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Are galaxies still evolving strongly? Christopher J. Miller

The Effects of Environment. Hubble Heritage Image. On Galaxy Evolution at Low-z. Are galaxies still evolving strongly? Christopher J. Miller. Part I. Defining the questions, methods, and tools of the research topic. Physical Processes of Galaxies. Galaxy Interactions.

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Are galaxies still evolving strongly? Christopher J. Miller

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  1. The Effects of Environment Hubble Heritage Image On Galaxy Evolution at Low-z Are galaxies still evolving strongly? Christopher J. Miller

  2. Part I Defining the questions, methods, and tools of the research topic

  3. Physical Processes ofGalaxies

  4. Galaxy Interactions • Few collisions, lots of interactions, but “horsehoes and handgrenades” • ~ energy 108 -109 Supernovae • Quick, ~108 Years • Relatively rare (in recent times) 1-5% maybe. Hard to measure. • Very, very hard to define (observationally) • Field Galaxies undergo mergers Hibbard Hibbard and Barnes

  5. Ram Pressure Stripping • Galaxies fall (gravitationally) through the hot intracluster gas. • 107 K, 10-4cm-3 • Hydrodynamic and Nbody simulations • Mapping of gas content in Virgo spirals shows the HI disks to be highly disturbed, but the molecular content unchanged. • Galaxies undergo ram pressure stripping when in the cores of clusters • Slower than colliding galaxies Vollner (Strasbourg)

  6. Strangulation • Halos are gradually (Gyrs) removed from disk galaxies • Lack of fuel only changes the star-formation properties (not necessarily the morphologies) Goto et al.

  7. Field Cluster White et al. Ram Pressure Stripping Strangulation Interaction

  8. Galaxy Properties

  9. Star-Formation History Bianchi et al., Condon et al., and others

  10. Active Galactic Nuclei vs. Miller et al. 2003

  11. Morphology Lenticular Spiral Spiral Spiral Elliptical Elliptical S0 Sa Sb Sc Barred Lenticular Barred Spiral Barred Spiral Barred Spiral E0 E6 Irregular S0a SBa SBb SBc Faulkes Telescope Project Irr

  12. Standard Bulge-to-Disk code takes ~2 minutes per galaxy (GIM2d). Need to get to at least seconds per galaxy to do large datasets. Close…… Bulge-to-Disk Ratio

  13. Concentration Index(poor man’s morphology) More Compact Goto et al.

  14. Galaxy Environments

  15. Density Estimation sdss.org

  16. Fixed Kernel Width is well-studied in the mathematical literature. Higher-order bias Use cross-validation to find the “optimal” aperture. But still, does one aperture size suit all? Also well studied in the mathematical literature. Common in past astrophysical research Variable kernel size low-order bias Never converges to the “truth” Kernel vs. Nearest-NeighborDensity Estimation Kernels Nearest Neighbors

  17. Galaxy Clusters • We use the SDSS-C4 galaxy cluster catalog • >90% complete, <5% contamination for M>2x1014 solar • Clusters identified and studied in the spectroscopic sample • >250 clusters in ~1000 sq. degrees

  18. Summary: Part I • Galaxy interactions, ram pressure stripping and strangulation affect the properties of galaxies. • Such properties include star-formation rate, AGN activity, and morphology. • By measuring the environment around every galaxy, we can try to isolate which of the above processes affect which of the above properties.

  19. Part II What do we already know?

  20. Gomez, Nichol, Miller et al. Balogh, Eke, Miller et al. Star-Formation vs. Environment

  21. AGN fraction vs. Environment Caution: Concentration Index is not a great morphology indicator (cannot separate E/S0’s for instance). Miller et al. 2003

  22. Star-formation and Clusters: Field Miller et al. in prep. Gomez, Miller, Nichol et al.

  23. Part III: A new research topic: Phenomenological Studies of Brightest Cluster Galaxies

  24. Doing Research the “VO way” • Start with an idea • E.g., galaxy properties as a function of environment. • Brightest Cluster Galaxy properties and their local environment • Explore • What images and/or catalogs are available? • Trial run • Start small • Production mode • Grow with time and code to re-run on newer, bigger, better data in the future.

