Discovery of an ∼30-yr-duration post-nova pulsating supersoft source in the Large Magellanic Cloud

ABSTRACT Supersoft X-ray sources (SSS) have been identified as white dwarfs accreting from binary companions and undergoing nuclear burning of the accreted material on their surface. Although expected to be a relatively numerous population from both binary evolution models and their identification as type Ia supernova progenitor candidates, given the very soft spectrum of SSSs relatively few are known. Here we report on the X-ray and optical properties of 1RXS J050526.3−684628, a previously unidentified accreting nuclear-burning white dwarf located in the Large Magellanic Cloud (LMC). XMM–Newton observations enabled us to study its X-ray spectrum and measure for the first time short-period oscillations of ∼170 s. By analysing newly obtained X-ray data by eROSITA, together with Swift observations and archival ROSAT data, we have followed its long-term evolution over the last 3 decades. We identify 1RXS J050526.3−684628 as a slowly evolving post-nova SSS undergoing residual surface nuclear burning, which finally reached its peak in 2013 and is now declining. Though long expected on theoretical grounds, such long-lived residual-burning objects had not yet been found. By comparison with existing models, we find that the effective temperature and luminosity evolution are consistent with an ∼0.7 M⊙ carbon–oxygen white dwarf accreting ${\sim} 10^{-9}~\rm {M}_{\odot }$ yr−1. Our results suggest that there may be many more undiscovered SSSs and ‘missed’ novae awaiting dedicated deep X-ray searches in the LMC and elsewhere.

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Excluding supersoft X-ray sources as progenitors for four Type Ia supernovae in the Large Magellanic Cloud

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/stz065 ◽

2019 ◽

Vol 484 (1) ◽

pp. 1317-1324 ◽

Cited By ~ 8

Author(s):

J Kuuttila ◽

M Gilfanov ◽

I R Seitenzahl ◽

T E Woods ◽

F P A Vogt

Keyword(s):

Large Magellanic Cloud ◽

Magellanic Cloud ◽

Type Ia Supernovae ◽

X Ray ◽

Type Ia ◽

Ia Supernovae

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Supersoft X-ray nebulae in the Large Magellanic Cloud

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/staa2213 ◽

2020 ◽

Vol 497 (3) ◽

pp. 3234-3250 ◽

Cited By ~ 1

Author(s):

Diego A Farias ◽

Alejandro Clocchiatti ◽

Tyrone E Woods ◽

Armin Rest

Keyword(s):

Interstellar Medium ◽

Large Magellanic Cloud ◽

Magellanic Cloud ◽

The Other ◽

X Rays ◽

X Ray ◽

Upper Limits ◽

Type Ia ◽

Source Models ◽

Flux Measurements

ABSTRACT Supersoft X-rays sources (SSSs) have been proposed as potential Type Ia supernova (SN Ia) progenitors. If such objects are indeed persistently X-ray luminous and embedded in sufficiently dense interstellar medium (ISM), they will be surrounded by extended nebular emission. These nebulae should persist even long after an SN Ia explosion, due to the long recombination and cooling times involved. With this in mind, we searched for nebular [O iii] emission around four SSSs and three SNRs in the Large Magellanic Cloud, using the 6.5-m Baade telescope at Las Campanas Observatory and the imacs camera. We confirm that, out of the four SSS candidates, only CAL 83 can be associated with an [O iii] nebula. The [O iii] luminosity for the other objects is constrained to ≲17 per cent of that of CAL 83 at 6.8 pc from the central source. Models computed with the photoionization code cloudy indicate that either the ISM densities in the environments of CAL 87, RX J0550.0-7151, and RX J0513.9-6951 must be significantly lower than surrounding CAL 83 or the average X-ray luminosities of these sources over the last ≲10 000 yr must be significantly lower than presently observed, in order to be consistent with the observed luminosity upper limits. For the three SNRs we consider (all with ages <1000 yr), our [O iii] flux measurements together with the known surrounding ISM densities strongly constrain the ionizing luminosity of their progenitors in the last several thousand years, independent of the progenitor channel.

