D. V. Stark (UNC), S. J. Kannappan (UNC), L. H. Wei (UMD), A. J....
Transcript of D. V. Stark (UNC), S. J. Kannappan (UNC), L. H. Wei (UMD), A. J....
Constraining the MultiPhase Gas Content of Galaxies in the Local Cosmic WebD. V. Stark (UNC), S. J. Kannappan (UNC), L. H. Wei (UMD), A. J. Baker (Rutgers), M. P. Haynes
(Cornell), R. Giovanelli (Cornell), F. Heitsch (UNC), and the RESOLVE and ALFALFA Teams
RESOLVE: A Comprehensive Mass CensusMass census of all galaxies with Mb a r y o n i c >~ 1.5x109 Ms u n in two subvolumes totaling ~53,000 Mpc3
Dynamical masses from SOAR longslit/imageslicer survey of ionized gas and stellar kinematicsCluster/Group masses from redshift campaign Stellar masses from SED+spectral fitting using public UV/opt/NIR surveysGas masses from methods described hereKey science includes:
➢ Multiscale constraints on missing baryons➢ Merger rates as a function of dynamical mass and gas mass ratio➢ Relationship of disk regrowth and pure disk galaxies to large scale structure➢ Origin of gas richness threshold at log Ms t a r s ~ 9.7 (Kannappan et al 2009)
IntroductionThe RESOLVE Survey is a census of gas, stars, and dark matter within a well defined volume of the local universe. Here, we describe how we will account for the gas mass within RESOLVE across various temperature regimes. We will use both direct observations (e.g. 21 cm fluxes) and scaling relations (e.g. photometric gas fractions) to measure HI and H2. We will also investigate the universe’s undetected baryonic mass, commonly known as the “Missing Baryons” and believed to be mainly warmhot ionized gas. Combining kinematically derived total masses with measurements of observable mass, we will constrain the missing baryons both within galaxies and in their surrounding environments, providing the most detailed mass census yet achieved over a large volume.
Atomic Hydrogen (HI)ALFALFARESOLVE partnership (data reduction underway)Starting point Minimum detectable HI mass < ~109 Ms u n
Further completionBlue dwarfs and galaxies outside ALFALFA footprint: Photometric gas fractions (See poster 470.18 by Eckert et al)Red galaxies: Robust ALFALFA upper limitsLarge scale structure: Can determine mass of ensemble of HI without direct detections via stacking spectra (Catinella et al 2010).
ConclusionsOur purpose is to make a full gas census within theRESOLVE survey
Methods vary from direct observations (21 cm) to scaling relations (photometric gas fractions)
Application of multiple methods allows more accurate determination of gas mass, while illuminating conditions where different gas phases are important
Study of H2 massphotometry relations reveals a central starburst cycle
Studies of ultrablue galaxies suggest another gas mass component unseen in HI and CO observations
For more information on RESOLVE, see posters 470.18 (Eckert et al) and 470.19 (Liu et al)
ReferencesBettoni, D., Galletta, G., GarciaBurillo, S. 2003, A&A, 405, 5Casasola, V., Bettoni, D., Galletta, G. 2004, A&A, 422, 941 Catinella et al., 2010, in pressGarnett, D. 2002, ApJ, 581, 1019Giovanelli, R., et al. 2005, AJ, 130, 2598Jansen, R. A., Fabricant, D., Franx, M., Caldwell, N. 2000a, ApJS, 126, 331Jansen, R. A., Franx, M., Fabricant, D., Caldwell, N. 2000b, ApJS, 126, 271Kannappan, S. J., Guie, J. M., and Baker, A. J. 2009. AJ, 138, 579Kannappan, S. J., Jansen, R. A., and Barton, E. J. 2004. AJ, 127, 1371Kannappan, S. J. and Wei, L. H. 2008, AIP Conf. Proc., 1035, 163Leroy, A., Bolatto, A. D., Simon, J. D., Blitz, L. 2005, ApJ, 625, 763Matthews, L. D., Gao, Y., Uson, J. M., Combes, F. 2005, AJ, 129, 1849Wei, L. H., Kannappan, S. J., Vogel, S. N., Baker, A. J. 2010, ApJ, 708, 841
Figure 1: Initial RESOLVE sample from Kannappan and Wei (2008). SDSS galaxies brighter than Mr=17.23, between cz=45007000 km/s, including galaxies with no SDSS redshift but with a redshift in HyperLeda.
