Subscribe to the gold package and get unlimited access to Shamra Academy
Register a new userThe X-ray Transient 2XMMi J003833.3+402133: A Candidate Magnetar at High Galactic Latitude
221
0
0.0
(
0
)
Authors
Joseph R. Callingham
Ask ChatGPT about the research
No Arabic abstract
We present detailed analysis of the transient X-ray source 2XMMi J003833.3+402133 detected by XMM-Newton in January 2008 during a survey of M 31. The X-ray spectrum is well fitted by either a steep power law plus a blackbody model or a double blackbody model. Prior observations with XMM-Newton, Chandra, Swift and ROSAT spanning 1991 to 2007, as well as an additional Swift observation in 2011, all failed to detect this source. No counterpart was detected in deep optical imaging with the Canada France Hawaii Telescope down to a 3sigma lower limit of g = 26.5 mag. This source has previously been identified as a black hole X-ray binary in M 31. While this remains a possibility, the transient behaviour, X-ray spectrum, and lack of an optical counterpart are equally consistent with a magnetar interpretation for 2XMMi J003833.3+402133. The derived luminosity and blackbody emitting radius at the distance of M 31 argue against an extragalactic location, implying that if it is indeed a magnetar it is located within the Milky Way but 22deg out of the plane. The high Galactic latitude could be explained if 2XMMi J003833.3+402133 were an old magnetar, or if its progenitor was a runaway star that traveled away from the plane prior to going supernova.
rate research
Read More
The nature of the bipolar, $gamma$-ray Fermi bubbles (FB) is still unclear, in part because their faint, high-latitude X-ray counterpart has until now eluded a clear detection. We stack ROSAT data at varying distances from the FB edges, thus boosting the signal and identifying an expanding shell behind the southwest, southeast, and northwest edges, albeit not in the dusty northeast sector near Loop I. A Primakoff-like model for the underlying flow is invoked to show that the signals are consistent with halo gas heated by a strong, forward shock to $sim$keV temperatures. Assuming ion--electron thermal equilibrium then implies a $sim10^{56}$ erg event near the Galactic centre $sim7$ Myr ago. However, the reported high absorption-line velocities suggest a preferential shock-heating of ions, and thus more energetic ($sim 10^{57}$ erg), younger ($lesssim 3$ Myr) FBs.
We report the discovery of the transient ultraluminous X-ray source (ULX) CXOU J122602.3+125951 (hereafter M86 tULX-1), located 352 (19 kpc) northwest of the centre of the giant elliptical galaxy M86 (NGC 4406) in the Virgo Cluster. The spectrum of M86 tULX-1 can be fit by a power-law plus multicolour-disc model with a 1.0 [+0.8 -2.6] index and an 0.66 [+0.17 -0.11] keV inner-disc temperature, or by a power law with a 1.86 +/- 0.10 index. For an isotropically emitting source at the distance of M86, the luminosity based on the superposition of spectral models is (5 +/- 1) x 10^39 erg/s. Its relatively hard spectrum places M86 tULX-1 in a hitherto unpopulated region in the luminosity-disc temperature diagram, between other ULXs and the (sub-Eddington) black-hole X-ray binaries. We discovered M86 tULX-1 in an archival 148-ks 2013 July Chandra observation, and it was not detected in a 20-ks 2016 May Chandra observation, meaning it faded by a factor of at least 30 in three years. Based on our analysis of deep optical imaging of M86, it is probably not located in a globular cluster. It is the brightest ULX found in an old field environment unaffected by recent galaxy interaction. We conclude that M86 tULX-1 may be a stellar-mass black hole of ~30 - 100 M_Sun with a low-mass giant companion, or a transitional object in a state between the normal stellar-mass black holes and the ultraluminous state.
