Improved Mass and Radius Constraints for Quiescent Neutron Stars in Omega Cen and NGC 6397

Abstract

We use Chandra and XMM observations of the globular clusters $\omega$ Cen and NGC 6397 to measure the spectrum of their quiescent neutron stars (NSs), and thus to constrain the allowed ranges of mass and radius for each. We also use Hubble Space Telescope photometry of NGC 6397 to identify a potential optical companion to the quiescent NS, and find evidence that the companion lacks hydrogen. We carefully consider a number of systematic problems, and show that the choices of atmospheric composition, interstellar medium abundances, and cluster distances can have important effects on the inferred NS mass and radius. We find that for typical NS masses, the radii of both NSs are consistent with the 10-13 km range favored by recent nuclear physics experiments. This removes the evidence suggested by Guillot and collaborators for an unusually small NS radius, which relied upon the small inferred radius of the NGC 6397 NS.

arXiv commentSubmitted to MNRAS. 17 pages

References in corpus (84)

• The chemical composition of the Sun
• On the Absorption of X-rays in the Interstellar Medium
• The European Photon Imaging Camera on XMM-Newton: The MOS Cameras
• Atomic Data for Astrophysics. II. New Analytic Fits for Photoionization Cross Sections of Atoms and Ions
• Neutron Star Observations: Prognosis for Equation of State Constraints
• The Equation of State from Observed Masses and Radii of Neutron Stars
• Neutron Star Cooling
• Drizzle: A Method for the Linear Reconstruction of Undersampled Images
• Equation of state and neutron star properties constrained by nuclear physics and observation
• Constraints on the symmetry energy and neutron skins from experiments and theory
• The Relation Between Optical Extinction and Hydrogen Column Density in the Galaxy
• A Radio Pulsar/X-ray Binary Link
• Swings between rotation and accretion power in a millisecond binary pulsar
• An ACS Survey of Globular Clusters V: Star Catalog for Each Cluster
• Astrophysical Measurement of the Equation of State of Neutron Star Matter
• Crustal Heating and Quiescent Emission from Transiently Accreting Neutron Stars
• Distances and ages of NGC 6397, NGC 6752 and 47 Tuc
• A Hydrogen Atmosphere Spectral Model Applied to the Neutron Star X7 in the Globular Cluster 47 Tucanae
• The dynamical distance and intrinsic structure of the globular cluster omega Centauri
• A Neutron Star with a Carbon Atmosphere in the Cassiopeia A Supernova Remnant
• A state change in the low-mass X-ray binary XSS J12270-4859
• The Neutron Stars of Soft X-Ray Transients
• Neutron Star Masses and Radii from Quiescent Low-Mass X-ray Binaries
• Measurement of the Radius of Neutron Stars with High S/N Quiescent Low-mass X-ray Binaries in Globular Clusters
• The long-term evolution of the spin, pulse shape, and orbit of the accretion-powered millisecond pulsar SAX J1808.4-3658
• The White Dwarf Cooling Sequence of NGC6397
• Analysis of the Quiescent Low-Mass X-ray Binary Population in Galactic Globular Clusters
• The white dwarf cooling sequence in NGC 6791
• White Dwarf Donors in Ultracompact Binaries: The Stellar Structure of Finite Entropy Objects
• Cataclysmic Variables from SDSS II. The Second Year
• Evidence for accretion rate change during type I X-ray bursts
• Chandra Exposes the Core Collapsed Globular Cluster NGC 6397
• Variable Thermal Emission from Aql X-1 in Quiescence
• Cluster AgeS Experiment: The Age and Distance of the Globular Cluster omega Centauri Determined from Observations of the Eclipsing Binary OGLEGC17
• Variability in the Thermal Emission from Accreting Neutron Star Transients
• An Age Difference of 2 Gyr between a Metal-Rich and a Metal-Poor Globular Cluster
• On the possibility of a helium white dwarf donor in the presumed ultracompact binary 2S 0918-549
• Models of Type I X-Ray Bursts in 4U 1820-30
• Cross-calibration of the X-ray Instruments onboard the Chandra, INTEGRAL, RXTE, Suzaku, Swift, and XMM-Newton Observatories using G21.5-0.9
• Model Atmospheres for Low Field Neutron Stars
• Stellar Encounter Rate in Galactic Globular Clusters
• Cross-calibrating X-ray detectors with clusters of galaxies: an IACHEC study
• Is FIRST J102347.6+003841 Really a Cataclysmic Binary?
• Stability of helium accretion discs in ultracompact binaries
• A Dynamical Signature of Multiple Stellar Populations in 47 Tucanae
