Thermal Emission and Radioactive Lines, but No Pulsar, in the Broadband X-Ray Spectrum of Supernova 1987A

Dennis Alp; Josefin Larsson; Claes Fransson

doi:10.3847/1538-4357/ac052d

UV and X-ray observations of the neutron star LMXB EXO 0748–676 in its quiescent state

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/staa3734 ◽

2020 ◽

Vol 501 (1) ◽

pp. 1453-1462

Author(s):

A S Parikh ◽

N Degenaar ◽

J V Hernández Santisteban ◽

R Wijnands ◽

I Psaradaki ◽

...

Keyword(s):

Neutron Star ◽

Thermal Emission ◽

Hubble Space Telescope ◽

Dense Matter ◽

Continuum Emission ◽

Quiescent State ◽

X Ray ◽

Low Level ◽

Low Mass ◽

Different Origins

ABSTRACT The accretion behaviour in low-mass X-ray binaries (LMXBs) at low luminosities, especially at <1034 erg s−1, is not well known. This is an important regime to study to obtain a complete understanding of the accretion process in LMXBs, and to determine if systems that host neutron stars with accretion-heated crusts can be used probe the physics of dense matter (which requires their quiescent thermal emission to be uncontaminated by residual accretion). Here, we examine ultraviolet (UV) and X-ray data obtained when EXO 0748–676, a crust-cooling source, was in quiescence. Our Hubble Space Telescope spectroscopy observations do not detect the far-UV continuum emission, but do reveal one strong emission line, C iv. The line is relatively broad (≳3500 km s−1), which could indicate that it results from an outflow such as a pulsar wind. By studying several epochs of X-ray and near-UV data obtained with XMM–Newton, we find no clear indication that the emission in the two wavebands is connected. Moreover, the luminosity ratio of LX/LUV ≳ 100 is much higher than that observed from neutron star LMXBs that exhibit low-level accretion in quiescence. Taken together, this suggests that the UV and X-ray emission of EXO 0748–676 may have different origins, and that thermal emission from crust-cooling of the neutron star, rather than ongoing low-level accretion, may be dominating the observed quiescent X-ray flux evolution of this LMXB.

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Testing the accuracy of reflection-based supermassive black hole spin measurements in AGN

Astronomy and Astrophysics ◽

10.1051/0004-6361/201732377 ◽

2018 ◽

Vol 614 ◽

pp. A44 ◽

Cited By ~ 15

Author(s):

E. S. Kammoun ◽

E. Nardini ◽

G. Risaliti

Keyword(s):

Thermal Emission ◽

Signal To Noise Ratio ◽

Galactic Nuclei ◽

Relativistic Effects ◽

High Signal ◽

X Ray ◽

Multiple Components ◽

Spin Parameter ◽

Partial Covering ◽

Spin Measurements

Context. X-ray reflection is a very powerful method to assess the spin of supermassive black holes (SMBHs) in active galactic nuclei (AGN), yet this technique is not universally accepted. Indeed, complex reprocessing (absorption, scattering) of the intrinsic spectra along the line of sight can mimic the relativistic effects on which the spin measure is based. Aims. In this work, we test the reliability of SMBH spin measurements that can currently be achieved through the simulations of high-quality XMM-Newton and NuSTAR spectra. Methods. Each member of our group simulated ten spectra with multiple components that are typically seen in AGN, such as warm and (partial-covering) neutral absorbers, relativistic and distant reflection, and thermal emission. The resulting spectra were blindly analysed by the other two members. Results. Out of the 60 fits, 42 turn out to be physically accurate when compared to the input model. The SMBH spin is retrieved with success in 31 cases, some of which (9) are even found among formally inaccurate fits (although with looser constraints). We show that, at the high signal-to-noise ratio assumed in our simulations, neither the complexity of the multi-layer, partial-covering absorber nor the input value of the spin are the major drivers of our results. The height of the X-ray source (in a lamp-post geometry) instead plays a crucial role in recovering the spin. In particular, a success rate of 16 out of 16 is found among the accurate fits for a dimensionless spin parameter larger than 0.8 and a lamp-post height lower than five gravitational radii.

