Why are there uneven bright areas in this photo of black hole?












2












$begingroup$


enter image description here



In the above photo of recently released black hole created by using datas from EHT, why are the region below is more bright than the one above? Is it because of the rotation of the accretion disk? Also what is the orientation of the accretion disk? Are we looking at head on?










share|improve this question









$endgroup$








  • 1




    $begingroup$
    Great question! I'd just seen this video but you beat me to it :-)
    $endgroup$
    – uhoh
    4 hours ago












  • $begingroup$
    Related astronomy.stackexchange.com/questions/30332/…
    $endgroup$
    – Rob Jeffries
    4 mins ago
















2












$begingroup$


enter image description here



In the above photo of recently released black hole created by using datas from EHT, why are the region below is more bright than the one above? Is it because of the rotation of the accretion disk? Also what is the orientation of the accretion disk? Are we looking at head on?










share|improve this question









$endgroup$








  • 1




    $begingroup$
    Great question! I'd just seen this video but you beat me to it :-)
    $endgroup$
    – uhoh
    4 hours ago












  • $begingroup$
    Related astronomy.stackexchange.com/questions/30332/…
    $endgroup$
    – Rob Jeffries
    4 mins ago














2












2








2





$begingroup$


enter image description here



In the above photo of recently released black hole created by using datas from EHT, why are the region below is more bright than the one above? Is it because of the rotation of the accretion disk? Also what is the orientation of the accretion disk? Are we looking at head on?










share|improve this question









$endgroup$




enter image description here



In the above photo of recently released black hole created by using datas from EHT, why are the region below is more bright than the one above? Is it because of the rotation of the accretion disk? Also what is the orientation of the accretion disk? Are we looking at head on?







black-hole






share|improve this question













share|improve this question











share|improve this question




share|improve this question










asked 5 hours ago









Kushal BhuyanKushal Bhuyan

354212




354212








  • 1




    $begingroup$
    Great question! I'd just seen this video but you beat me to it :-)
    $endgroup$
    – uhoh
    4 hours ago












  • $begingroup$
    Related astronomy.stackexchange.com/questions/30332/…
    $endgroup$
    – Rob Jeffries
    4 mins ago














  • 1




    $begingroup$
    Great question! I'd just seen this video but you beat me to it :-)
    $endgroup$
    – uhoh
    4 hours ago












  • $begingroup$
    Related astronomy.stackexchange.com/questions/30332/…
    $endgroup$
    – Rob Jeffries
    4 mins ago








1




1




$begingroup$
Great question! I'd just seen this video but you beat me to it :-)
$endgroup$
– uhoh
4 hours ago






$begingroup$
Great question! I'd just seen this video but you beat me to it :-)
$endgroup$
– uhoh
4 hours ago














$begingroup$
Related astronomy.stackexchange.com/questions/30332/…
$endgroup$
– Rob Jeffries
4 mins ago




$begingroup$
Related astronomy.stackexchange.com/questions/30332/…
$endgroup$
– Rob Jeffries
4 mins ago










3 Answers
3






active

oldest

votes


















3












$begingroup$

I believe we are seeing one of the effects of the accretion disk rotating at very high speeds. This is called relativistic beaming, and it occurs because particles (in this case matter in the accretion disk) that are travelling at relativistic speeds (say, upwards of .2c), tend to preferentially emit their radiation in a cone towards the direction of motion.



This suggests that the matter at the bottom of the picture (the brightest blobs) are travelling towards us, and the darker parts are travelling away. Since the black hole tends to warp light around itself, I'm not sure from the photo of the orientation of the accretion disk.






share|improve this answer









$endgroup$





















    1












    $begingroup$

    No, you aren't seeing the shape of the accretion disk and its plane is aligned with main N-S asymmetry. The reason for this asymmetry is almost entirely due to Doppler beaming and boosting of radiation arising in matter travelling at relativistic speeds. This in turn is almost entirely controlled by the orientation of the black hole spin. The black hole sweeps up material and magnetic fields almost irrespective of the orientation of any accretion disk.



    The pictures below from the fifth event horizon telescope paper makes things clear.



    Relative orientation of spin and accretion flow



    The black arrow indicates the direction of black hole spin. The blue arrow indicates the initial rotation of the accretion flow. The jet of M87 is more or less East-West (projected onto the page), but the right hand side is pointing towards the Earth. It is assumed that the spin vector of the black hole is aligned (or anti-aligned) with this.



    The two left hand plots show agreement with the observations. What they have in common is that the black hole spin vector is into the page (anti-aligned with the jet). Gas is forced to rotate in the same way and results in projected relativistic motion towards us south of the black hole and away from us north of the black hole. Doppler boosting and beaming does the rest.



    As the paper says:




    the location of the peak flux in the ring is controlled by the black hole spin: it always lies roughly 90 degrees counterclockwise from the projection of the spin vector on the sky.







    share|improve this answer









    $endgroup$





















      0












      $begingroup$

      The article: "Ergoregion instability of exotic compact objects: electromagnetic and gravitational perturbations and the role of absorption", (Feb 15 2019), by Elisa Maggio, Vitor Cardoso, Sam R. Dolan, and Paolo Pani explains that this is due to rotational superradiance on page 10:




      "... the instability can be understood in terms of waves trapped within the photon-sphere barrier and amplified by superradiant scattering$^{[43]}$
      [43] R. Brito, V. Cardoso, and P. Pani, Lect. Notes Phys. 906, pp.1 (2015), arXiv:1501.06570.




