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simulation. |
8µm LF.Monochromatic 8 µm luminosity ( L8µm) is known to correlate well with |
the TIR luminosity [1, 6], especially for star-forming gala xies because the rest-frame |
8µmfluxaredominatedbyprominentPAHfeaturessuchasat6.2,7 .7and8.6 µm.The |
leftpanelofFig.1showsastrongevoltuionof8 µmLFs.Overplottedpreviousworkhad |
torelyonSEDmodelstoestimate L8µmfromtheSpitzer S24µmintheMIRwavelengths |
whereSEDmodelingisdifficultduetothecomplicatedPAHemi ssions.Here,AKARI’s |
mid-IR bands are advantageous in directly observing redshi fted restframe 8 µm flux in |
one of the AKARI’s filters, leading to more reliable measurem ent of 8µm LFs without |
uncertaintyfromtheSED modeling. |
12µm LF.12µm luminosity ( L12µm) represents mid-IR continuum, and known to |
correlate closely with TIR luminosity [11]. The middle pane l of Fig.1 shows a strong |
evoltuion of 12 µm LFs. Here the agreement with previous work is better becaus e (i) |
12µm continuum is easier to be modeled, and (ii) the Spitzer also captures restframe |
12µm inS24µmat z=1. |
TIRLF.Lastly,weshowtheTIRLFsintherightpanelofFig.1.Weused Lagache, |
Dole, & Puget [8]’s SED templates to fit the photometry using t he AKARI bands |
at>6µm (S7,S9W,S11,L15,L18WandL24). The TIR LFs show a strong evolution |
comparedto localLFs. At 0 .25<z<1.3,L∗ |
TIRevolvesas ∝(1+z)4.1±0.4.FIGURE2. Evolutionof TIRluminositydensitybasedon TIRLFs (redcir cles),8µmLFs (stars), and |
12µm LFs (filled triangles). The blue open squares and orange fill ed squares are for LIRG and ULIRGs |
only,alsobasedonour LTIRLFs.Overplotteddot-dashedlinesareestimatesfromtheli terature:LeFloc’h |
et al. [9], Magnelli et al. [10] , Pérez-González et al. [11], Caputi et al. [2], and Babbedge et al. [1] are |
in cyan, yellow, green, navy, and pink, respectively. The pu rple dash-dotted line shows UV estimate by |
Schiminovichet al.[13].Thepinkdashedlineshowsthe tota lestimateofIR(TIRLF)andUV [13]. |
Cosmic star formation history .We fit LFs in Fig.1 with a double-power law, then |
integrate to estimate total infrared luminosity density at various z. The restframe 8 |
and 12µm LFs are converted to LTIRusing [11, 2] before integration. The resulting |
evolution of the TIR density is shown in Fig.2. The right axis shows the star formation |
densityassumingKennicutt[7].We obtain ΩIR(z)∝(1+z)4.4±1.0. Comparisonto ΩUV |
[13] suggests that ΩTIRexplains 70% of Ωtotalatz=0.25, and that by z=1.3, 90% of |
the cosmic SFD is explained by the infrared. This implies tha tΩTIRprovides good |
approximationofthe Ωtotalatz>1. |
In Fig.2, we also show the contributions to ΩTIRfrom LIRGs and ULIRGs. From |
z=0.35 to z=1.4,ΩIRby LIRGs increases by a factor of ∼1.6, andΩIRby ULIRGs |
increases byafactorof ∼10. Moredetailsarein Gotoet al. [3]. |
Spatially-Resolved Spectroscopy of an E+A (post-starburs t) System .We per- |
formed a spatially-resolved medium resolution long-slit s pectroscopy of a nearby E+A |
(post-starburst) galaxy system with FOCAS/Subaru [4]. Thi s E+A galaxy has an obvi- |
ous companion galaxy 14kpc in front (Fig.3, left) with the ve locity difference of 61.8 |
km/s. |
WefoundthatH δequivalentwidth(EW)oftheE+Agalaxyisgreaterthan7Å gal axy |
wide (8.5 kpc) with no significant spatial variation. We dete cted a rotational velocity in |
the companion galaxy of >175km/s. The progenitor of the companion may have beenFIGURE 3. (left) The SDSS g,r,i-composite image of the J1613+5103. The long-slit position s are |
overlayed.The E+A galaxy is to the right (west), with bluer c olour. The companion galaxy is to the left |