We report the discovery of a candidate stellar-mass black hole in the Milky Way globular cluster M62. We detected the black hole candidate, which we term M62-VLA1, in the core of the cluster using deep radio continuum imaging from the Karl G. Jansky Very Large Array. M62-VLA1 is a faint source, with a flux density of 18.7 +/- 1.9 microJy at 6.2 GHz and a flat radio spectrum (alpha=-0.24 +/- 0.42, for S_nu = nu^alpha). M62 is the second Milky Way cluster with a candidate stellar-mass black hole; unlike the two candidate black holes previously found in the cluster M22, M62-VLA1 is associated with a Chandra X-ray source, supporting its identification as a black hole X-ray binary. Measurements of its radio and X-ray luminosity, while not simultaneous, place M62-VLA1 squarely on the well-established radio--X-ray correlation for stellar-mass black holes. In archival Hubble Space Telescope imaging, M62-VLA1 is coincident with a star near the lower red giant branch. This possible optical counterpart shows a blue excess, H alpha emission, and optical variability. The radio, X-ray, and optical properties of M62-VLA1 are very similar to those for V404 Cyg, one of the best-studied quiescent stellar-mass black holes. We cannot yet rule out alternative scenarios for the radio source, such as a flaring neutron star or background galaxy; future observations are necessary to determine whether M62-VLA1 is indeed an accreting stellar-mass black hole.
We present a comprehensive analysis of 20 years worth of multi-color photometric light curves, multi-epoch optical spectra, and X-ray data of an off-nuclear variable object SDSS1133 in Mrk 177 at $z=0.0079$. The UV-optical light curves reveal that SDSS1133 experienced three outbursts in 2001, 2014, and 2019. The persistent UV-optical luminosity in the non-outbursting state is $sim 10^{41}$ erg/s with small-scale flux variations, and peak luminosities during the outbursts reach $sim 10^{42}$ erg/s. The optical spectra exhibit enduring broad hydrogen Balmer P-Cygni profiles with the absorption minimum at $sim -2,000$ km/s, indicating the presence of fast moving ejecta. Chandra detected weak X-ray emission at a 0.3-10 keV luminosity of $L_{X} = 4 times 10^{38}$ erg/s after the 2019 outburst. These lines of evidence strongly suggests that SDSS1133 is an extremely luminous blue variable (LBV) star experiencing multiple giant eruptions with interactions of the ejected shell with different shells and/or circumstellar medium (CSM), and strongly disfavors the recoiling Active Galactic Nuclei (AGN) scenario suggested in the literature. We suggest that pulsational pair-instability may provide a viable explanation for the multiple energetic eruptions in SDSS1133. If the current activity of SDSS1133 is a precursor of a supernova explosion, we may be able to observe a few additional giant eruptions and then the terminal supernova explosion in future observations.
We report the results of an optical campaign carried out by the XMM-Newton Survey Science Centre with the specific goal of identifying the brightest X-ray sources in the XMM-Newton Galactic Plane Survey of Hands et al. (2004). In addition to photometric and spectroscopic observations obtained at the ESO-VLT and ESO-3.6m, we used cross-correlations with the 2XMMi, USNO-B1.0, 2MASS and GLIMPSE catalogues to progress the identification process. Active coronae account for 16 of the 30 identified X-ray sources. Many of the identified hard X-ray sources are associated with massive stars emitting at intermediate X-ray luminosities of 10^32-34 erg/s. Among these are a very absorbed likely hyper-luminous star with X-ray/optical spectra and luminosities comparable with those of eta Carina, a new X-ray selected WN8 Wolf-Rayet star, a new Be/X-ray star belonging to the growing class of Gamma-Cas analogs and a possible supergiant X-ray binary of the kind discovered recently by INTEGRAL. One of the sources, XGPS-25 has a counterpart which exhibits HeII 4686 and Bowen CIII-NIII emission lines suggesting a quiescent or X-ray shielded Low Mass X-ray Binary, although its properties might also be consistent with a rare kind of cataclysmic variable (CV). We also report the discovery of three new CVs, one of which is a likely magnetic system. The soft (0.4-2.0 keV) band LogN-LogS curve is completely dominated by active stars in the flux range of 1x10^-13 to 1x10^-14 erg/cm2/s. In total, we are able to identify a large fraction of the hard (2-10 keV) X-ray sources in the flux range of 1x10^-12 to 1x10^-13 erg/cm2/s with Galactic objects at a rate consistent with that expected for the Galactic contribution only. (abridged)
Log in to be able to interact and post comments
comments
Fetching comments
Sign in to be able to follow your search criteria