      In the article "Superradiance", (above) while considerably longer, maybe much more approachable. On page 38 where they explain the Penrose Process they offer a diagram which probably makes the understanding of this easier:




      Penrose Process



      "Figure 7: Pictorial view of the original Penrose processes. A particle with energy E$_0$ decays inside the ergosphere into two particles, one with negative energy E$_2$ < 0 which falls into the BH, while the second particle escapes to infinity with an energy higher than the original particle, E$_1$ > E$_0$.".




      From page 41:




      Simplified Penrose Explanation



      "Figure 8: The carousel analogy of the Penrose process. A body falls nearly from rest into a rotating cylinder, whose surface is sprayed with glue. At the surface the body is forced to co-rotate with the cylinder (analog therefore of the BH ergosphere, the surface beyond which no observer can remain stationary with respect to infinity). The negative energy states of the ergoregion are played by the potential energy associated with the sticky surface. If now half
      the object (in reddish) is detached from the first half (yellowish), it will reach infinity with more (kinetic) energy than it had initially, extracting rotational energy out of the system.".




      A further more complicated model, believed to be beyond what was asked, from page 46:




      Collisional Penrose Process



      "Figure 9: Pictorial view of the different collisional Penrose processes. Left: initial particleswith ingoing radial momentum (p$^r
      _1$
      < 0 and p$^r_2$ < 0). Particle 3 has initial ingoing radial
      momentum, but eventually finds a turning point and escapes to infinity. The maximum efficiency for this was shown to be quite modest η ∼ 1.5 $^{[168, 169, 170, 171]}$. Right: initial particles with p$^r_1$ > 0 and p$^r_2$ < 0. In this case particle 1 must have p$^r_1$ > 0 inside the ergosphere. For this process the efficiency can be unbound for extremal BHs $^{[172, 173]}$.



      [168] T. Piran and J. Shaham, “Upper Bounds on Collisional Penrose Processes Near Rotating Black Hole Horizons,” Phys.Rev. D16 (1977) 1615–1635.



      [169] T. Harada, H. Nemoto, and U. Miyamoto, “Upper limits of particle emission from high-energy collision and reaction near a maximally rotating Kerr black hole,” Phys.Rev. D86 (2012) 024027, arXiv:1205.7088 [gr-qc].



      [170] M. Bejger, T. Piran, M. Abramowicz, and F. Hakanson, “Collisional Penrose process near the horizon of extreme Kerr black holes,” Phys.Rev.Lett. 109 (2012) 121101, arXiv:1205.4350 [astro-ph.HE].



      [171] O. Zaslavskii, “On energetics of particle collisions near black holes: BSW effect versus Penrose process,” Phys.Rev. D86 (2012) 084030, arXiv:1205.4410 [gr-qc].



      [172] J. D. Schnittman, “A revised upper limit to energy extraction from a Kerr black hole,” arXiv:1410.6446 [astro-ph.HE].



      [173] E. Berti, R. Brito, and V. Cardoso, “Ultra-high-energy debris from the collisional Penrose process,” arXiv:1410.8534 [gr-qc].




      There is a summary on page 170 (nowhere near the end of the paper) which explains:




      "In gravitational theories, superradiance is intimately connected to tidal acceleration, even at Newtonian level. Relativistic gravitational theories predict the existence of BHs, gravitational vacuum solutions whose event horizon behaves as a one-way viscous membrane. This allows superradiance to occur in BH spacetimes, and to extract energy from vacuum even at the classical level. When semiclassical effects are taken into account, superradiance occurs
      also in static configurations, as in the case of Hawking radiation from a Schwarzschild BH.



      The efficiency of superradiant scattering of GWs by a spinning (Kerr) BH can be larger than 100% and this phenomenon is deeply connected to other important mechanisms associated to spinning compact objects, such as the Penrose process, the ergoregion instability, the Blandford-Znajek effect, and the CFS instability. Rotational superradiance might be challenging to observe in the laboratory, but its BH counterpart is associated with a number
      of interesting effects and instabilities, which may leave an observational imprint. We have presented a unified treatment of BH superradiant phenomena including charged BHs, higher dimensions, nonasymptotically flat spacetimes, analog models of gravity and theories beyond GR.".







      share|improve this answer









      $endgroup$














        Your Answer





        StackExchange.ifUsing("editor", function () {
        return StackExchange.using("mathjaxEditing", function () {
        StackExchange.MarkdownEditor.creationCallbacks.add(function (editor, postfix) {
        StackExchange.mathjaxEditing.prepareWmdForMathJax(editor, postfix, [["$", "$"], ["\\(","\\)"]]);
        });
        });
        }, "mathjax-editing");

