scholarly journals Early Super Soft Source Spectra in RS Oph

2015 ◽  
Vol 2 (1) ◽  
pp. 222-225
Author(s):  
J.-U. Ness
Keyword(s):  
Neutral Hydrogen ◽  
Emission Lines ◽  
X Ray ◽  
Hydrogen Column Density ◽  
Recurrent Nova ◽  
Source Spectra ◽  
Short Time ◽  
First Time ◽  
Shell Ionization

Recent Swift X-ray monitoring campaigns of novae have revealed extreme levels of variability during the early super-softsource (SSS) phase. The first time this was observed was during the 2006 outburst of the recurrent nova RS Oph which was also extensively covered by grating observations with XMM-Newton and Chandra. I focus here on an XMM-Newton observation taken on day 26.1, just before Swift confirmed the start of the SSS phase, and a Chandra observation taken on day 39.7. The first observation probes the evolution of the shock emission produced by the collision of the nova ejecta with the stellar wind of the companion. The second observation contains bright SSS emission longwards of 15°A while at short wavelengths, the shock component can be seen to have hardly changed. On top of the SSS continuum, additional emission lines are clearly seen, and I show that they are much stronger than those seen on day 26.1, indicating line pumping caused by the SSS emission. The lightcurve on day 39.7 is highly variable on short time scales while the long-term Swift light curve was still variable. In 2007, we have shown that brightness variations are followed by hardness variations, lagging behind 1000 seconds. I show now that the hardness variations are owed to variations in the depth of the neutral hydrogen column density of order 25%, particularly affecting the oxygen K-shell ionization edge at 0.5 keV.

scholarly journals A 2.5-5 μm spectroscopic study of hard X-ray selected AGNs with AKARI

2013 ◽  
Vol 9 (S304) ◽  
pp. 66-67
Author(s):  
A. Castro ◽  
T. Miyaji ◽  
M. Shirahata ◽  
S. Oyabu ◽  
D. Clark ◽  
...  
Keyword(s):  
Star Formation ◽  
Neutral Hydrogen ◽  
Infrared Camera ◽  
X Ray ◽  
Star Formation Activity ◽  
Hydrogen Column Density ◽  
Polycyclic Aromatic ◽  
Low X

AbstractWe explore the relationships between the 3.3 μm polycyclic aromatic hydrocarbon (PAH) feature and active galactic nucleus (AGN) properties of a sample of 54 hard X-ray selected bright AGNs, including both Seyfert 1 and Seyfert 2 type objects, using the InfraRed Camera (IRC) on board the infrared astronomical satellite AKARI. The sample is selected from the 9-month Swift/BAT survey in the 14-195 keV band and all of them have measured X-ray spectra at E ≲ 10 keV. These X-ray spectra provide measurements of the neutral hydrogen column density (NH) towards the AGNs. We use the 3.3 μm PAH luminosity (L3.3μm) as a proxy for star formation activity and hard X-ray luminosity (L14-195keV) as an indicator of the AGN activity. We searched for possible difference of star-formation activity between type 1 (un-absorbed) and type 2 (absorbed) AGNs. Our regression analysis of log L14-195keV versus log L3.3μm shows a positive correlation and the slope seems steeper for type 1/unobscured AGNs than that of type 2/obscured AGNs. The same trend has been found for the log (L14-195keV/MBH) versus log (L3.3μm/MBH) correlation. Our analysis show that the circum-nuclear star-formation is more enhanced in type 2/absorbed AGNs than type 1/un-absorbed AGNs for low X-ray luminosity/low Eddington ratio AGNs.

scholarly journals Optical Short-Time Variations in GK Persei during the 1983 Outburst

1987 ◽  
Vol 93 ◽  
pp. 485-485
Author(s):  
H. Steinle ◽  
W. Pietsck
Keyword(s):  
Accretion Disk ◽  
Time Resolution ◽  
X Rays ◽  
X Ray ◽  
Time Variations ◽  
Short Time ◽  
First Time ◽  
Calar Alto

AbstractDuring the August 1983 outburst of the old nova GK Persei observations with EXOSAT showed for the first time a 351 second periodicity in X-rays.Our fast photometry (U(B)V with 25 sec time resolution) was made at the end of the outburst in the nights of September 29 , and October 1–3 , using the 2.2 meter telescope at Calar Alto (Spain).Optical variations up to 10% in U and 4% in V with periodicities in the range 350 to 360 seconds were found, lasting only for few cycles.A comparison with the extrapolated prediction of the X-ray maxima did not show a coincidence, but rather an anticoincidence in several cases. This supports a model of reprocessed X-rays at the inner edge of an accretion disk.

