[Seminar]

Title: Herschel high-z submillimeter lensed galaxies. H2O, a new
diagnosis of their dense cores.
Speaker: Prof. Alain Omont
Affiliation: Institut d'Astrophysique de Paris (IAP)
Time:  Sep. 6, 2012 (Thursday) 09:30
Venue:  Meeting Room 401 (Main Building)
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Abstract:
Herschel extragalactic wide surveys which have observed about 1000 deg2, are
discovering hundreds of high-z submillimeter strongly lensed galaxies. Gravitational
magnification there allows a gain by an order of magnitude in sensitivity in studying submillimeter
galaxies at high redshift (z~1-5). I will first summarize the main results of these submm surveys,
and the strategy for identifying, characterizing and following up these sources. Then I will focus on
H2O line studies in these lenses. After evoking Herschel results on H2O emission in local Ultra-
Luminous Infrared Galaxies (ULIRGs, SFR > 100 Mo/yr), results will be presented on similar
objects at high-z. Observing a sample of lenses from the H-ATLAS survey, we have just shown
that H2O is detectable in practically all Herschel strongly lensed galaxies with the
current sensitivity of IRAM-PdBI. We show that the H2O line luminosity increases as LIR1.3.
It thus reaches pretty high values in HLIRGs (SFR > 1000 Mo/yr), which have no local
equivalents but are abundant at z ~ 2-4. H2O lines provide thus an important diagnosis in extreme
starburst and possibly AGN conditions of warm, dense cores of these galaxies. Other new lines such
as H2O isotopologues, OH, OH+, H2O+, HF will complement this diagnosis. However, modeling
the infrared dominated excitation of H2O and other lines remains difficult, especially in the context
of HLIRG cores where complex processes take place such as IR radiation transfer, shocks, cosmic
rays, AGN feedback and XDR chemistry, outflows, etc. I will finally evoke various possible
extensions of such studies, especially with ALMA.
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大样本恒星演化组
中国科学院天体结构与演化重点实验室
云南天文台学术委员会
2012-09-02