        StackExchange.ready(function() {
        var channelOptions = {
        tags: "".split(" "),
        id: "514"
        };
        initTagRenderer("".split(" "), "".split(" "), channelOptions);

        StackExchange.using("externalEditor", function() {
        // Have to fire editor after snippets, if snippets enabled
        if (StackExchange.settings.snippets.snippetsEnabled) {
        StackExchange.using("snippets", function() {
        createEditor();
        });
        }
        else {
        createEditor();
        }
        });

        function createEditor() {
        StackExchange.prepareEditor({
        heartbeatType: 'answer',
        autoActivateHeartbeat: false,
        convertImagesToLinks: false,
        noModals: true,
        showLowRepImageUploadWarning: true,
        reputationToPostImages: null,
        bindNavPrevention: true,
        postfix: "",
        imageUploader: {
        brandingHtml: "Powered by u003ca class="icon-imgur-white" href="https://imgur.com/"u003eu003c/au003e",
        contentPolicyHtml: "User contributions licensed under u003ca href="https://creativecommons.org/licenses/by-sa/3.0/"u003ecc by-sa 3.0 with attribution requiredu003c/au003e u003ca href="https://stackoverflow.com/legal/content-policy"u003e(content policy)u003c/au003e",
        allowUrls: true
        },
        noCode: true, onDemand: true,
        discardSelector: ".discard-answer"
        ,immediatelyShowMarkdownHelp:true
        });


        }
        });














        draft saved

        draft discarded


















        StackExchange.ready(
        function () {
        StackExchange.openid.initPostLogin('.new-post-login', 'https%3a%2f%2fastronomy.stackexchange.com%2fquestions%2f30343%2fwhy-are-there-uneven-bright-areas-in-this-photo-of-black-hole%23new-answer', 'question_page');
        }
        );

        Post as a guest















        Required, but never shown

























        3 Answers
        3






        active

        oldest

        votes








        3 Answers
        3






        active

        oldest

        votes









        active

        oldest

        votes






        active

        oldest

        votes









        3












        $begingroup$

        I believe we are seeing one of the effects of the accretion disk rotating at very high speeds. This is called relativistic beaming, and it occurs because particles (in this case matter in the accretion disk) that are travelling at relativistic speeds (say, upwards of .2c), tend to preferentially emit their radiation in a cone towards the direction of motion.



        This suggests that the matter at the bottom of the picture (the brightest blobs) are travelling towards us, and the darker parts are travelling away. Since the black hole tends to warp light around itself, I'm not sure from the photo of the orientation of the accretion disk.






        share|improve this answer









        $endgroup$


















          3












          $begingroup$

          I believe we are seeing one of the effects of the accretion disk rotating at very high speeds. This is called relativistic beaming, and it occurs because particles (in this case matter in the accretion disk) that are travelling at relativistic speeds (say, upwards of .2c), tend to preferentially emit their radiation in a cone towards the direction of motion.



          This suggests that the matter at the bottom of the picture (the brightest blobs) are travelling towards us, and the darker parts are travelling away. Since the black hole tends to warp light around itself, I'm not sure from the photo of the orientation of the accretion disk.






          share|improve this answer









          $endgroup$
















            3












            3








            3





            $begingroup$

            I believe we are seeing one of the effects of the accretion disk rotating at very high speeds. This is called relativistic beaming, and it occurs because particles (in this case matter in the accretion disk) that are travelling at relativistic speeds (say, upwards of .2c), tend to preferentially emit their radiation in a cone towards the direction of motion.



            This suggests that the matter at the bottom of the picture (the brightest blobs) are travelling towards us, and the darker parts are travelling away. Since the black hole tends to warp light around itself, I'm not sure from the photo of the orientation of the accretion disk.






            share|improve this answer









            $endgroup$



            I believe we are seeing one of the effects of the accretion disk rotating at very high speeds. This is called relativistic beaming, and it occurs because particles (in this case matter in the accretion disk) that are travelling at relativistic speeds (say, upwards of .2c), tend to preferentially emit their radiation in a cone towards the direction of motion.



            This suggests that the matter at the bottom of the picture (the brightest blobs) are travelling towards us, and the darker parts are travelling away. Since the black hole tends to warp light around itself, I'm not sure from the photo of the orientation of the accretion disk.







            share|improve this answer












            share|improve this answer



            share|improve this answer










            answered 2 hours ago









            Jim421616Jim421616

            713214




            713214























                1












                $begingroup$

                No, you aren't seeing the shape of the accretion disk and its plane is aligned with main N-S asymmetry. The reason for this asymmetry is almost entirely due to Doppler beaming and boosting of radiation arising in matter travelling at relativistic speeds. This in turn is almost entirely controlled by the orientation of the black hole spin. The black hole sweeps up material and magnetic fields almost irrespective of the orientation of any accretion disk.



                The pictures below from the fifth event horizon telescope paper makes things clear.



                Relative orientation of spin and accretion flow



                The black arrow indicates the direction of black hole spin. The blue arrow indicates the initial rotation of the accretion flow. The jet of M87 is more or less East-West (projected onto the page), but the right hand side is pointing towards the Earth. It is assumed that the spin vector of the black hole is aligned (or anti-aligned) with this.



