ABSTRACT The fraction of stars that are in binaries or triples at the time of stellar death and the fraction of these systems that survive the supernova explosion are crucial constraints for evolution models and predictions for gravitational wave source populations. These fractions are also subject to direct observational determination. Here, we search 10 supernova remnants containing compact objects with proper motions for unbound binaries or triples using Gaia EDR3 and new statistical methods and tests for false positives. We confirm the one known example of an unbound binary, HD 37424 in G180.0−01.7, and find no other examples. Combining this with our previous searches for bound and unbound binaries, and assuming no bias in favour of finding interacting binaries, we find that 72.0 per cent (52.2–86.4 per cent, 90 per cent confidence) of supernova producing neutron stars are not binaries at the time of explosion, 13.9 per cent (5.4–27.2 per cent) produce bound binaries, and 12.5 per cent (2.8–31.3 per cent) produce unbound binaries. With a strong bias in favour of finding interacting binaries, the medians shift to 76.0 per cent were not binaries at death, 9.5 per cent leave bound binaries, and 13.2 per cent leave unbound binaries. Of explosions that do not leave binaries, ${\lt}18.9{{\ \rm per\ cent}}$ can be fully unbound triples. These limits are conservatively for $M\gt 5\, \mathrm{M}_\odot$ companions, although the mass limits for some individual systems are significantly stronger. At birth, the progenitor of PSR J0538+2817 was probably a 13–$19\, \mathrm{M}_\odot$ star, and at the time of explosion, it was probably a Roche limited, partially stripped star transferring mass to HD 37424 and then producing a Type IIL or IIb supernova.
more »
« less
The progenitor of the Vela pulsar
With Gaia parallaxes, it is possible to study the stellar populations associated with individual Galactic supernova remnants (SNRs) to estimate the mass of the exploding star. Here, we analyse the luminous stars near the Vela pulsar and SNR to find that its progenitor was probably ($\mathrel {\raise.3ex\rm{\gt }\lower0.6ex\rm{\sim }}90\rm \,per\,cent$) low mass (8.1–$10.3\, {\rm M}_\odot$). The presence of the O star γ2 Vel a little over 100 pc from Vela is the primary ambiguity, as including it in the analysis volume significantly increases the probability (to 5 per cent) of higher mass ($\gt 20\, {\rm M}_\odot$) progenitors. However, to be a high-mass star associated with γ2 Vel’s star cluster at birth, the progenitor would have to be a runaway star from an unbound binary with an unusually high velocity. The primary impediment to analysing large numbers of Galactic SNRs in this manner is the lack of accurate distances. This can likely be solved by searching for absorption lines from the SNR in stars as a function of distance, a method which yielded a distance to Vela in agreement with the direct pulsar parallax. If Vela was a $10\, {\rm M}_\odot$ supernova in an external galaxy, the 50-pc search region used in extragalactic studies would contain only $\simeq 10\rm \,per\,cent$ of the stars formed in a 50-pc region around the progenitor at birth and $\simeq 90\rm \,per\,cent$ of the stars in the search region would have been born elsewhere.
more » « less- Award ID(s):
- 1814440
- NSF-PAR ID:
- 10363310
- Publisher / Repository:
- Oxford University Press
- Date Published:
- Journal Name:
- Monthly Notices of the Royal Astronomical Society
- Volume:
- 511
- Issue:
- 3
- ISSN:
- 0035-8711
- Format(s):
- Medium: X Size: p. 3428-3439
- Size(s):
- ["p. 3428-3439"]
- Sponsoring Org:
- National Science Foundation
More Like this
-
-
more » « less
ABSTRACT The most massive stars provide an essential source of recycled material for young clusters and galaxies. While very massive stars (VMSs, M>100 $\rm {\rm M}_{\odot }$) are relatively rare compared to O stars, they lose disproportionately large amounts of mass already from the onset of core H-burning. VMS have optically thick winds with elevated mass-loss rates in comparison to optically thin standard O-star winds. We compute wind yields and ejected masses on the main sequence, and we compare enhanced mass-loss rates to standard ones. We calculate solar metallicity wind yields from MESA stellar evolution models in the range 50–500 $\rm {\rm M}_{\odot }$, including a large nuclear network of 92 isotopes, investigating not only the CNO-cycle, but also the Ne–Na and Mg–Al cycles. VMS with enhanced winds eject 5–10 times more H-processed elements (N, Ne, Na, Al) on the main sequence in comparison to standard winds, with possible consequences for observed anticorrelations, such as C–N and Na–O, in globular clusters. We find that for VMS 95 per cent of the total wind yields is produced on the main sequence, while only ∼ 5 per cent is supplied by the post-main sequence. This implies that VMS with enhanced winds are the primary source of 26Al, contrasting previous works where classical Wolf–Rayet winds had been suggested to be responsible for galactic 26Al enrichment. Finally, 200 $\rm {\rm M}_{\odot }$ stars eject 100 times more of each heavy element in their winds than 50 $\rm {\rm M}_{\odot }$ stars, and even when weighted by an IMF their wind contribution is still an order of magnitude higher than that of 50 $\rm {\rm M}_{\odot }$ stars.