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Swift J004427.3−734801 – a probable Be/white dwarf system in the Small Magellanic Cloud

Monthly Notices of the Royal Astronomical Society Letters ◽

10.1093/mnrasl/slaa112 ◽

2020 ◽

Vol 497 (1) ◽

pp. L50-L55 ◽

Cited By ~ 1

Author(s):

M J Coe ◽

J A Kennea ◽

P A Evans ◽

A Udalski

Keyword(s):

Gravitational Lensing ◽

White Dwarf ◽

Magellanic Cloud ◽

Optical Monitoring ◽

Small Magellanic Cloud ◽

Optical Counterpart ◽

Infrared Excess ◽

X Ray ◽

Be Star ◽

Soft Spectrum

ABSTRACT Swift J004427.3−734801 is an X-ray source in the Small Magellanic Cloud (SMC) that was first discovered as part of the Swift S-CUBED programme in 2020 January. It was not detected in any of the previous 3 yr worth of observations. The accurate positional determination from the X-ray data has permitted an optical counterpart to be identified that has the characteristics of an O9V−B2III star. Evidence for the presence of an infrared excess and significant I-band variability strongly suggests that this is an OBe-type star. Over 17 yr worth of optical monitoring by the OGLE (Optical Gravitational Lensing Experiment) project reveals periods of time in which quasi-periodic optical flares occur at intervals of ∼21.5 d. The X-ray data obtained from the S-CUBED project reveal a very soft spectrum, too soft to be that from accretion on to a neutron star or black hole. It is suggested here that this is a rarely identified Be star–white dwarf binary in the SMC.

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Progenitor constraints on the Type Ia supernova SN 2014J from Hubble Space Telescope H β and [O iii] observations

Monthly Notices of the Royal Astronomical Society Letters ◽

10.1093/mnrasl/slz005 ◽

2019 ◽

Vol 484 (1) ◽

pp. L79-L84 ◽

Cited By ~ 5

Author(s):

Or Graur ◽

Tyrone E Woods

Keyword(s):

White Dwarf ◽

Hubble Space Telescope ◽

Particle Density ◽

Evolutionary Mechanisms ◽

Space Telescope ◽

X Ray ◽

Evolutionary Phase ◽

Type Ia ◽

Nuclear Burning ◽

Ia Supernovae

ABSTRACT Type Ia supernovae are understood to arise from the thermonuclear explosion of a carbon–oxygen white dwarf, yet the evolutionary mechanisms leading to such events remain unknown. Many proposed channels, including the classical single-degenerate scenario, invoke a hot, luminous evolutionary phase for the progenitor, in which it is a prodigious source of photoionizing emission. Here, we examine the environment of SN 2014J for evidence of a photoionized nebula in pre- and post-explosion [O iii] λ5007 Å and H β images taken with the Hubble Space Telescope. From the absence of any extended emission, we exclude a stable nuclear-burning white dwarf at the location of SN 2014J in the last ∼100 000 years, assuming a typical warm interstellar medium (ISM) particle density of 1 cm−3. These limits greatly exceed existing X-ray constraints at temperatures typical of known supersoft sources. Significant extreme-UV/soft X-ray emission prior to explosion remains plausible for lower ISM densities (e.g. $n_{\rm ISM}\sim 0.1\,\rm {cm}^{-3}$). In this case, however, any putative nebula would be even more extended, allowing deeper follow-up observations to resolve this ambiguity in the near future.

