Café GReCO le 30 mars

Voilà des articles interessants:

0903.2794 (Blasi: Pamela and cosmic rays)

0903.2829 (Dodelson et al.: DM and diffuse gamma-ray background)

0903.3041 (Boylan-kolkin et al: N-body simulation: millenium 2)

0903.2977 (Golovnev & Vanchurin: vector inflation)

0903.2986 (Wikstrom & Edsjo: neutrinos and DM)

 

A paper for the next Cafe

http://arxiv.org/pdf/0903.1852
Borriello, Cuoco & Miele
"Secondary radiation from the Pamela/ATIC excess and relevance for Fermi"

2 papiers

Trouvé 2 articles potentiellement intéressants :

arXiv:0903.1412  (inflation with SM Higgs + non-commutativity)

arXiv:0903.1520  (superHubble inhomogeneities & CMB)

Interesting (?) review

I am not going to discuss this, but I saw it and thought it could be nice to share
The Physics of Cosmic Acceleration
http://arxiv.org/pdf/0903.0866

R.R. Caldwell and M. Kamionkowski

Monday 9... continued

Look at these:

arXiv:0903.0818

Belokurov et al, "Sigue 2: a Prototype of the Population of Satellites of Satellites" 

arXiv: 0903:0591

Shi, "Testing of MOND with Local Group Timing"

arXiv:0903.0413

Bovi, "Substructure boosts to Dark Matter annihilation from Sommerfeld enhancement" 

arXiv:0903.0317

Iengo, "Sommerfeld enhancements for the Yukawa potential"

Another paper for monday 9

arXiv:0902.4750
Rouven Essig, Neelima Sehgal, Louis E. Strigari
Bounds on Cross-sections and Lifetimes for Dark Matter Annihilation and
Decay into Charged Leptons from Gamma-ray Observations of Dwarf Galaxies

Paper for monday 9

On the small-scale cutoff of the matter spectrum fluctuations (and smallest possible halo mass)
by Torsten Bringmann
http://arxiv.org/pdf/0903.0189

Another paper for Monday

I know that there are already many papers to discuss this Monday, but Fabio and I would like to suggest another paper on ultrahigh energy cosmic rays and neutrinos:

arXiv:0902.3993v1 "Neutrino diagnostics of ultra-high energy cosmic ray protons"
by Markus Ahlers, Luis A. Anchordoqui, Subir Sarkar

My Japanese collaborator Shigehiro Nagataki who works on the central engine of GRBs, neutrinos and ultrahigh energy cosmic rays (and who will also give a seminar in the morning) will be there, so he might have some comments on this paper too.

Autres papiers pour le lundi prochain (et les suivants..)

Voicì des autres papiers :

L.Pieri, M.Lattanzi and J.Silk,

arXiv: 0902.4330 sur le Sommerfeld effect et les galaxies nains du groupe local.

Bruch et al.

arXiv:0902.4001 sur les neutrinos et le sous-halos dans le disc de la Galaxie.

De-Chang et Stoikovich

arXiv: 0902.3662 sur les etoiles noires.

Bien! Nous avons plusiers de papiers pour ce Cafè GReCO. 

Nous attendons aussi beaucoup de gents que vien a les commentér!!

A lundì!!

Quelque papier pour lundi prochain - 2 mars

Bonjour, voici les premiers papiers pour lundi prochain.

Bringmann, Lavalle et Salati

arXiv:0902.3665 sur le mini trous noires.

The Fermi collaboration

arXiv:0902.1340 sur les observations de les premières sources gamma

Li et Barrow

arXiv 0902.3163 sur un modèle unifié de matiere noire 

Llinares et al

arXiv:0902.3010 sur la longue histoire de Mond VS Matiere Noire

Ibe et al

arXiv: 0902.2914 sur la "PAMELA saga"

A bientot, Lidia

un autre papiér

Voici un autre papiér sugeré par Miguel:

Abbasi et al. (Icecube collaboration)

arXiv:0902.2460

"Limits on a muon flux from neutralino annihilations in the Sun with Icecube 22-string detector"

Mercì a Miguel, et à bientot

Interesting papers for the Café GReCO on feb, monday 23rd

Bonjour a tous,

éssayéz vous à lir ces papiérs. Nous avons bisoin de volontaries pour les décrire!!!

