The NuSTAR from NASA

NuSTAR employs two grazing incidence focusing optics each of which consists of 133 concentric shells. The particular innovation enabling NuSTAR is that the optics are coated with depth-graded multilayers (alternating atomically thin layers of a high-density and low-density material); with NuSTAR's choice of Pt/SiC and W/Si multilayers, this enables reflectivity up to 79 keV (the platinum K-edge energy).

The optics are produced, at Goddard Space Flight Center, by heating thin (210 µm) sheets of flexible glass in an oven so that they slump over precision-polished cylindrical quartzmandrels of the appropriate radius. The coatings are applied by a group at the Danish Technical University.

The shells are then assembled, at the Nevis Laboratories of Columbia University, using graphite spacers machined to constrain the glass to the conical shape, and held together by epoxy. There are 4680 mirror segments in total (the 65 inner shells each comprise six segments and the 65 outer shells twelve; there are upper and lower segments to each shell, and there are two telescopes); there are five spacers per segment. Since the epoxy takes 24 hours to cure, one shell is assembled per day – it takes four months to build up one optic.

The expected point spread function for the flight mirrors is 43 arc-seconds, giving a spot size of about two millimeters at the focal plane; this is unprecedentedly good resolution for focusing hard-X-ray optics, though up to two orders of magnitude worse than the best resolution achieved at longer wavelengths by Chandra.

The optics have a 10.15-metre focal length, and so are held at the end of a long deployable mast; a laser metrology system is used to determine the exact relative positions of the optics and the focal plane at all times, so that each detected photon can be mapped back to the correct point on the sky even if the optics and the focal plane move relative to one another during an exposure.

Lenny ~ The Black Hole

Lenny is the smallest known black hole moving at  20 million miles per hour . It has the “cosmic equivalent of winds from a category five hurricane.”

Lenny is part of a binary system and is orbited by a star that’s similar to our own sun. It’s known as a stellar-mass black hole, meaning that its mass is similar to that of a large star.”

What is clear about Lenny, though, is that despite its small size, it produces fearsome winds of ionic gasses near its disk. Winds that astronomers have clocked at 20 million miles per hour – or about 3% of the speed of light. Those types of speeds are usually only seen near supermassive black holes that are hundreds of thousands of times more massive than Lenny.

The winds are generated by the magnetic field of black holes, which interact with the high-temperature ions to cause rapid movements. Those movements either take the form of winds or jets. In the latter, the ionic gasses fire in a focused stream in a direction perpendicular to the accretion disk surrounding a black hole.

The winds observed around Lenny aren’t constant, and depending on the movement of the gasses and the magnetic field, both jets and winds are seen.  In fact, it’s likely that jets are a fairly regular occurrence around Lenny, as the Rossi X-Ray Timing Explorer has observed a regular “heartbeat” of X-ray expulsions that would be consistent with a jet firing from the black hole.

What’s particularly interesting about the winds produced by Lenny is that they’re not only unusually fast for a black hole of its size, but it’s also causing more matter to fly away from the black hole than to be attracted to it.

It seems that the past year has really provided a wealth of new information about black holes and how they work, often to the surprise of the astronomers and physicists observing them. Hopefully, a lot of these surprises and information will go a long way towards gaining a greater understanding of how black holes work.  And by doing so, hopefully physicists will understand more about the fundamental laws of nature.

Accretion disc - The disc around Blackholes

An accretion disc is a structure formed by diffuse material in orbital motion around a central body. The central body is typically a star. Gravity causes material in the disc to spiral inward towards the central body. Gravitational forces compress the material causing the emission of electromagnetic radiation. The frequency range of that radiation depends on the central object. Accretion discs of young stars and protostars radiate in the infrared; those around neutron stars and black holes in the x-ray part of the spectrum.

Accretion discs are a ubiquitous phenomenon in astrophysics; active galactic nuclei, protoplanetary discs, and gamma ray bursts all involve accretion discs. These discs very often give rise to jets coming from the vicinity of the central object. Jets are an efficient way for the star-disc system to shed angular momentum without losing too much mass.

