Flare State Research Articles

Transient quasi-periodic oscillations in the gamma-ray light curves of bright blazars

ABSTRACT Transient quasi-periodic oscillations (QPOs) are extremely interesting observational phenomena. However, the precise physical mechanisms leading to their generation are still hotly debated. We performed a systematic search for transient QPO signals using Weighted Wavelet Z-transforms on the gamma-ray light curves of 134 bright blazars with peak flux exceeding 1 × 10−6 ph cm−2 s−1 as monitored by Fermi-LAT. Artificial light curves were generated from the power spectral density and probability distribution functions of the original light curves to assess the significance level of transient QPO. We discuss several physical mechanisms that produce transient QPOs, with the helical jet model providing the best explanation. This study identified four new transient QPO events. Interestingly, repetitive transient QPOs are observed in PKS 0537-441, and nested transient QPOs are detected in PKS 1424−41. Additionally, we find that transient QPOs tend to occur in the flare state of the blazar. Finally, we estimate the incidence of transient QPO events to be only about 3 per cent.

The orbital period of the recurrent nova V2487 Oph revealed

ABSTRACT We present the first reliable determination of the orbital period of the recurrent nova V2487 Oph (Nova Oph 1998). We derived a value of 0.753 ± 0.016 d (18.1 ± 0.4 h) from the radial velocity curve of the intense He ii λ4686 emission line as detected in time-series X-shooter spectra. The orbital period is significantly shorter than earlier claims, but it makes V2487 Oph one of the longest period cataclysmic variables known. The spectrum of V2487 Oph is prolific in broad Balmer absorptions that resemble a white dwarf spectrum. However, we show that they come from the accretion disc viewed at low inclination. Although highly speculative, the analysis of the radial velocity curves provides a binary mass ratio q ≈ 0.16 and a donor star mass M2 ≈ 0.21 M⊙, assuming the reported white dwarf mass M1 = 1.35 M⊙. A subgiant M-type star is tentatively suggested as the donor star. We were lucky to inadvertently take some of the spectra when V2487 Oph was in a flare state. During the flare, we detected high-velocity emission in the Balmer and He ii λ4686 lines exceeding −2000 km s−1 at close to orbital phase 0.4. Receding emission up to 1200 km s−1 at about phase 0.3 is also observed. The similarities with the magnetic cataclysmic variables may point to magnetic accretion on to the white dwarf during the repeating flares.