Figure 3: (Left) Relation between Ms t a r s and ∆(BR), where ∆(BR) = BR from the halflight radius to the 75% light radius minus BR within the halflight radius. Residuals in Ms t a r s vs ∆(BR) define ∆(BR)m c o r r (bluecenteredness), adapted from the definition in Kannappan, Jansen, and Barton (2004). (Right) H2/HI ratio versus ∆(BR)m c o r r , showing the rising and falling H2 fractions associated with a central starburst. Kannappan, Jansen, Barton (2004) find that bluecenteredness is correlated with small interactions that can drive the observed burst cycle.
Figure 5: (Left) Ultrablue galaxies (BK < 2.5) show lower HI/Ms t a rs than expected based on the rest of the galaxy population (Data from Nearby Field Galaxy Survey Database). (Right) Ultrablue galaxies also show discrepancies in baryonic mass. The addition of COderived H2 masses suggest the missing element is not molecular gas, but is more likely warmhot ionized gas (Data from Bettoni et al 2003, Casasola et al (2004), Leroy et al (2005), Matthews et al (2005), and Garnett (2002)).
How do we account for the gas mass?
Figure 2: The RESOLVE footprint. Shaded regions mark ALFALFA overlap (85%). (Upper Right) ALFALFA detections as a function of distance (courtesy of M. Haynes). RESOLVE lies between 65 and 100 Mpc.
Figure 4: Multiple measures of H2/HI fraction: ∆(BR)m c o r r (left), ∆(UB)m c o r r (middle) which follows same definition as ∆(BR)m c o r r except with UB color, and the global Hα equivalent width integrated over the whole galaxy (right). Investigation of individual galaxies highlights reasons why certain parameters fail to correlate with H2 mass. For example, NGC 2780 and IC 2520 contain widespread dust, causing photometric measures (e.g. ∆(BR)m c o r r ) to fail but spectroscopic measures (e.g. Hα equivalent width) to succeed in predicting H2 mass. NGC 5762 and NGC 7077 appear to be pre and/or poststarburst galaxies, indicating why Hα does not correlate with their H2 mass.
NGC 2780 IC 2520 NGC 5762 NGC 7077Spring Region Fall Region
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Unseen Phases (Missing Baryons)Compare baryonic to total mass on large & small scalesPossible new way to detect ionized gas reservoirs:
➢ Blue galaxies show low baryon fractions and low HI/Ms t a r s
(despite gas richness) relative to expectations (Fig. 5)➢ Not gas loss – estimated SN feedback energy << energy needed to produce extended gas halos this massive
➢ Not just a mass dependency on nonbaryonic dark matter (low mass red galaxies follow expectations)
➢ Missing mass likely warmhot ionized gas, or possibly low metallicity cold molecular gas – undetected mass can be estimated via relations seen in Figure 5.
Star formation signatures can also distinguish between unseen baryonic and nonbaryonic dark matter in the large scale RESOLVE mass inventory
Molecular Hydrogen (H2)Aim to calibrate “cheap” methods to estimate H2 masses, in order to bootstrap from more demanding direct measurements (e.g. 1 2 CO emission)
A. Correlation between H2/HI ratio and color gradients, which suggests centralstarburst cycle (see Figure 3)
B. Reversing standard star formation laws (e.g. Hα H→ 2)Combination of H2 indicators provides more reliable mass measurements and helps determine when H2 mass is significantPreliminary results below draw on the Nearby Field Galaxy Survey database, includingphotometry and spectroscopy from Jansen et al (2000a,b), HI data from Wei et al. (2010), and new H2 data from our IRAM program underway.
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