India AstroSat unravels black hole secrets like never before (GS Paper 3, Science and Technology)
Why in news?
- In a new study, an international team of scientists has used India's AstroSat's full multi-wavelength capabilities to unravel the mysteries of an X-ray binary system hosting a black hole.
X-ray binary system:
- An X-ray binary system is a type of binary star system consisting of two celestial objects: a compact object, typically a neutron star or a black hole, and a normal star, often a companion star.
- The term "X-ray binary" arises because these systems emit a significant amount of X-ray radiation.
Details:
- AstroSat, equipped with three X-ray payloads and a UV telescope, captured soft and hard X-ray emissions and far ultraviolet radiation, painting a comprehensive portrait of the black hole in the X-ray binary system MAXI J1820+070.
- This marks a historic achievement for AstroSat, showcasing the first utilisation of its full multi-wavelength capabilities.
- The collaborative effort includes researchers from India, the United Kingdom, Abu Dhabi, and Poland.
Black hole X-ray binaries:
- Black hole X-ray binaries involve a stellar-mass black hole and a companion star engaged in complex gravitational interactions.
- The black hole's powerful gravitational pull draws in vast amounts of stellar material from its luminous counterpart, releasing energy primarily in X-rays.
MAXI J1820+070:
- MAXI J1820+070, a transient black hole X-ray binary located approximately 9,800 light-years away, gained attention in 2018 during its outburst, becoming the second brightest object in the X-ray sky.
- Accreting black holes in transient X-ray binaries emit electromagnetic radiation across a broad energy spectrum, spanning radio waves to X-rays.
- This study focused on the 2018 outburst of MAXI J1820+070, combining AstroSat's UV, soft and hard X-ray data with observations from Las Cumbres Observatory and NASA's NICER mission.
- The research uncovered the inner accretion disk's significant recession from the black hole during the hard state, forming a structured corona with distinct components.
- In contrast, the soft state saw the disk moving closer to the black hole, while the corona's emission diminished.
Observations made:
- AstroSat's Soft X-ray Telescope (SXT), Large Area X-ray Proportional Counter (LAXPC), and Cadmium Zinc Telluride Imager (CZTI) played crucial roles in understanding the system's accretion geometry.
- The study also measured the black hole's spin, revealing it to be moderately to highly spinning.
- Additionally, a captivating connection between X-ray emission near the black hole and optical/UV emission from the outer accretion disk was unveiled.
Way Forward:
- The researchers found substantial reprocessing of X-rays in the outer disk, indicating a higher proportion in the hard state and suggesting the presence of a warped or convex outer disk.
From restoring forests to river basins, seven conservation initiatives across continents recognised by UN
(GS Paper 3, Environment)
Why in news?
- The United Nations named seven initiatives from across Africa, Latin America, the Mediterranean and Southeast Asia as the intergovernmental organisation’s World Restoration Flagships.
- The projects revolve around revival and preservation of ecosystems at the tipping point of outright degradation caused by wildfires, drought, deforestation and pollution.
- Together, they are expected to restore about 40 million hectares and create around 500,000 jobs
The award:
- The award conferred by the United Nations Environment Programme (UNEP) and Food and Agriculture Organization (FAO) of the UN makes the initiatives eligible for technical and financial support from the organisation.
- The winning initiatives were announced ahead of the 6th session of the UN Environment Assembly, which is the world’s highest-level decision-making body for matters related to the environment. It will take place from February 26-March 1, 2024 at the UNEP headquarters in Nairobi, Kenya.
- The awards serve as a part of the UN Decade on Ecosystem Restoration, led by the two agencies.
- The campaign aims to prevent, halt and reverse the degradation of ecosystems on every continent and in every ocean.
- The awards track notable initiatives that provide support to global commitments in order to restore one billion hectares, an area larger than China, according to the official statement made by the UN.
Projects that were honoured:
The Restoring Mediterranean Forests Initiative:
- It involves the countries of Lebanon, Morocco, Tunisia and Türkiye. It consists of a novel approach said to have protected and restored natural habitats and vulnerable ecosystems.
- It is also said to have led to around two million hectares of forests restored across the region since 2017. Along with this, over eight million hectares are planned for restoration by 2030.
The Living Indus initiative:
- It received approval from the Pakistan parliament in the wake of the devastating 2022 climate change-induced floods.
- Its official launch took place at the 27th Conference of Parties to the UN Framework Convention on Climate Change in Sharm el-Sheikh.
- The initiative aims to restore 25 million hectares of the river basin by 2030, encompassing 30 per cent of Pakistan’s surface area through the implementation of 25 high-impact interventions for policymakers, practitioners and civil society.
- It designates the Indus River as a living entity with rights; a measure taken to protect rivers elsewhere as well. It involves Australia, Bangladesh, Bolivia, Brazil, Canada, Ecuador, India, New Zealand, Peru and Sri Lanka.
The Acción Andina social movement:
- Led by Peruvian conservation non-profit ECOAN aims to protect and restore a forest area of one million hectares.
- About 25,000 people from remote Andean communities are engaged in the process to restore 5,000 hectares and protect more than 11,000 hectares of Andean forests.
- They are expected to benefit from the initiative by 2030 in various ways--from access to medicine, solar panels, and clean-burning clay stoves, to improved grazing management, sustainable agriculture, microbusiness, and ecotourism management of Indigenous cultures.
- It also works to secure land titles for local communities, protecting the forest from future mining, timber exploitation and other drivers of degradation.
The Sri Lanka Mangrove Regeneration initiative:
- It is a science-driven programme co-led by local communities. It focuses on the restoration of natural balance in the ecosystem.
- Since its launch in 2015, efforts have led to 500 hectares of restored mangroves.
The Terai Arc Landscape initiative:
- It aimed to restore the forests of critical corridors of the Terai Arc Landscape in collaboration with local communities working as citizen scientists, community-based anti-poaching units, forest guards, among others.
- Measures like the restoration of 66,800 hectares of Nepal’s forests, among others, were said to improve the livelihoods of about 500,000 households in the country.
Regreening Africa’s agriculture:
- It is expected to benefit over 6,00,000 households.
- It continues to increase carbon storage, boost crop and grass yields, make soil more resilient (by preventing floods) and treat it with fixed nitrogen that acts as a natural fertiliser.
Growing forests in Africa's drylands initiative:
- It aims to expand from 41,000 restored hectares today to 229,000 hectares by 2030.
- With the involvement of African farmers, tens of millions of trees are planted under the project every year.