Skin-Related Quality of Life During Autoimmune Bullous Disease Course

Autoimmune bullous diseases (AIBDs) are chronic relapsing-remitting conditions with significant morbidity. Skin-related quality of life (SRQL) may vary by AIBD subtype and disease type. Disease severity and flare severity can be difficult to define; SRQL can offer a key insight. To investigate the Skindex-16 score as an SRQL measure in AIBD subtypes during flare and nonflare states and to evaluate Skindex-16 construct validity. This retrospective cross-sectional study was conducted from September 1, 2016, to February 1, 2020, among 192 patients at the University of Utah Health autoimmune dermatology clinic with pemphigoid, pemphigus, dermatitis herpetiformis, and linear immunoglobulin A disease. Patients had an encounter-associated diagnosis, Skindex-16 scores, and self-reported flare status. Statistical analysis was performed from March 2022 to June 2023. Autoimmune bullous disease subtype and patient-reported flare status. Skindex-16 domain scores (emotions, symptoms, and functioning; range, 0-100, where 0 indicates no effect on SRQL and 100 maximum effect) and individual item scores were described by disease and flare status. Flare scores were expected to be higher by at least the standard error of measurement (SEm). Convergent validity was assessed using Spearman correlation among Skindex-16 scores, serologic titers, and other patient-reported outcome measures. Floor or ceiling domain scores (<20% of sample scoring either lowest or highest possible domain scores, respectively) were assessed for Skindex-16. Structural validity was assessed using confirmatory factor analysis (CFA). The study included 192 patients with 212 visits (median age, 68 years [IQR, 58-76 years]; 123 of 212 women [58.0%]) with Skindex-16 scores (64 in flare state and 148 in nonflare state). Median Skindex-16 domain scores were higher for all disease categories among patients in the flare state compared with those in the nonflare state (pemphigoid [emotions: flare, 52.4 (IQR, 38.1-69.0); nonflare, 7 (IQR, 0-17); symptoms: flare, 37.5 (IQR, 29.2-58.0); nonflare, 13 (IQR, 0-25); functioning: flare, 26.7 (IQR, 10.0-56.7); nonflare, 0 (IQR, 0-3)]; pemphigus [emotions: flare, 54.8 (IQR, 31.0-81.0; nonflare, 0 (IQR, 0-19); symptoms: flare, 58.3 (IQR, 41.7-70.8); nonflare, 4 (IQR, 0-12.5); functioning: flare, 26.7 (IQR, 13.3-83.3); nonflare, 0 (IQR, 0-3.33)]; dermatitis herpetiformis [emotions: flare, 72.6 (IQR, 34.7-90.5); nonflare, 14.3 (IQR, 2.4-26.2); symptoms: flare, 69 (IQR, 31.3-85.4); nonflare, 12.5 (IQR, 0-29.2); functioning: flare, 38.3 (IQR, 5.0-63.2); nonflare, 0 (IQR, 0-13.3)]. This difference exceeded SEm cut points. Cronbach α was greater than 0.80 for all domains and AIBDs. Moderate or low correlations were seen with desmoglein 1 and bullous pemphigoid 180 titers. Moderate correlation existed between Skindex-16 and Patient-Reported Outcomes Measurement Information System Depression scores (emotions: ρ = 0.40; symptoms: ρ = 0.41; functioning: ρ = 0.48), and strong correlation existed between Skindex-16 and patient-reported disease severity (emotions: ρ = 0.71; symptoms: ρ = 0.73; functioning: ρ = 0.66). Floor domain scores greater than 20% were seen among patients in the nonflare state, but ceiling domain scores were rare (<10% for all domains); CFA model fit was poor. In this cross-sectional study, SRQL was highly associated with flare of AIBDs. Skin-related quality of life was worse during periods without flare among patients with pemphigoid and dermatitis herpetiformis compared with pemphigus, highlighting residual SRQL morbidity. Skindex-16 showed good construct validity, but the poor CFA model fit needs further research. Clinical measurement of SRQL in AIBDs can add critical disease-severity information.

Possible Detection of a Flare-associated Coronal Mass Ejection on an M-dwarf

We here report a probable detection of a stellar coronal mass ejection (CME) in active M dwarf KIC 8093473 by performing an analysis on its time resolved X-ray spectra observed by the XMM-Newton satellite. Compared to the value at the quiescent state and the interstellar one, our spectral modeling returns a marginal (and probably evolving) excess of hydrogen column density in the flare state at a significance level of 1σ, which can be understood by an additional absorption due to a flare-associate CME. The CME mass is then estimated to be ∼7 × 1018–2 × 1020 g according to the ice cream cone model.

Chromatic optical polarization of BL Lac: while faint and bright

ABSTRACT Due to the first results on astrophysical X-ray polarization provided by IXPE observatory, the interest in wavelength-dependent synchrotron polarization of BL Lac-type objects increases. This paper presents the results of multiband optical observations of the well-known blazar named BL Lac (z = 0.069) in polarized light. It was shown that the object’s emission, regardless of its phase of activity, is characterized by the intraday variability of brightness and polarization with changes occurring on a time-scale of up to 1.5 h without any stable oscillation period. Polarimetric observations in the different optical bands show that the degree and angle of polarization of the blazar depend on the wavelength, and the maximum chromatism, as well as the maximum observed polarization degree, was detected during the minimum brightness state; during the flare state, the polarization chromatism changed along with the flux gradient on the time-scale of an hour. Qualitatively, such behaviour can be described by the shock-in-jet model, yet the chromatism amplitude and its rapid changes differ significantly from the model predictions and challenge the numerical calculations.

