Observational Cosmology (C. Porciani / K. Basu) Lecture 11 - - PowerPoint PPT Presentation

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Observational Cosmology (C. Porciani / K. Basu) Lecture 11 - - PowerPoint PPT Presentation

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Observational Cosmology (C. Porciani / K. Basu) Lecture 11 Starbursts and Sub-mm Galaxies (high-z universe through dust) Course website: http://www.astro.uni-bonn.de/~kbasu/astro845.html Observational Cosmology Lecture 11 (K. Basu):

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Observational Cosmology Lecture 11 (K. Basu): Starbursts and Sub-mm Galaxies

Course website: http://www.astro.uni-bonn.de/~kbasu/astro845.html

Lecture 11

Starbursts and Sub-mm Galaxies

(high-z universe through dust)

Observational Cosmology

(C. Porciani / K. Basu)

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Observational Cosmology Lecture 11 (K. Basu): Starbursts and Sub-mm Galaxies

Outline of today’s lecture

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Structure formation and the first stars

Distant starbursts, SED of sub-millimeter galaxies

Global star formation and the stellar IMF Imaging blank sky at sub-mm wavelengths Sub-mm galaxies lensed by clusters

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Observational Cosmology Lecture 11 (K. Basu): CMB spectrum and anisotropies

Starbursts and galaxy evolution

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z

1100 1 6 20

Epoch of Reionization Cosmic ‘Dark Ages’ Starbursts and QSOs Major themes and questions regarding the formation and evolution of galaxies:

  • First stars and AGN
  • Mergers vs. cold streams driving galaxy

formation

  • Spatially resolved distributions of SF, gas,

stellar populations, metallicities

  • Rotation curves & connection to halo;

angular momentum distribution

  • Co-evolution of massive black holes and

host galaxies

  • Roles of mergers vs. secular evolution /

environment

  • Bulge vs disk formation
  • Roles of stellar and AGN feedback
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Observational Cosmology Lecture 11 (K. Basu): CMB spectrum and anisotropies

Evolutionary history of starbursts

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Dust plays two crucial roles in star formation process

  • protects fragile molecules from being dissociated by intense UV &
  • ptical interstellar radiation field & hence enables collapse of

molecular gas to start

  • the dust provides an effjcient way for the protostar to radiate away

energy associated with the gravitational collapse of the molecular envelope, allowing growth of protostar to continue Although dust is important we still know very little about the composition and properties of the grains

Observational Cosmology Lecture 11 (K. Basu): CMB spectrum and anisotropies

Dust and star formation

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Observational Cosmology Lecture 11 (K. Basu): CMB spectrum and anisotropies

Dust obscured star formation

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Optical (HST) Sub-millimeter (450 μm)

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Observational Cosmology Lecture 11 (K. Basu): CMB spectrum and anisotropies

Archetypical interacting galaxy

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Arp 244 (“Antenna”)

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Observational Cosmology Lecture 11 (K. Basu): CMB spectrum and anisotropies

Location of starburst

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CO + Optical

The starburst is hidden behind dense dust clouds

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Observational Cosmology Lecture 11 (K. Basu): CMB spectrum and anisotropies

Location of starburst

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850µm

CO + Optical

The starburst is hidden behind dense dust clouds

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The submillimeter extragalactic Background

Hughes et al. 1998

SCUBA first resolved the submm background

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Observational Cosmology Lecture 11 (K. Basu): CMB spectrum and anisotropies

SEDs of galaxies

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Observational Cosmology Lecture 11 (K. Basu): CMB spectrum and anisotropies

SED of starbursts

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Observational Cosmology Lecture 11 (K. Basu): CMB spectrum and anisotropies

Distant starbursts

12 Aravena PhD Thesis 2009

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Observational Cosmology Lecture 11 (K. Basu): CMB spectrum and anisotropies

Negative k-correction

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Observational Cosmology Lecture 11 (K. Basu): CMB spectrum and anisotropies

Negative k-correction

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Observational Cosmology Lecture 11 (K. Basu): CMB spectrum and anisotropies

