scholarly journals A new possible accretion scenario for ultra-luminous X-ray sources

2019 ◽  
Vol 489 (1) ◽  
pp. 366-384 ◽  
Author(s):  
Shogo B Kobayashi ◽  
K Nakazawa ◽  
K Makishima
Keyword(s):  
Emission Lines ◽  
Emission Model ◽  
Massive Black Holes ◽  
X Ray ◽  
Local Structures ◽  
Upper Limits ◽  
Nearby Galaxies ◽  
Model Independent ◽  
Spectral States ◽  
Spectral State

ABSTRACT Using archival data from Suzaku, XMM–Newton, and NuSTAR, nine representative ultra-luminous X-ray sources (ULXs) in nearby galaxies were studied. Their X-ray spectra were all reproduced with a multicolour disc emission model plus its Comptonization. However, the spectral shapes of individual sources changed systematically depending on the luminosity, and defined three typical spectral states. These states differ either in the ratio between the Comptonizing electron temperature and the innermost disc temperature, or in the product of Compton y-parameter and fraction of the Comptonized disc photons. The luminosity range at which a particular state emerges was found to scatter by a factor of up to 16 among the eight ULXs. By further assuming that the spectral state is uniquely determined by the Eddington ratio, the sample ULXs are inferred to exhibit a similar scatter in their masses. This gives a model-independent support to the interpretation of ULXs in terms of relatively massive black holes. None of the spectra showed noticeable local structures. Especially, no Fe K-shell absorption/emission lines were detected, with upper limits of 30–40 eV in equivalent width from the brightest three among the sample: NGC 1313 X-1, Holmberg IX X-1, and IC 342 X-1. These properties disfavour ordinary mass accretion from a massive companion star, and suggest direct Bondi–Hoyle accretion from dense parts of the interstellar medium.

scholarly journals Discovery and follow-up of the unusual nuclear transient OGLE17aaj

2019 ◽  
Vol 622 ◽  
pp. L2 ◽  
Author(s):  
M. Gromadzki ◽  
A. Hamanowicz ◽  
L. Wyrzykowski ◽  
K. V. Sokolovsky ◽  
M. Fraser ◽  
...  
Keyword(s):  
Light Curve ◽  
Black Body ◽  
Emission Lines ◽  
First Year ◽  
Tidal Disruption ◽  
Massive Black Holes ◽  
X Ray ◽  
New Type ◽  
Narrow Emission

Aims. We report on the discovery and follow-up of a peculiar transient, OGLE17aaj, which occurred in the nucleus of a weakly active galaxy. We investigate whether it can be interpreted as a new candidate for a tidal disruption event (TDE). Methods. We present the OGLE-IV light curve that covers the slow 60-day-long rise to maximum along with photometric, spectroscopic, and X-ray follow-up during the first year. Results. OGLE17aaj is a nuclear transient exhibiting some properties similar to previously found TDEs, including a long rise time, lack of colour-temperature evolution, and high black-body temperature. On the other hand, its narrow emission lines and slow post-peak evolution are different from previously observed TDEs. Its spectrum and light-curve evolution is similar to F01004-2237 and AT 2017bgt. Signatures of historical low-level nuclear variability suggest that OGLE17aaj may instead be related to a new type of accretion event in active super-massive black holes.

scholarly journals FORMATION AND DESTRUCTION OF JETS IN X-RAY BINARIES

2012 ◽  
Vol 08 ◽  
pp. 287-292
Author(s):  
IOANNIS CONTOPOULOS ◽  
NIKOLAOS D. KYLAFIS ◽  
DEMOSTHENES KAZANAS ◽  
DIMITRIS M. CHRISTODOULOU
Keyword(s):  
Physical Mechanism ◽  
Compact Object ◽  
Physical Explanation ◽  
X Ray ◽  
Radio Jets ◽  
History Of ◽  
X Ray Binaries ◽  
Spectral States ◽  
Spectral State ◽  
Natural Way

Neutron-star and black hole X-ray binaries (XRBs) exhibit radio jets, whose properties depend on the X-ray spectral state and history of the source. There is general agreement about the type of the accretion disk around the compact object in the various spectral states. What is missing is a physical explanation for the appearance, disappearance, and re-appearance of jets. We will demonstrate that by invoking a simple physical mechanism proposed more than ten years ago, the so-called Poynting-Robertson Cosmic Battery (PRCB), we can explain in a natural way the disk–jet connection in XRBs.