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1/4 Ke V Diffuse Background and the Local Interstellar Medium

International Astronomical Union Colloquium ◽

10.1017/s0252921100024362 ◽

1989 ◽

Vol 120 ◽

pp. 536-536

Author(s):

S.L. Snowden

Keyword(s):

Interstellar Medium ◽

Filling Factor ◽

Thermal Emission ◽

Mean Free Path ◽

Physical Parameters ◽

X Rays ◽

Local Interstellar Medium ◽

X Ray ◽

Diffuse Background ◽

X Ray Background

The 1/4 keV diffuse X-ray background (SXRB) is discussed in relation to the local interstellar medium (LISM). The most likely source for these soft X-rays is thermal emission from a hot diffuse plasma. The existence of a non-zero flux from all directions and the short ISM mean free path of these X-rays (1020HI cm-2), coupled with ISM pressure constraints, imply that the plasma has a local component and that it must, at least locally (nearest hundred parsecs), have a large filling factor. Our understanding of the geometry and physical parameters of the LISM is therefore directly tied to our understanding of the SXRB.

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Detecting shocked intergalactic gas with X-ray and radio observations

Astronomy and Astrophysics ◽

10.1051/0004-6361/201935439 ◽

2019 ◽

Vol 627 ◽

pp. A5 ◽

Cited By ~ 8

Author(s):

F. Vazza ◽

S. Ettori ◽

M. Roncarelli ◽

M. Angelinelli ◽

M. Brüggen ◽

...

Keyword(s):

Large Scale ◽

Intergalactic Medium ◽

Thermal Emission ◽

Intergalactic Gas ◽

Radio Observations ◽

X Ray ◽

Large Scale Structures ◽

Hot Gas ◽

Scale Structures ◽

Radio Band

Detecting the thermal and non-thermal emission from the shocked cosmic gas surrounding large-scale structures represents a challenge for observations, as well as a unique window into the physics of the warm-hot intergalactic medium. In this work, we present synthetic radio and X-ray surveys of large cosmological simulations in order to assess the chances of jointly detecting the cosmic web in both frequency ranges. We then propose best observing strategies tailored for existing (LOFAR, MWA, and XMM) or future instruments (SKA-LOW and SKA-MID, Athena, and eROSITA). We find that the most promising targets are the extreme peripheries of galaxy clusters in an early merging stage, where the merger causes the fast compression of warm-hot gas onto the virial region. By taking advantage of a detection in the radio band, future deep X-ray observations will probe this gas in emission, and help us to study plasma conditions in the dynamic warm-hot intergalactic medium with unprecedented detail.

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An unusual transient following the short GRB 071227

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/stz2040 ◽

2019 ◽

Vol 489 (1) ◽

pp. 13-27

Author(s):

R A J Eyles ◽

P T O’Brien ◽

K Wiersema ◽

R L C Starling ◽

B P Gompertz ◽

...

Keyword(s):

Gamma Ray ◽

Thermal Emission ◽

Chemical Properties ◽

Major Axis ◽

Optical Observations ◽

X Ray ◽

Very Large Telescope ◽

The Galaxy ◽

Simple Extrapolation ◽

Emission Models

ABSTRACT We present X-ray and optical observations of the short duration gamma-ray burst GRB 071227 and its host at z = 0.381, obtained using Swift, Gemini South, and the Very Large Telescope. We identify a short-lived and moderately bright optical transient, with flux significantly in excess of that expected from a simple extrapolation of the X-ray spectrum at 0.2–0.3 d after burst. We fit the SED with afterglow models allowing for high extinction and thermal emission models that approximate a kilonova to assess the excess’ origins. While some kilonova contribution is plausible, it is not favoured due to the low temperature and high luminosity required, implying superluminal expansion and a large ejecta mass of ∼0.1 M$\odot$. We find, instead, that the transient is broadly consistent with power-law spectra with additional dust extinction of E(B − V) ∼ 0.4 mag, although a possibly thermal excess remains in the z band. We investigate the host, a spiral galaxy with an edge-on orientation, resolving its spectrum along its major axis to construct the galaxy rotation curve and analyse the star formation and chemical properties. The integrated host emission shows evidence for high extinction, consistent with the afterglow findings. The metallicity and extinction are consistent with previous studies of this host and indicate the galaxy is a typical, but dusty, late-type SGRB host.

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Radio and infrared emission by O-type and related stars

Symposium - International Astronomical Union ◽

10.1017/s007418090001336x ◽

1979 ◽

Vol 83 ◽

pp. 117-130 ◽

Cited By ~ 1

Author(s):

M. J. Barlow

Keyword(s):

Thermal Emission ◽

Infrared Emission ◽

Close Binaries ◽

Excellent Review ◽

X Ray ◽

X Ray Binaries

In addition to O-type stars, this review will discuss the radio and infrared properties of B supergiants and Wolf-Rayet stars, since it is generally accepted that these objects represent later stages in the evolution of O stars. The radio properties of X-ray binaries which exhibit non-thermal emission will not be discussed. Hjellming (1977) gives an excellent review of the radio properties of close binaries, including X-ray binaries.

