Rare luminous nebula spotted 10 billion light years away poses cosmic puzzle

February 26, 2017

Feb 26: Astronomers have spotted an enormous, glowing blob of gas in the distant universe, with no obvious source of power for the light it is emitting. Called an “enormous Lyman-alpha nebula” (ELAN), it is the brightest and among the largest of these rare objects, only a handful of which have been observed, the researchers said.

lya-nebula

The newly discovered nebula was found at a distance of 10 billion light years in the middle of a region with an extraordinary concentration of galaxies. Researchers found this massive overdensity of early galaxies, called a “protocluster,” through a novel survey project led by Zheng Cai, Hubble postdoctoral fellow at University of California, Santa Cruz in the US.

“Our survey was not trying to find nebulae. We"re looking for the most overdense environments in the early universe, the big cities where there are lots of galaxies,” said Cai, who is first author of a paper on the discovery to be published in the Astrophysical Journal.

“We found this enormous nebula in the middle of the protocluster, near the peak density,” Cai said. ELANs are huge blobs of gas surrounding and extending between galaxies in the intergalactic medium. They are thought to be parts of the network of filaments connecting galaxies in a vast cosmic web.

Previously discovered ELANs are likely illuminated by the intense radiation from quasars, but it is not clear what is causing the hydrogen gas in the newly discovered nebula to emit Lyman-alpha radiation (a characteristic wavelength of light absorbed and emitted by hydrogen atoms), the researchers said.

The newly discovered ELAN is known as MAMMOTH-1. “It"s a terrifically energetic phenomenon without an obvious power source,” said study co-author J. Xavier Prochaska, Professor at University of California, Santa Cruz.

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Agencies
March 16,2020

While Google is still working on a coronavirus screening and tracking website, Microsoft Bing team has already launched a web portal for tracking COVID-19 infections worldwide.

The website, accessible at bing.com/covid, provides up-to-date infection statistics for each country.

The COVID-19 Tracker currently lists 168,835 as total confirmed cases, 84,558 active cases, 77,761 recovered cases and 6,516 deaths.

There are at least 3,244 confirmed cases of novel coronavirus in the US and at least 61 deaths.

"Lots of Bing folks worked (from home) this past week to create a mapping and authoritative news resource for COVID19 info," Michael Schechter, General Manager for Bing Growth and Distribution at Microsoft, was quoted as saying in a ZDNet report on Sunday.

An interactive map allows site visitors to click on the country to see the specific number of cases and related articles from a variety of publishers.

Data is being aggregated from sources like the World Health Organization (WHO), the US Centers for Disease Control and Prevention (CDC), and the European Centre for Disease Prevention and Control (ECDC).

Microsoft announced the website two days after US President Donald Trump said Google has begun working on COVID-19-related portal for US citizens.

Google's website is being built by Verily, a subsidiary of Alphabet focused on healthcare services.

"More than 1,700 engineers are currently working on the site", Trump said during a press briefing last week.

The tool will triage people who are concerned about their COVID-19 risk into testing sites based on guidance from public health officials and test availability.

Initially, there was some confusion on Google's coronavirus portal but the company later announced that it is "partnering with the US Government in developing a nationwide website that includes information about COVID-19 symptoms, risk, and testing information."

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Agencies
July 15,2020

New Delhi, Jul 15: The employees union of state-run telecom operator BSNL will stage protests across the country on Thursday on a host of issues including the cancellation of its 4G tender and non-payment of salaries.

All major unions are organising ‘lunch-hour black-flag' demonstrations throughout the country under the banner of All Unions and Association of BSNL (AUAB), said a statement by AUAB. These demonstrations will be organised, by maintaining social distancing and by taking other precautions, like wearing of masks. The BSNL employees will also wear black-badges the whole day on July 16.

The employees body would demand that BSNL should immediately be allowed to roll out its 4G services and the tender should be issued immediately. Further, they want that in the matter of procuring new equipment and upgradation, there should not be any discrimination between BSNL and other private telecom service providers.

Recently, the Centre cancelled the 4G upgradation tender for BSNL as it had decided to come up with fresh specifications for the upgrade process, in a move to keep Chinese technology companies at bay as the border tussle escalated with the northern neighbour.

The Department of Telecommunications (DoT) would issue a fresh tender for the same, and people in the know said that Chinese companies may not be allowed to participate.

"The agitational programme is being organised to express the deep anguish and resentment of the employees against cancellation of BSNL's 4G tender, cancellation of BSNL's proposal for upgradation of its 49,300 BTSs to 4G, abnormal delay in issuing ‘Add on Order' for 4G equipments, inordinate delay in the implementation of BSNL's Revival Package and against the non-settlement of the burning problems of the employees," said the statement.