The most spectacular accretion discs found in nature are those of active galactic nuclei and of quasars, which are believed to be massive black holes at the center of galaxies. As matter spirals into a black hole, the intense gravitational gradient gives rise to intense frictional heating; the accretion disc of a black hole is hot enough to emit X-rays just outside of the event horizon. The large luminosity of quasars is believed to be a result of gas being accreted by supermassive black holes. This process can convert about 10 percent of the mass of an object into energy as compared to around 0.5 percent for nuclear fusion processes.

In close binary systems the more massive primary component evolves faster and has already become a white dwarf, a neutron star, or a black hole, when the less massive companion reaches the giant state and exceeds its Roche lobe. A gas flow then develops from the companion star to the primary. Angular momentum conservation prevents a straight flow from one star to the other and an accretion disc forms instead.

Accretion discs surrounding T Tauri stars or Herbig stars are called protoplanetary discs because they are thought to be the progenitors of planetary systems. The accreted gas in this case comes from the molecular cloud out of which the star has formed rather than a companion star.

However the the phenomenon behind the formation of Accretion disc jets remains an unsolved problem in Physics.

Pulsars in brief :-

Its about the PULSAR ...A pulsar is a neutron star that’s spinning in a special way. (Remember, everything in the universe spins). First you need to know something about poles. The Earth has two north poles and two south poles. Yes, it’s true. One set is because the Earth is spinning: the poles are the tips of the axis that the Earth spins on. The other set is because the Earth has a magnetic field: all magnets have a north side and a south side. On Earth, these two sets of poles are slightly misaligned.In a pulsar, the poles are even more misaligned, so as the star spins, the magnetic field is swung around in circles. When this happens to a neutron star, you get a super-bright beam of light beaming out from the magnetic poles. Since these poles are swinging around, so do the beams of light – just like a lighthouse.

Massive black holes found in distant galaxies

The find of supermassive black holes growing in surprisingly small galaxies suggest that central black holes form at an early stage in galaxy evolution, U.S. astronomers say. All massive galaxies host a central supermassive black hole, but active black holes are rarely seen in small “dwarf” galaxies. “It’s kind of a chicken or egg problem: Which came first, the supermassive black hole or the massive galaxy? This study shows that even low-mass galaxies have supermassive black holes,” said first author Jonathan Trump, a postdoctoral researcher at the University of California, Santa Cruz. The galaxies observed with the help of the Hubble Space Telescope are about 10 billion light-years away, giving astronomers a view of galaxies as they appeared when the universe was less than a quarter of its current age. “When we look 10 billion years ago, we’re looking at the teenage years of the universe. So these are very small, young galaxies,” Trump said. The findings also challenge current beliefs about black hole formation. “Up to now, observations of distant galaxies have consistently reinforced the local findings -- distant black holes actively accreting in big galaxies only,” said coauthor Sandra Faber, University Professor of astronomy and astrophysics at UC Santa Cruz and CANDELS principal investigator. “We now have a big puzzle: What happened to these dwarf galaxies?” One possibility is that at least some of them are the progenitors of present-day massive galaxies like the Milky Way. “Their star formation rate is about ten times that of the Milky Way,” Trump said. “There may be a connection between that and the active galactic nuclei. When gas is available to form new stars, it’s also available to feed the black hole,” he added.

Milky Ways 'twin' discovered astronomers Supermassive black-hole.

Astronomers have found that the center of the galaxy nearest to our own hosts a twin of Sagittarius A*, the bright radio source that lies at the core of our Milky Way and which harbors a massive black hole.

Astronomers have spent years speculating that a giant, mysterious force lay at the centre of the Milky Way 26,000 light years - or 158 trillion miles - away, but it wasn't until recently that they learnt what it was.

Ghez's ground-breaking research focuses on the origin and early life of stars and planets, and the distribution and nature of the matter in our galaxy. 

Using new techniques for peering into the heart of the galaxy, Ghez's observations proved that scores of stars were rapidly orbiting what could only be a black hole.

But it wasn't the kind of garden-variety black hole created when a star explodes and dies; it was hundreds of thousands of times as powerful - a "supermassive" black hole - at the centre of our galaxy.

Black holes are collapsed stars so dense that nothing can escape their gravitational pull, not even light.

Black holes cannot be seen directly, but their influence on nearby stars is visible, and provides a signature, Ghez said.

The supermassive black hole, with a mass more than 3 million times that of our sun, is in the constellation of Sagittarius. Our galaxy's core Black Hole is called Sagittarius A*, or Sgr A*, located south in the summer sky.

