Scientists reveal marvellous x-ray mask absorber in the active galaxy NGC 6814
2023-09-22
(Press-News.org)
A research team led by Prof. WANG Junxian from the University of Science and Technology of China (USTC) of the Chinese Academy of Sciences (CAS) revealed a clumped, multi-component eclipsing absorber in a study of X-ray occultation events in the active galaxy NGC 6814. The results were published in Monthly Notices of the Royal Astronomical Society on Aug. 23.
Active galactic nuclei have strong X-ray emission originating in a compact region near the supermassive black hole, the so-called corona region. When an absorbing cloud passes across the observer's line of sight, the corona is obscured by the cloud, significantly affecting the observed X-ray flux and spectral pattern, which is known as an X-ray occultation event. X-ray occultation events carry a wealth of time-varying information, which is useful for investigating the nature of the limiting coronal regions and of the occulting cloud. However, such occultations are infrequent and unpredictable. even if we are lucky enough to capture such rare occultations, their analytical interpretation still faces a great challenge: active galactic nuclei have significant intrinsic spectral variations. Hence, it is difficult to rigorously distinguish absorption variations from intrinsic spectral variations based on spectroscopic analyses alone.
To solve the problem, the team introduced the ‘softer-when-brighter’ variation pattern of active galactic nuclei into the analysis of occultation events, attaining additional independent constraints on spectroscopic analyses with the aid of the hardness ratio (HR)–count rate (CR) plot. The team applied this technique to a high-quality occultation event captured by the XMM-Newton telescope in NGC 6814 and successfully revealed a partially covering ‘Compton-thick’ absorption component in the eclipsing cloud.
The team also found that the occultation absorber in NGC 6814 was clumpy and consisted of many small clouds. In addition, the two thinner absorption layers detected by the high-resolution spectra of the XMM RGS equipment may be debris stripped from the main occultation cloud, similar to the stardust around comets.
Therefore, the team was able to successfully depict an exhaustive picture of the entire marvelous eclipsing system: a clumpy, multiphase cluster of clouds. At the same time, the size of the corona is very small, about 10 times the gravitational radius.
This work improves our understanding of the gas surrounding supermassive black holes, highlights the importance of the HR-CR plot in analyzing occultation events, and provides a new way of searching for and interpreting more occultation events.
Jane FAN Qiong
Tel: +86-551-63607280
E-mail:englishnews@ustc.edu.cn
END
ELSE PRESS RELEASES FROM THIS DATE:
2023-09-22
UNIVERSITY PARK, Pa. — Macrophages are little cells vital to the immune system and could possibly inform cell-based therapies for a variety of medical conditions. However, realizing the full potential of macrophage therapies relies on being able to see what these cellular allies are doing inside our bodies, and a team of Penn State researchers may have developed a way to watch them do their thing.
In a study published in the journal Small, the Penn State researchers report a novel ultrasound imaging technique to view macrophages continuously in mammal tissue, with potential for human ...
2023-09-22
On August 23, 2023, a research team led by SHI Chaowei from the University of Science and Technology of China (USTC) of the Chinese Academy of Sciences (CAS) published a paper titled "Fluoride permeation mechanism of the Fluc channel in liposomes revealed by solid-state NMR" in Science Advances. The team adopted the fluoride ion channel protein Fluc-Ec1 combined with deuterium substitution and 19F labeling methods, paving a new path for membrane protein nuclear magnetic resonance (NMR) research.
NMR not only provides insights into molecular structures ...
2023-09-22
UNIVERSITY PARK, Pa. — The Earth’s crust continued a slow process of reworking for billions of years, rather than rapidly slowing its growth some 3 billion years ago, according to a Penn State-led research team. The new finding contradicts existing theories that suggest the rapid formation of tectonic plates earlier in Earth’s history, researchers said.
They published the research in Geochemical Perspectives Letters.
The work may help answer a fundamental question about our planet and could hold clues as to the formation of other planets, according to lead author ...
2023-09-22
How similar are dinosaurs to modern birds? This question is at the heart of a new study that examined how proteins found in dinosaur feathers changed over millions of years and under extreme heat.
Previous studies suggest that dinosaur feathers contained proteins that made them less stiff than modern bird feathers. Now, researchers with University College Cork (UCC), the Stanford Synchrotron Radiation Light Source (SSRL) at the Department of Energy's SLAC National Accelerator Laboratory and other institutions have discovered that dinosaur feathers originally had a very similar protein composition to those of modern birds. That result ...
2023-09-22
A single brain is unfathomably complex. So brain researchers, whether they’re looking at datasets built from 300,000 neurons in 81 mice or from MRIs of 1,200 young adults, are now dealing with so much information that they must also come up with new methods to comprehend it. Developing new analysis tools has become as important as using them to understand brain health and development.
A team including researchers at the University of Washington recently used new software to compare MRIs from 300 babies and discovered that myelin, a part of the brain’s so-called white matter, develops much slower after birth. The researchers published their findings Aug. ...
2023-09-22
A clinical trial has launched to test whether early intensive immune modulation for hospitalized COVID-19 patients with relatively mild illness is beneficial. The placebo-controlled study, part of the global clinical trials consortium known as Strategies and Treatments for Respiratory Infections and Viral Emergencies (STRIVE), will enroll approximately 1,500 people at research sites around the world. It is supported by the National Institutes of Health’s National Institute of Allergy and Infectious Diseases (NIAID) in partnership with NIH’s National Center for Advancing Translational Sciences (NCATS).
Immune ...
2023-09-22
PHILADELPHIA – A study in the Proceedings of the National Academy of Sciences (PNAS) identifies five factors that Annenberg Public Policy Center (APPC) researchers say reflect public assessments of science and are associated with public support for increasing funding of science and support for federal funding of basic research. These factors are whether science and scientists are perceived to be credible and prudent, and whether their work is perceived to be untainted by bias, self-correcting, and beneficial.
Drawing on 13 questions in APPC’s 2022 nationally representative ...
2023-09-22
A new editorial published in the Heart and Mind journal proposes an innovative systems medicine approach to address the epidemic of clinician burnout and holistically improve clinician mental health and wellbeing (Heart and Mind: September 18, 2023. | DOI: 10.4103/hm.HM-D-23-00013, published ahead of print).
In the US and globally, clinician burnout has reached epidemic levels, with over 50% of physicians and healthcare providers reporting symptoms. Besides impairing quality of life, burnout increases risk of mental health disorders, cardiovascular disease and impaired ...
2023-09-22
LAWRENCE — It’s an Ice Age mystery that’s been debated for decades among anthropologists: Exactly when and how did the flow of Homo sapiens in Eurasia happen? Did a cold snap or a warming spell drive early human movement from Africa into Europe and Asia?
A new study appearing in Science Advances compares Pleistocene vegetation communities around Lake Baikal in Siberia, Russia, to the oldest archeological traces of Homo sapiens in the region. The researchers use the “remarkable evidence” to tell a compelling story from 45,000-50,000 years ago with new detail: how the first humans migrated across ...
2023-09-22
Most healthcare facilities in many Low- and Middle-income Countries (LMICs) are unprepared to treat patients with cardiovascular diseases – despite these conditions leading to millions of people dying prematurely every year, a new study reveals.
Experts analysed health survey data from eight LMICs across four World Health Organisation world regions to discover that most facilities are unprepared to deliver services to treat or manage cardiovascular disease risk factors (CVDRF) such as diabetes and hypertension.
However, the increased ...
LAST 30 PRESS RELEASES:
[Press-News.org] Scientists reveal marvellous x-ray mask absorber in the active galaxy NGC 6814