scholarly journals He I λ 10 830 Å in the transmission spectrum of HD209458 b

2019 ◽  
Vol 629 ◽  
pp. A110 ◽  
Author(s):  
F. J. Alonso-Floriano ◽  
I. A. G. Snellen ◽  
S. Czesla ◽  
F. F. Bauer ◽  
M. Salz ◽  
...  
Keyword(s):  
Close Relation ◽  
Emission Lines ◽  
Resolving Power ◽  
Velocity Change ◽  
X Ray ◽  
Transiting Planets ◽  
Upper Limits ◽  
Extreme Uv ◽  
Calar Alto ◽  
Excess Absorption

Context. Recently, the He I triplet at 10 830 Å was rediscovered as an excellent probe of the extended and possibly evaporating atmospheres of close-in transiting planets. This has already resulted in detections of this triplet in the atmospheres of a handful of planets, both from space and from the ground. However, while a strong signal is expected for the hot Jupiter HD 209458 b, only upper limits have been obtained so far. Aims. Our goal is to measure the helium excess absorption from HD 209458 b and assess the extended atmosphere of the planet and possible evaporation. Methods. We obtained new high-resolution spectral transit time-series of HD 209458 b using CARMENES at the 3.5 m Calar Alto telescope, targeting the He I triplet at 10 830 Å at a spectral resolving power of 80 400. The observed spectra were corrected for stellar absorption lines using out-of-transit data, for telluric absorption using the MOLECFIT software, and for the sky emission lines using simultaneous sky measurements through a second fibre. Results. We detect He I absorption at a level of 0.91 ± 0.10% (9 σ) at mid-transit. The absorption follows the radial velocity change of the planet during transit, unambiguously identifying the planet as the source of the absorption. The core of the absorption exhibits a net blueshift of 1.8 ± 1.3 km s−1. Possible low-level excess absorption is seen further blueward from the main absorption near the centre of the transit, which could be caused by an extended tail. However, this needs to be confirmed. Conclusions. Our results further support a close relation between the strength of planetary absorption in the helium triplet lines and the level of ionising, stellar X-ray, and extreme-UV irradiation.

scholarly journals Optical spectroscopy of 4U 1812–12

2020 ◽  
Vol 644 ◽  
pp. A63
Author(s):  
M. Armas Padilla ◽  
T. Muñoz-Darias ◽  
F. Jiménez-Ibarra ◽  
J. A. Fernández-Ontiveros ◽  
J. Casares ◽  
...  
Keyword(s):  
Flux Ratio ◽  
Emission Lines ◽  
Optical Observations ◽  
Source Spectrum ◽  
Evolutionary Models ◽  
Optical Counterpart ◽  
X Ray ◽  
Upper Limit ◽  
Upper Limits ◽  
Potential Member

The persistent low-luminosity neutron star X-ray binary 4U 1812−12 is a potential member of the scarce family of ultra-compact systems. We performed deep photometric and spectroscopic optical observations with the 10.4 m Gran Telescopio Canarias in order to investigate the chemical composition of the accreted plasma, which is a proxy for the donor star class. We detect a faint optical counterpart (g ∼ 25, r ∼ 23) that is located in the background of the outskirts of the Sharpless 54 H II region, whose characteristic nebular lines superimpose on the X-ray binary spectrum. Once this is corrected for, the actual source spectrum lacks hydrogen spectral features. In particular, the Hα emission line is not detected, with an upper limit (3σ) on the equivalent width of < 1.3 Å. Helium (He I) lines are also not observed, even though our constraints are not restrictive enough to properly test the presence of this element. We also provide stringent upper limits on the presence of emission lines from other elements, such as C and O, which are typically found in ultra-compact systems with C−O white dwarfs donors. The absence of hydrogen features, the persistent nature of the source at low luminosity, and the low optical–to–X-ray flux ratio confirm 4U 1812−12 as a compelling ultra-compact X-ray binary candidate, for which we tentatively propose a He-rich donor based on the optical spectrum and the detection of short thermonuclear X-ray bursts. In this framework, we discuss the possible orbital period of the system according to disc instability and evolutionary models.

scholarly journals Massive black holes in high-redshift Lyman Break Galaxies

2021 ◽  
Vol 502 (2) ◽  
pp. 2757-2769
Author(s):  
M C Orofino ◽  
A Ferrara ◽  
S Gallerani
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Upper Bound ◽  
Luminosity Function ◽  
High Redshift ◽  
Emission Lines ◽  
Tree Model ◽  
Massive Black Holes ◽  
X Ray ◽  
Lyman Break Galaxies