scholarly journals Phase-targeted X-ray diffraction

2016 ◽  
Vol 49 (5) ◽  
pp. 1561-1571 ◽  
Author(s):  
G. M. Hansford
Keyword(s):  
Rock Specimen ◽  
Low Cost ◽  
Emission Lines ◽  
Quartz Powder ◽  
X Ray Diffraction ◽  
Scattering Angle ◽  
X Ray ◽  
Diffraction Peaks ◽  
First Time ◽  
Xrd Method

A powder X-ray diffraction (XRD) method to enhance the signal of a specific crystalline phase within a mixture is presented for the first time. Specificity to the targeted phase relies on finding coincidences in the ratios of crystal d spacings and the ratios of elemental characteristic X-ray energies. Such coincidences can be exploited so that the two crystal planes diffract through the same scattering angle at two different X-ray energies. An energy-resolving detector placed at the appropriate scattering angle will detect a significantly enhanced signal at these energies if the target mineral or phase is present in the sample. When implemented using high scattering angles, for example 2θ > 150°, the method is tolerant to sample morphology and distance on the scale of ∼2 mm. The principle of the method is demonstrated experimentally using Pd Lα1 and Pd Lβ1 emission lines to enhance the diffraction signal of quartz. Both a pure quartz powder pellet and an unprepared mudstone rock specimen are used to test and develop the phase-targeted method. The technique is further demonstrated in the sensitive detection of retained austenite in steel samples using a combination of In Lβ1 and Ti Kβ emission lines. For both these examples it is also shown how the use of an attenuating foil, with an absorption edge close to and above the higher-energy characteristic X-ray line, can serve to isolate to some degree the coincidence signals from other fluorescence and diffraction peaks in the detected spectrum. The phase-targeted XRD technique is suitable for implementation using low-cost off-the-shelf components in a handheld or in-line instrument format.

scholarly journals Long Term UV Continuum and Line Variability in NGC 1275

2021 ◽  
Vol 20 (1) ◽  
Author(s):  
Bryan Rithesh Miranda ◽  
Vijayakumar H Doddamani ◽  
Vedavathi P
Keyword(s):  
Emission Line ◽  
Spectroscopic Data ◽  
Wavelength Region ◽  
Emission Lines ◽  
Observational Period ◽  
Flux Variability Analysis ◽  
Variability Analysis ◽  
Ngc 1275 ◽  
First Time

In this paper, we present our results for the first time on long term emission-line and continuum variability studies using the International Ultraviolet Explorer’s final archive of UV spectroscopic data obtained in the wavelength region from 1150 Å to 3200 Å for NGC 1275, a dust dominated BL Lac characterized by the Rmax and  F-variance parameter. The UV continuum flux variability analysis presented in this paper covers more number of emission-line free continuum windows in the UV region centred at  1710 Å, 1800 Å, 2625 Å, 2875 Å & 3025 Å. We have obtained a higher value of Fvar  ~ 45 % at 1710 Å and a lower value of ~ 30 % at 1800 Å for the IUE's observational period of 1978 - 1989. The Lyα, C IV, C III] and Mg II emission lines have been observed as weaker line features on fewer occasions intermittently.

LMC X–4: Different Types of Long-Term Variability

2017 ◽  
Vol 14 (S339) ◽  
pp. 146-146
Author(s):  
S. Molkov
Keyword(s):  
Binary Systems ◽  
Noise Model ◽  
High Mass ◽  
Time Interval ◽  
Spin Torque ◽  
X Ray ◽  
Spin Period ◽  
Different Types ◽  
First Time

AbstractThis talk presented a summary of our study of different types of long-term variability in the high-mass X-ray binary LMC X-4, by taking advantage of more than 43 years of measurements in the X-ray domain. In particular, we investigated the 30-day cycle of modulation of the X-ray emission from the source (super-orbital or precessional variability), and refined the orbital period and its first derivative. We showed that the precession period in the time-interval 1991–2015 is near its equilibrium value of Psup = 30.370 days, while the observed historical changes in the phase of this variability can be interpreted in terms of the ‘red noise’ model. We obtained an analytical law from which the precession phase can be determined to within 5% throughout the entire time-interval under consideration. Our analysis revealed for the first time that the source is displaying near-periodic variations of its spin period, on a time-scale of roughly 6.8 years, thus making LMC X-4 one of the (few) known binary systems that show remarkable long-term spin–torque reversals.

scholarly journals GRB 171205A/SN 2017iuk: A local low-luminosity gamma-ray burst

2018 ◽  
Vol 619 ◽  
pp. A66 ◽  
Author(s):  
V. D’Elia ◽  
S. Campana ◽  
A. D’Aì ◽  
M. De Pasquale ◽  
S. W. K. Emery ◽  
...  
Keyword(s):  
Gamma Ray ◽  
High Energy ◽  
Host Galaxy ◽  
Isotropic Energy ◽  
Optical Telescope ◽  
X Ray ◽  
Hydrogen Column Density ◽  
Peak Energy ◽  
First Time