• Constraining the equation of state of supra-nuclear dense matter from XMM-Newton observations of neutron stars in globular clusters
• Deep ACS Imaging in the Globular Cluster NGC 6397: The Cluster Color Magnitude Diagram and Luminosity Function
• Giants in the globular cluster omega Centauri: dust production, mass loss and distance
• Photometric determination of the mass accretion rates of pre-main sequence stars. I. Method and application to the SN1987A field
• Identification of A Transient Neutron Star in Quiescence in the Globular Cluster NGC 5139
• M-type giants as optical counterparts of X-ray sources 4U 1700+24 and 4U 1954+319
• A pulsational distance to Omega Centauri based on Near-Infrared Period-Luminosity relations of RR Lyrae stars
• Quiescent X-ray emission from Cen X-4: a variable thermal component
• Indirect evidence for an active radio pulsar in the quiescent state of the transient ms pulsar SAX J1808.4-3658
• A Chandra X-ray Observatory Study of PSR J1740--5340 and Candidate Millisecond Pulsars in the Globular Cluster NGC 6397
• Neutron Star Radius Measurement with the Quiescent Low-Mass X-ray Binary U24 in NGC 6397
• An XMM-Newton observation of the globular cluster Omega Centauri
• Constraints on neutron star mass and radius in GS 1826-24 from sub-Eddington X-ray bursts
• Discovery of a 205.89 Hz accreting-millisecond X-ray pulsar in the globular cluster NGC 6440
• Identification of Faint Chandra X-ray Sources in the Core-Collapsed Globular Cluster NGC 6397: Evidence for a Bimodal Cataclysmic Variable Population
• Optical Observations of SAX J1808.4-3658 During Quiescence
• The Spectral Energy Distributions of White Dwarfs in 47 Tucanae: The Distance to the Cluster
• Neutron star atmosphere composition: the quiescent, low-mass X-ray binary in the globular cluster M28
• Helium-Core White Dwarfs in the Globular Cluster NGC 6397
• Rotational Broadening and Doppler Tomography of the Quiescent X-Ray Nova Centaurus X-4
• Relative distances of Omega Centauri and 47 Tucanae
• X-Ray spectra from protons illuminating a neutron star
• The optical counterpart to the X-ray transient IGR J18245-2452 in the globular cluster M28
• Time-resolved optical observations of five cataclysmic variables detected by INTEGRAL
• An ultracompact X-ray binary in the globular cluster NGC 1851
• HST/ACS Imaging of Omega Centauri: Optical Counterpart for the Quiescent Low-Mass X-Ray Binary
• A Deep Chandra X-ray Limit on the Putative IMBH in Omega Centauri
• VLT spectroscopy of XTE J2123-058 during quiescence
• Deep HST Imaging in NGC 6397: Stellar Dynamics
• Mass/Radius Constraints on the Quiescent Neutron Star in M13 Using Hydrogen and Helium Atmospheres
• Doppler tomography of the transient X-ray binary Centaurus X-4 in quiescence
• X-ray Spectral Identification of Three Candidate Quiescent Low-Mass X-ray Binaries in the Globular Cluster NGC 6304
• HST/ACS Imaging of Omega Centauri: Optical Counterparts of Chandra X-Ray Sources
• An anti-correlation between X-ray luminosity and H-alpha equivalent width in X-ray binaries
• A Chandra Study of the Galactic Globular Cluster Omega Centauri
• Aql X-1 in Outburst and Quiescence
• Optical spectroscopy of the quiescent counterpart to EXO 0748-676
• On the consistency of neutron-star radius measurements from thermonuclear bursts
• Hα photometry of low mass stars in 47 Tucanae: chromospheric activity and exotica

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• The MAVERIC survey: A transitional millisecond pulsar candidate in Terzan 5
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• Symmetry energy and neutron star properties in the saturated Nambu-Jona-Lasinio model
• Investigating Variability of Quiescent Neutron Stars in the Globular Clusters NGC 6440 and Terzan 5
• On obtaining neutron-star mass and radius constraints from quiescent low-mass X-ray binaries in the Galactic plane
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• Systematic Uncertainties in the Spectroscopic Measurements of Neutron-Star Masses and Radii from Thermonuclear X-ray Bursts. III. Absolute Flux Calibration
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• Neutron Star Radius-to-mass Ratio from Partial Accretion Disc Occultation as Measured through Fe K$\alpha$ Line Profiles
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• Exploration of faint X-ray and radio sources in the massive globular cluster M14: A UV-bright counterpart to Nova Ophiuchus 1938
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