What's inside a black hole is one of the biggest mysteries in physics.

Albert Einstein's general-relativity theory that predicted black holes in the first place says that all the matter inside them gets squashed into a central point of infinite density called a singularity.

But then, 'things break down mathematically', according to Christian Böhmer of University College London.

Bohmer has suggested a new theory called quantum loop, that when matter gets swallowed by a black hole it could fall into an entirely other universe contained inside the black hole, or get trapped inside a wormhole-like connection to a second black hole.

Since 1995 Ghez has been using the W.M. Keck Observatory's 10-meter Keck I Telescope on top of Hawaii's Mauna Kea - the world's largest optical and infrared telescope - to study the movement of 200 stars close to the galactic centre.

Twenty stars near the galactic center are orbiting ever closer to the black hole at a blinding speed of up to 3 million miles per hour about 10 times the speed at which stars typically move.

Her discoveries, along with the work of scientists studying other galaxies, have led astronomers to the surprising conclusion that most, if not all, of the universe's hundreds of billions of galaxies have supermassive black holes at their core.

Even more striking, the astronomers have found that the black holes' mass and nature are closely related to the size and makeup of the surrounding galaxies.

Black holes appear to be both creators and destroyers, swallowing stars or gases that come too close while also spewing out jets of super-high-energy particles and radiation generated by this violent feeding process.

The supermassives are drawing astronomers and astrophysicists back into black hole research.

In 1915 Albert Einstein laid the groundwork for the existence of these mind-boggling phenomena but research on them languished for decades because there was no way to observe them directly.

Mysteries abound. Many researchers have offered theories of how supermassive black holes might have formed, but there is no agreement. 

All new Black hole revealed - looks like "Eye of Sauron"

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     In the "pupil" of the eye, X-rays (blue) from the Chandra X-ray Observatory are combined with optical data (yellow) showing positively charged hydrogen ("H II") from observations with the 1-meter Jacobus Kapteyn Telescope on La Palma.

The red around the pupil shows neutral hydrogen detected by radio observations with the NSF's Very Large Array. This neutral hydrogen is part of a structure near the center of NGC 4151 that has been distorted by gravitational interactions with the rest of the galaxy, and includes material falling towards the center of the galaxy.

The yellow blobs around the red ellipse are regions where star formation has recently occurred.

A recent study has shown that the X-ray emission was likely caused by an outburst powered by the supermassive black hole located in the white region in the center of the galaxy. Evidence for this idea comes from the elongation of the X-rays running from the top left to the bottom right and details of the X-ray spectrum. There are also signs of interactions between a central source and the surrounding gas, particularly the yellow arc of H II emission located above and to the left of the black hole.

Two different scenarios to explain the X-ray emission have been proposed. One possibility is that the central black hole was growing much more quickly about 25,000 years ago (in Earth's time frame) and the radiation from the material falling onto the black hole was so bright that it stripped electrons away from the atoms in the gas in its path. X-rays were then emitted when electrons recombined with these ionized atoms.

The second possibility also involved a substantial inflow of material into the black hole relatively recently. In this scenario the energy released by material flowing into the black hole in an accretion disk created a vigorous outflow of gas from the surface of the disk. This outflowing gas directly heated gas in its path to X-ray emitting temperatures. Unless the gas is confined somehow, it would expand away from the region in less than 100,000 years. In both of these scenarios, the relatively short amount of time since the last episode of high activity by the black hole may imply such outbursts occupy at least about 1 percent of the black hole's lifetime.

NGC 4151 is located about 43 million light-years away from the Earth and is one of the nearest galaxies which contains an actively growing black hole. Because of this proximity, it offers one of the best chances of studying the interaction between an active supermassive black hole and the surrounding gas of its host galaxy. Such interaction, or "feedback", is recognized to play a key role in the growth of supermassive black holes and their host galaxies. If the X-ray emission in NGC 4151 originates from hot gas heated by the outflow from the central black hole, it would be strong evidence for feedback from active black holes to the surrounding gas on galaxy scales. 

This would resemble the larger scale feedback, observed on galaxy cluster scales, from active black holes interacting with the surrounding gas, as seen in objects like the Perseus Cluster.