ABSTRACT Several evidences indicate that Lyman Break Galaxies (LBGs) in the Epoch of Reionization (redshift z &gt; 6) might host massive black holes (MBHs). We address this question by using a merger-tree model combined with tight constraints from the 7 Ms Chandra survey and the known high-z super-MBH population. We find that a typical LBG with MUV = −22 residing in an Mh ≈ 1012 M⊙ halo at z = 6 host an MBH with mass M• ≈ 2 × 108 M⊙. Depending on the fraction, fseed, of early haloes planted with a direct collapse black hole seed (Mseed = 105M⊙), the model suggests two possible scenarios: (i) if fseed = 1, MBHs in LBGs mostly grow by merging and must accrete at a low (λE ≃ 10−3) Eddington ratio not to exceed the experimental X-ray luminosity upper bound $L_\mathrm{ X}^* = 10^{42.5} {\rm erg\, s}^{-1}$; (ii) if fseed = 0.05, accretion dominates (λE ≃ 0.22) and MBH emission in LBGs must be heavily obscured. In both scenarios the UV luminosity function is largely dominated by stellar emission up to very bright mag, $M_{\rm UV} \lower.5ex\hbox{$\,\, \buildrel\gt \over \sim \,\,$}-23$, with BH emission playing a subdominant role. Scenario (i) poses extremely challenging, and possibly unphysical, requirements on DCBH formation. Scenario (ii) entails testable implications on the physical properties of LBGs involving the FIR luminosity, emission lines, and the presence of outflows.

scholarly journals Possible Detection of X-Ray Emitting Circumstellar Material in the Synchrotron-dominated Supernova Remnant RX J1713.7−3946

2021 ◽  
Vol 923 (2) ◽  
pp. 187
Author(s):  
Dai Tateishi ◽  
Satoru Katsuda ◽  
Yukikatsu Terada ◽  
Fabio Acero ◽  
Takashi Yoshida ◽  
...  
Keyword(s):  
Supernova Remnant ◽  
Thermal Emission ◽  
Abundance Ratio ◽  
Emission Lines ◽  
Emission Model ◽  
X Ray ◽  
Circumstellar Material ◽  
Elemental Abundances ◽  
Reflection Grating ◽  
Rayet Star

Abstract We report on a discovery of an X-ray emitting circumstellar material (CSM) knot inside the synchrotron dominant supernova remnant RX J1713.7−3946. This knot was previously thought to be a Wolf–Rayet star (WR 85), but we realized that it is in fact ∼40″ away from WR 85, indicating no relation to WR 85. We performed high-resolution X-ray spectroscopy with the Reflection Grating Spectrometer (RGS) on board XMM-Newton. The RGS spectrum clearly resolves a number of emission lines, such as N Lyα, O Lyα, Fe xviii, Ne x, Mg xi, and Si xiii. The spectrum can be well represented by an absorbed thermal-emission model with a temperature of k B T e = 0.65 ± 0.02 keV. The elemental abundances are obtained to be N / H = 3.5 ± 0.8 N / H ⊙ , O / H = 0.5 ± 0.1 O / H ⊙ , Ne / H = 0.9 ± 0.1 Ne / H ⊙ , Mg / H = 1.0 ± 0.1 Mg / H ⊙ , Si / H = 1.0 ± 0.2 Si / H ⊙ , and Fe / H = 1.3 ± 0.1 Fe / H ⊙ . The enhanced N abundance with others being about the solar values allows us to infer that this knot is CSM ejected when the progenitor star evolved into a red supergiant. The abundance ratio of N to O is obtained to be N / O = 6.8 − 2.1 + 2.5 N / O ⊙ . By comparing this to those in outer layers of red supergiant stars expected from stellar evolution simulations, we estimate the initial mass of the progenitor star to be 15 M ⊙ ≲ M ≲ 20 M ⊙.

scholarly journals Observation of the new emission line at ~3.5 keV in X-ray spectra of galaxies and galaxy clusters

2016 ◽  
Vol 6 (1) ◽  
pp. 3-15 ◽  
Author(s):  
D. Iakubovskyi
Keyword(s):  
Dark Matter ◽  
Emission Line ◽  
Galaxy Clusters ◽  
Particle Physics ◽  
Emission Lines ◽  
Beyond The Standard Model ◽  
Future Directions ◽  
X Ray ◽  
The Standard Model ◽  
Nearby Galaxies

The detection of an unidentified emission line in the X-ray spectra of cosmic objects would be a `smoking gun' signature for the particle physics beyond the Standard Model. More than a decade of its extensive searches results in several narrow faint emission lines reported at 3.5, 8.7, 9.4 and 10.1 keV. The most promising of them is the emission line at ~3.5 keV reported in spectra of several nearby galaxies and galaxy clusters. Here I summarize its up-to-date status, overview its possible interpretations, including an intriguing connection with the radiatively decaying dark matter, and outline future directions for its studies.

