4FGL J1120.0-2204: A Unique Gamma-ray Bright Neutron Star Binary with an Extremely Low Mass Proto-White Dwarf

Abstract

We have discovered a new X-ray emitting compact binary that is the likely counterpart to the unassociated Fermi-LAT GeV $\gamma$-ray source 4FGL J1120.0-2204, the second brightest Fermi source that still remains formally unidentified. Using optical spectroscopy with the SOAR telescope, we have identified a warm ($T_{\text{eff}}\sim 8500$ K) companion in a 15.1-hr orbit around an unseen primary, which is likely a yet-undiscovered millisecond pulsar. A precise Gaia parallax shows the binary is nearby, at a distance of only $\sim 820$ pc. Unlike the typical "spider" or white dwarf secondaries in short-period millisecond pulsar binaries, our observations suggest the $\sim 0.17M_{\odot }$ companion is in an intermediate stage, contracting on the way to becoming an extremely low-mass helium white dwarf (a "pre-ELM" white dwarf). Although the companion is apparently unique among confirmed or candidate millisecond pulsar binaries, we use binary evolution models to show that in $\sim 2$ Gyr, the properties of the binary will match those of several millisecond pulsar-white dwarf binaries with very short ($<1$ d) orbital periods. This makes 4FGL J1120.0-2204 the first system discovered in the penultimate phase of the millisecond pulsar recycling process.

arXiv commentAccepted to ApJ; 15 pages, 8 figures, 2 tables

References in corpus (88)

