Eccentricities of millisecond pulsars with intermediate-mass progenitors

Abstract

One channel to form millisecond pulsars with CO white dwarf companions is through the stable Roche-lobe overflow of intermediate-mass ($3{\mathrm{M}}_{\odot }\lesssim M\lesssim 5{\mathrm{M}}_{\odot }$) stars at the end of the main sequence (Case A) or the beginning of the hydrogen shell burning phase (Case B). We reproduce previous numerical calculations of this channel and supplement them with a simple analytical model that relates the final orbital period $P(M,m_{\mathrm{wd}})$ to the white dwarf's mass and to its progenitor's initial mass $M$. We also theoretically calculate for the first time the eccentricity $e$ in this process, which is set by the fluctuating gravitational quadrupole moment of the progenitor's convective envelope during Roche-lobe detachment. Intermediate-mass progenitors detach when their non-degenerate cores ignite helium, in contrast to low-mass ($M\lesssim 2{\mathrm{M}}_{\odot }$) stars with degenerate cores that detach when their envelopes become too light to support a burning shell. Despite the order of magnitude higher envelope mass at detachment $m_{\mathrm{e}}$ in our case, the eccentricity is barely affected because $e\propto m_{\mathrm{e}}^{1/6}$, explaining why intermediate-mass ($m_{\mathrm{wd}}\lesssim 0.6{\mathrm{M}}_{\odot })$ CO white dwarfs have similar eccentricities to lower mass helium white dwarfs. Massive CO and ONe white dwarfs ($m_{\mathrm{wd}}\gtrsim 0.6{\mathrm{M}}_{\odot })$, on the other hand, probably formed through a different channel of unstable Roche-lobe overflow during helium shell burning (Case C), followed by common envelope inspiral. The measured eccentricities of these massive white dwarfs remain to be explained.

matches published version

References in corpus (29)

• Modules for Experiments in Stellar Astrophysics (MESA)
• Modules for Experiments in Stellar Astrophysics (MESA): Giant Planets, Oscillations, Rotation, and Massive Stars
• The ATNF Pulsar Catalogue
• Modules for Experiments in Stellar Astrophysics (MESA): Binaries, Pulsations, and Explosions
• Modules for Experiments in Stellar Astrophysics (MESA): Convective Boundaries, Element Diffusion, and Massive Star Explosions
• Modules for Experiments in Stellar Astrophysics (MESA): Pulsating Variable Stars, Rotation, Convective Boundaries, and Energy Conservation
• Masses, Radii, and Equation of State of Neutron Stars
• Common Envelope Evolution: Where we stand and how we can move forward
• Modules for Experiments in Stellar Astrophysics (MESA): Time-Dependent Convection, Energy Conservation, Automatic Differentiation, and Infrastructure
• The relativistic pulsar-white dwarf binary PSR J1738+0333 II. The most stringent test of scalar-tensor gravity
• The second data release from the European Pulsar Timing Array I. The dataset and timing analysis
• Formation of millisecond pulsars with CO white dwarf companions - II. Accretion, spin-up, true ages and comparison to MSPs with He white dwarf companions
• The ELM Survey. VIII. 98 Double White Dwarf Binaries
• Formation of millisecond pulsars with CO white dwarf companions - I. PSR J1614-2230: Evidence for a neutron star born massive
• Formation of Extremely Low-mass White Dwarfs in Double Degenerates
• Direct formation of millisecond pulsars from rotationally delayed accretion-induced collapse of massive white dwarfs
• Coping with loss: Stability of mass transfer from post-main sequence donor stars
• The origin of pulsating ultra-luminous X-ray sources: Low- and intermediate-mass X-ray binaries containing neutron star accretors
• Common envelope evolution of eccentric binaries
• Formation of Millisecond Pulsars from Intermediate- and Low-Mass X-ray Binaries
• Formation of Extremely Low-mass White Dwarfs Binaries
• Eight Millisecond Pulsars Discovered in the Arecibo PALFA Survey
• The FAST Galactic Plane Pulsar Snapshot survey: VIII. 116 binary pulsars
• On the orbital properties of millisecond pulsar binaries
• Revisiting Common Envelope Evolution -- A New Semi-Analytic Model for N-body and Population Synthesis Codes
• A Red Giants' Toy Story
• Asymmetrical mass ejection from proto-white dwarfs and the formation of eccentric millisecond pulsar binaries
• Eccentric millisecond pulsars by resonant convection
• White dwarf eccentricity fluctuation and dissipation by AGB convection