How Far Away Is It - 2015 Review - Dark Matter (1080p)

hello and welcome to our 2015 update this past year marked the 25th anniversary of the hubble space telescope we're going to see caverns carved out of dust by new stars we're going to get a look at the veil nebula moving see it expand we'll see through the Eagle Nebula we'll take a very close look at the end dromeda galaxy we'll see a galaxy on the edge of the local void also in 2015 CERN reopened the Large Hadron Collider after a two-year closure to upgrade the power to almost twice what it was when they found the Higgs boson at these levels it might be able to find dark matter and Hubble discovered a supernova predicted it and found it due to gravitational lensing around dark matter so with two key 2015 updates I thought it'd be appropriate to dig deeper into just what dark matter is so we'll conclude this update with a deep look a dark matter first let's take a look at the updates from inside Milky Way here we are zooming into the great Orion molecular cloud as we enter the cloud we see the Jets from a central star that is hidden by gas and dust the Jets collide with the surrounding gas and dust and clear vast spaces like a stream of water ploughing into a hill of sand the Hubble Space Telescope is entering its 25th year in operation here it imaged three sections of the beautiful veil nebula in 1997 we saw those in our segment on star clusters and supernovae in 2015 Hubble took another look overlaying new images with the old this allows scientists to study how far the nebula has expanded since it was photographed over 18 years ago despite the nebulas complexity and distance from us the movement of some of the delicate structures is clearly visible particularly the faint red hydrogen filaments Hubble has also revisited the famous Eagle Nebula capturing the multicolored glow of gas clouds and wispy treadmills of dark cosmic dust with these new images come better contrast and clearer views of the region in addition to this new visible light image Hubble has also produced an infrared image infrared penetrates much of the obscuring dust and gas and unveils newborn stars hidden in the visible light view here we are zooming into the Milky Way's Center 26,000 light-years away this is a small section of Hubble's view of the dense collection of stars crammed together in the Galactic bulge Kyah is the mission to record information about a billion stars it is now accumulated 340 billion positional measurements 68 billion brightness data points and 6.7 billion spectra this image based on housekeeping data from Gaia portrays the outline of our galaxy it was obtained by plotting the total number of stars crossing Gaia's focal-plane per second this is a measure of the density of stars in the region that is being scanned you you in 2015 the Hubble Space Telescope captured the sharpest and most detailed image ever taken of the galaxy it shows over 100 million stars and thousands of star clusters embedded in a section of a galaxy's disc stretching across over 48 thousand light-years it traces the galaxy from its central bulge on the left where stars are densely packed together across lanes of stars and dust to the sparser outskirts of its outer disc on the right zooming into the boxed field we see some foreground Milky Way stars in the line-of-sight to Andromeda and a couple of distant spiral galaxies shining through and dramatis disc the large group of blue stars in the galaxy indicates star forming regions in the spiral arms while the dark silhouettes of obscured regions trace out complex dust structures underlying the entire galaxy is a smooth distribution of cooler red stars that trace Andromeda's evolution over billions of years a large number of star clusters can be seen in this analysis of Andromeda this 150 light years across view of AP 14 and others like it are helping astronomers interpret the light from more distant galaxies that have similar structure astronomers have previously noted that the Milky Way sits in a large flat array of galaxies called the local sheet this sheet of galaxies bounds a void called the local void the void size is not known but it is at least 150 million light-years wide and 230 million light-years long it's center is approximately 75 million light-years from us Hubble has taken a beautiful picture of NGC 6500 3 a lonely galaxy on the edge of this void it spans some 30,000 light years in this image bright red patches of gas can be seen scattered through its swirling spiral arms mixed with bright blue regions that contain newly forming stars with dark brown dust lanes snaking across the galaxy's bright arms and center Hana's ver WEP is one of the strangest space objects ever seen a mysterious glowing green blob of gas is floating in space near a spiral galaxy IC 2497 the object is so huge that it stretches more than 44 thousand light-years 236 thousand light-years from the galaxy's core it turns out that it's part of a 300,000 light-years long tidal tail that wraps around icy 2497 our current understanding is that this part of the tail was illuminated by a high-energy beam created by matter falling into the galaxy's central black hole their unmistakable emerald hue is caused by ionized oxygen which glows green in our segment on the cosmos in how far away is a video book we