HISTORY OF GALAXY INTERACTIONS AND THEIR IMPACT ON STAR FORMATION OVER THE LAST 7 Gyr FROM GEMS

By S. Jogee, Sarah H. Miller, K. Penner, R. Skelton, Christopher J. Conselice, R. Somerville, Eric F. Bell, Xianzhong Zheng, Hans-Walter Rix, A. Robaina and 15 more. 2009

179 citations recorded by the source corpus.

We perform a comprehensive estimate of the frequency of galaxy mergers and their impact on star formation over z∼ 0.24–0.80 (lookback time Tb∼ 3–7 Gyr) using ∼3600 (M⩾ 1 × 109 M☉) galaxies with GEMS Hubble Space Telescope, COMBO-17, and Spitzer data. Our results are as follows. (1) Among ∼790 high-mass (M⩾ 2.5 × 1010 M☉) galaxies, the visually based merger fraction over z∼ 0.24–0.80, ranges from 9% ± 5% to 8% ± 2%. Lower limits on the major merger and minor merger fraction over this interval range from 1.1% to 3.5%, and 3.6% to 7.5%, respectively. This is the first, albeit approximate, empirical estimate of the frequency of minor mergers over the last 7 Gyr. Assuming a visibility timescale of ∼0.5 Gyr, it follows that over Tb∼ 3–7 Gyr, ∼68% of high-mass systems have undergone a merger of mass ratio >1/10, with ∼16%, 45%, and 7% of these corresponding respectively to major, minor, and ambiguous “major or minor” mergers. The average merger rate is ∼ a few ×10−4 galaxies Gyr−1 Mpc−3. Among ∼2840 blue-cloud galaxies of mass M⩾ 1.0 × 109 M☉, similar results hold. (2) We compare the empirical merger fraction and merger rate for high-mass galaxies to three Λ cold dark matter-based models: halo occupation distribution models, semi-analytic models, and hydrodynamic SPH simulations. We find qualitative agreement between observations and models such that the (major+minor) merger fraction or rate from different models bracket the observations, and show a factor of 5 dispersion. Near-future improvements can now start to rule out certain merger scenarios. (3) Among ∼3698 M⩾ 1.0 × 109 M☉ galaxies, we find that the mean star formation rate (SFR) of visibly merging systems is only modestly enhanced compared to non-interacting galaxies over z∼ 0.24–0.80. Visibly merging systems only account for a small fraction (<30%) of the cosmic SFR density over Tb∼ 3–7 Gyr. This complements the results of Wolf et al. over a shorter time interval of Tb∼ 6.2–6.8 Gyr, and suggests that the behavior of the cosmic SFR density over the last 7 Gyr is predominantly shaped by non-interacting galaxies.

Subfields: Astronomy and Astrophysics, Instrumentation

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In Astronomy and Astrophysics