T. Clifton et al

arXiv:0902:1313

about small angle CMB and curvature of the universe

N. Mavromatos et al

arXiv:0901.3932

Can TeVeS avoid dark matter on galactic scales?

J. Read et al

arXiv:0902.0009

A Dark Matter disk in three cosmological simulations of Milky Way mass galaxies

Venez nombreux. Il est un moment où tous nous pouvons apprendre ou enseigner quelque chose! 

One last-minute suggestion

I was forgetting to point you to 

Dark Matter annihilation rates with velocity-dependent annihilation cross-section

B. Robertson and A. Zentner

arXiv:0902.0362

See you in a hour!

Other suggestions for the next Café Greco

Hi, here are some other suggestions you may find interesting:

arXiv: 0902.0039

Cumberbatch et al, "Can the WMAP haze really be a signature of annihilating neutralino dark matter?

arXiv:0902.0593

Hooper & Zurek "The PAMELA and ATIC signals from Kaluza-Klein Dark Matter"

Some suggestions for the next

Not knowing exactly when the next cafe is going to be, I am posting suggestions I receive.

They will be discussed at the first chance.

Larissa proposes the following 

"Dynamical fine tuning in brane inflation" by J. Cline, L. Hoi and B. Underwood

http://arXiv.org/abs/0902.0339

We  still have leftover the GRB explanation of the Pamela/ATIC data (see link in another post) which I am sure Kumiko will be enthusiastic to discuss (sorry to frame you :) )

A possible explanation of the same data has been proposed in terms of SN remnants only by 

Shavir, Nakar and Piran

http://arXiv.org/abs/0902.0376

and I am sure more material will pile up in the next days.

Stay tuned!

Suggestions for monday february 2nd

For coming monday we have suggestions of diverse nature:

Patrick volunteers to lead the discussion on the paper 

http://arxiv.org/abs/0901.3474

where Brandenberger et al. propose an explanation of the Pamela positron excess in terms of non-superconducting cosmic strings.

We also have a paper which was not discussed last week, proposed by Lidia and Gianfranco, about the anisotropy properties of galactic and extra-galactic dark matter annihilation

http://arxiv.org/abs/0901.2921

by Mattia Fornasa et al.

I have also spotted a paper on a explanation of the Pamela + ATIC signals in terms of a nearby GRB 

http://arxiv.org/abs/0812.4851

by Kunihito Ioka

and I am sure there are experts on acceleration mechanisms who are eager to comment on it... :)

Please feel free to post (or send me, and I will post them for you) other suggestions at your leisure.

Another suggestion for monday 26th

Joe will lead the discussion on this paper, wich proposes a solution of the missing satellite problem.

"A quantitative explanation of the observed population of Milky Way satellite galaxies"

http://arxiv.org/abs/0901.2116

by S. Koposov, J. Yoo, H.W. Rix, D.H. Weinberg, A.V. Maccio', and J. Miralda-Escude'

Suggestions for Jan 26

Anisotropy probe of galactic and extra-galactic Dark Matter annihilations

Authors: Mattia Fornasa, Lidia Pieri, Gianfranco Bertone, Enzo Branchini

(Submitted on 19 Jan 2009)

Abstract: We study the flux and the angular power spectrum of gamma-rays produced by Dark Matter (DM) annihilations in the Milky Way (MW) and in extra-galactic halos. The annihilation signal receives contributions from: a) the smooth MW halo, b) resolved and unresolved substructures in the MW, c) external DM halos at all redshifts, including d) their substructures. Adopting a self-consistent description of local and extra-galactic substructures, we show that the annihilation flux from substructures in the MW dominates over all the other components for angles larger than O(1) degrees from the Galactic Center, unless an extreme prescription is adopted for the substructures concentration. We also compute the angular power spectrum of gamma-ray anisotropies and find that, for an optimistic choice of the particle physics parameters, an interesting signature of DM annihilations could soon be discovered by the Fermi LAT satellite at low multipoles, l<100,>10^4 solar masses. For the substructures models we have adopted, we find that the contribution of extra-galactic annihilations is instead negligible at all scales.