LRG1, a Novel Serum Biomarker for Idiopathic Multicentric Castleman Disease Activity

Objective: To investigate the relationship between serum Leucine-Rich α-2-Glycoprotein-1 (LRG1) and idiopathic multicentric Castleman disease (iMCD) activity, and to verify the effectiveness of LRG1 in monitoring treatment response. Methods: Clinical data and serum samples were collected from iMCD patients in flare and remission state diagnosed between August 2015 and April 2022 in Peking Union Medical College Hospital. Enzyme-linked Immunosorbent Assay was performed to quantify LRG1 concentration, which was further analyzed with patients' clinical data. Results: 81 patients were included, with 10 cases of iMCD-TAFRO and 40 cases of severe-disease, and 110 serum samples were acquired. The average LRG1 concentration was 113.5±14.27μg/mL in 76 samples of disease flare, 47.48±14.23μg/mL in 16 biochemical PR, and 14.4±1.18μg/mL in 18 biochemical CR samples. The difference is significant among different disease states (Flare vs PR, p = 0.0019; Flare vs CR, p < 0.0001; PR vs CR, p = 0.0349). Paired sample of 20 cases showed significant decrease of serum LRG1 from Flare to PR/CR (-35.36±5.94μg/mL, p < 0.0001) after treatment (figure 1A). Serum LRG1 level was also elevated in those iMCD-TAFRO cases with normal serum CRP level during disease flare. Baseline LRG1 level was significantly higher in patients with severe disease (142.6±23.2μg/mL vs 81.2±14.0μg/mL, p = 0.0271), which could be identified efficiently by baseline LRG1 over 57.75μg/mL (AUC = 0.655, p = 0.0203, sensitivity 70%, specificity 63.89%). Among 38 patients using thalidomide-cyclophosphamide-prednisone (TCP) regimen as first-line treatment, the median time to next treatment in patients with baseline LRG1 over 57.75μg/mL was significantly shorter than those under 57.75μg/mL (10 vs 30 months, HR: 2.254, 95% CI: 1.052-4.828, p = 0.0277) (figure 1B). Conclusion: Serum LRG1 level could mirror disease activity, and could be utilized to monitor the treatment response, especially in iMCD-TAFRO subtype. Serum LRG1 level over 57.75μg/mL could efficiently identify patients with severe iMCD, and had the potential to predict the efficacy of TCP regimen. Figure 1View largeDownload PPTFigure 1View largeDownload PPT Close modal

Transcription Factor c-Maf Promotes Immunoregulation of Programmed Cell Death 1-Expressed CD8+ T Cells in Multiple Sclerosis.

Background and ObjectivesMultiple sclerosis (MS) is an inflammatory demyelinating disease of the CNS. CD8+ T cells are prominently found at inflammatory sites. Recent advances in understanding checkpoint molecules, including programmed cell death 1 (PD-1), expressed on CD8+ T cells, highlight the immune regulatory roles of this T-cell subset; however, the role of CD8+ T cells in MS is unclear. Thus, we aimed to reveal the characteristics of PD-1–expressed (PD-1+) CD8+ T cells in MS.MethodsWe performed a cohort, case-control study for phenotyping analysis of PD-1+CD8+ T cells in disease remission and flare states using CSF and peripheral blood samples of 45 patients with MS or clinically isolated syndrome and 12 healthy subjects. We further analyzed the transcriptome of sorted PD-1+CD8+ T cells obtained from interferon (IFN)-β–treated patients and validated their regulatory machinery using in vitro cell culture assays with lentiviral gene transfer.ResultsIn the disease remission state, PD-1+CD8+ T cells were decreased in the peripheral blood of patients with MS and resolved in patients treated with IFN-β treatment who showed immune regulatory cytokine interleukin (IL)-10 expression. In the disease flare state, we found that PD-1+CD8+ T cells were enriched in the CSF, which predicted a good response to subsequent IV steroid therapy. Transcriptome analysis of sorted PD-1+CD8+ T cells revealed the transcription factor c-Maf as a potential major regulator of the gene module, including multiple coinhibitory molecules. Furthermore, c-Maf expressed in CD8+ T cells induced PD-1 expression and production of IL-10 as well as suppressed alloactivated CD4+ T-cell survival.DiscussionThis study uncovered a favorable role of PD-1+CD8+ T cells against MS and demonstrated that c-Maf–driven IL-10 is an immune regulatory machinery.