(east). (right) H δEW is plotted against D4000. The diamonds and triangles are f or the E+A core/north |
spectra, respectively. The squares and crosses are for the c ompanion galaxy’s core/north spectra. Gray |
lines are population synthesis models with 5-100% delta bur st population added to the 10G-year-old |
exponentially-decaying( τ=1Gyr)underlyingstellarpopulation.SalpeterIMFandmet allicityof Z=0.008 |
areassumed.Onthe models,burstagesof0.1,0.25,0.5and2 G yraremarkedwiththefilled circles. |
a rotationally-supported, but yet passive S0 galaxy. The ag e of the E+A galaxy after |
quenching the star formation is estimated to be 100-500Myr, with its centre having |
slightly younger stellar population. The companion galaxy is estimated to have older |
stellarpopulationof >2 Gyrs ofagewithnosignificantspatialvariation(Fig.3, ri ght). |
Thesefindingsareinconsistentwithasimplepicturewheret hedynamicalinteraction |
createsinfallofthegasreservoirthatcausesthecentrals tarburst/post-starburst.Instead, |
ourresultspresentanimportantexamplewherethegalaxy-g alaxyinteractioncantrigger |
agalaxy-widepost-starburstphenomena. |
REFERENCES |
1. BabbedgeT.S.R., et al.,2006,MNRAS, 370,1159 |
2. CaputiK.I.,et al.,2007,ApJ,660,97 |
3. GotoT.,et al. 2010,A&AAKARI specialissue |
4. GotoT.,YagiM.,YamauchiC., 2008,MNRAS, 391,700 |
5. HopkinsA.M.,ConnollyA. J.,HaarsmaD. B.,CramL. E.,200 1,AJ, 122,288 |
6. HuangJ.-S.,et al.,2007,ApJ, 664,840 |
7. KennicuttR. C.,Jr., 1998,ARA&A,36,189 |
8. LagacheG., DoleH.,PugetJ.-L.,2003,MNRAS, 338,555 |
9. LeFloc’hE.,etal., 2005,ApJ,632,169 |
10. MagnelliB., et al.2009,A&A,496,57 |
11. Pérez-GonzálezP. G.,etal., 2005,ApJ,630,82 |
12. RushB., MalkanM. A.,SpinoglioL.,1993,ApJS,89,1 |
13. SchiminovichD.,et al.,2005,ApJ, 619,L47 |
14. Wada T.,et al.,2008,PASJ, 60,517 |
arXiv:1001.0008v2 [hep-th] 6 Jan 2010Multi-Stream Inflation: Bifurcations and Recombinations i n the Multiverse |
Yi Wang∗ |
Physics Department, McGill University, Montreal, H3A2T8, Canada |
In this Letter, we briefly review the multi-stream inflation s cenario, and discuss its implications in |
the string theory landscape and the inflationary multiverse . In multi-stream inflation, the inflation |
trajectory encounters bifurcations. If these bifurcation s are in the observable stage of inflation, then |
interesting observational effects can take place, such as do main fences, non-Gaussianities, features |
and asymmetries in the CMB. On the other hand, if the bifurcat ion takes place in the eternal stage |
of inflation, it provides an alternative creation mechanism of bubbles universes in eternal inflation, |
as well as a mechanism to locally terminate eternal inflation , which reduces the measure of eternal |
inflation. |
I. INTRODUCTION |
Inflation [1] has become the leading paradigm for the |
very early universe. However, the detailed mechanism |
for inflation still remains unknown. Inspired by the pic- |
ture of string theory landscape [2], one could expect that |
the inflationary potential has very complicated structure |
[3]. Inflation in the string theory landscape has impor- |
tantimplicationsinbothobservablestageofinflationand |
eternal inflation. |
The complicated inflationary potentials in the string |
theory landscape open up a great number of interest- |
ing observational effects during observable inflation. Re- |
searchesinvestigatingthecomplicatedstructureofthein- |
flationary potential include multi-stream inflation [4, 5], |
quasi-single field inflation [6], meandering inflation [7], |
old curvaton [8], etc. |
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