covered how on the widest scale the universe forms a web of galaxies surrounding great voids and that the web filaments are galaxies grouped into super clusters it has always been difficult for astronomers to determine where one super cluster ends and another begins but now a team of astronomers have collected data on thousands of galaxies around us to understand their peculiar motion you'll recall from our segment on local super clusters that the peculiar motion of an object is its motion less that part of its motion associated with the Hubble flow due to the expanding universe they use this data to identify which galaxies are moving towards us shown in blue and which galaxies are moving away from us shown in red with this data they were able to create a map of the paths galaxies are migrating along these paths are called cosmic flows using this motion they came up with a new way to map the distribution of matter in the universe in our segment on the Virgo supercluster we counted the Virgo galaxy cluster and a few hundred others as our local supercluster but using this new technique we see that the Virgo supercluster is part of a much larger structure that is 100 times larger and more massive the astronomers who made this discovery have named the new super cluster Laniakea a wine for immeasurable Heaven here is an illustration of Laniakea along with Perseus Pisces and adjacent super cluster the boundary is where the super cluster objects are shearing apart like the North American Great Divide separates water flowing to the Atlantic Ocean from water flowing to the Pacific Ocean in this view the red dot shows our Milky Way's location in Laniakea you until the early part of the 20th century it went without saying that the matter we see is most of the matter there is that would be protons and neutrons with accelerating electrons creating the light we see but that came into question in the early 1930s when Fritz Zwicky a Swiss astronomer at of Caltech studied the Coma Cluster 321 million light years away with a thousand galaxies spanning 25 million light-years in diameter he looked at it in a number of ways two of which are very revealing in one he used galaxies motion to calculate mass and in the other use galaxies luminosity to calculate mass his processes are not precise but they do provide ballpark figures for the mass of the cluster for motion he had the cluster galaxies radial velocities from the Doppler shift in the light we see he then generalized them into their three-dimensional velocity dispersion statistical equivalent this galaxies motion gives us the kinetic energy for the cluster Sawicki use the well-understood varial theorem that has the kinetic energy of a system equal to one-half its gravitational potential energy this allows us to solve for the mass of the cluster this is the mass as measured by his gravitational effects the second way he calculated the clusters mass was to use the clusters luminosity you may recall from our discussion on the hertzsprung-russell diagram and our how far away is its segment on distant stars that there is a relationship between a star's mass and its luminosity we can use that relationship to estimate the mass of groups of stars by measuring their luminosity we use the mass-to-light ratio of the Sun as the base for comparisons for example the Omega Centauri globular cluster as a mass-to-light ratio of 3.6 Wiki measured the luminosity the average galaxy in the Coma Cluster using a mass to light ratio of three he calculated its mass when he multiplied the average times a thousand galaxies in the cluster he came out with a number that was over a hundred times less than the mass calculated via the virial theorem based on gravity in other words the motion of the galaxies in the cluster indicated a mass that was over a hundred times the mass from luminous matter wiki concluded that either the laws of gravity as we know them Newton's and Einsteins did not work for volumes as large as the Coma Cluster or the luminous matter is only a very small part of the total matter of the cluster he called the rest of the matter dark matter and suggested the gravitational lensing could help quantify this dark matter but back in the 1930s nobody believed him fast forward to the 1970s attention was focused on an anomaly associated with the velocity of stars orbiting spiral galaxies resolving the velocities of individual stars and distant galaxies is not feasible but in spiral galaxies where all the stars in the disk are rotating in the same direction a good aggregate estimate is possible with elliptical galaxies the motion of stars around the center are chaotic so we have no velocity data to use and therefore no anomalies to identify to see how the velocities give us a measure of mass we'll start with our solar system here's the rotation curve we get when we map the velocity of the planets orbiting the Sun because the Sun has 99% of all the matter in the system the mass within any orbit will be relatively fixed at the sun's mass therefore the further away from the central mass we get the weaker the gravitational pull and the slower the orbital velocity this model is called Keplerian because it follows Kepler's laws for orbital motion now a galaxy is much more complex than a solar system the mass within increasing orbital volumes