                The two left hand plots show agreement with the observations. What they have in common is that the black hole spin vector is into the page (anti-aligned with the jet). Gas is forced to rotate in the same way and results in projected relativistic motion towards us south of the black hole and away from us north of the black hole. Doppler boosting and beaming does the rest.



                As the paper says:




                the location of the peak flux in the ring is controlled by the black hole spin: it always lies roughly 90 degrees counterclockwise from the projection of the spin vector on the sky.







                share|improve this answer









                $endgroup$


















                  1












                  $begingroup$

                  No, you aren't seeing the shape of the accretion disk and its plane is aligned with main N-S asymmetry. The reason for this asymmetry is almost entirely due to Doppler beaming and boosting of radiation arising in matter travelling at relativistic speeds. This in turn is almost entirely controlled by the orientation of the black hole spin. The black hole sweeps up material and magnetic fields almost irrespective of the orientation of any accretion disk.



                  The pictures below from the fifth event horizon telescope paper makes things clear.



                  Relative orientation of spin and accretion flow



                  The black arrow indicates the direction of black hole spin. The blue arrow indicates the initial rotation of the accretion flow. The jet of M87 is more or less East-West (projected onto the page), but the right hand side is pointing towards the Earth. It is assumed that the spin vector of the black hole is aligned (or anti-aligned) with this.



                  The two left hand plots show agreement with the observations. What they have in common is that the black hole spin vector is into the page (anti-aligned with the jet). Gas is forced to rotate in the same way and results in projected relativistic motion towards us south of the black hole and away from us north of the black hole. Doppler boosting and beaming does the rest.



                  As the paper says:




                  the location of the peak flux in the ring is controlled by the black hole spin: it always lies roughly 90 degrees counterclockwise from the projection of the spin vector on the sky.







                  share|improve this answer









                  $endgroup$
















                    1












                    1








                    1





                    $begingroup$

                    No, you aren't seeing the shape of the accretion disk and its plane is aligned with main N-S asymmetry. The reason for this asymmetry is almost entirely due to Doppler beaming and boosting of radiation arising in matter travelling at relativistic speeds. This in turn is almost entirely controlled by the orientation of the black hole spin. The black hole sweeps up material and magnetic fields almost irrespective of the orientation of any accretion disk.



                    The pictures below from the fifth event horizon telescope paper makes things clear.



                    Relative orientation of spin and accretion flow



                    The black arrow indicates the direction of black hole spin. The blue arrow indicates the initial rotation of the accretion flow. The jet of M87 is more or less East-West (projected onto the page), but the right hand side is pointing towards the Earth. It is assumed that the spin vector of the black hole is aligned (or anti-aligned) with this.



                    The two left hand plots show agreement with the observations. What they have in common is that the black hole spin vector is into the page (anti-aligned with the jet). Gas is forced to rotate in the same way and results in projected relativistic motion towards us south of the black hole and away from us north of the black hole. Doppler boosting and beaming does the rest.



                    As the paper says:




                    the location of the peak flux in the ring is controlled by the black hole spin: it always lies roughly 90 degrees counterclockwise from the projection of the spin vector on the sky.







                    share|improve this answer









                    $endgroup$



                    No, you aren't seeing the shape of the accretion disk and its plane is aligned with main N-S asymmetry. The reason for this asymmetry is almost entirely due to Doppler beaming and boosting of radiation arising in matter travelling at relativistic speeds. This in turn is almost entirely controlled by the orientation of the black hole spin. The black hole sweeps up material and magnetic fields almost irrespective of the orientation of any accretion disk.



                    The pictures below from the fifth event horizon telescope paper makes things clear.



                    Relative orientation of spin and accretion flow



                    The black arrow indicates the direction of black hole spin. The blue arrow indicates the initial rotation of the accretion flow. The jet of M87 is more or less East-West (projected onto the page), but the right hand side is pointing towards the Earth. It is assumed that the spin vector of the black hole is aligned (or anti-aligned) with this.



                    The two left hand plots show agreement with the observations. What they have in common is that the black hole spin vector is into the page (anti-aligned with the jet). Gas is forced to rotate in the same way and results in projected relativistic motion towards us south of the black hole and away from us north of the black hole. Doppler boosting and beaming does the rest.



                    As the paper says:




                    the location of the peak flux in the ring is controlled by the black hole spin: it always lies roughly 90 degrees counterclockwise from the projection of the spin vector on the sky.








                    share|improve this answer












                    share|improve this answer



                    share|improve this answer










                    answered 12 mins ago









                    Rob JeffriesRob Jeffries

                    54.3k4112174




                    54.3k4112174























                        0












                        $begingroup$

                        The article: "Ergoregion instability of exotic compact objects: electromagnetic and gravitational perturbations and the role of absorption", (Feb 15 2019), by Elisa Maggio, Vitor Cardoso, Sam R. Dolan, and Paolo Pani explains that this is due to rotational superradiance on page 10:




                        "... the instability can be understood in terms of waves trapped within the photon-sphere barrier and amplified by superradiant scattering$^{[43]}$
                        [43] R. Brito, V. Cardoso, and P. Pani, Lect. Notes Phys. 906, pp.1 (2015), arXiv:1501.06570.




