diff --git a/CHANGELOG.rst b/CHANGELOG.rst
index ddd32f0..e643d2d 100644
--- a/CHANGELOG.rst
+++ b/CHANGELOG.rst
@@ -4,6 +4,12 @@
 Changelog
 =========
 
+
+1.6.0 (unreleased)
+==================
+- Added Phi function from Strolger et al (2020)
+
+
 1.5.3 (2021-07-14)
 ==================
 - Better normalization rates and fits for Greggio DTDs
diff --git a/README.rst b/README.rst
index 89b1cea..14143c5 100644
--- a/README.rst
+++ b/README.rst
@@ -141,6 +141,11 @@ The ``dtd_sn`` param in the config file can be set to use any of the available D
 :greggio-WDD1: DTD from model Wide DD 1 Gyr from Greggio, L. (2005)
 :greggio-SDCH: DTD from model SD Chandra from Greggio, L. (2005)
 :greggio-SDSCH: DTD from model SD sub-Chandra from Greggio, L. (2005)
+:strolger-fit1: Phi function from Strolger et al (2020) with (ξ, ω, 𝛼) = (10, 600, 220)
+:strolger-fit2: Phi function from Strolger et al (2020) with (ξ, ω, 𝛼) = (110, 1000, 2)
+:strolger-fit3: Phi function from Strolger et al (2020) with (ξ, ω, 𝛼) = (350, 1200, 20)
+:strolger-fit4: Phi function from Strolger et al (2020) with (ξ, ω, 𝛼) = (6000, 6000, -2)
+:strolger-optimized: Phi function from Strolger et al (2020) with (ξ, ω, 𝛼) = (-1518, 51, 50)
 
 Supernovae yields
 -----------------
@@ -215,3 +220,4 @@ Starmatrix is built upon a long list of previous works from different authors/pa
 * *Gronow, S. et al.*, 2021, A&A
 * *Mori, K. et al.*, 2018, ApJ, 863:176
 * *Chen, X., Hu, L. & Wang, L.*, 2021, ApJ
+* *Strolger et al*, 2020, ApJ, Vol 890, 2. doi: 10.3847/1538-4357/ab6a97
diff --git a/docs/configuration.rst b/docs/configuration.rst
index f8d9052..a92aced 100644
--- a/docs/configuration.rst
+++ b/docs/configuration.rst
@@ -87,6 +87,11 @@ The ``dtd_sn`` param in the config file can be set to use any of the available D
 :greggio-WDD1: DTD from model Wide DD 1 Gyr from Greggio, L. (2005)
 :greggio-SDCH: DTD from model SD Chandra from Greggio, L. (2005)
 :greggio-SDSCH: DTD from model SD sub-Chandra from Greggio, L. (2005)
+:strolger-fit1: Phi function from Strolger et al (2020) with (ξ, ω, 𝛼) = (10, 600, 220)
+:strolger-fit2: Phi function from Strolger et al (2020) with (ξ, ω, 𝛼) = (110, 1000, 2)
+:strolger-fit3: Phi function from Strolger et al (2020) with (ξ, ω, 𝛼) = (350, 1200, 20)
+:strolger-fit4: Phi function from Strolger et al (2020) with (ξ, ω, 𝛼) = (6000, 6000, -2)
+:strolger-optimized: Phi function from Strolger et al (2020) with (ξ, ω, 𝛼) = (-1518, 51, 50)
 
 Supernovae yields
 -----------------
diff --git a/docs/credits.rst b/docs/credits.rst
index f9dd88c..7f885a3 100644
--- a/docs/credits.rst
+++ b/docs/credits.rst
@@ -36,6 +36,7 @@ Starmatrix is built upon a long list of previous works from different authors/pa
 * *Leung & Nomoto*, 2018, ApJ, Vol 861, Issue 2, Id 143
 * *Leung & Nomoto*, 2020, ApJ, Vol 888, Issue 2, Id 80
 * *Chen, X., Hu, L. & Wang, L.*, 2021, ApJ
+* *Strolger et al*, 2020, ApJ, Vol 890, 2. doi: 10.3847/1538-4357/ab6a97
 
 License
 -------
diff --git a/src/starmatrix/dtds.py b/src/starmatrix/dtds.py
index 5bfdda5..03943c7 100644
--- a/src/starmatrix/dtds.py
+++ b/src/starmatrix/dtds.py
@@ -7,10 +7,14 @@ Contains some predefined DTDs from different papers/authors:
 * Maoz & Graur (2017)
 * Castrillo et al (2020)
 * Greggio, L. (2005)
+* Strolger et al. (2020)
 