Finding counterparts for redshifts

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  • 5

20' 10' 0 -10' -20'

[arcmin]

Near-IR (K band) plus radio 1.4 GHz contours

mm “Blank Field Surveys”

vigorous starbursts (HLIRGs) and QSOs

MAMBO 1.2mm

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5

  • 5

20' 10' 0 -10' -20'

[arcmin]

Near-IR (K band) plus radio 1.4 GHz contours

mm “Blank Field Surveys”

vigorous starbursts (HLIRGs) and QSOs

MAMBO 1.2mm

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HST images of submm galaxies (Chapman et al.) apparently these are interacting, irregular systems

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K R I

MAMBO Bure radio Dannerbauer et al. 2002

K Optical counterparts are very faint!

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estimated from the mm/radio flux ratio, which steepens with increasing z.

Redshift Distribution

Aretxaga et al. 2007

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Observational Cosmology Lecture 11 (K. Basu): CMB spectrum and anisotropies

Redshift distribution of SMGs

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Chapman, Blain, Ivison & Smail 2003

KECK spectroscopy of SCUBA/MAMBO galaxies

  • SMGs are at high z.
  • radio-submm photo-z agree on average with

spectroscopic z

  • radio selection introduces bias against z>3.

It has been very difficult to follow up SMGs without radio counterparts: potentially high-z or cold dust.

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Observational Cosmology Lecture 11 (K. Basu): CMB spectrum and anisotropies

Problems with inferred SF

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Observational Cosmology Lecture 11 (K. Basu): CMB spectrum and anisotropies

Cosmic star formation history

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  • Studying the star formation history (temporal evolution of the

star formation is key in understanding galaxy evolution in its broader context

The star formation rate (SFR) is the key driver of structure evolution in the ISM, and strongly influences galaxy formation and evolution via energy, momentum, and chemical feedback from subsequent stellar winds and supernova explosions.

  • UV emission from the first generation of massive stars is most likely

responsible for the re-ionization of the Universe at z > 6, and the integrated light of evolving stellar populations generated a difguse cosmic IR to X-ray backgrounds.

  • IR-UV continuum emission and optical line emission can be used to

determine the specific SFR in galaxies, and an extinction corrected rate density, SFR(z), can be estimated.

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Energy generation in the universe

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Lilly-Madau plot: Observations (data points) and theoretical models based on hierarchical structure formation (lines). The normalization assumes Salpeter

  • IMF. From review by A. Blain (2002).

Field redshift surveys to z~1 (Lilly et al 1996, Ellis et al 1996) Counts of LBGs at z>2 (Madau et al 1996)

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Various probes of the global SF rate: ρ✶(z) M⊙◉☉⨁ yr-1 comoving Mpc-3

  • UV continuum (GALEX, LBGs)
  • H and [O II] emission in

spectroscopic surveys

  • mid-IR dust emission
  • 1.4 GHz radio emission

No simple “best method”: each has pros and cons (dust extinction, sample depth, z range and physical calibration uncertainties) Each has difgerent time-sensitivity to main sequence activity so if SFR not uniform do not expect same answers for the same sources

Observational Cosmology Lecture 11 (K. Basu): CMB spectrum and anisotropies

Star formation indicators

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Observational Cosmology Lecture 11 (K. Basu): CMB spectrum and anisotropies

Cosmic SF: Calibration

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Observational Cosmology Lecture 11 (K. Basu): CMB spectrum and anisotropies

Star-formation in the universe

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State of the art: Mesurement of cosmic star formation history, taken from Rojopakarn et al. 2010 (black = 24μ rest frame luminosity, blue = extinction corrected UV, red = IR, grey = radio, X-ray, OII, Hα)

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Observational Cosmology Lecture 11 (K. Basu): CMB spectrum and anisotropies

Initial Mass Function for stars

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Why it is important?

