Searcharxiv⌕ Search
Home/Archive/arXiv

arXiv · astro-ph/0701070

Chandra and XMM-Newton discovery of the transient X-ray pulsar in the nearby spiral galaxy NGC2403

Sergey Trudolyubov·William Priedhorsky·France Cordova
View original source ↗Read source document ↗Export metadata ↓

Abstract

We report on the discovery and analysis of the transient X-ray pulsar CXO/XMMU J073709.13+653544 detected in the 2004 August-October Chandra and XMM observations of the nearby spiral galaxy NGC2403. The source exhibits X-ray pulsations with a period P~18 s, a nearly sinusoidal pulse shape and pulsed fraction 46-70%. The source shows a rapid decrease of the pulsation period from 18.25 s on Aug. 9 to 17.93 s on Sep. 12 and possibly 17.56 s on Oct. 3, 2004. The X-ray spectra of the source are hard and are well fitted with an absorbed simple power law of photon index 0.9~1.2. The X-ray properties of the source and the absence of an optical/UV counterpart allow us to identify CXO/XMMU J073709.13+653544 as accreting X-ray pulsar in NGC2403. The maximum unabsorbed luminosity of the source in the 0.3-7 keV range, ~2.6x10e38 erg/s at 3.2 Mpc, is at least 260 times higher than its quiescent luminosity. The corresponding luminosity in the 0.3-100 keV energy range could be as high as ~1.2x10e39 erg/s, assuming the typical pulsar energy spectrum with high-energy cut-off at 10-20 keV. The rate of decrease of the pulsation period of the source (-10e-7 s/s) is one of the fastest observed among accreting pulsars. The evolution of the pulsation period suggests that it is dominated by the intrinsic spin-up of the compact object. The accretion rate implied by X-ray luminosity of CXO/XMMU J073709.13+653544 could account for the observed spin-up rate, assuming that the X-ray source is powered by disk accretion onto highly magnetized neutron star. Based on the transient behavior and overall X-ray properties of the source, we conclude that it could be an X-ray pulsar belonging to either a Be binary system or a low-mass system similar to GRO J1744-28.

Explore related subjects

astro-ph

Keep this discovery

Explore connections, maps & timelines

BibTeXRIS

Sergey Trudolyubov, William Priedhorsky, France Cordova. 2007-03-29. Chandra and XMM-Newton discovery of the transient X-ray pulsar in the nearby spiral galaxy NGC2403. https://doi.org/10.1086/518500

Cite the original work for its findings. Save a collection to share your selection of sources.

KEEP EXPLORING

Related papers

arXiv2020

Cosmic Variance and Its Effect on the Luminosity Function Determination in Deep High z Surveys

We study cosmic variance in deep high redshift surveys and its influence on the determination of the luminosity function for high redshift galaxies. For several survey geometries relevant for HST and JWST instruments, we characterize the distribution of the galaxy number counts. This is obtained by means of analytic estimates via the two point correlation function in extended Press-Schechter theory as well as by using synthetic catalogs extracted from N-body cosmological simulations of structure formation. We adopt a simple luminosity - dark halo mass relation to investigate the environment effects on the fitting of the luminosity function. We show that in addition to variations of the normalization of the luminosity function, a steepening of its slope is also expected in underdense fields, similarly to what is observed within voids in the local universe. Therefore, to avoid introducing artificial biases, caution must be taken when attempting to correct for field underdensity, such as in the case of HST UDF i-dropout sample, which exhibits a deficit of bright counts with respect to the average counts in GOODS. A public version of the cosmic variance calculator based on the two point correlation function integration is made available on the web.

astro-ph↗
arXiv2020

Receiver control for the Submillimeter Array

Efficient operation of a submillimeter interferometer requires remote (preferably automated) control of mechanically tuned local oscillators, phase-lock loops, mixers, optics, calibration vanes and cryostats. The present control system for these aspects of the Submillimeter Array (SMA) will be described. Distributed processing forms the underlying architecture and the software is split between hardware platforms in a leader/follower arrangement. In each antenna cabin, a serial network of up to ten independent 80C196 microcontroller boards attaches to the real-time PowerPC computer (running LynxOS). A multi-threaded, gcc-compiled leader program on the PowerPC accepts top-level requests via remote procedure calls (RPC), subsequently dispatches tuning commands to the relevant follower microcontrollers, and regularly reports the system status to optical-fiber-based reflective memory for common access by the telescope monitor and error reporting system. All serial communication occurs asynchronously via encoded, variable-length packets. The microcontrollers respond to the requested commands and queries by accessing non-volatile, rewriteable lookup-tables (when appropriate) and executing embedded software that operates additional electronic devices (DACs, ADCs, etc.). Since various receiver hardware components require linear or rotary motion, each microcontroller also implements a position servo via a one-millisecond interrupt service routine which drives a DC-motor/encoder combination that remains standard across each subsystem.

astro-ph↗
arXiv2019

Classical analysis of the rotational dynamic of spiral galaxies: Quo Vadis Dark Matter?

In this paper we study a stellar dynamic model for the stars' rotational-dynamics, with a distribution of its own mass, rotating around its center with a higher density, like spiral galaxies happen, by means of a classical calculus of the rotation velocities of a particle around its rotational axis, inside a smoothed distribution of matter. The stars are supposed to be particles and their distribution in the galaxy is modelled as a matter distribution inversely proportional to its distance from its center. Two kinds of matter distribution are supposed: one with constant density, and other with radial distribution. Two types of galaxy symmetry are also considered: spherical and oblate ellipsoidal. Using only classical mechanics arguments it is shown that the calculated velocity distribution inside the galaxy is similar to that obtained from astronomical observations, without the necessity of suppose the existence of dark matter or other phenomena.

astro-ph↗