The umbrella body of BSNL's employees' unions noted that rolling out of 4G services is the backbone for the revival of this telecom PSU, but the recent cancellation of the tender floated by BSNL for procuring 4G equipment at a cost of Rs 9,300 crore, has brought the company back to square one.

It said that BSNL is already having 49,300 base transceiver stations (BTS), which are 4G compatible and through minor upgradation, all these equipment can be converted into 4G BTSs with an investment of about Rs 1,500 crore.

In addition to this, BSNL could have added another 15,000 BTSs, by placing an Add on Order to the existing mobile tender, it added.

Noting that in October 2019, the PSU could have rolled out pan-India 4G services, AUAB said: "Being the sole owner of the company, the Government of India also cannot shirk its responsibility in this matter."

"Adding insult to injury, the tender floated by BSNL to procure 4G equipment, has been cancelled by the government, based on a complaint from the Telecom Equipments and Services Promotional Council (TEPC)," it said.

AUAB said that BSNL is already lagging four years behind the private operators, in terms of 4G and the cancellation of the tender is going to inordinately delay the company's 4G launch.

Saying that TEPC's contention has been to bar foreign companies from participating in BSNL's tender, AUAB statement pointed out that when private operators are procuring equipment from multinationals, "why BSNL alone should be compelled to procure 4G equipments from domestic vendors, whose 4G technology is not tested or proven so far."

It alleged a conspiracy to destabilise BSNL by disrupting its rolling out of 4G services.

AUAB further said that even after the lapse of nine months, the implementation of the much publicised BSNL's Revival Package is moving at a snail's pace.

"Except the swift retrenchment of 79,000 BSNL employees under VRS, all other assurances given in BSNL's Revival Package have been put in cold storage."

The management should ensure that the salary payment of the employees is made on the last working day of every month. Deductions made from employees' salary, on account of "society dues", should immediately be remitted, it said.

Regarding the monetisation of the company's assets under the revival package, the organisation said that the land asset should not be handed over to corporates, at "throwaway" prices.

"These lands should be sold in a transparent manner and at the prevailing market rates. They should not be sold at book value or at circle rates. The AUAB will strictly monitor these dealings," it said.

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Agencies
July 2,2020

Leiden, Jul 2: Astronomers have discovered a luminous galaxy caught in the act of reionizing its surrounding gas only 800 million years after the Big Bang.

The research, led by Romain Meyer, PhD student at UCL in London, UK, has been presented at the virtual annual meeting of the European Astronomical Society (EAS).

Studying the first galaxies that formed 13 billion years ago is essential to understanding our cosmic origins. One of the current hot topics in extragalactic astronomy is 'cosmic reionization,' the process in which the intergalactic gas was ionized (atoms stripped of their electrons).

Cosmic reionization is similar to an unsolved murder: We have clear evidence for it, but who did it, how and when? We now have strong evidence that hydrogen reionization was completed about 13 billion years ago, in the first billion years of the universe, with bubbles of ionized gas slowly growing and overlapping.

The objects capable of creating such ionized hydrogen bubbles have however remained mysterious until now: the discovery of a luminous galaxy in which 60-100 percent of ionizing photons escape, is likely responsible for ionizing its local bubble. This suggests the case is closer to being solved.

The two main suspects for cosmic reionization are usually 1) a population of numerous faint galaxies leaking ~10 percent of their energetic photons, and 2) an 'oligarchy' of luminous galaxies with a much larger percentage (>50 percent) of photons escaping each galaxy.

In either case, these first galaxies were very different from those today: galaxies in the local universe are very inefficient leakers, with only <2-3 percent of ionizing photons escaping their host. To understand which galaxies governed cosmic reionization, astronomers must measure the so-called escape fractions of galaxies in the reionization era.

The detection of light from excited hydrogen atoms (the so-called Lyman-alpha line) can be used to infer the fraction of escaping photons. On the one hand, such detections are rare because reionization-era galaxies are surrounded by neutral gas which absorbs that signature hydrogen emission.

On the other hand, if this hydrogen signal is detected it represents a 'smoking gun' for a large ionized bubble, meaning we have caught a galaxy reionizing its surroundings. The size of the bubble and the galaxy's luminosity determines whether it is solely responsible for creating this ionized bubble or if unseen accomplices are necessary.

The discovery of a luminous galaxy 800 million years after the Big Bang supports the scenario where an 'oligarchy' of bright leakers emits most of the ionizing photons.

"It is the first time we can point to an object responsible for creating an ionized bubble, without the need for a contribution from unseen galaxies.

Additional observations with the upcoming James Webb Space Telescope will enable us to study further what is likely one of the best suspects for the unsolved case of cosmic reionization," said Meyer.

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