Detection of the Missing Baryons in the Warm-Hot Intergalactic Medium – 19 Settembre 2018, ore 11:00 Aula IB09

INAF – Ossrvatorio Astronomico di Roma

Fabrizio Nicastro

It has been known for decades that the observed number of baryons in the local Universe falls about 30-40% short of the total number of baryons

predicted by Big-Bang Nucleosynthesis, inferred by density fluctuations of the Cosmic Microwave Background and seen during the first 2-3 billion

years of the universe (redshift z>2-3) in the so called “Lyman-α Forest”. While theory provides a reasonable solution to this paradox, by locating

the missing baryons in hot and tenuous filamentary gas connecting galaxies, it also sanctions the difficulty of detecting them because their by far

largest constituent, hydrogen, is mostly ionized and therefore virtually invisible in ordinary signal-to-noise Far-Ultraviolet spectra. Indeed, despite

the large observational efforts, only a few marginal claims of detection have been made so far.

Here I will first review the observational efforts pursued over the past 15 years by several groups and will then present our recent results that show

that the missing baryons are indeed found in a tenuous warm-hot and moderately enriched medium that traces large concentrations of galaxies

and permeates the space between and around them. I will show that the number of OVII systems detected down to the sensitivity threshold of our

data, agrees well with numerical simulation predictions for the long-sought hot intergalactic medium, and its detection adds a fundamental tile to

the long-standing missing baryon puzzle. Finally, I will comment on the implications of these new results for future high resolution X-ray missions

(e.g. Athena).

Area Tor Vergata – IAPS – Via Fosso Del Cavaliere, 100 


9 commenti
  1. says:

    Wow! This blogg looks just like my old one! It’s oon a entirely different topic but it has pretty much the same layout and design. Wonderful choice of colors!

  2. says:

    Its like you read my mind! You appear to know a lot about this, like youu wrote thee book in itt or
    something. I think that you could do with some
    pics to drive the message home a bit, but other than that,
    this is great blog. An excellent read. I will definitely be

  3. vintage green stone ring
    vintage green stone ring says:

    I carry on listening to the newscast speak about receiving
    boundless online grant applications so I have been looking
    around for the top site to gett one. Could you advise
    me please, where could i geet some?

  4. Gretchen
    Gretchen says:

    A person necessarily lend a hsnd to make seriously posts I might state.

    This is the first time I frequented your web page aand so far?

    I surprised with the research you made to create this particular pos incredible.
    Wondeerful job!

  5. arrange
    arrange says:

    This рage really has all the information and facts I wanted about this subject and
    didn’t know who to аsk.

  6. mail hosting satın al
    mail hosting satın al says:

    It’s a pity you don’t have a donate button! I’d definitely donate to this fantastic blog!
    I guess for now i’ll settle for book-marking and adding
    your RSS feed to my Google account. I look forward to nnew updates and will talk about this
    site with my Facbook group. Talk soon!

Lascia un Commento

Want to join the discussion?
Feel free to contribute!

Lascia una risposta

L'indirizzo email non verrà pubblicato.