Temporal and spectral study of PKS B1222 + 216 flares in 2014

ABSTRACT We report on a temporal and spectral study of a flat-spectrum radio quasar, PKS B1222 + 216, in a flare state to get insight into the acceleration and emission mechanisms inside the jet. It is one of the brightest and highly active blazars in the MeV–GeV regime. The long-term multiwaveband light curves of this object showed flaring activity in 2014, with two distinct flares. The work presented here includes the study of flux-index variation, flare fitting, and hardness ratio, and the spectral modelling of X-ray and γ-ray data. The flux-index correlation found in the MeV–GeV regime indicates a ‘softer when brighter’ feature. The modelling of γ-ray light curves suggests that low-energy particles initiate both the flares, followed by the injection of high-energy particles. The short rise time indicates the presence of Fermi first-order acceleration. A single-zone leptonic model is used to fit the multiwaveband spectral energy distributions generated for both flares. The spectral energy distribution modelling shows that inverse Compton scattering of the photon field reprocessed from the broad-line region primarily accounts for the GeV emission. In addition, we have reported a shift in the break energy in the soft X-ray regime during flares, which is due to a rapid change in the injection spectrum.

Possible ∼0.4 h X-ray quasi-periodicity from an ultrasoft active galactic nucleus

RX J1301.9+2747 is an ultrasoft active galactic nucleus (AGN) with unusual X-ray variability that is characterized by a long quiescent state and a short-lived flare state. The X-ray flares are found to recur quasi-periodically on a timescale of 13−20 ks. Here, we report the analysis of the light curve in the quiescent state from two XMM-Newton observations spanning 18.5 years, along with the discovery of a possible quasi-periodic X-ray oscillation (QPO) with a period of ∼1500 s. The QPO is detected at the same frequency in the two independent observations, with a combined significance of &gt; 99.89%. The QPO is in agreement with the relation between frequency and black hole mass (MBH) that has been reported in previous works for AGNs and Galactic black hole X-ray binaries (XRBs). The QPO frequency is stable over almost two decades, suggesting that it may correspond to the high-frequency type found in XRBs and originates, perhaps, from a certain disk resonance mode. In the 3:2 twin-frequency resonance model, our best estimate on the MBH range implies that a maximal black hole spin can be ruled out. We find that all ultrasoft AGNs reported so far display quasi-periodicities in the X-ray emission, suggesting a possible link on the part of the extreme variability phenomenon to the ultrasoft X-ray component. This indicates that ultrasoft AGNs could be the most promising candidates in future searches for X-ray periodicities.

Excluding possible sites of high-energy emission in 3C 84

ABSTRACT The FR-I galaxy 3C 84, that is identified with the misaligned blazar NGC 1275, is well known as one of the very few radio galaxies emitting gamma-rays in the TeV range. Yet, the gamma-ray emission region cannot be pinpointed and the responsible mechanisms are still unclear. We calculate the optical absorption depth of high-energy photons in the broad-line region of 3C 84 depending on their energy and distance to the central black hole. Based on these calculations, a lower limit on the distance of the emission region from the central black hole can be derived. These lower limits are estimated for two broad-line region geometries (shell and ring) and two states of the source, the low state in 2016 October–December and a flare state in 2017 January. For the shell geometry, we can place the emission region outside the Ly α radius. For the ring geometry and the low flux activity, the minimal distance between the black hole, and the gamma-ray emission region is close to the Ly α radius. In the case of the flaring state (ring geometry), the results are not conclusive. Our results exclude the region near the central black hole as the origin of the gamma-rays detected by Fermi–LAT and Major Atmospheric Gamma-Ray Imaging Cherenkov. With these findings, we can constrain the theoretical models of acceleration mechanisms and compare the possible emission region to the source’s morphology resolved by radio images from the Very Long Baseline Array.

