John's new Presentation

John's new Presentation

Primordial Black Holes and Dark Matter? John Miller (Oxford) Collaborators: Ilia Musco (Oslo) Antonella Garzilli (SISSA) Contents of the Universe: Evidence from the CMB, supernovae, gravitational lensing, nucleosynthesis and motion of stars in galaxies ~ 73% in dark energy ~ 23% in dark matter

~ 4% in atomic matter 2 What makes up the dark matter? - we know that its Non-Baryonic in the sense that it mustnt mess up cosmological nucleosynthesis - widely thought to be particles which are: - Weakly-Interacting (mainly gravity) & Cold(??) - main candidate: supersymmetric particles But could it be Primordial Black Holes (PBHs) formed

< 1 min after the Big Bang?? up in - standard matter and radiation locked 3 PBHs before Constraints from microlensing, etc: Allowed mass range for PBHs as significant dark matter - 1017 1026 g (rs ~ 100 fm 10-2 cm) 4

Could we detect the allowed range by interactions with stars? - PBHs moving in the Galaxy with ~ virial velocity (2 x 107 cm/s) could collide with stars - get interaction with stellar matter via dynamical friction - brightening of star - asteroseismic disturbance - possible ignition of nuclear reactions How could so many PBHs with masses in this range be formed? 5 Standard picture for the formation of cosmic

structures - originated as small quantum fluctuations then inflated onto supra-horizon scales - subsequently come back inside the horizon again as the Universe continues to expand; they can then collapse - start on the supra-horizon scale as a mixture of growing and decaying modes in a linear regime - but the decaying modes soon become small, leaving just the growing modes

- these are special types of perturbation 6 Large-scale structure: - comes from perturbations re-entering the horizon in the matter-dominated era In the radiation-dominated era: - just 2 possibilities for re-entering perturbations: to - those above a critical amplitude collapse form black holes

- smaller ones disperse into the background - PBHs formed from growing-modes follow a scaling law 7 Scaling law for PBHs: What you get in PBHs depends on P() - probably need help from a phase transition to temporarily soften the equation of state - mechanism might work but it looks difficult to get the right number of PBHs 8

Conclusions is - Having microscopic PBHs as the dark matter not ruled out by present observations - Finding direct evidence for them is hard but not impossible - There is a plausible mechanism to form them but it looks difficult to get the right number - seems to need a continuous phase transition

and the fluctuation spectral index n to increase suitably at small scales - Bottom line: Having PBHs as the dark matter is a very long shot, but is not ruled out and probably deserves further study 9

Recently Viewed Presentations

  • Welcome to Rosshall Academys Transitions Information Evening To

    Welcome to Rosshall Academys Transitions Information Evening To

    Information Evenings at each Primary School. April/May 2018. Ready for Rosshall Programme at associate Primaries. Pastoral Care staff and S1/2 pupils visit P7 classes. Monday 30th April - Friday 4th May 2018, inclusive. Two-days induction at Rosshall. Wednesday 23rd and...
  • This exercise program was developed and made available

    This exercise program was developed and made available

    All of Missouri experiences freezing temperatures every year. In winter there is an average of about 110 days with temperature below 32° Freezing Rain is super-cooled on its descent and freezes after contact with freezing or below temp. objects on...
  • ONION - Company Profile

    ONION - Company Profile

    The first Software Testers are certified in 1998 2002 The I ISTQB® (International Software Testing Qualifications Board) is founded by 8 member boards: Austria, Denmark, Finland, Germany, Sweden, Switzerland, the Netherlands and UK 2003 The syllabus for the "Advanced Level"...
  • Presentazione standard di PowerPoint

    Presentazione standard di PowerPoint

    semper reformanda Tuttavia, le malattie e perfino gli scandali non potranno nascondere l'efficienza dei servizi, che la Curia Romana con fatica, con responsabilità, con impegno e dedizione rende al Papa e a tutta la Chiesa, e questa è una vera...
  • The News Report - mrsimnett.files.wordpress.com

    The News Report - mrsimnett.files.wordpress.com

    First, read through the OSSLT Scoring Criteria The criteria is vague so make sure your news report has enough detail to get you to the top. A passing mark is . only . a 50 or a 60! Then… Read...
  • Overview of IEEE 802.22 Standard

    Overview of IEEE 802.22 Standard

    1( replace the 2nd paragraph of 7.2.8.1 with the following: "Hence, when the PMK is created, it is created with a specific lifetime." 2) Modify the last sentence of the 3rd paragraph of 7.2.8.1 as follows: "Reauthentication shall be required...
  • Lecture 9: Trade-off theory - Zafer Yuksel

    Lecture 9: Trade-off theory - Zafer Yuksel

    Price the company used to call the bonds from the market. Call price > face value, why? The company would like to call the bond when the market interest rate is lower than the bond's coupon. When the company calls...
  • Utopia vs. Dystopia - Humble Independent School District

    Utopia vs. Dystopia - Humble Independent School District

    Utopia vs. Dystopia Brave New World as a Dystopia What is a Utopia? Literally it means "a place that does not exist" Basically it is the "perfect" society Utopistic narratives involve the descriptions of societies similar to the author's own...