  25. Explore

  26. Inventory: What will we need? • Data • Clusters (centers, masses, shapes, BCG) • Galaxy magnitudes, colors, shapes • Gas (X-ray) fluxes, extents • Functions/Tools • Luminosity distances, absolute magnitudes, k-corrections, angular diameters, statistical tools, plotting techniques, image display • Services • Skynodes, Coneservices, SIAP services, Registry Trial Run

  27. The SDSS-C4 Cluster Catalogwww.ctio.noao.edu/~chrism/C4Miller et al. 2005, AJ, 130 968

  28. Get the SDSS Data Get the images radius = zang(radius_fixed,c4data[I].z)/60.0 ; In arcminutes siapcall,c4data[I].ra_bcgphot, c4data[I].dec_bcgphot, radius/60.0, $ url=“http://casjobs.sdss.org/vo/DR4SIAP/SIAP.asmx/getSiapInfo?&FORMAT=image/jpeg” + $ “&BANDPASS=*&", root="images/sdss_c4_"+strtrim(string(c4data[I].cluster_id),2) Get the catalog data qry = " SELECT o.ra,o.dec, o.expAB_r, o.isoPhi_r " " FROM SDSSDR2:PhotoPrimary o " + $ " WHERE o.type = 3 AND o.petroMag_r < 23.0 " + $ " AND Region('Circle J2000 " + strtrim(string(c4data[I].ra_bcgphot,format='(f10.3)'),2) + $ " " + strtrim(string(c4data[I].dec_bcgphot, format='(f10.3)'),2) + $ " " + strtrim(string(radius, format='(f4.2)'),2) + "') ” skyclient, qry=qry,str=sdss_gals separ, sep, c4data[i].ra_bcgphot, sdss_gals.sdssdr2_ra, $ c4data[i].dec_bcgphot, sdss_gals.sdssdr2_dec min = min(sep, minit)

  29. Get the SDSS-2MASS Matches Get the 2MASS-SDSS cross matches qry = " SELECT o.ra,o.dec, o.modelMag_u, o.modelMagErr_u, o.modelMag_g,” + $ “ o.modelMagErr_g, o.modelMag_r, o.modelMagErr_r, o.modelMag_i, o.modelMagErr_i, “ + $ “o.modelMag_z, o.modelMagErr_z, o.extinction_u, o.extinction_g, o.extinction_r, “ + $ “o.extinction_i, o.extinction_z, t.j_m, t.k_m, t.h_m, t.j_msigcom, t.k_msigcom, t.h_msigcom " + $ " FROM SDSSDR2:PhotoPrimary o, TWOMASS:PhotoPrimary t " + $ " WHERE XMATCH(o,t)<" + strtrim(string(chisq),2) + " " + " AND o.type = 3 " + $ " AND Region('Circle J2000 " + strtrim(string(c4data[I].ra_bcgphot,format='(f10.3)'),2) + $ ” " + strtrim(string(c4data[I].dec_bcgphot, format='(f10.3)'),2) + $ " " + strtrim(string(radius, format='(f4.2)'),2) + "') " skyclient,qry=qry,str=sdss_2mass_gals

  30. Get the X-ray data Get the WGACAT sources conecall, c4data[I].ra_bcgphot, c4data[I].dec_bcgphot, radius/60.0, str=str, $ url = "http://heasarc.gsfc.nasa.gov/cgi-bin/vo/cone/coneGet.pl?table=wgacat&r" If a WGACAT source exists, get the PSPC image conecall, c4data[I].ra_bcgphot, c4data[I].dec_bcgphot, radius/60.0, str=str, $ url = http://heasarc.gsfc.nasa.gov/cgi-bin/vo/cone/coneGet.pl?table=xmmssc& sizeit = size(str);If there is XMM-SSC data, get the image IF (sizeit[1] gt 1) THEN BEGIN separ, separ, c4data[i].ra_bcgphot, str.ra, c4data[i].dec_bcgphot, str.dec min = min(separ, minit) bcg_EP[I] = str[minit].ep_flux IF not (keyword_set(nosiap)) THEN siapcall,c4data[I].ra_bcgphot, c4data[I].dec_bcgphot, 0.1, $ url="http://xsa.vilspa.esa.es:8080/aio/jsp/siap.jsp", $ root="images/xmm_bcg_c4_"+strtrim(string(c4data[I].cluster_id),2), /metadata,str=str ENDIF

