CCAT Studies of Nearby Galaxies. Gordon Stacey Cornell University. CCAT: The Nearby Universe. Starforming galaxies Continuum studies Spectral line studies Examples Active galactic nuclei: revealing the torus. Motivation. Extinction – we need to be able to observe the sources
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ISO 175 mContinuum Observations
M31: Haas et al. 1998
NOAO: M. Rushing
Spitzer IRAC Image
Image the Antennae in 4 bands (200, 350, 450, 850 um) in less than 2 hours, or only 10 minutes without the 200 um band!
Image M83 in 43 bands (350, 450, 850 um) in 4 hours.
Wright et al. 1991
CO Rotational DiagramNeutral lines from the Galaxy
It is clear that the CO cooling power on a galactic scale arises in the submm bands
The combined cooling in the 370 and 610 m lines equals the total cooling in all of the CO lines
It is the molecular gas reservoir that constrains future episodes of starformation
CO(7-6)/[CI] 370 m line intensity ratio vs. density for various values for the strength of the ISRF, G (Kaufman et al. 1999)The [CI] and CO(7-6) Lines
This line ratio of particular interest, as it is very density sensitive
n(H2)~ 4.5 104 cm-3, T = 120 K
CO is heated by cosmic rays (~ 800 MW value) from the nuclear starburst.
Bradford et al. 2003, ApJ 586, 891
SPIFI-JCMT [CI] 371 um & CO(76) (372 um) spectrum of the NGC 253 nucleus
TMB = 1 K
[CI]Starburst Galaxies: Mid-J CO and [CI] 370 um Lines
[CI] and CO(76) lines simultaneously mapped from NGC 253:
Cosmic ray enhancement of C0 abundance (cf. Farquhar, et al. 1994)
Added heat at cloud cores will inhibit cloud collapse – halting starburst
Nikola et al. 2005
TMB = 100 mK
TMB = 200 mK
TMB = 50 mK
Isaak et al. 2005
ISO: [NII] 122 m
ISO: [CII] 158 m
ISO: [OIII] 88 m
ISO mapping shows how the far-IR lines trace starformation with 70” beam
Can easily resolve the far-IR continuum, ionized gas ([NII]), atomic/molecular gas [CI] and dense molecular gas (mid-J CO) as they cross the spiral arms – can we trace the compression and “ignition” of the next generation of stars?
ISO: [OIII] 88 m
6” Resolution CO (1-0) Map on false-color HI (Rand Lord, & Higdon 1999)
KAO Map in [CII] 55” Beam (Geis et al.)
A long slit spectrometer would reduce this time by the number of beams along the slit (probably ~ 32) so that the whole project will take only about an hour
is not derived from stars are termed “active
Artist’s conception of the doughnut shaped torus that confines the emission from an active nucleus (Credit ESA).
Predictions are significantly below the detection limits of ISO/LWS at 48 m and 153 m – however, CCAT could detect such a source in the CO(1312) line at 200 um withSNR ~ 100 in 20 minutes
*fabs is the fraction of hard x-ray emission absorbed by the torus (~10%), and LX44 is the ionizing luminosity in units of 1044 ergs –s-1 (Krolik & Lepp,1989)
Line flux prediction ~ 5 105 L, or 7 10-17 W/m2! – easily detectable SNR 100 in 20 minutes.
The [CII]/far-IR continuum ratio as a function of G (from Kaufmann et al)Redshifted [CII]
Detecting [CII] from highly redshifted galaxies probes star formation in the epoch of galaxy formation
BP Filter Wheel
ZEUS Spectral Coverage
LP Filter 2
4He Cold Finger
LP Filter 1
Spectral coverage of ZEUS, superposed on the Mauna Kea windows.
Dual stage 3He refrigerator
4He cryostatThe Redshift (z) and Early Universe Spectrometer (ZEUS)
Estimates of the comoving star formation history (Blain et al). Filled squares and circles toward the bottom represent the original Madau plot based on optical/UV HDF observations (Madau et al). Open squares correct this data for dust extinction (Pettini et al). The 7 upper curves are models that are consistent with the SCUBA data. The solid lines beneath the curves mark the redshft ranges accessible to ZEUS.
ZEUS WindowsFar-IR Lines and the Early Universe
Milky WayRedshifted [CII] Emission Yields Far-UV Field Strength and Redshifts
[CII] still readily detectable!