• Measuring Reddening with SDSS Stellar Spectra and Recalibrating SFD
• Modules for Experiments in Stellar Astrophysics (MESA)
• PARSEC: stellar tracks and isochrones with the PAdova and TRieste Stellar Evolution Code
• The Leiden/Argentine/Bonn (LAB) Survey of Galactic HI: Final data release of the combined LDS and IAR surveys with improved stray-radiation corrections
• Modules for Experiments in Stellar Astrophysics (MESA): Giant Planets, Oscillations, Rotation, and Massive Stars
• 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
• A new extensive library of PHOENIX stellar atmospheres and synthetic spectra
• Estimating distances from parallaxes. V: Geometric and photogeometric distances to 1.47 billion stars in Gaia Early Data Release 3
• The Man Behind the Curtain: X-rays Drive the UV through NIR Variability in the 2013 AGN Outburst in NGC 2617
• Modules for Experiments in Stellar Astrophysics (MESA): Pulsating Variable Stars, Rotation, Convective Boundaries, and Energy Conservation
• A statistical study of 233 pulsar proper motions
• Fermi Large Area Telescope First Source Catalog
• First Results from the Catalina Real-time Transient Survey
• A 3D Dust Map Based on Gaia, Pan-STARRS 1 and 2MASS
• The All-Sky Automated Survey for Supernovae (ASAS-SN) Light Curve Server v1.0
• Gaia Early Data Release 3: Parallax bias versus magnitude, colour, and position
• Achieving better than 1 minute accuracy in the Heliocentric and Barycentric Julian Dates
• The Second Fermi Large Area Telescope Catalog of Gamma-ray Pulsars
• Two distinct halo populations in the solar neighborhood. Evidence from stellar abundance ratios and kinematics
• Evolutionary Binary Sequences for Low- and Intermediate-Mass X-ray Binaries
• The Evolution of Compact Binary Star Systems
• High-precision timing of 42 millisecond pulsars with the European Pulsar Timing Array
• GROND - a 7-channel imager
• A millisecond pulsar in a stellar triple system
• On the use of Gaia magnitudes and new tables of bolometric corrections
• New evolutionary sequences for extremely low mass white dwarfs: Homogeneous mass and age determinations, and asteroseismic prospects
• SkyMapper Southern Survey: Second Data Release (DR2)
• The ELM Survey. I. A Complete Sample of Extremely Low Mass White Dwarfs
• Gaia reveals a metal-rich in-situ component of the local stellar halo
• Models of low-mass helium white dwarfs including gravitational settling, thermal and chemical diffusion, and rotational mixing
• Formation of black widows and redbacks -- two distinct populations of eclipsing binary millisecond pulsars
• Chandra X-Ray Observations of Nineteen Millisecond Pulsars in the Globular Cluster 47 Tucanae
• The Joker: A custom Monte Carlo sampler for binary-star and exoplanet radial velocity data
• Local Stellar Kinematics from RAVE Data: I. Local Standard of Rest
• The ELM Survey. II. Twelve Binary White Dwarf Merger Systems
• LMXB and IMXB Evolution: I. The Binary Radio Pulsar PSR J1614-2230
• Intra-Binary Shock Heating of Black Widow Companions
• Optical spectroscopy and demographics of redback millisecond pulsar binaries
• Classification and Ranking of Fermi LAT Gamma-ray Sources from the 3FGL Catalog using Machine Learning Techniques
• Fermi Large Area Telescope Fourth Source Catalog Data Release 2
• The ELM Survey. VIII. 98 Double White Dwarf Binaries
• The formation of low-mass helium white dwarfs orbiting pulsars: Evolution of low-mass X-ray binaries below the bifurcation period
• Stellar Encounter Rate in Galactic Globular Clusters
• High-Precision Timing of 5 Millisecond Pulsars: Space Velocities, Binary Evolution and Equivalence Principles
• EL CVn-type binaries - Discovery of 17 helium white dwarf precursors in bright eclipsing binary star systems
• The Green Bank North Celestial Cap Pulsar Survey III: 45 New Pulsar Timing Solutions
• X-Ray Observations of Black Widow Pulsars
• Millisecond Pulsars and Black Holes in Globular Clusters
• A Metal-Rich Low-Gravity Companion to a Massive Millisecond Pulsar
• Evolutionary trajectories of ultra-compact "black widow" pulsars with very low mass companions
• Constraining Relativistic Bow Shock Properties in Rotation-Powered Millisecond Pulsar Binaries
• Dynamical Formation of Millisecond Pulsars in Globular Clusters
• The NANOGrav Nine-year Data Set: Astrometric Measurements of 37 Millisecond Pulsars
• Discovery of a stripped red giant core in a bright eclipsing binary system
• Einstein@Home Discovery of the Gamma-ray Millisecond Pulsar PSR J2039-5617 Confirms Its Predicted Redback Nature
• Properties and Evolution of the Redback Millisecond Pulsar Binary PSR J2129-0429
• Machine Learning Regression of stellar effective temperatures in the second $Gaia$ Data Release
• Evolving LMXBs: CARB Magnetic Braking
• B-ducted Heating of Black Widow Companions
• X-ray Census of Millisecond Pulsars in the Galactic field
• Multiband Optical Light Curves of Black-Widow Pulsars
• Birth of the ELMs: a ZTF survey for evolved cataclysmic variables turning into extremely low-mass white dwarfs
• Discovery of Two New Thermally Bloated Low-Mass White Dwarfs Among the Kepler Binaries
• PSR J1012+5307: a millisecond pulsar with an extremely low-mass white dwarf companion
• Discovery of the Optical/Ultraviolet/Gamma-ray Counterpart to the Eclipsing Millisecond Pulsar J1816+4510
• Gaia pulsars and where to find them
• Variable Heating and Flaring of Three Redback Millisecond Pulsar Companions
• Search for transitions between states in redbacks and black widows using seven years of Fermi-LAT observations
• A multi-wavelength view of the neutron star binary 1FGL J1417.7--4402: A progenitor to canonical millisecond pulsars
• Chemical Abundances in the Secondary Star of the Neutron Star Binary Centaurus X-4
• The sdA problem - III. New extremely low-mass white dwarfs and their precursors from Gaia astrometry
• Exploiting Orbital Constraints from Optical Data to Detect Binary Gamma-ray Pulsars
• Accretion-induced Collapse from Magnetic White Dwarf Binaries and Formation of Binary Millisecond Pulsars: Redbacks and Black Widows
• Timing of Eight Binary Millisecond Pulsars Found with Arecibo in Fermi-LAT Unidentified Sources
• Classification of New X-ray Counterparts for Fermi Unassociated Gamma Ray Sources Using the Swift X-Ray Telescope
• A multi-wavelength investigation of candidate milli-second pulsars in unassociated $\gamma$-ray sources
• Face changing companion of the redback millisecond pulsar PSR J1048+2339
• A New Candidate Transitional Millisecond Pulsar in the Sub-luminous Disk State: 4FGL J0407.7--5702
• Discovery of a New Redback Millisecond Pulsar Candidate: 4FGL J0940.3-7610
• Roche Lobe Underfilling of the Secondary Star in PSR J102347.6+003841?
• Timing of Five PALFA-Discovered Millisecond Pulsars
• A New Likely Redback Millisecond Pulsar Binary with a Massive Neutron Star: 4FGL J2333.1--5527
• PSR J1306--40: An X-ray Luminous Redback with an Evolved Companion
• X-ray Spectra and Multiwavelength Machine Learning Classification for Likely Counterparts to Fermi 3FGL Unassociated Sources
• Convection and rotation boosted prescription of magnetic braking: application to the formation of extremely low-mass white dwarfs
• The chemical composition of the peculiar companion to the millisecond pulsar in NGC 6397
• Searches for millisecond pulsar candidates among the unidentified Fermi objects

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• A 350-MHz Green Bank Telescope Survey of Unassociated Fermi LAT Sources: Discovery and Timing of Ten Millisecond Pulsars
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