is not fixed like it is in the solar system if you move out from the center of a galaxy there is considerable mass added in addition to the mass of the central bulge this is because of the large number of stars dust and gas in the galaxy's disk for instance it is estimated that the mass of the central bulge of the Milky Way is 20 billion solar masses we saw in our segment on the Milky Way that the velocity of the Sun around the center of the galaxy is 200 kilometers per second and it's distance from the center is 26,000 light-years so the mass of the galaxy's interior to the sun's orbit is approximately 74 billion solar masses a good deal more than the Bulge itself but at the outer edges of the disk the star density drops off dramatically in the 1970s everyone expected to see rotation curves that look like this but in 1975 an American astronomer Vera Rubin published galaxy rotation curves for the Milky Way and a number of other galaxies that showed a remarkable result where the velocities were expected to fall off they remained relatively constant if our current theory of gravity holds up for galactic distances then this curve tells us that our model of the Milky Way is missing something in order for objects far from the center of the galaxy to be moving faster than predicted there must be significant additional mass far from the galactic center exerting gravitational pulls on those stars in other words dark matter here's Vera Rubens measurements of the velocity curve for Andromeda and here's the rotation curve for NGC 6500 3 the galaxy on the edge of the local void that we covered earlier using accurate and high-resolution emission lines from neutral hydrogen astronomers modeled the mass distribution of this galaxy they use the mass-to-light ratio in the visible disc a galaxy's core radius and the circular velocity of the halo the study found the contribution to the rotation curve of three types of matter gas luminous matter and dark matter with this new understanding about the possibility and impact of dark matter astronomers turn their attention back to galaxy clusters like the one studied by the wiki in 1936 back then wiki suggested the gravitational lensing could be used to better understand dark matter our case in point galaxy is known as the bullet cluster the varial motion of its galaxies indicates that a collision has occurred two massive clusters have passed through each other billions of years ago and member galaxies are now flying apart if we zoom in a bit closer we can see the tell-tale arcs of more distant galaxies lens by the gravity of the bullet cluster counting the lens objects and the estimated amount of light bending involved for each one a map of the area containing most of the mass the cluster can be superimposed we have used blue to indicate the locations where the vast majority of the matter must be located in order to get the observed lensing here we have the cluster's hot x-ray emitting gas detected by the Chandra x-ray Observatory the two pink clumps contain most of the normal matter sometimes referred to as baryonic matter or matter made up of protons and neutrons the bullet-shaped clump on the right is the hot gas from one cluster which passed through the hot gas from the other cluster during the collision when we superimpose the dark baryonic and visible components of the clusters mass we get the full picture the galaxies and the dark matter have traveled a great deal further than the gas this indicates that the galaxies and dark matter in the two colliding clusters did not interfere with each other in other words they passed through each other without slowing down on the other hand during the collision the gas clouds were slowed by a drag force similar to air resistance this combination had the effect of separating the gas from the dark matter this separation is considered to be direct evidence that Dark Matter exists measurements indicate that the galaxy clusters on average have 85% dark matter 14% intergalactic gas and only 1% stars in 2014 a team of astronomers found a supernova in this galaxy cluster over five billion light-years away the supernova actually happened in a galaxy four billion light years beyond that making it nine billion light-years away the huge mass of the foreground galaxies and galaxy cluster and the light from the distant supernova creating four separate images of the same explosion the images are arranged around an elliptical galaxy in a formation known as an Einstein cross following this discovery astronomers modeled several possible gas and dark matter distributions in the galaxy cluster each model predicted that another image of this supernova will appear in the cluster but they had different time estimates ranging from 2015 through 2025 in December 2015 it appeared for the first time in history the time and location of a supernova was accurately predicted we actually saw the supernova happen instead of detecting a flash in the sky and turning telescopes to its location we had the telescope's already focused on the correct area and recorded the event from beginning to end this was powerful evidence for dark matter we have seen two kinds of evidence for dark matter one from galaxy rotation curves for dark matter around spiral galaxies and the other from gravitational lensing for galaxy clusters