Context. Gamma-ray bursts (GRBs) occurring in the local Universe constitute an interesting sub-class of the GRB family, since their luminosity is on average lower than that of their cosmological analogs. Attempts to understand in a global way this peculiar behaviour is still not possible, since the sample of low redshift GRBs is small, and the properties of individual objects are too different from each other. In addition, their closeness (and consequently high fluxes) make these sources ideal targets for extensive follow-up even with small telescopes, considering also that these GRBs are conclusively associated with supernova (SN) explosions. Aims. We aim to contribute to the study of local bursts by reporting the case of GRB 171205A. This source was discovered by Swift Burst Alert Telescope (BAT) on 2017, December 5 and soon associated with a low redshift host galaxy (z = 0.037), and an emerging SN (SN 2017iuk). Methods. We analyzed the full Swift dataset, comprising the UV-Optical Telescope (UVOT), X-ray Telescope (XRT) and BAT data. In addition, we employed the Konus-Wind high energy data as a valuable extension at γ-ray energies. Results. The photometric SN signature is clearly visible in the UVOT u, b and ν filters. The maximum emission is reached at ∼13 (rest frame) days, and the whole bump resembles that of SN 2006aj, but lower in magnitude and with a shift in time of +2 d. A prebump in the ν-band is also clearly visible, and this is the first time that such a feature is not observed achromatically in GRB–SNe. Its physical origin cannot be easily explained. The X-ray spectrum shows an intrinsic Hydrogen column density NH,int = 7.4+4.1−3.6 × 1020 cm−2, which is at the low end of the N H, int, even considering just low redshift GRBs. The spectrum also features a thermal component, which is quite common in GRBs associated with SNe, but whose origin is still a matter of debate. Finally, the isotropic energy in the γ-ray band, Eiso = 2.18+0.63−5.0 × 1049 erg, is lower than those of cosmological GRBs. Combining this value with the peak energy in the same band, Ep = 125+141−37 keV, implies that GRB 171205A is an outlier of the Amati relation, as are some other low redshift GRBs, and its emission mechanism should be different from that of canonical, farther away GRBs.

scholarly journals An Archival Study of HST Observations of Her X-1/HZ Her

1996 ◽  
Vol 158 ◽  
pp. 381-382
Author(s):  
F. H. Cheng ◽  
S. D. Vrtilek ◽  
J. C. Raymond
Keyword(s):  
Accretion Disk ◽  
Model Fitting ◽  
Rotation Period ◽  
Emission Lines ◽  
High Quality ◽  
Detailed Model ◽  
Companion Star ◽  
X Ray ◽  
First Time ◽  
Archival Study

Her X-1 is an X-ray pulsar with a rotation period of 1.24 s and a binary period of 1.7d (Tananbaum et al. 1972). The 1.7 d variations in optical and ultraviolet flux are attributed to X-ray heating of the companion star and disk (e.g. Howarth & Wilson 1983, hereafter HW83). The system displays a 35 d period, attributed to the effects of a tilted, precessing, accretion disk. Optical and ultraviolet flux variations continue unchanged throughout. This work is motivated by the following reasons:• The observed IUE spectra have significantly flatter slopes than those predicted by previous models (e.g. HW83).• The observed strength of the Balmer jump is anomalously low compared to that expected for a normal B star (Anderson et al. 1994).• HST observations obtained by Anderson et al. (1994) in order to study emission lines have yielded high quality spectra of the continuum emission from HZ Her, enabling for the first time detailed model fitting efforts.

Case report of extensive foreign body of esophagus with spread to laryngopharynx and larynx

2021 ◽  
Vol 20 (4) ◽  
pp. 79-82
Author(s):  
B. B. Uraskulova ◽  
◽  
A. O. Gyusan ◽  
Keyword(s):  
Foreign Body ◽  
Foreign Bodies ◽  
Clinical Observation ◽  
Irregular Shape ◽  
Air Bubbles ◽  
X Ray ◽  
Excessive Salivation ◽  
Difficulty Breathing ◽  
Short Time