                        In the article "Superradiance", (above) while considerably longer, maybe much more approachable. On page 38 where they explain the Penrose Process they offer a diagram which probably makes the understanding of this easier:




                        Penrose Process



                        "Figure 7: Pictorial view of the original Penrose processes. A particle with energy E$_0$ decays inside the ergosphere into two particles, one with negative energy E$_2$ < 0 which falls into the BH, while the second particle escapes to infinity with an energy higher than the original particle, E$_1$ > E$_0$.".




                        From page 41:




                        Simplified Penrose Explanation



                        "Figure 8: The carousel analogy of the Penrose process. A body falls nearly from rest into a rotating cylinder, whose surface is sprayed with glue. At the surface the body is forced to co-rotate with the cylinder (analog therefore of the BH ergosphere, the surface beyond which no observer can remain stationary with respect to infinity). The negative energy states of the ergoregion are played by the potential energy associated with the sticky surface. If now half
                        the object (in reddish) is detached from the first half (yellowish), it will reach infinity with more (kinetic) energy than it had initially, extracting rotational energy out of the system.".




                        A further more complicated model, believed to be beyond what was asked, from page 46:




                        Collisional Penrose Process



                        "Figure 9: Pictorial view of the different collisional Penrose processes. Left: initial particleswith ingoing radial momentum (p$^r
                        _1$
                        < 0 and p$^r_2$ < 0). Particle 3 has initial ingoing radial
                        momentum, but eventually finds a turning point and escapes to infinity. The maximum efficiency for this was shown to be quite modest η ∼ 1.5 $^{[168, 169, 170, 171]}$. Right: initial particles with p$^r_1$ > 0 and p$^r_2$ < 0. In this case particle 1 must have p$^r_1$ > 0 inside the ergosphere. For this process the efficiency can be unbound for extremal BHs $^{[172, 173]}$.



                        [168] T. Piran and J. Shaham, “Upper Bounds on Collisional Penrose Processes Near Rotating Black Hole Horizons,” Phys.Rev. D16 (1977) 1615–1635.



                        [169] T. Harada, H. Nemoto, and U. Miyamoto, “Upper limits of particle emission from high-energy collision and reaction near a maximally rotating Kerr black hole,” Phys.Rev. D86 (2012) 024027, arXiv:1205.7088 [gr-qc].



                        [170] M. Bejger, T. Piran, M. Abramowicz, and F. Hakanson, “Collisional Penrose process near the horizon of extreme Kerr black holes,” Phys.Rev.Lett. 109 (2012) 121101, arXiv:1205.4350 [astro-ph.HE].



                        [171] O. Zaslavskii, “On energetics of particle collisions near black holes: BSW effect versus Penrose process,” Phys.Rev. D86 (2012) 084030, arXiv:1205.4410 [gr-qc].



                        [172] J. D. Schnittman, “A revised upper limit to energy extraction from a Kerr black hole,” arXiv:1410.6446 [astro-ph.HE].



                        [173] E. Berti, R. Brito, and V. Cardoso, “Ultra-high-energy debris from the collisional Penrose process,” arXiv:1410.8534 [gr-qc].




                        There is a summary on page 170 (nowhere near the end of the paper) which explains:




                        "In gravitational theories, superradiance is intimately connected to tidal acceleration, even at Newtonian level. Relativistic gravitational theories predict the existence of BHs, gravitational vacuum solutions whose event horizon behaves as a one-way viscous membrane. This allows superradiance to occur in BH spacetimes, and to extract energy from vacuum even at the classical level. When semiclassical effects are taken into account, superradiance occurs
                        also in static configurations, as in the case of Hawking radiation from a Schwarzschild BH.



                        The efficiency of superradiant scattering of GWs by a spinning (Kerr) BH can be larger than 100% and this phenomenon is deeply connected to other important mechanisms associated to spinning compact objects, such as the Penrose process, the ergoregion instability, the Blandford-Znajek effect, and the CFS instability. Rotational superradiance might be challenging to observe in the laboratory, but its BH counterpart is associated with a number
                        of interesting effects and instabilities, which may leave an observational imprint. We have presented a unified treatment of BH superradiant phenomena including charged BHs, higher dimensions, nonasymptotically flat spacetimes, analog models of gravity and theories beyond GR.".







                        share|improve this answer









                        $endgroup$


















                          0












                          $begingroup$

                          The article: "Ergoregion instability of exotic compact objects: electromagnetic and gravitational perturbations and the role of absorption", (Feb 15 2019), by Elisa Maggio, Vitor Cardoso, Sam R. Dolan, and Paolo Pani explains that this is due to rotational superradiance on page 10:




                          "... the instability can be understood in terms of waves trapped within the photon-sphere barrier and amplified by superradiant scattering$^{[43]}$
                          [43] R. Brito, V. Cardoso, and P. Pani, Lect. Notes Phys. 906, pp.1 (2015), arXiv:1501.06570.