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Molecules in the Magellanic Clouds

Symposium - International Astronomical Union ◽

10.1017/s0074180900201046 ◽

1991 ◽

Vol 148 ◽

pp. 415-420 ◽

Cited By ~ 1

Author(s):

R. S. Booth ◽

Th. De Graauw

Keyword(s):

High Resolution ◽

Molecular Clouds ◽

Short Review ◽

Large Magellanic Cloud ◽

Magellanic Cloud ◽

Magellanic Clouds ◽

Giant Molecular Clouds ◽

Interstellar Molecules ◽

First Time ◽

Excitation Conditions

In this short review we describe recent new observations of millimetre transitions of molecules in selected regions of the Magellanic Clouds. The observations were made using the Swedish-ESO Submillimetre Telescope, SEST, (Booth et al. 1989), the relatively high resolution of which facilitates, for the first time, observations of individual giant molecular clouds in the Magellanic Clouds. We have mapped the distribution of the emission from the two lowest rotational transitions of 12CO and 13CO and hence have derived excitation conditions for the molecule. In addition, we have observed several well-known interstellar molecules in the same regions, thus doubling the number of known molecules in the Large Magellanic Cloud (LMC). The fact that all the observations have been made under controlled conditions with the same telescope enables a reasonable intercomparison of the molecular column densities. In particular, we are able to observe the relative abundances among the different isotopically substituted species of CO.

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Line observations of the 30-Dor complex and N159A5 with the MPE imaging NIR spectrometer FAST

Symposium - International Astronomical Union ◽

10.1017/s0074180900200375 ◽

1991 ◽

Vol 148 ◽

pp. 205-206 ◽

Cited By ~ 1

Author(s):

A. Krabbe ◽

J. Storey ◽

V. Rotaciuc ◽

S. Drapatz ◽

R. Genzel

Keyword(s):

Spatial Resolution ◽

Molecular Hydrogen ◽

Near Infrared ◽

Large Magellanic Cloud ◽

Magellanic Cloud ◽

Emission Lines ◽

Resolving Power ◽

Max Planck ◽

First Time ◽

Infrared Array

Images with subarcsec spatial resolution in the light of near-infrared atomic (Bry) and molecular hydrogen H2 (S(1) v=1-0) emission lines were obtained for some extended, pointlike objects in the Large Magellanic Cloud (LMC) for the first time. We used the Max-Planck-Institut für extraterrestrische Physik (MPE) near-infrared array spectrometer FAST (image scale 0.8”/pix, spectral resolving power 950) at the ESO/MPI 2.2m telescope, La Silla. We present some results on the 30-Dor complex and N159A5.

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New optically identified supernova remnants in the Large Magellanic Cloud

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/staa3382 ◽

2020 ◽

Vol 500 (2) ◽

pp. 2336-2358

Author(s):

Miranda Yew ◽

Miroslav D Filipović ◽

Milorad Stupar ◽

Sean D Points ◽

Manami Sasaki ◽

...

Keyword(s):

Supernova Remnants ◽

Supernova Remnant ◽

Narrow Band Imaging ◽

Large Magellanic Cloud ◽

Magellanic Cloud ◽

Main Body ◽

Found Objects ◽

Type Ia ◽

Optical Sample

ABSTRACT We present a new optical sample of three Supernova Remnants (SNRs) and 16 Supernova Remnant (SNR) candidates in the Large Magellanic Cloud (LMC). These objects were originally selected using deep H α, [S ii], and [O iii] narrow-band imaging. Most of the newly found objects are located in less dense regions, near or around the edges of the LMC’s main body. Together with previously suggested MCSNR J0541–6659, we confirm the SNR nature for two additional new objects: MCSNR J0522–6740 and MCSNR J0542–7104. Spectroscopic follow-up observations for 12 of the LMC objects confirm high [S ii]/H α emission-line ratios ranging from 0.5 to 1.1. We consider the candidate J0509–6402 to be a special example of the remnant of a possible type Ia Supernova (SN) which is situated some 2° (∼1.75 kpc) north from the main body of the LMC. We also find that the SNR candidates in our sample are significantly larger in size than the currently known LMC SNRs by a factor of ∼2. This could potentially imply that we are discovering a previously unknown but predicted, older class of large LMC SNRs that are only visible optically. Finally, we suggest that most of these LMC SNRs are residing in a very rarefied environment towards the end of their evolutionary span where they become less visible to radio and X-ray telescopes.

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