MAGIC RESULTS ON BINARY SYSTEMS

2012 ◽  
Vol 08 ◽  
pp. 67-72
Author(s):  
◽  
ROBERTA ZANIN ◽  
OSCAR BLANCH ◽  
JUAN CORTINA ◽  
TOBIAS JOGLER ◽  
...  
Keyword(s):  
Binary Systems ◽  
Gamma Ray ◽  
High Energy ◽  
Significant Activity ◽  
X Ray ◽  
Upper Limits ◽  
Very High Energy ◽  
X Ray Binaries ◽  
Spectral States ◽  
Significant Effort

Three X-ray binary systems have been unambiguously detected at TeV energies: LS 5039, LS I +61° +303, PSR B1259-63. Additionally, the TeV source HESS J0632+057 has been found to be a new binary system. The recent detection of the microquasar Cygnus X-3, between 100 MeV and few GeV, confirms that also this sub-class of accreting binaries displaying radio relativistic jets provides interesting candidates for very-high-energy (VHE) gamma-ray observations. The MAGIC telescopes made a significant effort to search for signals from X-ray binaries. This article will present the new results on LS I 61° +303, which show a reduction in the VHE γ-ray flux in the periodic outburst phase with respect to previous campaigns. MAGIC observed also HESS J0632 +057 in 2010 and 2011, covering an X-ray outburst reported by Swift in February 2011. These observations show significant activity in VHE gamma-rays temporally coincident with the X-ray outburst. In addition, this article will review MAGIC results on the microquasars Cygnus X-3, Cygnus X-1, and Scorpius X-1 which report constraining flux upper limits in different X-ray spectral states and as well as during flux enhancements at high energies.

scholarly journals Short gamma-ray bursts within 200 Mpc

2020 ◽  
Vol 492 (4) ◽  
pp. 5011-5022 ◽  
Author(s):  
S Dichiara ◽  
E Troja ◽  
B O’Connor ◽  
F E Marshall ◽  
P Beniamini ◽  
...  
Keyword(s):  
Confidence Interval ◽  
Gamma Ray ◽  
Gamma Ray Bursts ◽  
Local Universe ◽  
X Ray ◽  
Upper Limit ◽  
Upper Limits ◽  
Nearby Galaxies ◽  
The One ◽  
Short Grbs

ABSTRACT We present a systematic search for short-duration gamma-ray bursts (GRBs) in the local Universe based on 14 yr of observations with the Neil Gehrels Swift Observatory. We cross-correlate the GRB positions with the GLADE catalogue of nearby galaxies, and find no event at a distance ≲100 Mpc and four plausible candidates in the range 100 Mpc ≲ D ≲ 200 Mpc. Although affected by low statistics, this number is higher than the one expected for chance alignments to random galaxies, and possibly suggests a physical association between these bursts and nearby galaxies. By assuming a local origin, we use these events to constrain the range of properties for X-ray counterparts of neutron star mergers. Optical upper limits place tight constraints on the onset of a blue kilonova, and imply either low masses ($\lesssim 10^{-3}\, \mathrm{M}_{\odot }$) of lanthanide-poor ejecta or unfavorable orientations (θobs ≳ 30 deg). Finally, we derive that the all-sky rate of detectable short GRBs within 200 Mpc is $1.3^{+1.7}_{-0.8}$ yr−1 (68 per cent confidence interval), and discuss the implications for the GRB outflow structure. If these candidates are instead of cosmological origin, we set a upper limit of ≲2.0 yr−1 (90 per cent confidence interval) to the rate of nearby events detectable with operating gamma-ray observatories, such as Swift and Fermi.

scholarly journals Search for π0 decays to invisible particles

2021 ◽  
Vol 2021 (2) ◽  
Author(s):  
E. Cortina Gil ◽  
◽  
A. Kleimenova ◽  
E. Minucci ◽  
S. Padolski ◽  
...  
Keyword(s):  
Higgs Boson ◽  
Standard Model ◽  
Confidence Level ◽  
Branching Ratio ◽  
Standard Model Higgs Boson ◽  
Scalar Mixing ◽  
Upper Limit ◽  
Upper Limits ◽  
The Standard Model ◽  
Model Independent

Abstract The NA62 experiment at the CERN SPS reports a study of a sample of 4 × 109 tagged π0 mesons from K+ → π+π0(γ), searching for the decay of the π0 to invisible particles. No signal is observed in excess of the expected background fluctuations. An upper limit of 4.4 × 10−9 is set on the branching ratio at 90% confidence level, improving on previous results by a factor of 60. This result can also be interpreted as a model- independent upper limit on the branching ratio for the decay K+ → π+X, where X is a particle escaping detection with mass in the range 0.110–0.155 GeV/c2 and rest lifetime greater than 100 ps. Model-dependent upper limits are obtained assuming X to be an axion-like particle with dominant fermion couplings or a dark scalar mixing with the Standard Model Higgs boson.

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