                          In the article "Superradiance", (above) while considerably longer, maybe much more approachable. On page 38 where they explain the Penrose Process they offer a diagram which probably makes the understanding of this easier:




                          Penrose Process



                          "Figure 7: Pictorial view of the original Penrose processes. A particle with energy E$_0$ decays inside the ergosphere into two particles, one with negative energy E$_2$ < 0 which falls into the BH, while the second particle escapes to infinity with an energy higher than the original particle, E$_1$ > E$_0$.".




                          From page 41:




                          Simplified Penrose Explanation



                          "Figure 8: The carousel analogy of the Penrose process. A body falls nearly from rest into a rotating cylinder, whose surface is sprayed with glue. At the surface the body is forced to co-rotate with the cylinder (analog therefore of the BH ergosphere, the surface beyond which no observer can remain stationary with respect to infinity). The negative energy states of the ergoregion are played by the potential energy associated with the sticky surface. If now half
                          the object (in reddish) is detached from the first half (yellowish), it will reach infinity with more (kinetic) energy than it had initially, extracting rotational energy out of the system.".




                          A further more complicated model, believed to be beyond what was asked, from page 46:




                          Collisional Penrose Process



                          "Figure 9: Pictorial view of the different collisional Penrose processes. Left: initial particleswith ingoing radial momentum (p$^r
                          _1$
                          < 0 and p$^r_2$ < 0). Particle 3 has initial ingoing radial
                          momentum, but eventually finds a turning point and escapes to infinity. The maximum efficiency for this was shown to be quite modest η ∼ 1.5 $^{[168, 169, 170, 171]}$. Right: initial particles with p$^r_1$ > 0 and p$^r_2$ < 0. In this case particle 1 must have p$^r_1$ > 0 inside the ergosphere. For this process the efficiency can be unbound for extremal BHs $^{[172, 173]}$.



                          [168] T. Piran and J. Shaham, “Upper Bounds on Collisional Penrose Processes Near Rotating Black Hole Horizons,” Phys.Rev. D16 (1977) 1615–1635.



                          [169] T. Harada, H. Nemoto, and U. Miyamoto, “Upper limits of particle emission from high-energy collision and reaction near a maximally rotating Kerr black hole,” Phys.Rev. D86 (2012) 024027, arXiv:1205.7088 [gr-qc].



                          [170] M. Bejger, T. Piran, M. Abramowicz, and F. Hakanson, “Collisional Penrose process near the horizon of extreme Kerr black holes,” Phys.Rev.Lett. 109 (2012) 121101, arXiv:1205.4350 [astro-ph.HE].



                          [171] O. Zaslavskii, “On energetics of particle collisions near black holes: BSW effect versus Penrose process,” Phys.Rev. D86 (2012) 084030, arXiv:1205.4410 [gr-qc].



                          [172] J. D. Schnittman, “A revised upper limit to energy extraction from a Kerr black hole,” arXiv:1410.6446 [astro-ph.HE].



                          [173] E. Berti, R. Brito, and V. Cardoso, “Ultra-high-energy debris from the collisional Penrose process,” arXiv:1410.8534 [gr-qc].




                          There is a summary on page 170 (nowhere near the end of the paper) which explains:




                          "In gravitational theories, superradiance is intimately connected to tidal acceleration, even at Newtonian level. Relativistic gravitational theories predict the existence of BHs, gravitational vacuum solutions whose event horizon behaves as a one-way viscous membrane. This allows superradiance to occur in BH spacetimes, and to extract energy from vacuum even at the classical level. When semiclassical effects are taken into account, superradiance occurs
                          also in static configurations, as in the case of Hawking radiation from a Schwarzschild BH.



                          The efficiency of superradiant scattering of GWs by a spinning (Kerr) BH can be larger than 100% and this phenomenon is deeply connected to other important mechanisms associated to spinning compact objects, such as the Penrose process, the ergoregion instability, the Blandford-Znajek effect, and the CFS instability. Rotational superradiance might be challenging to observe in the laboratory, but its BH counterpart is associated with a number
                          of interesting effects and instabilities, which may leave an observational imprint. We have presented a unified treatment of BH superradiant phenomena including charged BHs, higher dimensions, nonasymptotically flat spacetimes, analog models of gravity and theories beyond GR.".







                          share|improve this answer









                          $endgroup$
















                            0












                            0








                            0





                            $begingroup$

                            The article: "Ergoregion instability of exotic compact objects: electromagnetic and gravitational perturbations and the role of absorption", (Feb 15 2019), by Elisa Maggio, Vitor Cardoso, Sam R. Dolan, and Paolo Pani explains that this is due to rotational superradiance on page 10:




                            "... the instability can be understood in terms of waves trapped within the photon-sphere barrier and amplified by superradiant scattering$^{[43]}$
                            [43] R. Brito, V. Cardoso, and P. Pani, Lect. Notes Phys. 906, pp.1 (2015), arXiv:1501.06570.




                            In the article "Superradiance", (above) while considerably longer, maybe much more approachable. On page 38 where they explain the Penrose Process they offer a diagram which probably makes the understanding of this easier:




                            Penrose Process



                            "Figure 7: Pictorial view of the original Penrose processes. A particle with energy E$_0$ decays inside the ergosphere into two particles, one with negative energy E$_2$ < 0 which falls into the BH, while the second particle escapes to infinity with an energy higher than the original particle, E$_1$ > E$_0$.".




