Abstract
We report on the Swift/XRT Deep Galactic Plane Survey discovery and multiwavelength follow-up observations of a new intermediate polar (IP) cataclysmic variable, Swift J183920.1-045350. A ...449.7 s spin period is found in XMM-Newton and NuSTAR data, accompanied by a 459.9 s optical period that is most likely the synodic, or beat period, produced from a 5.6 hr orbital period. The orbital period is seen with moderate significance in independent long-baseline optical photometry observations taken with the ZTF and SAAO telescopes. We find that the X-ray pulse fraction of the source decreases with increasing energy. The X-ray spectra are consistent with the presence of an Fe emission line complex with both local and interstellar absorption. In the optical spectra, strong H
α
, H
i
, He
i,
and He
ii
emission lines are observed, all common features in magnetic CVs. The source properties are thus typical of known IPs, with the exception of its estimated distance of
2.26
−
0.83
+
1.93
kpc, which is larger than typical, extending the reach of the CV population in our Galaxy.
Abstract
During 2020 April and May, SGR J1935+2154 emitted hundreds of short bursts and became one of the most prolific transient magnetars. At the onset of the active bursting period, a 130 s burst ...“forest,” which included some bursts with peculiar time profiles, were observed with the Fermi/Gamma-ray Burst Monitor (GBM). In this Letter, we present the results of time-resolved spectral analysis of this burst “forest” episode, which occurred on 2020 April 27. We identify thermal spectral components prevalent during the entire 130 s episode; high-energy maxima appear during the photon flux peaks, which are modulated by the spin period of the source. Moreover, the evolution of the
ν
F
ν
spectral hardness (represented by
E
peak
or blackbody temperature) within the lightcurve peaks is anti-correlated with the pulse phases extrapolated from the pulsation observed within the persistent soft X-ray emission of the source six hours later. Throughout the episode, the emitting area of the high-energy (hotter) component is 1–2 orders of magnitude smaller than that for the low-energy component. We interpret this with a geometrical viewing angle scenario, inferring that the high-energy component likely originates from a low-altitude hotspot located within closed toroidal magnetic field lines.
The light curves of gamma-ray bursts (GRBs) are believed to result from internal shocks reflecting the activity of the GRB central engine. Their temporal deconvolution can reveal potential ...differences in the properties of the central engines in the two populations of GRBs which are believed to originate from the deaths of massive stars (long) and from mergers of compact objects (short). We present here the results of the temporal analysis of 42 GRBs detected with the Gamma-ray Burst Monitor onboard the Fermi Gamma-ray Space Telescope. We deconvolved the profiles into pulses, which we fit with lognormal functions. The distributions of the pulse shape parameters and intervals between neighboring pulses are distinct for both burst types and also fit with lognormal functions. We have studied the evolution of these parameters in different energy bands and found that they differ between long and short bursts. We discuss the implications of the differences in the temporal properties of long and short bursts within the framework of the internal shock model for GRB prompt emission.
The optimal targeted temperature in patients with shockable rhythm is unclear, and current guidelines recommend targeted temperature management with a correspondingly wide range between 32°C and ...36°C. Our aim was to study survival and neurologic outcome associated with targeted temperature management strategy in postarrest patients with initial shockable rhythm.
Observational substudy of the Coronary Angiography after Cardiac Arrest without ST-segment Elevation trial.
Nineteen hospitals in The Netherlands.
The Coronary Angiography after Cardiac Arrest trial randomized successfully resuscitated patients with shockable rhythm and absence of ST-segment elevation to a strategy of immediate or delayed coronary angiography. In this substudy, 459 patients treated with mild therapeutic hypothermia (32.0-34.0°C) or targeted normothermia (36.0-37.0°C) were included. Allocation to targeted temperature management strategy was at the discretion of the physician.
None.
After 90 days, 171 patients (63.6%) in the mild therapeutic hypothermia group and 129 (67.9%) in the targeted normothermia group were alive (hazard ratio, 0.86 95% CI, 0.62-1.18; log-rank p = 0.35; adjusted odds ratio, 0.89; 95% CI, 0.45-1.72). Patients in the mild therapeutic hypothermia group had longer ICU stay (4 d 3-7 d vs 3 d 2-5 d; ratio of geometric means, 1.32; 95% CI, 1.15-1.51), lower blood pressures, higher lactate levels, and increased need for inotropic support. Cerebral Performance Category scores at ICU discharge and 90-day follow-up and patient-reported Mental and Physical Health Scores at 1 year were similar in the two groups.
In the context of out-of-hospital cardiac arrest with shockable rhythm and no ST-elevation, treatment with mild therapeutic hypothermia was not associated with improved 90-day survival compared with targeted normothermia. Neurologic outcomes at 90 days as well as patient-reported Mental and Physical Health Scores at 1 year did not differ between the groups.
