Towards an HI census Towards an HI census of the Local Universe: of the Local Universe:

further adventures in further adventures in NIBLES NIBLES

Tana JosephTana Joseph

OverviewOverview

What is NIBLES?What is NIBLES? The HI dataThe HI data The optical dataThe optical data

Some curious resultsSome curious results Re-analysis of the photometryRe-analysis of the photometry

ImplicationsImplications

What is NIBLES?What is NIBLES?

NIBLES: Nançay Interstellar Baryonic Legacy NIBLES: Nançay Interstellar Baryonic Legacy Extragalactic SurveyExtragalactic Survey

Quantify HI content of galaxies in the Local Quantify HI content of galaxies in the Local UniverseUniverse

4000 SDSS galaxies with4000 SDSS galaxies with 900< cz < 12 000 km/s (Local Universe)900< cz < 12 000 km/s (Local Universe) -10-10mm > M > Mz z > -24> -24mm

All morphological typesAll morphological types

The HI dataThe HI data

Preliminary HI data for 600 galaxiesPreliminary HI data for 600 galaxies

Compared to NHICAT data (Wong et al., 2006)Compared to NHICAT data (Wong et al., 2006) Velocities agree well with NHICAT dataVelocities agree well with NHICAT data

HI data reliable HI data reliable

Some curious resultsSome curious results

Preliminary results: Preliminary results: very high mass to very high mass to light ratioslight ratios

What could the problem be?What could the problem be?

Are these data points real?Are these data points real? No other systems found with such high MNo other systems found with such high MHIHI/L (Warren /L (Warren

et al., 2006, van Zee, 2001)et al., 2006, van Zee, 2001) Highest: MHighest: MHIHI/L/LBB = 22 M = 22 M/L/L

Since HI data ok, photometry probably at faultSince HI data ok, photometry probably at fault Incorrect magnitudes due to circular aperture?Incorrect magnitudes due to circular aperture? But Strauss et al., 2002 find no problems for highly But Strauss et al., 2002 find no problems for highly

inclined systemsinclined systems

What could the problem be?What could the problem be?

Optical “confusion” sources?Optical “confusion” sources? E.g. SDSS012206+005616 and E.g. SDSS012206+005616 and

SDSS012213+005731 (MSDSS012213+005731 (MBB=-13=-13mm,M,MHIHI/L/LBB = 367 M = 367 M/L/L))

are part of NGC0493 (Mare part of NGC0493 (MBB=-20=-20mm,M,MHIHI/L/LBB = 0.5 M = 0.5 M/L/L)) Not enough to account for all high MNot enough to account for all high MHIHI/L values/L values

Re-analysis of the Re-analysis of the photometric dataphotometric data

Individual photometry performed onIndividual photometry performed on a subsample of 403 galaxies out of 1385 (g a subsample of 403 galaxies out of 1385 (g

band)band) All galaxies in range -10All galaxies in range -10mm > M > Mzz > -14 > -14m m (i band) (i band) Using Source Extractor and JPK’s pipelineUsing Source Extractor and JPK’s pipeline

mmSESE - m - mSDSSSDSS vs. vs.

Petrosian radiusPetrosian radius

The g band photometryThe g band photometry

g band magnitude g band magnitude comparisoncomparison

mmSESE - m - mSDSSSDSS vs. vs. Petrosian radiusPetrosian radius

The I band photometryThe I band photometry

i band magnitude i band magnitude comparisoncomparison

Re-analysis of the Re-analysis of the photometric dataphotometric data

Galaxies with RGalaxies with RPP < 8’’ < 8’’

have underestimated have underestimated magnitudes in both g magnitudes in both g and i bandsand i bands

Excising sources with Excising sources with RRP P < 8” gives much < 8” gives much

better agreement better agreement between SDSS and between SDSS and SE dataSE data

Re-analysis of the Re-analysis of the photometric dataphotometric data

MMHIHI/L/Lgg re-determined re-determined

using SDSS using SDSS magnitudes for Rmagnitudes for RP P > >

8” and SE 8” and SE magnitudes for Rmagnitudes for RP P < <

8” 8”

Re-analysis of the Re-analysis of the photometric dataphotometric data

MMHIHI/L/Lii re-determined re-determined

using SDSS using SDSS magnitudes for Rmagnitudes for RP P > >

8” and SE 8” and SE magnitudes for Rmagnitudes for RP P < <

8”8”

ImplicationsImplications

No galaxies with MNo galaxies with Mgg > -13 > -13mm and M and Mii > -12 > -12mm

remain when using SE data for sources remain when using SE data for sources with Rwith RP P < 8” !< 8” !

Implications for various studies using Implications for various studies using SDSS photometry:SDSS photometry: The Luminosity function of the Local UniverseThe Luminosity function of the Local Universe Galaxy formation and evolution theories and Galaxy formation and evolution theories and

modelsmodels

Thank youThank you