Towards a complete redshift catalog for galaxies in the Local Universe

Transcript

1. Towards a complete redshift catalog for galaxies in the Local Universe 20 October 2017 “The Redshift Completeness of Local Galaxy Catalogs” Kulkarni et al. 2017 “Census of the Local Universe (CLU) I: Characterization of Galaxy Catalogs from Preliminary Fields” Cook et al. 2017 Anna Ho Journal Club 2MASS extended source catalog redshift survey, modified from Tully et al. (2014) 200 Mpc z = 0.05
2. Why the Local Universe? Details of local analogs to high-redshift galaxies Efficient LIGO follow-up (LIGO d = 40 +/- X Mpc) (NGC 4993 d = 40 Mpc) Classifying transients (e.g. origin of Ia SNe)
3. Outline 4. Improving completeness — what are the challenges? 1. Measuring completeness — what are the challenges? 2. An approach to measuring completeness (Kulkarni 2017) 5. An approach to improving completeness (Cook 2017) 3. Measurement of completeness using ASAS-SN SNe
4. Challenges in measuring completeness: inhomogeneity RCF: Redshift Completeness Fraction Movie from Tully et al. (2014)
5. Kulkarni 2017: Using ASAS-SN Ia SNe to measure the RCF Input Catalog: All-Sky Automated Survey for SNe • V < 17 Why Ia SNe? • Bright, homogeneous LC • Probe old and young stellar populations Eq. from Scannapieco & Bildsten (2005)
6. Kulkarni 2017: Using ASAS-SN Ia SNe to measure the RCF Procedure: 1. Discover supernova 2. Measure redshift 3. If z < 0.05, check if NED had galaxy redshift before supernova 4. RCF = fraction with NED redshifts
7. Redshift distribution of 261 SNe Redshift Number of Ia SNe Number of CC SNe Fig adapted from Kulkarni et al. (2017)
8. RCF of ASAS-SN Galaxies Table adapted from Kulkarni et al. (2017)
9. How complete is our understanding of local mass? 0.00 0.01 0.02 0.03 0.04 0.05 zhost 26 25 24 23 22 21 20 19 18 17 MKs,host (mag) NED !NED Using 2MASS Ks-band: Redshift For Ia, RCF =[67%–73%] Fig adapted from Kulkarni et al. (2017)
10. 0.00 0.01 0.02 0.03 0.04 0.05 zhost 20 19 18 17 16 15 14 13 MUV,host (mag) NED !NED How complete is our understanding of local SFR? Using GALEX NUV: Redshift For Ia: the RCF =[63%–76%] Fig adapted from Kulkarni et al. (2017)
11. Challenges in measuring distance: many-mag spread in luminosity Fig adapted from Blanton & Moustakas (2009)
12. Challenges in measuring distance Many-mag spread in luminosity Photometric redshifts are not reliable in the nearby universe (errors are ∆z = 0.02, 0.03 out of 0.05) SDSS has spectra of half a million extragalactic sources in 9400 deg2 has missed galaxies due to strong color selection (LRG program), fiber collisions, classification errors
13. • Largest-area H-alpha imaging survey for nearby emission-line galaxies + compilation of all public catalogs • 3π of the sky (3626 pointings) in 4 narrowband filters • 234,500 galaxies from compilation • Spectroscopic follow-up of all galaxy candidates with no previous distance information in 14 preliminary fields (0.3% of total pointings) • Of 334 galaxies, 124 really had z < 0.05 Cook et al. 2017: Conducting a Census of the Local Universe (CLU)
14. Cook et al. 2017: Conducting a Census of the Local Universe (CLU) Fig adapted from Cook et al. (2017)
15. 3π of the sky, 3626 pointings Fig adapted from Cook et al. (2017) 262 64 15 3 0
17. 2 oddballs from spectroscopic follow-up of all candidates in 14 fields (0.3%) Fig adapted from Cook et al. (2017) Flux density (erg cm-2 s-1) Fig adapted from Cook et al. (2017) Wavelength (Å) QSO Green pea Hγ Hβ Hα Hα Hβ Hγ [OIII] [OIII] [SII] [SII] 9000 4000 5000 8000 7000 6000
18. Where to from here? < 18 SN survey with ZTF (1000 SNe, RCF 3%) Measuring completeness Improving completeness H-alpha survey will continue CLU-south? Model using galaxy morphologies? Similar for 529 TNS SNe (Cassese & Kulkarni, in prep)
19. RCF of ASAS-SN Galaxies SN Total # ✓ NED ✗ NED RCF 64 missing to z = 0.05: 40 not covered by SDSS 8 have no photoz 5 have photoz > 0.05 11 have inaccurate photoz to z = 0.03: Table adapted from Kulkarni (2017)
20. SN Ia rate depends on SFR and mass Fig adapted from Sullivan et al. (2006)
21. Characterized completeness using LVL sample (< 11 Mpc) Fig adapted from Cook et al. (2017)