Foreign bodies of the respiratory tract and esophagus remain one of the pressing problems in medicine, which is associated with the possibility of developing complications that can end in death. We present our clinical observation that demonstrates the long-term presence of a large foreign body fixed in the area of the pharyngeal narrowing of the esophagus and extending into the larynx and the vestibule of the larynx. Patient T., 57 years old, went to the emergency department of the Karachay-Cherkessia Republican Clinical Hospital with complaints of severe sore throat, inability to swallow, excessive salivation, increased body temperature to 37,5 °C, difficulty breathing, mixed shortness of breath, which persist for 3 days. The examination revealed: the epiglottis is mobile, the mucous membrane of the larynx is hyperemic, edematous, with an abundance of saliva, at the level of the vestibular part of the larynx, in the area of the arytenoid cartilage and aryepiglottic folds, an irregular shape was visualized, with smooth edges, a thin, hard whitish plate. Computed tomography of the cervical spine: in the esophagus, at the level of C4-C5 vertebrae, a foreign body with a metallic density of +2900 hU units, elongated, irregular shape, measuring 2.2 by 3.3 cm, with perifocal air bubbles is determined. A preliminary diagnosis was made: Foreign body of the esophagus, laryngopharynx with a spread to the vestibule of the larynx. 3 days after the retention of the foreign body under intubation anesthesia, it is captured using forceps with serrated cups and removed during direct laryngoscopy. There were no complications during the manipulation. The combination of X-ray and endoscopic examinations with the help of innovative medical and diagnostic equipment made it possible to establish a diagnosis in a short time, choose the most effective treatment tactics and remove a foreign body through natural pathways.

scholarly journals The X-shooter GRB afterglow legacy sample (XS-GRB)

2019 ◽  
Vol 623 ◽  
pp. A92 ◽  
Author(s):  
J. Selsing ◽  
D. Malesani ◽  
P. Goldoni ◽  
J. P. U. Fynbo ◽  
T. Krühler ◽  
...  
Keyword(s):  
Selection Criteria ◽  
Column Density ◽  
Neutral Hydrogen ◽  
Cosmic Time ◽  
Late Time ◽  
Host Galaxies ◽  
X Ray ◽  
Hydrogen Column Density ◽  
X Ray Absorption

In this work we present spectra of all γ-ray burst (GRB) afterglows that have been promptly observed with the X-shooter spectrograph until 31/03/2017. In total, we have obtained spectroscopic observations of 103 individual GRBs observed within 48 hours of the GRB trigger. Redshifts have been measured for 97 per cent of these, covering a redshift range from 0.059 to 7.84. Based on a set of observational selection criteria that minimise biases with regards to intrinsic properties of the GRBs, the follow-up effort has been focused on producing a homogeneously selected sample of 93 afterglow spectra for GRBs discovered by the Swift satellite. We here provide a public release of all the reduced spectra, including continuum estimates and telluric absorption corrections. For completeness, we also provide reductions for the 18 late-time observations of the underlying host galaxies. We provide an assessment of the degree of completeness with respect to the parent GRB population, in terms of the X-ray properties of the bursts in the sample and find that the sample presented here is representative of the full Swift sample. We have constrained the fraction of dark bursts to be <28 per cent and confirm previous results that higher optical darkness is correlated with increased X-ray absorption. For the 42 bursts for which it is possible, we have provided a measurement of the neutral hydrogen column density, increasing the total number of published HI column density measurements by ∼33 per cent. This dataset provides a unique resource to study the ISM across cosmic time, from the local progenitor surroundings to the intervening Universe.

scholarly journals Environmental Effects on Properties of Type 2 QSOs

2009 ◽  
Vol 5 (S267) ◽  
pp. 106-106
Author(s):  
Lin-wen Chen ◽  
Li-Ting Hsu
Keyword(s):  
Column Density ◽  
Neutral Hydrogen ◽  
Photometric Redshifts ◽  
X Ray ◽  
Sky Survey ◽  
Hydrogen Column Density ◽  
Population Figure ◽  
Two Populations ◽  
Projected Distance

Type 2 QSOs (QSO2s) are intrinsically luminous QSOs embedded in dusty environments. In this work, we study the radio, optical, and soft X-ray properties of 887 optically selected [O III]-based QSO2s (Reyes et al. 2008) at z<0.83 to investigate the connection between QSO2s and their environments. We use SDSS data to measure the luminosity-limited galaxy counts in a volume centered on each QSO2 and defined by Δ z<0.1 (based on photometric redshifts) and within a projected distance of 1.5 Mpc of the QSO2 (δ1.5Mpc). We used ROSAT All Sky Survey (RASS) data to estimate the X-ray excess. Hsu & Chen (2010), after correcting for Galactic absorption, obtain a lower limit for the intrinsic neutral hydrogen column density (NH) toward each of the QSO2s. About 50% of these sources have NH > 1022 cm−2. We take this value as a threshold to subdivide QSO2s into high- and low-NH groups, and compare their environments. The distributions δ1.5Mpc of the two populations show that, in regions of higher galaxy density, QSO2s are dominated by the high-NH population (Figure 1), suggesting a closer connection between more obscured QSO2s and surrounding galaxies.

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