Talk detail

Participant	Margalit, Ben
Institution	Columbia University - 538 West 120th Street - New York - NY - USA

Session	GB7	Accepted	Yes	Order	2	Time	15:45	30'
Talk	Oral abstract	Title	Multi-messenger Constraints on the Nuclear EOS: GW170817 and the future ahead
Coauthors	Margalit, Ben; Metzger, Brian D.
Abstract	The first directly-detected binary neutron star (NS) merger GW170817, as observed through both gravitaional-waves (GW) and across the electromagnetic (EM) spectrum, has opened a new page in multi-messenger astronomy. I will review and describe methods by which the (uncertain) equation-of-state (EOS) of cold dense nuclear matter can be constrained by combining inferences from both GW and EM signatures of binary NS mergers. Applying these methods to GW170817, I show that a new, strong, upper limit on the maximal mass of a non-rotating NS emerges. I will discuss these results, and overview the landscape ahead, addressing the question of - what are the parameter regions in which future multi-messenger observations of binary NS mergers will tighten constraints on the nuclear EOS?
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Session	GB1	Accepted	Yes	Order	6	Time	17:50	25'
Talk	Oral abstract	Title	Unveiling the Engines of Fast Radio Bursts, Super-luminous Supernovae, and Gamma-ray Bursts
Coauthors	Margalit, Ben; Metzger, Brian D.; Berger, Edo; Nicholl, Matt; Eftekhari, Tarraneh; Margutti, Raffaella
Abstract	Young, rapidly spinning magnetars have been suggested as the central engines behind a diverse set of transient astrophysical phenomena, including gamma-ray bursts (GRB), super-luminous supernovae (SLSNe), and fast radio bursts (FRBs). However, a significant barrier to direct confirmation of the magnetar hypothesis is the challenge of directly observing non-thermal emission from the central engine at early times due to the dense surrounding ejecta. I will present CLOUDY calculations of the time-dependent evolution of the temperature and ionization structure of expanding supernova ejecta due to photo-ionization by a magnetar engine, in order to study the escape of radio waves (absorbed by ionized gas) and asses the evolution of the local dispersion measure due to the ejecta. We find that the repeating FRB 121102 is consistent with originating from a young, ~30-100 yr, magnetar similar to those inferred to power SLSNe, and its high rotation-measure can be produced within the same nebula that is proposed to power the quiescent radio source observed co-located with FRB 121102.
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Session	BN3	Accepted	Yes	Order	8	Time	18:45	30'
Talk	Oral abstract	Title	White Dwarf – Neutron Star Mergers: from Peculiar Supernovae to Pulsar Planets
Coauthors	Margalit, Ben; Metzger, Brian D.
Abstract	The merger of binaries consisting of a white dwarf (WD) and a neutron star (NS), though much less studied than their NS-NS/WD-WD brethren, are relatively common astrophysical events which may contribute to the transient sky. I will present recent work modeling the post-merger accretion flows on both short (~min) and long (~kyr) timescales. Nuclear burning in the early hyper-Eddington accreting flow fuses matter up the alpha-chain, heating the geometrically thick disk to a marginally bound state prone to outflows. These outflows may power a rapidly-evolving (~week-long) optical transient, broadly consistent with the class of `Ca-rich gap transients'. Finally, by modeling the long-term disk evolution, I show that a WD-NS merger provides a natural mechanism for creating planets orbiting the millisecond pulsar PSR B1257+12, providing new insight into the unusually high proper motion of the pulsar-planet system.
Pdf file