                            From page 41:




                            Simplified Penrose Explanation



                            "Figure 8: The carousel analogy of the Penrose process. A body falls nearly from rest into a rotating cylinder, whose surface is sprayed with glue. At the surface the body is forced to co-rotate with the cylinder (analog therefore of the BH ergosphere, the surface beyond which no observer can remain stationary with respect to infinity). The negative energy states of the ergoregion are played by the potential energy associated with the sticky surface. If now half
                            the object (in reddish) is detached from the first half (yellowish), it will reach infinity with more (kinetic) energy than it had initially, extracting rotational energy out of the system.".




                            A further more complicated model, believed to be beyond what was asked, from page 46:




                            Collisional Penrose Process



                            "Figure 9: Pictorial view of the different collisional Penrose processes. Left: initial particleswith ingoing radial momentum (p$^r
                            _1$
                            < 0 and p$^r_2$ < 0). Particle 3 has initial ingoing radial
                            momentum, but eventually finds a turning point and escapes to infinity. The maximum efficiency for this was shown to be quite modest η ∼ 1.5 $^{[168, 169, 170, 171]}$. Right: initial particles with p$^r_1$ > 0 and p$^r_2$ < 0. In this case particle 1 must have p$^r_1$ > 0 inside the ergosphere. For this process the efficiency can be unbound for extremal BHs $^{[172, 173]}$.



                            [168] T. Piran and J. Shaham, “Upper Bounds on Collisional Penrose Processes Near Rotating Black Hole Horizons,” Phys.Rev. D16 (1977) 1615–1635.



                            [169] T. Harada, H. Nemoto, and U. Miyamoto, “Upper limits of particle emission from high-energy collision and reaction near a maximally rotating Kerr black hole,” Phys.Rev. D86 (2012) 024027, arXiv:1205.7088 [gr-qc].



                            [170] M. Bejger, T. Piran, M. Abramowicz, and F. Hakanson, “Collisional Penrose process near the horizon of extreme Kerr black holes,” Phys.Rev.Lett. 109 (2012) 121101, arXiv:1205.4350 [astro-ph.HE].



                            [171] O. Zaslavskii, “On energetics of particle collisions near black holes: BSW effect versus Penrose process,” Phys.Rev. D86 (2012) 084030, arXiv:1205.4410 [gr-qc].



                            [172] J. D. Schnittman, “A revised upper limit to energy extraction from a Kerr black hole,” arXiv:1410.6446 [astro-ph.HE].



                            [173] E. Berti, R. Brito, and V. Cardoso, “Ultra-high-energy debris from the collisional Penrose process,” arXiv:1410.8534 [gr-qc].




                            There is a summary on page 170 (nowhere near the end of the paper) which explains:




                            "In gravitational theories, superradiance is intimately connected to tidal acceleration, even at Newtonian level. Relativistic gravitational theories predict the existence of BHs, gravitational vacuum solutions whose event horizon behaves as a one-way viscous membrane. This allows superradiance to occur in BH spacetimes, and to extract energy from vacuum even at the classical level. When semiclassical effects are taken into account, superradiance occurs
                            also in static configurations, as in the case of Hawking radiation from a Schwarzschild BH.



                            The efficiency of superradiant scattering of GWs by a spinning (Kerr) BH can be larger than 100% and this phenomenon is deeply connected to other important mechanisms associated to spinning compact objects, such as the Penrose process, the ergoregion instability, the Blandford-Znajek effect, and the CFS instability. Rotational superradiance might be challenging to observe in the laboratory, but its BH counterpart is associated with a number
                            of interesting effects and instabilities, which may leave an observational imprint. We have presented a unified treatment of BH superradiant phenomena including charged BHs, higher dimensions, nonasymptotically flat spacetimes, analog models of gravity and theories beyond GR.".







                            share|improve this answer









                            $endgroup$



                            The article: "Ergoregion instability of exotic compact objects: electromagnetic and gravitational perturbations and the role of absorption", (Feb 15 2019), by Elisa Maggio, Vitor Cardoso, Sam R. Dolan, and Paolo Pani explains that this is due to rotational superradiance on page 10:




                            "... the instability can be understood in terms of waves trapped within the photon-sphere barrier and amplified by superradiant scattering$^{[43]}$
                            [43] R. Brito, V. Cardoso, and P. Pani, Lect. Notes Phys. 906, pp.1 (2015), arXiv:1501.06570.




                            In the article "Superradiance", (above) while considerably longer, maybe much more approachable. On page 38 where they explain the Penrose Process they offer a diagram which probably makes the understanding of this easier:




                            Penrose Process



                            "Figure 7: Pictorial view of the original Penrose processes. A particle with energy E$_0$ decays inside the ergosphere into two particles, one with negative energy E$_2$ < 0 which falls into the BH, while the second particle escapes to infinity with an energy higher than the original particle, E$_1$ > E$_0$.".




