation with theinner disk radius increasing from $R_\mathrm{in}\approx3\,R_\mathrm{g}$ to$R_\mathrm{in}\approx8\,R_\mathrm{g}$, narrow Fe emission whose centroiddecreases from $6.8\pm0.1$ keV to $6.3 \pm 0.1$ keV, and an increase inlow-frequency ($10^{-3}$-$10^{-1}$ Hz) variability. Due to the high spin weconclude that the source is likely to be a black hole rather than a neutronstar, and we discuss physical interpretations of the low apparent luminosity aswell as the narrow Fe emission.

MAXI and NuSTAR observations of the faint X-ray transient MAXI J1848-015 in the GLIMPSE-C01 Cluster