Discerning the radiative dissipation mechanism for prompt emission in gamma-ray bursts (GRBs) requires detailed spectroscopic modeling that straddles the Delta *nF Delta *n peak in the 100 keV-1 MeV ...range. Historically, empirical fits such as the popular Band function have been employed with considerable success in interpreting the observations. While extrapolations of the Band parameters can provide some physical insight into the emission mechanisms responsible for GRBs, these inferences do not provide a unique way of discerning between models. By fitting physical models directly, this degeneracy can be broken, eliminating the need for empirical functions; our analysis here offers a first step in this direction. One of the oldest, and leading, theoretical ideas for the production of the prompt signal is the synchrotron shock model. Here we explore the applicability of this model to a bright Fermi gamma-ray burst monitor (GBM) burst with a simple temporal structure, GRB 090820A. Our investigation implements, for the first time, thermal and non-thermal synchrotron emissivities in the RMFIT forward-folding spectral analysis software often used in GBM burst studies. We find that these synchrotron emissivities, together with a blackbody shape, provide at least as good a match to the data as the Band GRB spectral fitting function. This success is achieved in both time-integrated and time-resolved spectral fits.
We obtained radio observations of the symbiotic binary and known recurrent nova T Coronae Borealis following a period of increased activity in the optical and X-ray bands. A comparison of our ...observations with those made prior to 2015 indicates that the system is in a state of higher emission in the radio as well. The spectral energy distributions are consistent with optically thick thermal bremsstrahlung emission from a photoionized source. Our observations indicate that the system was in a state of increased ionization in the companion wind, possibly driven by an increase in accretion rate, with the radio photosphere located well outside the binary system.
Whether sex is associated with outcomes of out-of-hospital cardiac arrest (OHCA) is unclear.
This study examined sex differences in survival in patients with OHCA without ST-segment elevation ...myocardial infarction (STEMI).
Using data from the randomized controlled Coronary Angiography after Cardiac Arrest (COACT) trial, the primary point of interest was sex differences in OHCA-related one-year survival. Secondary points of interest included the benefit of immediate coronary angiography compared to delayed angiography until after neurologic recovery, angiographic and clinical outcomes.
In total, 522 patients (79.1% men) were included. Overall one-year survival was 59.6% in women and 63.4% in men (HR 1.18; 95% CI: 0.76-1.81;p = 0.47). No cardiovascular risk factors were found that modified survival. Women less often had significant coronary artery disease (CAD) (37.0% vs. 71.3%;p < 0.001), but when present, they had a worse prognosis than women without CAD (HR 3.06; 95% CI 1.31–7.19;p = 0.01). This was not the case for men (HR 1.05; 95% CI 0.67–1.65;p = 0.83). In both sexes, immediate coronary angiography did not improve one-year survival compared to delayed angiography (women, odds ratio (OR) 0.87; 95% CI 0.58–1.30;p = 0.49; vs. men, OR 0.97; 95% CI 0.45–2.09;p = 0.93).
In OHCA patients without STEMI, we found no sex differences in overall one-year survival. Women less often had significant CAD, but when CAD was present they had worse survival than women without CAD. This was not the case for men. Both sexes did not benefit from a strategy of immediate coronary angiography as compared to delayed strategy with respect to one-year survival.
Netherlands trial register (NTR) 4973.
ABSTRACT Radio observations of young stellar objects (YSOs) enable the study of ionized plasma outflows from young protostars via their free-free radiation. Previous studies of the low-mass young ...system T Tau have used radio observations to model the spectrum and estimate important physical properties of the associated ionized plasma (local electron density, ionized gas content, and emission measure). However, without an indication of the low-frequency turnover in the free-free spectrum, these properties remain difficult to constrain. This paper presents the detection of T Tau at 149 MHz with the Low Frequency Array (LOFAR)-the first time a YSO has been observed at such low frequencies. The recovered total flux indicates that the free-free spectrum may be turning over near 149 MHz. The spectral energy distribution is fitted and yields improved constraints on local electron density ( cm−3), ionized gas mass ( ), and emission measure ( pc cm−6).
From 2008 July to 2009 October, the Gamma-ray Burst Monitor (GBM) on board the Fermi Gamma-ray Space Telescope has detected 320 gamma-ray bursts (GRBs). About 20% of these events are classified as ...short based on their T 90 duration below 2 s. We present here for the first time time-resolved spectroscopy at timescales as short as 2 ms for the three brightest short GRBs observed with GBM. The time-integrated spectra of the events deviate from the Band function, indicating the existence of an additional spectral component, which can be fit by a power law with index ~--1.5. The time-integrated E peak values exceed 2 MeV for two of the bursts and are well above the values observed in the brightest long GRBs. Their E peak values and their low-energy power-law indices ( Delta *a) confirm that short GRBs are harder than long ones. We find that short GRBs are very similar to long ones, but with light curves contracted in time and with harder spectra stretched toward higher energies. In our time-resolved spectroscopy analysis, we find that the E peak values range from a few tens of keV up to more than 6 MeV. In general, the hardness evolutions during the bursts follow their flux/intensity variations, similar to long bursts. However, we do not always see the E peak leading the light-curve rises and confirm the zero/short average light-curve spectral lag below 1 MeV, already established for short GRBs. We also find that the time-resolved low-energy power-law indices of the Band function mostly violate the limits imposed by the synchrotron models for both slow and fast electron cooling and may require additional emission processes to explain the data. Finally, we interpreted these observations in the context of the current existing models and emission mechanisms for the prompt emission of GRBs.
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