both leave us with only two possibilities either our current theory of gravity just doesn't extend the galaxies and/or galaxy clusters or most of the universe is made up of one or more unknown substances that interact with normal matter by a gravity but not much else a tremendous amount of research is actively trying to find out what this stuff is here are some of the possibilities hydrogen weakly interacting massive particles wimps for short neutrinos let's take a quick look at each of these here's a European Southern Observatory artist's representation of the distribution of dark matter around the Milky Way galaxy you may recall from our how far away is it segment on the Milky Way that in September of 2012 Chandra found evidence that the Milky Way galaxy is embedded with a large amount of hot gas in the halo counting this vast amount of gas the mass of the halo is estimated to equal the mass of the stars in the galaxy this could be the solution for star orbital speeds and might be the answer for spiral galaxy Dark Matter it could not be the answer for galaxy clusters though but then again it doesn't have to be another possibility is the existence of a new set of extended standard model particles there are a variety of theories that predict wimps in late 2015 the Large Hadron Collider at CERN came back online after a two-year upgrade it can now reach 13 trillion electron volts almost double the collision energy before the upgrade at this level it might be enough to produce a wimp of course the particle would not be detected because it wouldn't interact with any layer of the detector however it would carry away energy and momentum so physicists could infer their existence from the amount of energy and momentum missing after a collision you may remember from our how small is an elementary particle segment that this is exactly the same way LSN Worcester found the neutrino back in 1927 this brings us to the last possibility we'll cover in our discussion on elementary particles we found that the neutrino is a critical component in many nuclear reactions and the detection of solar neutrinos and of neutrinos from supernova 1987a marked the beginning of neutrino astronomy over the life of the universe countless numbers have been produced there are over a billion times more abundant than the electrons protons and neutrons that make up stars planets and people but are there enough of them to account for the dark matter in galaxy clusters neutrino astronomy is trying to discover the answer to this question today we have built amazing neutrino detectors such as the super-kamiokande in Japan to better understand these fundamental but elusive particles the super-kamiokande is located 1,000 metres underground in a Japanese mine it contains a lake holding 50,000 tons of ultra-pure water surrounded by an inner detector with over 11,000 photomultiplier tubes flash when struck by a photon created by a neutrino interaction with the water the speed of light in water is slower than the speed of light in a vacuum a neutrino interaction with the electrons or nuclei of water can produce a charged particle that moves faster than the speed of light in water this creates a cone of light known as Chernykh off radiation this is the optical equivalent of a sonic boom the Chernykh off light is projected as a ring on the wall of the detector and recorded by the photomultipliers with so much of the scientific community searching for an answer we can expect to know if neutrinos wimps hydrogen new gravitational theories or something else can explain the movement of stars around galaxies and galaxies around clusters hopefully there will be news to report on this topic in the 2016 update before listing all the sources I use to make this 2015 update I'd like to point to two websites you might find interesting one is Galaxy Zoo it's a site where you help with over a million catalogued Hubble Galaxy images inez Baruch was found just this way by Dutch school teacher Han Ivonne Ark the name is Dutch for Hanny's object amazing space Hubble's sister site is launching a new look and feel amazing space takes users on a journey of astronomical discovery through the nearby in distant cosmos from the combined perspective of the hubble space telescope and its successor the James Webb Space Telescope take a look and here are two articles worth reading this is Fritz wiggies 1937 paper that first introduces the idea of dark matter you'll find that it needs some amount of mathematics to understand the second paper is a recent article by Vera Rubin that you'll find easier to read and don't forget every video segment on the how far away isn't YouTube channel including this one as a document with the text pictures links and notes located on how far away is it com slash documents here are the links to the Hubble and other locations where I found the information contained in this 2015 update these are the places you can go to learn more thank you for watching

Channel: David Butler

Views: 273,456

Keywords: Dark matter, Spitzer, Chandra, ESO, Hubbel, Veil Nebula, Eagle Nebula, NGC 6503, Local Void, Hanny’s Voorwerp, Gaia, CERN, LHC, Coma Cluster, Andromeda, Bullet Cluster, Zwicky, Rubin, WIMPS, Neutrino, Kamiokande, Laniakea

Id: dw_Uw4ueFkw

Length: 31min 36sec (1896 seconds)

Published: Wed Feb 10 2016