1. P. Hopkins
2. L. Hernquist
3. R. Somerville
4. R. Dav'e
5. Thomas J. Cox
6. Volker Springel
7. A. Dekel
8. T. Naab

In Instrumentation

1. P. Hopkins
2. L. Hernquist
3. R. Somerville
4. R. Dav'e
5. Thomas J. Cox
6. A. Dekel
7. D. Keres̆
8. T. Naab

Citations in the corpus

• The effect of mass ratio on the morphology and time-scales of disc galaxy mergers: Effect of mass ratio on merger morphology (2009, background): “However, recent studies of the visual classification of galaxy mergers suggests that ∼ 50% of visually disturbed galaxies may result from minor mergers (Jogee et al 2009; Darg et al. 2009).”
• Star formation in galaxy mergers with realistic models of stellar feedback and the interstellar medium (2012, background): “…in many previous studies, we are not saying that most of the stars form in the starburst: this is typically ∼10 per cent of the total stellar mass (Jogee et al. 2009; Robaina et al. 2009; Hopkins et al. 2010; Hopkins & Hernquist 2010), with the rest formed in the ‘isolated disc’ mode (including…”
• HYDRODYNAMICS OF HIGH-REDSHIFT GALAXY COLLISIONS: FROM GAS-RICH DISKS TO DISPERSION-DOMINATED MERGERS AND COMPACT SPHEROIDS (2010, background): “First, determinations of the merger rate from highredshift surveys are usually based on irregular structures or disturbed kinematics (e.g., Conselice et al. 2003; Lotz et al. 2006, 2008; Overzier et al. 2010; Jogee et al. 2009; López-Sanjuan et al. 2009; Puech 2010).”
• An analytic model for the evolution of the stellar, gas and metal content of galaxies (2011, background): “In a global context, major mergers are seen to be responsible for only a small fraction of overall cosmic star formation (e.g. Jogee et al. 2009), although they may be where much of the central black hole mass growth occurs (e.g. Di Matteo et al. 2005).”
• THE DRIVING MECHANISM OF STARBURSTS IN GALAXY MERGERS (2010, background): “Nevertheless, the overall contribution of mergers to the SF budget of galaxies remains uncertain and quiescent SF in isolated systems could dominate (Jogee et al. 2009; Robaina et al. 2009; Förster Schreiber et al. 2009; Daddi et al. 2010b).”
• Forming a large disc galaxy from a z < 1 major merger (2008, background): “Their number density has been estimated to be of the order of 10−(3−4) h−1 Mpc−3 Gyr−1 (Lin et al. 2008; Jogee et al. 2009), possibly increasing with redshift.”
• Galaxy evolution in cosmological simulations with outflows ― I. Stellar masses and star formation rates (2011, background): “…galaxies appear to be consuming their gas rapidly enough that fuel must be constantly replenished (Tacconi et al. 2010; Papovich et al. 2010), but merger-induced starbursts do not appears to be driving global star formation (Brinchmann et al. 2004; Noeske et al. 2007; Jogee et al. 2009).”
• The effect of gas fraction on the morphology and time-scales of disc galaxy mergers (2009, background): “The majority of z ≤ 1 merger candidates with strong visual disturbances, asymmetries or double nuclei appear blue (e.g. Bell et al. 2005; Lotz et al. 2008a; Jogee et al. 2009).”
• THE BULK OF THE BLACK HOLE GROWTH SINCE z ∼ 1 OCCURS IN A SECULAR UNIVERSE: NO MAJOR MERGER–AGN CONNECTION (2010, methodology): “…in models (Di Matteo et al. 2007) and observations (Bergvall et al. 2003), and (3) its overall contribution is relatively modest (Di Matteo et al. 2008; Jogee et al. 2009), with no more than 10% of star formation in massive galaxies being triggered by major mergers at z ∼ 0.6 (Robaina et al. 2009).”
• MERGERS AND BULGE FORMATION IN ΛCDM: WHICH MERGERS MATTER? (2009, background): “Jogee et al. (2009) estimate empiricallythat ∼ 30−40% of their (by-eye) morphologically-identified sample represent contamination from 1/10< µgal < 1/3 minor 20 For the explicit dependence on these parameters, see Lotz etal.”
• MERGERS IN ΛCDM: UNCERTAINTIES IN THEORETICAL PREDICTIONS AND INTERPRETATIONS OF THE MERGER RATE (2010, background): “…are in mergers – strongly morphologically disturbed or in “major” similar-mass pairs about to merge (at small scales and small relative velocities) (Bridge et al. 2007, 2010; Kartaltepe et al. 2007; Conselice et al. 2009; Jogee et al. 2009; Lotz et al. 2008b; Lin et al. 2008; Robaina et al. 2010).”
• Star Formation in the Milky Way and Nearby Galaxies (2012, background): “This suggests that most of the decrease in the cosmic SFR in recent epochs has been driven by downsiz- ing in the level of steady-state star formation (e.g., Bell et al. 2005; Jogee et al. 2009).”
• THE COSMOLOGICAL SIZE AND VELOCITY DISPERSION EVOLUTION OF MASSIVE EARLY-TYPE GALAXIES (2011, result): “Estimates of merger rates for massive galaxies due to observations of disturbed systems (Jogee et al. 2009; Kaviraj et al. 2011; Lotz et al. 2011), as well as semi-analytic models lead to similar results.”
• The impact of gas inflows on star formation rates and metallicities in barred galaxies (2011, background): “The level of the SFR enhancement in close pairs is similar out to z ∼ 1, despite the global increase of the volume averaged SFRs at these earlier epochs (Jogee et al. 2009; Robaina et al. 2009).”
• Galaxy pairs in the Sloan Digital Sky Survey – VIII. The observational properties of post-merger galaxies (2013, unknown): “…redshifts (e.g. Kennicutt et al. 1987; Barton, Geller & Kenyon 2000; Kewley, Geller & Barton 2006; Woods, Geller & Barton 2006; Smith et al. 2007; Jogee et al. 2009; Rupke, Kewley & Chien 2010; Koss et al. 2010, 2012; Silverman et al. 2011; Wong et al. 2011; Ramos-Almeida et al. 2011, 2012; Xu…”
• THE MAJOR AND MINOR GALAXY MERGER RATES AT z < 1.5 (2011, background): “Multiple authors have estimated the fractional merger rate ℜmerg instead of Γmerg where ℜmerg = fmerg 〈Tobs〉 = Cmergfpair 〈Tobs〉 (6) (e.g. López-Sanjuan et al. 2009, Bundy et al. 2009, Bridge, Carlberg, & Sullivan 2010, Conselice et al. 2009, Jogee et al. 2009).”
• The effects of gas on morphological transformation in mergers: implications for bulge and disc demographics (2009, background): “‘Quiescent’ (non-merger-driven) star formation dominates at all redshifts (see also Wolf et al. 2005; Menanteau et al. 2006; Hopkins et al. 2006; Noeske et al. 2007; Jogee et al. 2009).”
• GOODS-Herschel: the far-infrared view of star formation in active galactic nucleus host galaxies since z ≈ 3 (2011, background): “1 has taken place in galaxies undergoing internally-induced evolution, whichalso appears to be the case for the majority of stellar mass build up over this redshift range (e.g., Bell et al. 2005; Jogee et al. 2009).”
• THE EVOLUTION OF GALAXY NUMBER DENSITY AT z < 8 AND ITS IMPLICATIONS (2016, background): “…the distant supernova and gamma-ray burst rate, the star formation rate of the universe, and how new galaxies are created/destroyed through mergers (e.g., Bridge et al. 2007; Lin et al. 2008; Jogee et al. 2009; Conselice et al. 2011; Bluck et al. 2012; Conselice 2014; Ownsworth et al. 2014).”