New Insights into Classical Novae

Chomiuk, Laura; Metzger, Brian D.; Shen, Ken J.

doi:10.48550/arxiv.2011.08751

Cited by 17 publications

(29 citation statements)

References 252 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The evolution of WDs accreting gas from the stellar wind of a companion star has been extensively studied previously, which can give rise to very rich phenomena depending on the accretion rate (see e.g., Gallagher & Starrfield 1978;Fujimoto 1982;Iben 1982;Hachisu et al 1996;Cassisi et al 1998;Wolf et al 2013;Chomiuk et al 2020). A novae is ignited due to unstable burning of hydrogen on the WD surface if ṁwd < ṁwd,stable , where ṁwd,stable ≈ (2 × 10 −8 − 4 × 10 −7 )M /yr depending on the WD mass is the minimal accretion rate for sustaining stable burning.…”

Section: Wdsmentioning

confidence: 99%

Supercritical accretion of stellar-mass compact objects in active galactic nuclei

Pan,

Yang

2021

Preprint

View full text Add to dashboard Cite

Accretion disks of active galactic nuclei (AGN) have been proposed as promising sites for producing both (stellar-mass) compact object mergers and extreme mass ratio inspirals. Along with the disk-assisted migration/evolution process, ambient gas materials inevitably accrete onto the compact objects. The description of this process is subject to significant theoretical uncertainties in previous studies. It was commonly assumed that either an Eddington accretion rate or a Bondi accretion rate (or any rate in between) takes place, although these two rates can differ from each other by several orders of magnitude. As a result, the mass and spin evolution of compact objects within AGN disks are essentially unknown. In this work, we construct a relativistic supercritical inflow-outflow model for black hole (BH) accretion. We show that the radiation efficiency of the supercritical accretion of a stellar-mass BH (sBH) is generally too low to explain the proposed electromagnetic counterpart of GW190521. Applying this model to sBHs embedded in AGN disks, we find that, although the gas inflow rates at Bondi radii of these sBHs are in general highly super-Eddington, a large fraction of inflowing gas eventually escapes as outflows so that only a small fraction accretes onto the sBH, resulting in mildly super-Eddington BH absorption in most cases. We also implement this inflow-outflow model to study the evolution of neutron stars (NS) and white dwarfs (WD) in AGN disks, taking into account corrections from star sizes and star magnetic fields. It turns out to be difficult for WDs to grow to the Chandrasekhar limit via accretion because WDs are spun up more efficiently to reach the shedding limit before the Chandrasekhar limit. For NSs the accretion-induced collapse is possible if NS magnetic fields are sufficiently strong to guide the accretion flow outside the NS surface, keeping the NS in a slow rotation state during the whole accretion process.

show abstract

Section: Wdsmentioning

confidence: 99%

Supercritical accretion of stellar-mass compact objects in active galactic nuclei

Pan,

Yang

2021

Preprint

View full text Add to dashboard Cite

show abstract

“…Gamma-ray emission has been detected from more than a dozen novae in the GeV-range with most of the sources being classical novae (see Chomiuk et al 2020, for a recent review). For example, Fermi and H.E.S.S.…”