The High-energy Radiation Environment around a 10 Gyr M Dwarf: Habitable at Last?

Abstract Recent work has demonstrated that high levels of X-ray and UV activity on young M dwarfs may drive rapid atmospheric escape on temperate, terrestrial planets orbiting within the habitable zone. However, secondary atmospheres on planets orbiting older, less active M dwarfs may be stable and present more promising candidates for biomarker searches. In order to evaluate the potential habitability of Earth-like planets around old, inactive M dwarfs, we present new Hubble Space Telescope and Chandra X-ray Observatory observations of Barnard’s Star (GJ 699), a 10 Gyr old M3.5 dwarf, acquired as part of the Mega-MUSCLES program. Despite the old age and long rotation period of Barnard’s Star, we observe two FUV (δ 130 ≈ 5000 s; E 130 ≈ 1029.5 erg each) and one X-ray (E X ≈ 1029.2 erg) flares, and we estimate a high-energy flare duty cycle (defined here as the fraction of the time the star is in a flare state) of ∼25%. A publicly available 5 Å to 10 μm spectral energy distribution of GJ 699 is created and used to evaluate the atmospheric stability of a hypothetical, unmagnetized terrestrial planet in the habitable zone (r HZ ∼ 0.1 au). Both thermal and nonthermal escape modeling indicate (1) the quiescent stellar XUV flux does not lead to strong atmospheric escape: atmospheric heating rates are comparable to periods of high solar activity on modern Earth, and (2) the flare environment could drive the atmosphere into a hydrodynamic loss regime at the observed flare duty cycle: sustained exposure to the flare environment of GJ 699 results in the loss of ≈87 Earth atmospheres Gyr−1 through thermal processes and ≈3 Earth atmospheres Gyr−1 through ion loss processes. These results suggest that if rocky planet atmospheres can survive the initial ∼5 Gyr of high stellar activity, or if a second-generation atmosphere can be formed or acquired, the flare duty cycle may be the controlling stellar parameter for the stability of Earth-like atmospheres around old M stars.

Atopic dermatitis microbiomes stratify into ecologic dermotypes enabling microbial virulence and disease severity

Atopic dermatitis (AD) is a common skin disease affecting up to 20% of the global population, with significant clinical heterogeneity and limited information about molecular subtypes and actionable biomarkers. Although alterations in the skin microbiome have been described in subjects with AD during progression to flare state, the prognostic value of baseline microbiome configurations has not been explored. Our aim was to identify microbial signatures on AD skin that are predictive of disease fate. Nonlesional skin of patients with AD and healthy control subjects were sampled at 2 time points separated by at least 4 weeks. Using whole metagenome analysis of skin microbiomes of patients with AD and control subjects (n= 49 and 189 samples), we identified distinct microbiome configurations (dermotypes Aand B). Blood was collected for immunophenotyping, and skin surface samples were analyzed for correlations with natural moisturizing factors and antimicrobial peptides. Dermotypes were robust and validated across 2 additional cohorts (63 individuals), with strong enrichment of subjects with AD in dermotype B. Dermotype B was characterized by reduced microbial richness, depletion of Cutibacterium acnes, Dermacoccus and Methylobacterium species, individual-specific outlier abundance of Staphylococcus species (eg, S epidermidis, S capitis, S aureus), and enrichment in metabolic pathways (eg, branched chain amino acids and arginine biosynthesis) and virulence genes (eg, β-toxin, δ-toxin) that defined a pathogenic ecology. Skin surface and circulating host biomarkers exhibited a distinct microbial-associated signature that was further reflected in more severe itching, frequent flares, and increased disease severity in patients harboring the dermotype B microbiome. We report distinct clusters of microbial profiles that delineate the role of microbiome configurations in AD heterogeneity, highlight a mechanism for ongoing inflammation, and provide prognostic utility toward microbiome-based disease stratification.

