HI gas content of SDSS galaxies revealed by ALFALFA Ying Zu ( ) - - PowerPoint PPT Presentation

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hi gas content of sdss galaxies revealed by alfalfa
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HI gas content of SDSS galaxies revealed by ALFALFA Ying Zu ( ) - - PowerPoint PPT Presentation

Sep 28, 2022 413 likes •721 views

Tianlai Collaboration Meeting HI gas content of SDSS galaxies revealed by ALFALFA Ying Zu ( ) Shanghai Jiao Tong University Zu 2018 ( arXiv:1808.10501) Galaxy Formation: Baryon Cycling HI disc Tulimson et al. 2018 Galaxy Formation in

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HI gas content of SDSS galaxies revealed by ALFALFA

Ying Zu (祖颖)

Tianlai Collaboration Meeting

Zu 2018 (arXiv:1808.10501)

Shanghai Jiao Tong University

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HI disc

Galaxy Formation: Baryon Cycling

Tulimson et al. 2018

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Galaxy Formation in Intensity Mapping Context

Figure courtesy: Patrick Breysse

Galaxy positions Red: galaxies above flux limit Intensity Mapping

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First cosmological detection of HI intensity map

Chang et al. 2010

Cross-correlation between GBT IM & DEEP2 gal. at z=0.8

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Galaxy-HI cross-spectrum measures HI mass

Woltz et al. 2017

Shot noise Galaxy-HI cross P(k)

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Synergy btw Ti Tianlai IM & DESI Br Brig ight Gala alaxy xy Sur urvey

  • DESI BGS: >10 million galaxies, median z ~ 0.2
  • Takes place during bright time
  • Two priority Tiers: r<19.5 and 19.5<r<20.0
  • 14,000 sq deg with 3 passes of sky
  • Like SDSS, but bigger and deeper!
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We need to understand the connection between galaxy optical properties and HI gas content in the local Universe

Arecibo SDSS

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ALFALFA Survey

The Arecibo Legacy Fast ALFA (ALFALFA) survey is the largest blind extragalactic HI survey of the local HI universe to date. The completed ALFALFA survey has detected more than 30,000 extragalactic HI line sources out to z~0.06. Great synergy with optical surveys like the SDSS.

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Can we predict HI content directly from stars?

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Joint SDSS-ALFALFA Sample

Zu 2018 (arXiv:1808.10501)

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HI-to-stellar Mass Ratio (HI fraction)

Kannappan 2004 Zhang et al 2009 Li et al 2012

But current HI surveys suffer severe Malmquist bias

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Malmquist Bias in ALFALFA

Redshift Galaxy Number SDSS

Ideal ALFALFA w/out Malmquist bias Real ALFALFA with Malmquist bias

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N galaxies in SDSS volume-limited sample, n of which were HI-detected, and N-n were non-detections.

Malmquist Bias: Likelihood has two components

Zu 2018 (arXiv:1808.10501)

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Zu 2018 (arXiv:1808.10501)

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Observed HI fraction vs. expected HI Fraction

Zu 2018 (arXiv:1808.10501)

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No Bias in the HI predictor

Biased estimator

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HI Mass function: non-detections accounted for

Zu 2018 (arXiv:1808.10501)

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Metallicity: Star Formation vs. Gas Accretion

Metal production: stellar nucleosynthesis yield from star formation Metal loss: metal expulsion due to outflows driven by star formation Metal dilution: Accretion of pristine gas from the IGM

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Mass-Metallicity Relation (MZR)

Tremonti et al. 2004

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Star Formation Rate (SFR) dependence of MZR

Yates et al. 2012

Mannucci+2010 metallicity Tremonti+2004 metallicity

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HI Excess: Deviation of obs. HI fraction from expectation

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Metallicity depends on Relative sSFR and HI excess

Zu 2018 (arXiv:1808.10501)

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Metallicity: Star Formation < GasAccretion?

Zu 2018 (arXiv:1808.10501)

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Metallicity: Star Formation < GasAccretion?

Metal production: stellar nucleosynthesis yield from star formation Metal loss: metal expulsion due to outflows driven by star formation Metal dilution: Accretion of pristine gas from the IGM

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HI Excess should depend on large-scale environment

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Chung et al. 2009

HI contour on SDSS image

Outskirt of Vi Virgo Po Positive HI Excess? Inside Vi Virgo Ze Zero HI Excess? Center of Vi Virgo Ne Negat gative HI HI Excess?

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Average HI Excess

Weak anti-correlation btw HI excess and

Zu 2018 (arXiv:1808.10501)

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Cross-correlation btw red/blue galaxies and HI

HI-poor HI-rich Blue Red

Zu 2018 (arXiv:1808.10501)

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Ram pressure stripping removes the cold gas reservoir on much shorter time scale (< 1 Gyr) than quenching (~ a few Gyrs). Satellite galaxies can still form stars while gradually being quenched after infall (see Wetzel+ 2013; Simha+ 2014)

Kronberger et al. 2007

is likely caused by gas stripping in clusters

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Conclusions

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We develop a method to predict HI fraction from stellar mass and color, using a joint SDSS-ALFALFA sample. Potentially useful for understanding the cross-spectrum between Tianlai IM and DESI BGS galaxies.

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We eliminate the impact of Malmquist bias of HI detections on the predictor by properly accounting for the HI-detection probability of each SDSS galaxy in the

  • analysis. The predictor has an estimated scatter of 0.27 dex.

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We demonstrate that the HI excess is likely the main driver of the scatter in the mass-metallicity relation, a key ingredient in solving galactic baryon cycling.

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The environmental dependence of HI can be effectively captured by a cross- correlation coefficient between HI excess and red galaxy overdensity (-0.18). Important for understanding the cross-correlation coefficient between galaxies and HI intensity map.