  • Link between stellar and galactic evolution
  • Insight into theories of star formation
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Observational Cosmology Lecture 11 (K. Basu): CMB spectrum and anisotropies

Salpeter IMF

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Observational Cosmology Lecture 11 (K. Basu): CMB spectrum and anisotropies

Salpeter IMF at low mass

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Observational Cosmology Lecture 11 (K. Basu): CMB spectrum and anisotropies

Modified stellar IMF

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Observational Cosmology Lecture 11 (K. Basu): CMB spectrum and anisotropies

Uncertainties on the IMF

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Is the IMF `universalʼ? i.e. is ξ(M) the same function everywhere? Most theorists say no. Predict that fragmentation is easier if the gas can cool, so primordial gas without any metals should form more massive stars. Observationally, little or no evidence for variations in the IMF in our galaxy or nearby galaxies.

Credit: H. Lux, University of Zurich

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IMF and the SF history

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Simulations suggest a strong bias of the Initial Mass Function (IMF) to larger stellar masses with decreasing metallicity and thus, on average, higher redshift. In turn this afgects the mass-loss of these early stars, and their subsequent explosions. Low metallicity implies low mass loss, so that early stars will be more massive than present stars, even if the IMF were universal. While most massive stars today explode as Type II core collapse supernovae (cc SNe or SNII), a near zero-metallicity star (Pop III) of ~150 M⊙◉☉⨁ more likely dies by pair instability. Feedback on the environment from the first generation of supernovae is difgerent than in a present-day galaxy. Star formation today takes place in dense molecular clouds, while in the early Universe it was hampered by ineffjcient cooling in pristine H-He environments.

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Observational Cosmology Lecture 11 (K. Basu): CMB spectrum and anisotropies

Optical to IR difguse background

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CMB

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Observational Cosmology Lecture 11 (K. Basu): CMB spectrum and anisotropies

Optical to IR difguse background

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Observational Cosmology Lecture 11 (K. Basu): CMB spectrum and anisotropies

Optical to IR difguse background

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SUBARU BVr’i’z’ SuprimeCam

(Taniguchi et al.)

1.4 deg

COSMOS

(2 sq. deg.)

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SUBARU BVr’i’z’ SuprimeCam

(Taniguchi et al.)

BOLOCAM MAMBO AzTEC

1.4 deg

COSMOS

(2 sq. deg.)

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rms ~ 1 mJy 15 sources S/N > 4 12 sources S/N = 3.5-4 and radio paper in ApJS

COSMOS

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rms ~ 1 mJy 15 sources S/N > 4 12 sources S/N = 3.5-4 and radio paper in ApJS

COSMOS

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Observational Cosmology Lecture 11 (K. Basu): CMB spectrum and anisotropies

MAMBO number counts

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Observational Cosmology Lecture 11 (K. Basu): CMB spectrum and anisotropies

MAMBO number counts

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MAMBO 1.2mm

5% of CIB

Bertoldi ea. 07

2 3 4 5 7 10 flux density [mJy]

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Observational Cosmology Lecture 11 (K. Basu): CMB spectrum and anisotropies

MAMBO number counts

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MAMBO 1.2mm

5% of CIB

Bertoldi ea. 07

2 3 4 5 7 10 flux density [mJy]

Voss ea. 06

ALMA! (Holdaway ea.)

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Observational Cosmology Lecture 11 (K. Basu): CMB spectrum and anisotropies

Sub-mm source counts

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Only a small fraction of the CIB has been resolved

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Observational Cosmology Lecture 11 (K. Basu): CMB spectrum and anisotropies

Sub-mm source counts

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Observational Cosmology Lecture 11 (K. Basu): CMB spectrum and anisotropies

Sub-mm galaxies behind clusters

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Observation of galaxy clusters at sub-mm wavelengths almost always reveal a host of sources coming out of the confusion. These are distant, faint sub-mm galaxies. Study of the faint end (< 2 mJy)

  • f these sub-mm galaxy population is important to constrain the

cosmic star formation history.

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Observational Cosmology Lecture 11 (K. Basu): CMB spectrum and anisotropies

Lensed sub-mm galaxies

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Knudsen et al. 2008

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Observational Cosmology Lecture 11 (K. Basu): CMB spectrum and anisotropies

Behind the Bullet cluster

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Johansson et al. 2010 z = 3.9