Section: Novaementioning

confidence: 99%

Adiabatic-radiative shock systems in YSO jets and novae outflows

del Valle,

Araudo,

Suzuki-Vidal

2022

Preprint

View full text Add to dashboard Cite

Context. The termination regions of non-relativistic jets in protostars and supersonic outflows in classical novae are nonthermal emitters. This has been confirmed by radio and gamma-ray detection, respectively. A two-shock system is expected to be formed in the termination region where the jet/outflow material and the ambient medium impact. Given the high densities in these systems, radiative shocks are expected to form. However, in the presence of high velocities, the formation of adiabatic shocks is also possible. A case of interest is when the two types of shocks occur simultaneously. Adiabatic shocks are more efficient at particle acceleration while radiative shocks strongly compress the gas. Furthermore, a combined adiabatic-radiative shock system is very prone to develop instabilities in the contact discontinuity leading to mixing, turbulence and density enhancement. Additionally, these dense non-relativistic jets/outflows are excellent candidates for laboratory experiments as demonstrated by magnetohydrodynamics scaling. Aims. We aim at studying the combination of adiabatic and radiative shocks in protostellar jets and novae outflows. We focus on determining the conditions under which this combination is feasible together with its physical implications. Methods. We perform an analytical study of the shocks in both types of sources for a set of parameters by comparing cooling times and propagation velocities. We also estimate the timescales for the growth of instabilities in the contact discontinuity separating both shocks. The hydrodynamical evolution of a jet colliding with an ambient medium is studied with 2D numerical simulations confirming our initial theoretical estimates. Results. We show that for a wide set of observationally constrained parameters the combination of an adiabatic and a radiative shock is possible at the working surface of the termination region in jets from young stars and novae outflows. We find that instabilities are developed at the contact discontinuity, mixing the shocked materials. Additionally, we explore the magnetohydrodynamic parameter scaling required for studying protostellar jets and novae outflows using laboratory experiments on laser facilities. Conclusions. The coexistence of an adiabatic and a radiative shock is expected at the termination region of protostellar jets and novae outflows. This scenario is very promising for particle acceleration and gamma-ray emission. The parameters for scaled laboratory experiments are very much in line with plasma conditions achievable in currently operating high-power laser facilities. This opens the door to new means for studying novae outflows never considered before.

show abstract

“…During this stage, the density profile of ejecta becomes shallower (α ∼ 3). This density profile implies that the nova atmosphere has a very large geometrical extension and thereby a very large range of temperatures and ionization states within the continuum and line-forming regions (Hauschildt 2008;Chomiuk, Metzger & Shen 2020). Assuming that the kinematics of the novae ejecta could be consistently explained by clumpy gas expelled during a single ballistic or free expansion (Mason et al 2018) which follows linear velocity law (v ∝ r), we adopted the α = 3 for our model calculations, a typical value which was used in the photoionization modeling of other novae (e.g.…”

Section: Modelling Proceduresmentioning

confidence: 99%

Photoionization modeling of the dusty nova V1280 Scorpii

Pandey,

Das,

Shaw

et al. 2021

Preprint

View full text Add to dashboard Cite

We perform photoionization modeling of the dusty nova V1280 Scorpii (V1280 Sco) with an aim to study the changes in the physical and chemical parameters. We model pre and post dust phase, optical and near-Infrared (NIR), spectra using the photoionization code CLOUDY, v.17.02, considering a two-component (low density and high density region) model. From the best-fit model, we find that the temperature and luminosity of the central ionizing source in the pre-dust phase is in the range 1.32 -1.50 ×10 4 K and 2.95 -3.16 ×10 36 ergs −1 , respectively, which increase to 1.58 -1.62 ×10 4 K and 3.23 -3.31 ×10 36 ergs −1 , respectively, in the post-dust phase. It is found that a very high hydrogen density (∼ 10 13 − 10 14 cm −3 ) is required for the generation of spectra properly. Dust condensation conditions are achieved at high ejecta density (∼ 3.16 × 10 8 cm −3 ) and low temperature (∼2000 K) in the outer region of the ejecta. It is found that a mixture of small (0.005 -0.25µm) amorphous carbon dust grains and large (0.03 -3.0µm) astrophysical silicate dust grains iis present n the ejecta in the post-dust phase. Our model yields a very high elemental abundance values as C/H = 13.5 -20, N/H = 250, O/H = 27 -35, by number, relative to solar in the ejecta, during the pre-dust phase, which decrease in the post-dust phase.

show abstract

New Insights into Classical Novae

Cited by 17 publications

References 252 publications

Supercritical accretion of stellar-mass compact objects in active galactic nuclei

Supercritical accretion of stellar-mass compact objects in active galactic nuclei

Adiabatic-radiative shock systems in YSO jets and novae outflows

Photoionization modeling of the dusty nova V1280 Scorpii

Contact Info

Product

Resources

About