QUARK-NOVAE IN LOW-MASS X-RAY BINARIES. II. APPLICATION TO G87-7 AND TO GRB 110328A

Journal Article · Tue Dec 20 04:00:00 EST 2011 · Astrophysical Journal

DOI:https://doi.org/10.1088/0004-637X/743/2/116· OSTI ID:22004471

Ouyed, Rachid ^[1]; Staff, Jan ^[2]; Jaikumar, Prashanth ^[3]

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1. Department of Physics and Astronomy, University of Calgary, 2500 University Drive NW, Calgary, Alberta T2N 1N4 (Canada)
2. Department of Physics and Astronomy, Louisiana State University, 202 Nicholson Hall, Tower Dr., Baton Rouge, LA 70803-4001 (United States)
3. Department of Physics and Astronomy, California State University Long Beach, 1250 Bellflower Blvd., Long Beach, CA 90840 (United States)

We propose a simple model explaining two outstanding astrophysical problems related to compact objects: (1) that of stars such as G87-7 (alias EG 50) that constitute a class of relatively low-mass white dwarfs (WDs) which nevertheless fall away from the C/O composition and (2) that of GRB 110328A/Swift J164449.3+57345 which showed spectacularly long-lived strong X-ray flaring, posing a challenge to standard gamma-ray burst models. We argue that both these observations may have an explanation within the unified framework of a quark-nova (QN) occurring in a low-mass X-ray binary (LMXB; neutron star (NS)-WD). For LMXBs, where the binary separation is sufficiently tight, ejecta from the exploding NS triggers nuclear burning in the WD on impact, possibly leading to Fe-rich composition compact WDs with mass 0.43 M{sub Sun} < M{sub WD} < 0.72 M{sub Sun }, reminiscent of G87-7. Our results rely on the assumption, which ultimately needs to be tested by hydrodynamic and nucleosynthesis simulations, that under certain circumstances the WD can avoid the thermonuclear runaway. For heavier WDs (i.e., M{sub WD} > 0.72 M{sub Sun }) experiencing the QN shock, degeneracy will not be lifted when carbon burning begins, and a sub-Chandrasekhar Type Ia supernova may result in our model. Under slightly different conditions and for pure He WDs (i.e., M{sub WD} < 0.43 M{sub Sun }), the WD is ablated and its ashes raining down on the quark star (QS) leads to accretion-driven X-ray luminosity with energetics and duration reminiscent of GRB 110328A. We predict additional flaring activity toward the end of the accretion phase if the QS turns into a black hole.

• OSTI ID: 22004471
• Journal Information: Astrophysical Journal, Journal Name: Astrophysical Journal Journal Issue: 2 Vol. 743; ISSN ASJOAB; ISSN 0004-637X
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTRONOMY AND ASTROPHYSICS
ASTROPHYSICS
BLACK HOLES
CARBON BURNING
COMPUTERIZED SIMULATION
COSMIC GAMMA BURSTS
FLARING
LUMINOSITY
MASS
NEUTRON STARS
NEUTRONS
NOVAE
NUCLEOSYNTHESIS
QUARKS
STAR EVOLUTION
SUPERNOVAE
WHITE DWARF STARS
X RADIATION