-
ABSTRACT It remains a major challenge to derive a theory of cloud-scale ($\lesssim100$ pc) star formation and feedback, describing how galaxies convert gas into stars as a function of the galactic environment. Progress has been hampered by a lack of robust empirical constraints on the giant molecular cloud (GMC) lifecycle. We address this problem by systematically applying a new statistical method for measuring the evolutionary timeline of the GMC lifecycle, star formation, and feedback to a sample of nine nearby disc galaxies, observed as part of the PHANGS-ALMA survey. We measure the spatially resolved (∼100 pc) CO-to-H α flux ratio and find a universal de-correlation between molecular gas and young stars on GMC scales, allowing us to quantify the underlying evolutionary timeline. GMC lifetimes are short, typically $10\!-\!30\,{\rm Myr}$, and exhibit environmental variation, between and within galaxies. At kpc-scale molecular gas surface densities $\Sigma _{\rm H_2}\ge 8\,\rm {M_\odot}\,{{\rm pc}}^{-2}$, the GMC lifetime correlates with time-scales for galactic dynamical processes, whereas at $\Sigma _{\rm H_2}\le 8\,\rm {M_\odot}\,{{\rm pc}}^{-2}$ GMCs decouple from galactic dynamics and live for an internal dynamical time-scale. After a long inert phase without massive star formation traced by H α (75–90 per cent of the cloud lifetime), GMCs disperse within just $1\!-\!5\,{\rm Myr}$ once massive stars emerge. The dispersal is most likely due to early stellar feedback, causing GMCs to achieve integrated star formation efficiencies of 4–10 per cent. These results show that galactic star formation is governed by cloud-scale, environmentally dependent, dynamical processes driving rapid evolutionary cycling. GMCs and H ii regions are the fundamental units undergoing these lifecycles, with mean separations of $100\!-\!300\,{{\rm pc}}$ in star-forming discs. Future work should characterize the multiscale physics and mass flows driving these lifecycles.more » « less
-
more » « less
ABSTRACT Stellar feedback plays a crucial role in regulating baryon cycles of a galactic ecosystem, and may manifest itself in the formation of superbubbles in the interstellar medium. In this work, we used a set of high-resolution simulations to systematically study the properties and evolution of superbubbles in galactic environments. The simulations were based on the SMUGGLE galaxy formation framework using the hydrodynamical moving-mesh code arepo, reaching a spatial resolution of $\sim 4 \, \rm pc$ and mass resolution of $\sim 10^3 \, \rm M_{\odot }$. We identified superbubbles and tracked their time evolution using the parent stellar associations within the bubbles. The X-ray luminosity-size distribution of superbubbles in the fiducial run is largely consistent with the observations of nearby galaxies. The size of superbubbles shows a double-peaked distribution, with the peaks attributed to early feedback (radiative and stellar wind feedback) and supernova feedback. The early feedback tends to suppress the subsequent supernova feedback, and it is strongly influenced by star formation efficiency, which regulates the environmental density. Our results show that the volume filling factor of hot gas (T > 105.5 K) is about $12~{{\ \rm per\ cent}}$ averaged over a region of 4 kpc in height and 20 kpc in radius centred on the disc of the galaxy. Overall, the properties of superbubbles are sensitive to the choice of subgrid galaxy formation models and can, therefore, be used to constrain these models.
-
ABSTRACT Accretion discs around supermassive black holes are promising sites for stellar mass black hole mergers detectable with LIGO. Here we present the results of Monte Carlo simulations of black hole mergers within 1-d AGN disc models. For the spin distribution in the disc bulk, key findings are: (1) The distribution of χeff is naturally centred around $\tilde{\chi }_{\rm eff} \approx 0.0$, (2) the width of the χeff distribution is narrow for low natal spins. For the mass distribution in the disc bulk, key findings are: (3) mass ratios $\tilde{q} \sim 0.5\!-\!0.7$, (4) the maximum merger mass in the bulk is $\sim 100\!-\!200\, \mathrm{M}_{\odot }$, (5) $\sim 1{{\ \rm per\ cent}}$ of bulk mergers involve BH $\gt 50\, \mathrm{M}_{\odot }$ with (6) $\simeq 80{{\ \rm per\ cent}}$ of bulk mergers are pairs of first generation BH. Additionally, mergers at a migration trap grow an IMBH with typical merger mass ratios $\tilde{q}\sim 0.1$. Ongoing LIGO non-detections of black holes $\gt 10^{2}\, \mathrm{M}_{\odot }$ puts strong limits on the presence of migration traps in AGN discs (and therefore AGN disc density and structure) as well as median AGN disc lifetime. The highest merger rate occurs for this channel if AGN discs are relatively short-lived (≤1 Myr) so multiple AGN episodes can happen per Galactic nucleus in a Hubble time.more » « less