Comparison of performance of specific (SLEQOL) and generic (SF36) health-related quality of life questionnaires and their associations with disease status of systemic lupus erythematosus: a longitudinal study

BackgroundThe utility of generic health-related quality of life (HRQoL) questionnaires in patients with systemic lupus erythematosus (SLE) is uncertain. We compared the performance of generic (SF36) and specific (SLEQOL) HRQoL surveys by examining their associations with the Global Rating of Change (GRC) and SLE clinical indicators.MethodsThe study included SLE patients who attended a single-center rheumatology clinic between 2013 and 2017. Patients completed both specific (SLEQOL) and generic (SF36) surveys and rated their GRC compared to the previous visit using a 7-point Likert scale on the same day of routine visits. Based on GRC scores, patients’ change in HRQoL was categorized as “no change,” “deterioration,” or “improvement.” Disease activity (SLEDAI-2K), flare, and lupus low disease activity state (LLDAS) were assessed at each visit, and organ damage (SDI) was determined annually. Pairwise correlations between SLEQOL and SF36 components were examined, and associations between GRC status and SLE disease indicators were compared using generalized estimating equations (GEE).ResultsThree hundred thirty-seven patients with 2062 visits were included in the analysis. SLEQOL correlated significantly with SF36. Patients reported improvements in HRQoL in 58%, deterioration in 15%, and “no change” in 27% of all visits. Compared to the “no change” group, mean SF36 and SLEQOL scores were significantly lower in the deterioration group and higher in the improvement group. The magnitude of changes observed with SLEQOL and SF36 in the deterioration and improvement groups was similar. Patients in LLDAS had significantly higher mean scores in both SLEQOL and SF36. In contrast, patients with active disease, especially those with cutaneous, renal, central nervous system, and musculoskeletal activity, had significantly lower SLEQOL and SF36. Flare and organ damage were also associated with lower SLEQOL and SF36-PCS (physical component) but not with SF36-MCS (mental component).ConclusionSLEQOL and SF36 similarly describe HRQoL in SLE. Both instruments demonstrated strong associations with GRC-based deterioration or improvement as well as SLE disease status. LLDAS was associated with improved HRQoL.

Infrared emission from dust and the spectral features of extragalactic gamma-ray sources

In this work, we investigate the role of emission by dust at infrared wavelengths in the absorption of gamma radiation from distant extragalactic sources, especially blazars. We use an existing EBL model based on direct starlight emission at UV/visible and secondary radiation due to dust (PAHs (polycyclic aromatic hydrocarbons), small and large grains) at IR due to partial absorption of the stellar component. The relative contribution of each grain type to the total EBL energy density was determined from a combined fit to the Markarian 501 (z∼ 0.034) SED in flare state, where both the parameters of the intrinsic source spectrum (with or without curvature) and the dust fractions were allowed to vary. By separating the attenuation due to each EBL component, the importance of individual grain types to the opacity of the extragalactic medium for the TeV emission of a blazar like Markarian 501 could be better understood. Using a nested log-likelihood ratio test, we compared null hypotheses represented by effective 1- and 2-grain models against a 3-grain alternative scenario. When the temperatures of the grains are fixed a priori, the 1-grain scenario with only PAHs can be excluded at more than 5σ (p=2.9× 10−8), irrespective of the curvature in the intrinsic spectrum. The effective 3-grain EBL model with the tuned fractions was finally used to fit the SEDs of a sample of extragalactic gamma-ray sources (dominated by blazars). Such a sample is still dominated by starlight attenuation, therefore, no statistically significant improvement in the quality of fits was observed when the tuned fractions are used to account for the EBL attenuation and the intrinsic spectrum parameters are allowed to vary during the fit. The potential of this kind of analysis when the next generation of IACTs, represented by the Cherenkov Telescope Array (CTA), starts observations is enormous. The newly discovered AGNs at a broad range of redshifts should break many of the degeneracies currently observed.