                            From page 41:




                            Simplified Penrose Explanation



                            "Figure 8: The carousel analogy of the Penrose process. A body falls nearly from rest into a rotating cylinder, whose surface is sprayed with glue. At the surface the body is forced to co-rotate with the cylinder (analog therefore of the BH ergosphere, the surface beyond which no observer can remain stationary with respect to infinity). The negative energy states of the ergoregion are played by the potential energy associated with the sticky surface. If now half
                            the object (in reddish) is detached from the first half (yellowish), it will reach infinity with more (kinetic) energy than it had initially, extracting rotational energy out of the system.".




                            A further more complicated model, believed to be beyond what was asked, from page 46:




                            Collisional Penrose Process



                            "Figure 9: Pictorial view of the different collisional Penrose processes. Left: initial particleswith ingoing radial momentum (p$^r
                            _1$
                            < 0 and p$^r_2$ < 0). Particle 3 has initial ingoing radial
                            momentum, but eventually finds a turning point and escapes to infinity. The maximum efficiency for this was shown to be quite modest η ∼ 1.5 $^{[168, 169, 170, 171]}$. Right: initial particles with p$^r_1$ > 0 and p$^r_2$ < 0. In this case particle 1 must have p$^r_1$ > 0 inside the ergosphere. For this process the efficiency can be unbound for extremal BHs $^{[172, 173]}$.



                            [168] T. Piran and J. Shaham, “Upper Bounds on Collisional Penrose Processes Near Rotating Black Hole Horizons,” Phys.Rev. D16 (1977) 1615–1635.



                            [169] T. Harada, H. Nemoto, and U. Miyamoto, “Upper limits of particle emission from high-energy collision and reaction near a maximally rotating Kerr black hole,” Phys.Rev. D86 (2012) 024027, arXiv:1205.7088 [gr-qc].



                            [170] M. Bejger, T. Piran, M. Abramowicz, and F. Hakanson, “Collisional Penrose process near the horizon of extreme Kerr black holes,” Phys.Rev.Lett. 109 (2012) 121101, arXiv:1205.4350 [astro-ph.HE].



                            [171] O. Zaslavskii, “On energetics of particle collisions near black holes: BSW effect versus Penrose process,” Phys.Rev. D86 (2012) 084030, arXiv:1205.4410 [gr-qc].



                            [172] J. D. Schnittman, “A revised upper limit to energy extraction from a Kerr black hole,” arXiv:1410.6446 [astro-ph.HE].



                            [173] E. Berti, R. Brito, and V. Cardoso, “Ultra-high-energy debris from the collisional Penrose process,” arXiv:1410.8534 [gr-qc].




                            There is a summary on page 170 (nowhere near the end of the paper) which explains:




                            "In gravitational theories, superradiance is intimately connected to tidal acceleration, even at Newtonian level. Relativistic gravitational theories predict the existence of BHs, gravitational vacuum solutions whose event horizon behaves as a one-way viscous membrane. This allows superradiance to occur in BH spacetimes, and to extract energy from vacuum even at the classical level. When semiclassical effects are taken into account, superradiance occurs
                            also in static configurations, as in the case of Hawking radiation from a Schwarzschild BH.



                            The efficiency of superradiant scattering of GWs by a spinning (Kerr) BH can be larger than 100% and this phenomenon is deeply connected to other important mechanisms associated to spinning compact objects, such as the Penrose process, the ergoregion instability, the Blandford-Znajek effect, and the CFS instability. Rotational superradiance might be challenging to observe in the laboratory, but its BH counterpart is associated with a number
                            of interesting effects and instabilities, which may leave an observational imprint. We have presented a unified treatment of BH superradiant phenomena including charged BHs, higher dimensions, nonasymptotically flat spacetimes, analog models of gravity and theories beyond GR.".








                            share|improve this answer












                            share|improve this answer



                            share|improve this answer










                            answered 2 hours ago









                            RobRob

                            1,4231417




                            1,4231417






























                                draft saved

                                draft discarded




















































                                Thanks for contributing an answer to Astronomy Stack Exchange!


                                • Please be sure to answer the question. Provide details and share your research!

                                But avoid



                                • Asking for help, clarification, or responding to other answers.

                                • Making statements based on opinion; back them up with references or personal experience.


                                Use MathJax to format equations. MathJax reference.


                                To learn more, see our tips on writing great answers.




                                draft saved


                                draft discarded














                                StackExchange.ready(
                                function () {
                                StackExchange.openid.initPostLogin('.new-post-login', 'https%3a%2f%2fastronomy.stackexchange.com%2fquestions%2f30343%2fwhy-are-there-uneven-bright-areas-in-this-photo-of-black-hole%23new-answer', 'question_page');
                                }
                                );

                                Post as a guest















                                Required, but never shown





















































                                Required, but never shown














                                Required, but never shown












                                Required, but never shown







                                Required, but never shown

































                                Required, but never shown














                                Required, but never shown












                                Required, but never shown







                                Required, but never shown







                                Popular posts from this blog

                                Liste der Baudenkmale in Friedland (Mecklenburg)

                                Single-Malt-Whisky

                                Czorneboh