 """
 
 import math
+import scipy.integrate
+import starmatrix.constants as constants
+from functools import lru_cache
 
 
 def select_dtd(option):
@@ -25,7 +29,12 @@ def select_dtd(option):
         "greggio-WDD1": dtd_wide_dd_1,
         "greggio-SDCH": dtd_sd_chandra,
         "greggio-SDSCH": dtd_sd_subchandra,
-        "chen": dtd_chen
+        "chen": dtd_chen,
+        "strolger-fit1": dtds_strolger["fit_1"],
+        "strolger-fit2": dtds_strolger["fit_2"],
+        "strolger-fit3": dtds_strolger["fit_3"],
+        "strolger-fit4": dtds_strolger["fit_4"],
+        "strolger-optimized": dtds_strolger["optimized"],
     }
     return dtds[option]
 
@@ -284,3 +293,57 @@ def dtd_chen(t):
     rate = 2.069e-4  # [SN / Yr / M*]
 
     return rate * dtd
+
+
+class Strolger:
+    def __init__(self, psi, omega, alpha):
+        self.psi = psi
+        self.omega = omega
+        self.alpha = alpha
+
+    def description(self):
+        return ("Delay Time Distributions (DTDs) from Strolger et al, "
+                "The Astrophysical Journal, 2020, 890, 2. "
+                "DOI: 10.3847/1538-4357/ab6a97")
+
+    def phi(self, t_gyrs):
+        t_myrs = t_gyrs * 1e3
+
+        u = t_myrs - self.psi
+        term_1 = (1/(self.omega * math.pi)) * math.exp((-(u**2))/(2*(self.omega**2)))
+
+        t_low = -math.inf
+        t_up = self.alpha*(u/self.omega)
+
+        if 12 < t_up:
+            term_2 = 2 * scipy.integrate.quad(self.term_2_f, t_low, 0)[0]
+        else:
+            term_2 = scipy.integrate.quad(self.term_2_f, t_low, t_up)[0]
+
+        return term_1 * term_2
+
+    def term_2_f(self, t_prime):
+        return math.exp(-math.pow(t_prime, 2)/2)
+
+    @lru_cache(maxsize=128)
+    def normalization_rate(self):
+        return self.efficiency() / self.phi_integrated()
+
+    def efficiency(self):
+        # SN/M* as Hubble-time-integrated production efficiency SN/Mo
+        return 1.03e-3
+
+    def phi_integrated(self):
+        return scipy.integrate.quad(self.phi, 0, constants.TOTAL_TIME)[0]
+
+    def at_time(self, t):
+        return self.normalization_rate() * self.phi(t)
+
+
+dtds_strolger = {
+    "fit_1": Strolger(10, 600, 220).at_time,
+    "fit_2": Strolger(110, 1000, 2).at_time,
+    "fit_3": Strolger(350, 1200, 20).at_time,
+    "fit_4": Strolger(6000, 6000, -2).at_time,
+    "optimized": Strolger(-1518, 51, 50).at_time,
+}
diff --git a/src/starmatrix/sample_input/params.yml b/src/starmatrix/sample_input/params.yml
index 35fa2c4..eb92429 100644
--- a/src/starmatrix/sample_input/params.yml
+++ b/src/starmatrix/sample_input/params.yml
@@ -54,6 +54,11 @@
 #            greggio-WDD1 = DTD from model Wide DD 1 Gyr from Greggio, L. (2005)
 #            greggio-SDCH = DTD from model SD Chandra from Greggio, L. (2005)
 #            greggio-SDSCH = DTD from model SD sub-Chandra from Greggio, L. (2005)
+#            strolger-fit1 = Phi from Strolger et al (2020) with (ξ, ω, 𝛼) = (10, 600, 220)
+#            strolger-fit2 = Phi from Strolger et al (2020) with (ξ, ω, 𝛼) = (110, 1000, 2)
+#            strolger-fit3 = Phi from Strolger et al (2020) with (ξ, ω, 𝛼) = (350, 1200, 20)
+#            strolger-fit4 = Phi from Strolger et al (2020) with (ξ, ω, 𝛼) = (6000, 6000, -2)
+#            strolger-optimized = Phi from Strolger et al (2020) with (ξ, ω, 𝛼) = (-1518, 51, 50)
 #          ]
 