Urinary leukotriene e4 level profile in various degrees of severity in atopic dermatitis patients in dermatovenereology outpatient clinic Dr. Soetomo General Hospital, Surabaya: A descriptive study

Atopic dermatitis (AD) is a chronic, relapsing skin inflammatory disease. Corticosteroid as the cornerstone treatment for AD has some flaw, especially for the chronic recalcitrant AD, since it has side effects and high possibility of rebound. Leukotriene receptor antagonist (LTRA) which has been used for asthma and allergic rhinitis now has been developed for treating AD, based on the similar mechanism of inflammation. Leukotriene (LT) is an inflammatory mediator that is thought to play role in the asthma, allergic rhinitis, and AD. Urinary leukotriene E4 (U-LTE4), the stable metabolite of LT, can be found in urine. This research aims to evaluate the role of LT in various degrees of severity in AD patients by measuring U-LTE4 levels using Enzyme Linked Immunosorbent Assay (ELISA). Twenty two AD patients who were in a flare state and came to the outpatient clinic on April – July 2017 were measured their U-LTE4 levels. The results demonstrated that mean of U-LTE4 levels increases consistently with intensity of the degree of severity, and this finding supports previous study that LT plays role in AD.

Update on Outcome Measure Development in Large-vessel Vasculitis: Report from OMERACT 2018.

The Outcome Measures in Rheumatology (OMERACT) Vasculitis Working Group seeks to develop validated outcome measures for use in trials for large-vessel vasculitis (LVV). An international Delphi exercise conducted among investigators identified items considered important to measure active disease. In parallel, qualitative research with patients was conducted, including interviews and focus groups. Next steps prioritized by the group for LVV include (1) defining disease states (remission, flare, and patient-acceptable symptom state) and (2) selection of patient-reported outcome tools. The ultimate goal is to develop an OMERACT-endorsed core set of outcome measures for use in clinical trials of LVV.

FAST ultra-wideband observation of abnormal emission-shift events of PSR B0919+06

PSR B0919+06 is known for its abnormal emission phenomenon, where the pulse emission window occasionally shifts progressively in longitude and returns afterwards. The physical mechanism behind this phenomenon is still under investigation. In this paper, we present our ultra-wideband observation of this pulsar using the Five-hundred-meter Aperture Spherical radio Telescope (FAST), with simultaneous measurements in the frequency ranges 280-780 MHz and 1250-1550 MHz. We have identified three abnormal events, each of which becomes less apparent as the frequency decreases. At 1400 MHz, the averaged profile slightly shifted after the first and third abnormal events, implying a relationship between abnormal event and profile variation. We also found a linear trend in the left-edge position of the averaged profiles between the first and third event as well as after the third event, suggesting the existence of a slow-drifting mode between the two major events. The second event has a comparatively small shift in phase and is thus categorized as a `small flare state'. During the third event, a sequence of approximately nine pulses was seen to significantly weaken in all frequency bands, likely associated with the pseudo-nulling observed at 150 MHz. A three-component de-composition analysis of the normal averaged profiles shows that the trailing component is dominant at our observing frequencies, while the centre component has a comparatively steeper spectrum. We found the overall flux density in an abnormal event to slightly differ from that in an ordinary state, and the difference shows a frequency dependence. A comparison of the normal, abnormal and dimmed averaged profile indicates that the leading component is likely to be stable in all states.

