Extragalactic hi surveys with the feed array
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Extragalactic HI Surveys with the Feed Array. Riccardo Giovanelli Cornell University. Main Scientific Goals: Investigate the faint end of the HI mass function (HIMF) Determine the local density dependence of the HIMF Map the distribution of luminous and dark matter

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Extragalactic HI Surveys with the Feed Array

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Extragalactic hi surveys with the feed array

Extragalactic HI Surveys with the Feed Array

Riccardo Giovanelli

Cornell University


Extragalactic hi surveys with the feed array

  • Main Scientific Goals:

  • Investigate the faint end of the HI mass function

  • (HIMF)

  • Determine the local density dependence of the HIMF

  • Map the distribution of luminous and dark matter

  • in the local (z < 0.1) Universe

  • Determine the gas-rich membership of nearby

  • groups of galaxies

  • Determine the population of gas-rich systems in the

  • Local Group and the periphery of the MW (HVCs)

  • Find (rare) OH Megamasers near z=0.25

  • Be surprised


Extragalactic hi surveys with the feed array

A few useful scaling laws…


Extragalactic hi surveys with the feed array

Beam dilution

[by comparison, HIPASS detects 1 million solar masses at 1 Mpc in 460 sec…]


Survey simulation ingredients

Survey simulation ingredients…


Extragalactic hi surveys with the feed array

HIMF

where

Zwaan et al. 97:

Rosenberg & Schneider 02:

[Mpc**-3 dex**-1]


Extragalactic hi surveys with the feed array

Source-to-beam extent

Integration time in sec

Signal width in km/s


Extragalactic hi surveys with the feed array

  • The reliability of a detection depends on S/N.

  • Model the probability p, that a “detection” at given S/N

  • will be confirmed, as

  • Model W_kms as Gauss deviate with dispersion 0.1 dex about

scramble disk inclination and add turbulent term

  • Model source size as


Extragalactic hi surveys with the feed array

  • Simulate random pointing errors and estimate

  • beam dilution factor

  • Model suppression of gas infall onto low mass

  • halos due to reionization (e.g. adopting the

  • “filtering mass” criterion of Gnedin & Hui 1998)

Next,

adopt a model for the cosmic density field


Extragalactic hi surveys with the feed array

Slice of the cosmic

Density field along

The Supergalactic

Plane

You are here


Extragalactic hi surveys with the feed array

Where are the

Low HI mass

Systems?

Normalized Cosmic Density

  • Most of the mass is to be found in regions of density

  • substantially higher than average

Caveat:

But, do low baryonic mass systems trace the cosmic

density distribution?


Extragalactic hi surveys with the feed array

  • A set of survey simulations:

  • All-AO, fast (6-sec) sky survey:

  • ALFALFA

  • 300 - sec ZOA ``staring’’ survey

  • ZOA

  • 60 - sec Virgo Cluster survey

  • VIRGO


Extragalactic hi surveys with the feed array

6 seconds


Extragalactic hi surveys with the feed array

6 seconds


Extragalactic hi surveys with the feed array

ZOA

300 sec

|b| < 10

AO limits


Extragalactic hi surveys with the feed array

ZOA

300 sec

|b| < 10

AO limits


Extragalactic hi surveys with the feed array

ZOA

300 sec

|b| < 10

AO limits


Extragalactic hi surveys with the feed array

Virgo

11h-13h RA

0 to 27 Dec

60 sec

800 hours


Extragalactic hi surveys with the feed array

What about synergies?


Extragalactic hi surveys with the feed array

What about synergies?


Extragalactic hi surveys with the feed array

1 second


Extragalactic hi surveys with the feed array

1 second

1 second


Extragalactic hi surveys with the feed array

3 seconds


Extragalactic hi surveys with the feed array

3 seconds


Extragalactic hi surveys with the feed array

[by comparison, HIPASS detects 1 million solar masses at 1 Mpc in 460 sec…]


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