 # sn_yields = [
diff --git a/src/starmatrix/settings.py b/src/starmatrix/settings.py
index cd22f91..8cceb63 100644
--- a/src/starmatrix/settings.py
+++ b/src/starmatrix/settings.py
@@ -34,7 +34,8 @@ default = {
 valid_values = {
     "imf": ["salpeter", "starburst", "chabrier", "ferrini", "kroupa", "miller_scalo", "maschberger"],
     "dtd_sn": ["rlp", "maoz", "castrillo", "greggio", "chen", "greggio-CDD04", "greggio-CDD1",
-               "greggio-WDD04", "greggio-WDD1", "greggio-SDCH", "greggio-SDSCH"],
+               "greggio-WDD04", "greggio-WDD1", "greggio-SDCH", "greggio-SDSCH",
+               "strolger-fit1", "strolger-fit2", "strolger-fit3", "strolger-fit4", "strolger-optimized"],
     "sn_yields": ["iwa1998",
                   "sei2013",
                   "ln2020",

diff --git a/src/starmatrix/tests/dtds/test_strolger.py b/src/starmatrix/tests/dtds/test_strolger.py
new file mode 100644
index 0000000..b5c68ab
--- /dev/null
+++ b/src/starmatrix/tests/dtds/test_strolger.py
@@ -0,0 +1,26 @@
+import pytest
+from starmatrix.dtds import Strolger
+
+
+def test_parameters_initialization():
+    strolger = Strolger(1000, 2000, 3000)
+    assert strolger.psi == 1000
+    assert strolger.omega == 2000
+    assert strolger.alpha == 3000
+
+
+def test_has_description():
+    assert Strolger(10, 10, 10).description() is not None
+
+
+def test_is_normalized():
+    dtd = Strolger(6000, 6000, -2)
+    sample_t = 6
+    dtd_point = dtd.at_time(sample_t)
+    assert dtd_point > 0
+    assert dtd_point == dtd.phi(sample_t) * dtd.normalization_rate()
+
+
+def test_normalization_rate_uses_hubble_efficiency():
+    dtd = Strolger(6000, 6000, -2)
+    assert dtd.normalization_rate() == 1.03e-3 / dtd.phi_integrated()
diff --git a/src/starmatrix/tests/test_dtds.py b/src/starmatrix/tests/test_dtds.py
index 25cf0fc..5e60cca 100644
--- a/src/starmatrix/tests/test_dtds.py
+++ b/src/starmatrix/tests/test_dtds.py
@@ -14,6 +14,7 @@ from starmatrix.dtds import dtd_wide_dd_1
 from starmatrix.dtds import dtd_sd_chandra
 from starmatrix.dtds import dtd_sd_subchandra
 from starmatrix.dtds import dtd_chen
+from starmatrix.dtds import dtds_strolger
 
 
 @pytest.fixture
@@ -31,10 +32,13 @@ def test_dtds_presence(available_dtds):
 
 def test_select_dtd(available_dtds):
     dtds = [dtd_ruiz_lapuente, dtd_maoz_graur, dtd_castrillo, dtd_greggio, dtd_chen,
-            dtd_close_dd_04, dtd_close_dd_1, dtd_wide_dd_04, dtd_wide_dd_1, dtd_sd_chandra, dtd_sd_subchandra]
+            dtd_close_dd_04, dtd_close_dd_1, dtd_wide_dd_04, dtd_wide_dd_1, dtd_sd_chandra, dtd_sd_subchandra,
+            dtds_strolger["fit_1"], dtds_strolger["fit_2"], dtds_strolger["fit_3"], dtds_strolger["fit_4"], dtds_strolger["optimized"]]
+
+    assert len(available_dtds) == len(dtds)
 
     for i in range(len(available_dtds)):
-        times = [0, 0.001, 0.04, 0.1, 0.4, 2, 9.] + list(np.random.rand(5)) + list(np.random.rand(5) * 9)
+        times = [0, 0.001, 0.04, 0.1, 0.4, 1, 2, 9.] + list(np.random.rand(5)) + list(np.random.rand(5) * 9)
         for time in times:
             assert select_dtd(available_dtds[i])(time) == dtds[i](time)
 

Add Strolger's phi
In `Strolger et al, ApJ, 2020, 890, 2` there is a Phi function used to fit Delay Time Distributions by parameter optimization.
![Strolger](https://user-images.githubusercontent.com/6528/125192595-f15f2800-e248-11eb-9c24-59140d0e7d93.png)

Task: Add Phi with different parameter options to Starmatrix: the 4 fits for binary population synthesis analyses for SD scenarios, and the optimized solution.
![fits](https://user-images.githubusercontent.com/6528/125192551-c379e380-e248-11eb-8f08-474b9f74b741.png)
![params](https://user-images.githubusercontent.com/6528/125192586-e5736600-e248-11eb-8f7b-a4a89e7c8e68.png)




src/starmatrix/tests/dtds/test_strolger.py::test_parameters_initialization src/starmatrix/tests/dtds/test_strolger.py::test_has_description src/starmatrix/tests/dtds/test_strolger.py::test_is_normalized src/starmatrix/tests/dtds/test_strolger.py::test_normalization_rate_uses_hubble_efficiency src/starmatrix/tests/test_dtds.py::test_dtds_presence src/starmatrix/tests/test_dtds.py::test_select_dtd src/starmatrix/tests/test_dtds.py::test_no_negative_time_values src/starmatrix/tests/test_dtds.py::test_dtd_correction_factor