Long-term Multiband Study of High-redshift Blazar S5 0836+71

We analyze 10 years of Fermi γ-ray observations of the high-redshift blazar S5 0836+71 (z = 2.172) that showed a strong flare in 2015 characterized by a several-fold increase in the γ-ray flux within a few days. The discrete correlation function between the γ-ray and the R band (AZT-8) shows a highly significant (>99.9% confidence) correlation with the γ-ray variations leading the R band by about 75 days. The spectral energy distributions are modeled, with the adoption of a synchrotron self-Compton plus external Compton (EC) model, to discuss the reasons of transition between the low- and high-flux states. In both the pre-flare and flare states, the EC seed photons might be dominated by reprocessed emission from the dusty torus rather than the broadline region (BLR). This implies the location of radiating blob outside the BLR and inside the dusty torus. From the pre-flare state to the flare state, δ and B decrease, whereas N0 and γmax increase accordingly. The results of the modeling suggest that the increase in the total number of emitting electrons and hardening of the power spectrum of emitting electrons are primary causes of the flare in γ-rays.

Heating of the solar photosphere during a white-light flare

Context. The Fe I lines observed by the Hinode/SOT spectropolarimeter were always seen in absorption, apart from the extreme solar limb. Here we analyse a unique dataset capturing these lines in emission during a solar white-light flare. Aims. We analyse the temperature stratification in the solar photosphere during a white-light flare and compare it with the post-white-light flare state. Methods. We used two scans of the Hinode/SOT spectropolarimeter to infer, by means of the LTE inversion code Stokes Inversion based on Response function (SIR), the physical properties in the solar photosphere during and after a white-light flare. The resulting model atmospheres are compared and the changes are related to the white-light flare. Results. We show that the analysed white-light flare continuum brightening is probably not caused by the temperature increase at the formation height of the photospheric continuum. However, the photosphere is heated by the flare approximately down to log τ = −0.5 and this results in emission profiles of the observed Fe I lines. From the comparison with the post-white-light flare state of the atmosphere, we estimate that the major contribution to the increase in the continuum intensity originates in the heated chromosphere.

Gamma-ray flaring activity of NGC1275 in 2016–2017 measured by MAGIC

We report on the detection of flaring activity from the Fanaroff-Riley I radio galaxy NGC 1275 in very-high-energy (VHE, E &gt; 100 GeV) gamma rays with the Major Atmospheric Gamma Imaging Cherenkov (MAGIC) telescopes. The observations were performed between 2016 September and 2017 February, as part of a monitoring programme. The brightest outburst, with ∼1.5 times the Crab Nebula flux above 100 GeV (C.U.), was observed during the night between 2016 December 31 and 2017 January 1. The flux is fifty times higher than the mean flux previously measured in two observational campaigns between 2009 October and 2010 February and between 2010 August and 2011 February. Significant variability of the day-by-day light curve was measured. The shortest flux-doubling timescale was found to be of (611 ± 101) min. The spectra calculated for this period are harder and show a significant curvature with respect to the ones obtained in the previous campaigns. The combined spectrum of the MAGIC data during the strongest flare state and simultaneous data from the Fermi-LAT around 2017 January 1 follows a power law with an exponential cutoff at the energy (492 ± 35) GeV. We further present simultaneous optical flux density measurements in the R-band obtained with the Kungliga Vetenskaps Akademien (KVA) telescope and investigate the correlation between the optical and gamma-ray emission. Due to possible internal pair-production, the fast flux variability constrains the Doppler factor to values that are inconsistent with a large viewing angle as observed in the radio band. We investigate different scenarios for the explanation of fast gamma-ray variability, namely emission from magnetospheric gaps, relativistic blobs propagating in the jet (mini-jets), or an external cloud (or star) entering the jet. We find that the only plausible model to account for the luminosities here observed would be the production of gamma rays in a magnetospheric gap around the central black hole, only in the eventuality of an enhancement of the magnetic field threading the hole from its equipartition value with the gas pressure in the accretion flow. The observed gamma-ray flare therefore challenges all the discussed models for fast variability of VHE gamma-ray emission in active galactic nuclei.