PDF

Dipolar Dark Matter and Dark Energy

Authors: Luc Blanchet, Alexandre Le Tiec

(Submitted on 20 Jan 2009)

Abstract: In previous work [L. Blanchet and A. Le Tiec, Phys. Rev. D 78, 024031 (2008)], a model of dark matter and dark energy based on the concept of gravitational polarization was investigated. This model was shown to recover the concordance cosmological scenario (Lambda-CDM) at cosmological scales, and the phenomenology of the modified Newtonian dynamics (MOND) at galactic scales. In this Letter we prove that the model can be formulated with a simple and physically meaningful matter action in general relativity. We also provide alternative derivations of the main results of the model.

PDF

Dark Matter Sees The Light

Authors: Patrick Meade, Michele Papucci, Tomer Volansky

(Submitted on 20 Jan 2009)

Abstract: We construct a Dark Matter (DM) annihilation module that can encompass the predictions from a wide array of models built to explain the recently reported PAMELA and ATIC/PPB-BETS excesses. We present a detailed analysis of the injection spectrums for DM annihilation and quantitatively demonstrate effects that have previously not been included from the particle physics perspective. With this module we demonstrate the parameter space that can account for the aforementioned excesses and be compatible with existing high energy gamma ray and neutrino experiments. However, we find that it is relatively generic to have some tension between the results of the HESS experiment and the ATIC/PPB-BETS experiments within the context of annihilating DM. We discuss ways to alleviate this tension and how upcoming experiments will be able to differentiate amongst the various possible explanations of the purported excesses.

PDF

Cafe on monday january 19th

Hello everybody,

coming monday I would like to discuss a paper from D. Rapetti and the rest of S. Allen's group:

http://arXiv.org/abs/0812.2259

on a test of modified gravity theories from the observed X-ray luminosity function of galaxy clusters. I am a little sceptical about some things in this paper, and there are few others I still do not understand so I would be glad if someone else could join efforts with me.

Also, I can propose you something that reminds me of my first astrophysical love: reionization and first stars.

In the paper

http://arXiv.org/abs/0812.3405

M. Alvarez et al. made a first ever attempt to connect reionization to the local Universe within the framework of a simulation. 

I have spotted few more papers about Pamela excess (they grow like mushrooms after a rainy shower) but we might keep for the future (unless someone else wishes differently). 

Anybody else is as usual welcome to propose whatever they found intriguing. 

Also, I would care to remind graduate students that the Cafe is a good gym to exercise their independence and curiosity (namely: post papers!) and that the only stupid thing about a question is not asking it (namely: if there is something you don't understand speak aloud!).

See you at the usual place, usual time.

Cafe on monday january the 12th

Hello everybody,

we start the first Cafe of the new Year with a joint presentation from Kumiko and myself: we will discuss the recent paper

http://arXiv.org/abs/0812.0597

from Jeltema, Kehayas and Profumo on gamma rays from clusters of galaxies, produced from cosmic rays and dark matter annihilation.

Gianfranco has proposed a paper by C. Alard

http://arXiv.org/abs/0901.0344

on a peculiar lensed system which seems to be compatible only with dark matter matter envelope around luminous objects, the discrepancy between light and gravitational mass being very hard to explain in modified gravity models.

If you have noticed any interesting paper in the last month please don't be shy and post it for our Cafe!

See you on monday same time, same place

Salut, and a cold and shining weekend.

No Cafe on monday, january 5th

Given the null response to the call, the first Cafe GReCO of 2009 will be on january 12th.