  31. Calculate the Absolute Magnitudes kcorrect,mags, magerrs, zs , kcorr, filterlist=filterlist, band_shift=0.0 bcg_absJ[I] = sdss_2mass_gals[minit].twomass_j_m - kcorr[5,minit] (5*alog10(lumdist(c4data[I].z)*1e6) + 5) See: http://cosmo.nyu.edu/blanton/kcorrect/v3_2-index.html See: Hogg et al. (2002) mR = MQ + DM(z) + KQR(z), where mR is the apparent magnitude MQ is the absolute magnitude DM(z) is the distance modulus, accounting angular diameter distance and cosmological surface-brightness dimming KQR(z) is the K-correction.

  32. Finally: Analyze Make Plots plot, -(bcg_isophi[wkeep]-90),c4data[wkeep].ang1000, psym=4, $ xtitle="BCG Position Angle (degrees)", $ ytitle="C4 Cluster Position Angle (within 1Mpc) (degrees)" Look for correlations result = r_correlate(-(bcg_isophi[w]-90), c4data[w].ang1000) Look at the BCGs Make Histograms h = histogram(abs(-(bcg_isophi[w]-90)-c4data[w].ang1000),omin=omin, binsize = 5)plot, 5*findgen(n_elements(h)) + omin, h, psym=10 Run statistical tests kstwo, delta_phi, zran,d,prob

  33. Example High Density BCGs

  34. Example Low Density BCGs

  35. X-ray BCGs PSPC SDSS RASS

  36. Results Part 1: • Statistical tests indicate a ~2 result that the BCG PA is aligned with the cluster PA. • BCG ellipticity shows no significant dependence on local density • BCG colors are 2 tenths bluer in the density regions. • BCGs luminosity shows no significant dependence on local density

  37. Results Part 2: • X-ray detected clusters favor the BCGs in the highest density regions. • Indicates a possible bias in BCG cluster studies.

  38. Lin and Mohr (2005) find evidence that BCGs grow over time and are more massive in the more massive clusters. Andernach et al. (2006) find BCG ellipticity decreases with cluster mass Harris et al. (2006) use ACS/WFC to discover strong color gradients in BCGs (old red star clusters live in the centers). Brough et al. find that X-ray the brightest luminous clusters have BCGs with shallow light profiles (more collisions). All of the above are consistent with bottom up hierarchical growth and inconsistent with top-downSee also Laine et al. (2003) Haruyoshi et al. (2003) find that BCG luminosities not correlated with the underlying viral density Collins et al. (2003) find that BCGs in high Lx clusters show no mass growth. Egami et al. (2006) suggest BCGs are star-forming (IR) Nelson et al. (2002) find that BCG sizes using NICMOS are the same size at z>0.5 as they are z=0. They find smaller radii at z=0.5 with WFPC2. All of the above are consistent with monolithic collapse. Understanding BCG Evolution

  39. Our New Conclusions • Given a starting point (re: Inventory and plan, tools), we can easily do and re-do research without having the majority of the data on our hard disks. • In this case, we collected SDSS optical, 2MASS infrared, and X-ray images and catalog data for a sample of 300 BCGs in the SDS C4 cluster catalog • We found (weak) evidence that the position angle of the BCG is aligned with the PA of the cluster. • We find a small fraction 5-10% of our BCGs have very high local densities. • We find a significant trend in bluer BCGs having higher local densities. • Hypothesis: these are younger BCGs in younger systems, still under-going collapse. • More questions to answer.

  40. Useful Sites: • www.ctio.noao.edu/~chrism/VOlib • www.ctio.noao.edu/~chrism/C4 • www.nvo.noao.edu • www.us-vo.org • http://us-vo.org/summer-school/2005/proceedings/presentations/miller/cluster_science.html

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