Transcript ALFALFA***H

ALFALFA
2012
Hα
8
14
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Hα
ISO Spitzer
CO HCN
AKARI WISE
Herschel
Hα
Spitzer 8
Spitzer24
PAH
Hα
Hα
Ha
Zhu et al. 2008
dwarfs
HI
HI
HI
SFR/M
HI
HI
FAST
Arecibo Legacy Fast ALFA survey (ALFALFA)
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Extragalatic spectral line survey
The largest single-aperture telescope (305m)
Arecibo L-band Feed Array (ALFA)
http://egg.astro.cornell.edu/alfalfa
7 pixel radio
camera
ALFALFA survey
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To cover 7000 sq deg of high galactic latitude sky
1345-1435 MHz (-2000 to +17,500 km/s for HI line)
5 km/s resolution
2-pass drift mode (total int. time per beam ~ 40 s)
~2.3 mJy rms (per spectral pixel)
– MHI~105 M in LG, ~107 M at Virgo
• 4400 hrs of telescope time, 5+ years
• Started Feb’05, 97% complete (779 runs) as of May’12
– ALFALFA 40% catalog: 15000+ detections covering a cosmologically
significant volume at z~0 (Haynes+ 2011)
Survey strategy
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ALFA beam size: 3.3’x3.8’
“Almost” fixed azimuth drift mode
First pass beams spaced by 14.6’
2nd pass offset from the 1st to give 1.05’ sampling
Highly efficient: 99% “open shutter” time
Galactic plane
fall
sky
spring sky
fall
sky
• ALFALFA
HI
Arecibo
SDSS
HI
7000
20000
0.06
40% α40 (Martin et al. 2010)
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Spitzer IRAC3.6
CfA
α40
Spitzer
2600
4.5
4588
3.6/4.5
ALFALFA
Zhu et al. 2008
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RA
Dec
RA
DEC
RA
DEC
22h to 3h
24d to 32d
2
7h30m to 16h30m
4d to 16d
3
7h30m to 16h30m
24d to 28d
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Hα
Hα
Hα
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2.16
2.4
Hα
BFOSC
YFOSC
0.07
500-1000
1000 2000 ALFALFA
Hα
3-5
NGC 5394/5
Arecibo
Spitzer WISE
Hα
SDSS
Spitzer WISE
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2)
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5)
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FAST
FAST
ALFALFA
KKR17
KKR17
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RA 15h11m10.2s
DEC +11d01m56s
z=0.0277,
8283km/s
M(HI) = 109.64 Msun
2012/06/15~17
seeing~2"
1h
KKR17
KKR17
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2
SDSS 5
18.21 17.35 17.01 17.45 17.01
B
-17.73
µ(B) = 24.18 magsec-2
KKR17
(1)
KKR17
(2)
KKR17
• KKR17 [NII]
1
• S(Ha)/S(Hb) = 2.58 < 2.87
SCUSS
fall sky
• ALFALFA
spring sky
+SCUSS
ALFALFA
fall sky