towards an hi census of the local universe: further adventures in nibles tana joseph
TRANSCRIPT
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