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Thermal X-ray emission identified from the millisecond pulsar PSR J1909–3744

Astronomy and Astrophysics ◽

10.1051/0004-6361/201732040 ◽

2019 ◽

Vol 627 ◽

pp. A141 ◽

Cited By ~ 2

Author(s):

N. A. Webb ◽

D. Leahy ◽

S. Guillot ◽

N. Baillot d’Etivaux ◽

D. Barret ◽

...

Keyword(s):

Neutron Star ◽

Equation Of State ◽

Thermal Emission ◽

Black Body ◽

Millisecond Pulsar ◽

Distance Measurements ◽

Millisecond Pulsars ◽

X Ray ◽

Link Type

Context. Pulsating thermal X-ray emission from millisecond pulsars can be used to obtain constraints on the neutron star equation of state, but to date only five such sources have been identified. Of these five millisecond pulsars, only two have well-constrained neutron star masses, which improve the determination of the radius via modelling of the X-ray waveform. Aims. We aim to find other millisecond pulsars that already have well-constrained mass and distance measurements that show pulsed thermal X-ray emission in order to obtain tight constraints on the neutron star equation of state. Methods. The millisecond pulsar PSR J1909–3744 has an accurately determined mass, M = 1.54 ± 0.03 M⊙ (1σ error) and distance, D = 1.07 ± 0.04 kpc. We analysed XMM-Newton data of this 2.95 ms pulsar to identify the nature of the X-ray emission. Results. We show that the X-ray emission from PSR J1909–3744 appears to be dominated by thermal emission from the polar cap. Only a single component model is required to fit the data. The black-body temperature of this emission is $ {kT}=0.26^{0.03}_{0.02} $ keV and we find a 0.2–10 keV un-absorbed flux of 1.1 × 10−14 erg cm−2 s−1 or an un-absorbed luminosity of 1.5 × 1030 erg s−1. Conclusion. Thanks to the previously determined mass and distance constraints of the neutron star PSR J1909–3744, and its predominantly thermal emission, deep observations of this object with future X-ray facilities should provide useful constraints on the neutron star equation of state.

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X-Ray Emission from Expanding Shells in NGC 3077

Symposium - International Astronomical Union ◽

10.1017/s0074180900197797 ◽

2004 ◽

Vol 217 ◽

pp. 310-311

Author(s):

Jürgen Ott ◽

Crystal L. Martin ◽

Fabian Walter

Keyword(s):

Thermal Emission ◽

Dwarf Galaxy ◽

Point Sources ◽

Starburst Galaxy ◽

Interstellar Gas ◽

X Ray ◽

Hot Gas ◽

Hα Emission ◽

Emission Models ◽

Expanding Shells

Deep Chandra observations of NGC 3077, a starburst dwarf galaxy in the M81 triplet, resolve the X-ray emission from several supershells. The emission is brightest in the cavities defined by expanding shells detected previously in Hα emission. Thermal emission models fitted to the data imply temperatures ranging from 1.3 to 4.9 × 106 K. The total 0.3–6.0 keV X-ray luminosity is 2 − 5 × 1039ergs−1 (depending on the selected thermal plasma model). Most (85%) of the X-ray luminosity in NGC 3077 comes from the hot interstellar gas; the remainder comes from six X-ray point sources. The radial density profile of the hot gas is not as steep as that expected in a freely expanding wind (e.g., as seen in the neighboring starburst galaxy M 82) implying that the hot gas is still confined by the Hα shells.

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Coronal Magnetic Fields of Algol Binaries from Microwave Spectra

International Astronomical Union Colloquium ◽

10.1017/s0252921100080258 ◽

1991 ◽

Vol 130 ◽

pp. 498-500

Author(s):

G. Umana ◽

C. Trigilio ◽

R. M. Hjellming ◽

S. Catalano ◽

M. Rodonò

Keyword(s):

Magnetic Fields ◽

Radio Emission ◽

Mass Exchange ◽

Thermal Emission ◽

Magnetic Activity ◽

Microwave Emission ◽

X Ray ◽

Coronal Magnetic Fields ◽

Hydrodynamic Processes ◽

Hot Corona

Algol-type binaries are basically known to undergo hydrodynamic processes related to mass exchange between components. Recent observations on radio, X-ray emission and flare-like events have raised the question of possible magnetic activity in the secondary component of these systems (Hall, 1989).From a microwave emission survey we have shown that the radio emission from Algol systems cannot be accounted for by thermal emission from an hot corona (T ≥ 107K) and that their radio luminosities compare very well with those of the magnetically active RS CVn systems (Umana et al., 1990).

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