Special Issue Editors

Dr. Dimitris M. Christodoulou

E-Mail Website
Guest Editor

Department of Mathematics and Statistics, University of Massachusetts Lowell, Lowell, MA 01854, USA
Interests: accretion: accretion disks; stars: magnetic fields; stars: neutron; X-rays: binaries; HMXBs and ULXs

Prof. Dr. Silas G.T. Laycock

E-Mail Website
Guest Editor

Department of Mathematical Sciences, University of Massachusetts Lowell, Lowell, MA 01854, USA
Interests: pulsars; black holes; binary stars; X-rays; high energy radiation; optical spectroscopy; adaptive optics

Dr. Demosthenes Kazanas

E-Mail Website
Guest Editor

NASA Goddard Space Flight Center, Greenbelt, MD 20771, USA
Interests: X-rays: binaries

Special Issue Information

Dear Colleagues,

We are soliciting contributions on the rapidly evolving field of HMXBs and ULX sources, whose compact objects are neutron stars. Though new results are certainly acceptable, we are also asking for reviews summarizing the general knowledge on the subject, because standard reviews in this field are currently lacking. Both observational and theoretical papers are welcome. We hope that this volume will be an acute summary of the state of the field, describing what we already know from previous X-ray observations and what we hope to learn in the recent future. The structure and evolution of magnetic fields in these X-ray sources are also themes of enormous contemporary interest in the field. ULX sources are included because it is currently thought that these sources also harbor neutron stars accreting above the Eddington limit.

Prof. Dr. Dimitris M. Christodoulou
Prof. Dr. Silas G.T. Laycock
Dr. Demosthenes Kazanas
Guest Editors

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Keywords

accretion, accretion disks
stars: magnetic fields
stars: neutron
X-rays: binaries

Published Papers (2 papers)

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Research

Jump to: Review

21 pages, 631 KiB

Open AccessArticle

Variable Magellanic HMXB Sources versus Variable ULX Sources: Nothing to Brag about the ULX Sources

by Dimitris M. Christodoulou, Silas G. T. Laycock, Rigel Cappallo, Ankur Roy, Sayantan Bhattacharya and Demosthenes Kazanas

Galaxies 2020, 8(4), 70; https://0-doi-org.brum.beds.ac.uk/10.3390/galaxies8040070 - 24 Sep 2020

Viewed by 2471

Abstract

We carry out a meta-analysis of ultraluminous X-ray (ULX) sources that show large variabilities (by factors of

> 10

) between their highest and lowest emission states in the X-ray energy range of 0.3–10 keV. We are guided by a recent stringent compilation [...] Read more.

We carry out a meta-analysis of ultraluminous X-ray (ULX) sources that show large variabilities (by factors of

> 10

) between their highest and lowest emission states in the X-ray energy range of 0.3–10 keV. We are guided by a recent stringent compilation of 25 such X-ray sources by Song et al. We examine the relation of

log N

versus

log S_{\max}

, where N is the number of sources radiating above the maximum-flux level

S_{\max}

. We find a strong deviation from all previously determined slopes in various high-mass X-ray binary (HMXB) samples. In fact, the ULX data clearly show a slope of

- 0.91

. Thus, ULX sources do not appear to be uniform and isotropic in our Universe. We compare the ULX results against the local X-ray luminosity function of HMXBs in the Small Magellanic Cloud (SMC) constructed from our latest library that includes 41 Chandra 0.3–8 keV sources and 56 XMM-Newton 0.2–12 keV sources. The ULX data are not drawn from the same continuous distribution as the SMC data (the ULX data peak at the low tails of the SMC distributions), and none of our data sets is drawn from a normal distribution or from a log-normal distribution (they all show marked excesses at both tails). At a significance level of

α = 0.05

(

2 σ

), the two-sample p-value of the Kolmogorov–Smirnov (KS) test gives

p = 4.7 \times 10^{- 3} < α

for the ULX versus the small Chandra sample and

p = 1.1 \times 10^{- 5} < < α

for the ULX versus the larger XMM-Newton sample, respectively. This adds to the evidence that ULX sources are not simply the higher end of the known local Be/X-ray pulsar distribution, but they represent a class of X-ray sources different from the young sources found in the SMC and in individual starburst galaxies. On the other hand, our two main SMC data sets are found to be statistically consistent, as they are drawn from the same continuous parent distribution (null hypothesis

H_{0}

): at the

α = 0.05

significance level, the two-sample KS test shows an asymptotic p-value of

0.308 > α

, which tells us to accept

H_{0}

. Full article

(This article belongs to the Special Issue High-Mass X-ray Binaries and Ultraluminous X-ray Sources Hosting Neutron Stars)

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Figure 1

Review

Jump to: Research

16 pages, 7299 KiB

Open AccessReview

From SN 2010da to NGC 300 ULX-1: Ten Years of Observations of an Unusual High Mass X-Ray Binary in NGC 300

by Breanna A. Binder, Stefania Carpano, Marianne Heida and Ryan Lau

Galaxies 2020, 8(1), 17; https://0-doi-org.brum.beds.ac.uk/10.3390/galaxies8010017 - 18 Feb 2020

Cited by 4 | Viewed by 5640

Abstract

In May 2010, an intermediate luminosity optical transient was discovered in the nearby galaxy NGC 300 by a South African amateur astronomer. In the decade since its discovery, multi-wavelength observations of the misnamed “SN 2010da” have continually reshaped our understanding of this high mass X-ray binary system. In this review, we present an overview of the multi-wavelength observations and attempt to understand the 2010 transient event, and later, the reclassification of this system as NGC 300 ULX-1: a red supergiant + neutron star ultraluminous X-ray source. Full article

(This article belongs to the Special Issue High-Mass X-ray Binaries and Ultraluminous X-ray Sources Hosting Neutron Stars)

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